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Perhaps it is inevitable, but the addition of explanatory text to this disambiguation page is beginning to change it into an unnecessary and redundant re-incarnation of the old "Energy" article (before it was subdivided). Is that really what you guys want? Let us remove the overview text and keep this just a list of pointers! JRSpriggs 08:00, 5 May 2007 (UTC)
Why do we need an intermediate length article on "real" energy? Because there needs to be some introductory article to the transformations of that sort of energy which is quantified in joules, whether in the natural or biological sciences or in technology. There's a certain sweeping story of how that kind of energy makes the universe work, which has really (by now) been totally butchered and distributed among subarticles, on energy in the sciences and technologies. So the story is really gone. If you want to read about how initial Big Bang energy, together with newly created space and quantum states to expand into, makes the universe run-- i.e., how the low entropy energy showed up at universe creation, and it is even now stored and filtered and suddenly released to give us all the phenomena that makes stuff "go," even now-- THEN you have to read all those subarticles. Too long. But now, there's no other choice. S B H arris 20:13, 9 May 2007 (UTC)
I just clicked on this page and found it with one sentence, so I wrote a quick history overview, without first looking at the talk page or knowing that it was a disambig. Anyway, the history section gives the reader a good springboard with which to dig into the numerous related links. -- Sadi Carnot 17:35, 19 May 2007 (UTC)
From the content forking page: "The generally accepted policy is that all facts and major Points of View on a certain subject should be treated in one article. Hence, whoever decided to change this page into a disambig was doing so in opposition to good encyclopedia writing protocol. Both Encarta and Britannica, for example, have overview articles on energy. Basically, we need to have at least the top 10 uses of the term "energy" defined on this page in the form of stubby header sections with "see main" links above each overview paragraph. The average reader isn't going to know how to wade through all the various links as they are now. -- Sadi Carnot 09:24, 20 May 2007 (UTC)
To Sadi Carnot: If you really think that this should be undone, I would suggest that the proper procedure would be to propose a merger of Energy (physics) back into Energy using the merger template. Otherwise, perhaps you should consider moving the history section which you created from this article to the Energy (physics) article or make it a separate article (if History of energy does not already exist) and link to it from here. JRSpriggs 08:22, 23 May 2007 (UTC)
All the other aspects of the scientific view of energy which once formed part of a great article ( See the last combined version) are now languishing in orphaned and almost meaningless isolation ( See Energy (Earth science) as an example. We need to bring them back together into one article , something under a name like Energy (science) , or Energy in science. We don’t want to perpetuate the idea that they are somehow different things. - Lumos3 23:15, 25 May 2007 (UTC)
I heartily support this perspective. But here's a question. Don't all the other sciences' concept of energy resolve to the physics concept? And thus shouldn't the unifying article be Energy (physics)? And how would this article differ from the Energy article prior to the "grand redesign" commenced by Hallenrm circa May 1, 2007? Robert K S 10:35, 5 June 2007 (UTC)
Just to forewarn everybody on this page, I plan on doing a full-rewrite on this page, so that Wikipedia as a decent approximately 32kb article on energy, on all the main topics, not just energy (physics). I will write it similar in style (header and section-size wise) to that of the thermodynamics article, which is the science of energy transformations. I’m short on time presently, but unless someone else does for me, I will then do it. I would appreciate outline suggestions below. I hope we can all work together on this. Thanks: -- Sadi Carnot 17:20, 9 June 2007 (UTC)
Looking at the above discussion, I can see that the physicists editors on the wikipedia, atleast the people participating in the above discussion are really paranoid? After all, what are they grudging about when they indeed have a full article dealing with energy in physics. I think, I have an answer, they want to dominate any article on energy, and that is the reason why scientist editors of other desciplines seldom contributed to the other article, because the number of physicists editors outnumber and try to dominate. The main advantage of the present form of energy page, is that it gives space to all sectore of human endaveour that deals with energy. Can, dear Sadi Carnot ever cover all these aspects in a single article of 32k. Let him. come up with an article that gets critical acclaim from all the scientist editors, and not just the disgrunted few who participated in the above discussion, only then hi should try to change the present format Hallenrm
Why are there two disambig pages, Energy and Energy (disambiguation). And why isn't the article Energy (physics) not here, as it would be in any real encyclopedia? -- Pjacobi
Yes, JH you are missing the big picture. Hallen has pawned off a lot of material to subpages, e.g. energy (physics), energy (biology) (the correct article is biological thermodynamics (which I wrote)), energy (chemistry) (the correct article is chemical thermodynamics (which I wrote)), energy (earth science) (the correct article would be geological thermodynamics (which I own two textbooks on)), etc. Basically, the whole thing is a big mess and is going to require more than a simple merge tag. Thanks for the words of encouragement. Talk soon: -- Sadi Carnot 01:23, 12 June 2007 (UTC)
Hallenrm, I see that you are the one who is causing all the problems here. I suggest you take a Wikibreak, for at least two weeks, from editing. Come back with a clear head and then work with us. Again this is a community project. Talk soon: -- Sadi Carnot 00:08, 12 June 2007 (UTC)
I still won't be able to do a full dig into the article for a bit, but in the mean time maybe we can vote on a good intro pic to use for the new article to represent all the related energy articles equally? Please visit: Wikipedia:Commons or upload a free-content image if you have one. I have put the previous gallery on a sub-page ( Talk:Energy/Photo-gallery) for the moment. -- Sadi Carnot 08:26, 12 June 2007 (UTC)
I suggest we come up with and agree on a proposal for the structure for all of the Energy articles. Get a consensus and then implement it.
Comments please. Lumos3 08:29, 12 June 2007 (UTC)
The info box next to http://en.wikipedia.org/wiki/Energy#Energy_and_the_laws_of_motion needs to be removed. It shows a picture of force being the derivative of momentum. These two quantities are completely different than energy, and referencing a completely different physics concept without explanation is misleading to someone trying to understand energy in classical mechanics.
I would remove it myself, but my lack of editing skills might result in some other part of the article being damaged.
I agree, I was just studying and noticed this error. Specifically I was looking for the difference between work, energy and momentum, this just confused everything! —Preceding
unsigned comment added by
142.244.161.13 (
talk)
18:31, 7 December 2008 (UTC)
Just a question that arose when reading about meteorological phenomena: what about ocean currents? For your reference:
(...)meteorological phenomena like wind, rain, hail, snow, lightning, tornadoes and hurricanes, are all a result of energy transformations brought about by solar energy on the planet Earth.
I realized that ocean currents are mainly caused by the gravity of the moon, as well as solar heating, and winds. The latter two of them are a result of solar energy, but moon gravity is not solar energy...
Ocean currents are not included in this article about energy, which is not directly the point here, but don't you think that many of those meteorological phenomena listed are caused by solar energy as well as gravity forces from the moon? Or is the moon not an energy source on earth like the sun is? The ocean currents caused by it can generate electricity as is done in the Norwegian fjords...
However, I can't see how this would work mechanically. I mean, the moon pulls on the water masses and causes the water to rise where the earth surface faces the moon, as well as on the opposite side, while the earth surfaces moves underneath the water mass. The resulting water currents would slow down the rotation of the earth, wouldn't they? And then
I found this page helpful about moon gravity: http://howthingswork.virginia.edu/print.php?title=The%20Sea%20and%20Surfing&startdate=0&enddate=99999999&topic=the%20sea%20and%20surfing
I hope this is not too much off-topic :-) -- Lindenlion ( talk) 08:23, 28 November 2007 (UTC)
A user has asked at an administrative noticeboard if this page belongs here or at the original location Energy. The content that it currently at the page called Energy should be merged into the page Energy (disambiguation); the final location of that page also needs to be discussed. What opinions do others have about the correct names for these pages? CMummert · talk 13:41, 1 May 2007 (UTC)
Not many people have commented here, but of those who have, only Charlie (Hallenrm) seems to favor the new arrangement, which has separate pages for energy in physics, chemistry, biology, etc. Others have said there's only one concept of energy being discussed in those fields, that all the pages except Energy (physics) are just stubs, and that there are already pages which address the applications of energy that are relevant to each field (e.g., biological thermodynamics). Charlie has said he hopes pages like Energy (Chemistry) will grow now that they've been created. Gnixon 16:42, 9 May 2007 (UTC)
Charlie, since you seem to be in the minority, maybe you could take some space here to lay out your arguments for the changes in a clear, concise way. So far it looks like people prefer the old way, but maybe there's some point that hasn't been appreciated. Gnixon 16:42, 9 May 2007 (UTC)
I would like to propose that a section about Energy Problems, is created to discuss issues about Global Warming, oil depletion,etc. we can not go on pretending those issues do not exist.
I have sent the following text, to Hillary Clinton,and would like to know your opinion.
Proposal about Public Policies. THEME: Energy.
The world requires, under the leadership of the U.S.A. a reform in energy policies:
The world needs, new Energy policies, based in energies that do not pollute, and do not create increases in the prices of corn or sugar (bio-fuels) for the poor people of the world, considering that bio-fuels do contain Carbon and therefore still generate CO2.
The only energy that does not pollute is Hydrogen (produced by algae), or hydraulic plants (like Hoover Dam), solar, wind, sea waves, geothermic, etc.
Nuclear energy is dangerous,as seen in history.
It is necessary that the rich countries, promote the creation of Alternative Energy Research Institutes, to research and promote solutions.
Mexico, Aguascalientes, Dagoflores -- 189.166.5.98 ( talk) 03:21, 3 April 2008 (UTC)
OK I understand Sadi Carnot's proposal is something like this. Lumos3 09:18, 12 June 2007 (UTC)
I suggest that as many editors as possible agree to this by stating so below or give counter proposals. Lumos3 10:12, 12 June 2007 (UTC)
Hallen states:
i would grant that he is a genius, but I will wait till he accomkplishes the task successfully, and applies himself to the task seriously rather than just giving warnings that have ni meaning, by the very nature of wikipedia.
COMMENT: People are banned all the time from article when they are insulting or nonconstructive. And I don't just mean sarcastically naming somebody a genius, as Hallen does, above. In the short time (since May 1) that this article has been in its present form, Hallen has left at least one insulting edit summary in the main article: [2] ("edits by sadi Carnot seem to lead nowhere except grunting in frustration") And not less than 3 insulting comments in the TALK section. [3] (Editors are lazy) [4] (Editors are paranoid) [5] (Two editors can hardly write sensible lines)
Nor is this odd behavior for him. There are a huge number of examples from Hallen's posts of this nature going back for more than a year, for he's insulted dozens of people, some many times. I'm quite capable of going back, collecting them all, and laying them before ArbCom. It surely will get Hallen banned in some way, because that is NOT how Wikipedia works. I hope I don't have to do this, as I don't want to do the work. And Hallen won't like the result if I do have to do it. But I will do it, if this behavior doesn't change. I hereby promise it. S B H arris 20:10, 12 June 2007 (UTC)
This is not the proper place to decide whether to ban a user, that's what Wikipedia:Requests for arbitration and other similar channels are for. -- Itub 07:49, 13 June 2007 (UTC)
Energy should be an article about energy in the sciences. A summary mention of industrial energy conversion would be fine too. E.g. da:Energi and es:Energía look OK, de:Energie generally speaking also, but it has grown a bit messy. I assume they all derive from a rather old version of the English article. -- Pjacobi 16:42, 12 June 2007 (UTC)
There seems to be momentum in the consensus (8-to-1); hence, for the moment, I’ll start a working subpage here: Talk:Energy/Energy (template). Although, it will still take me another week or two to really dig in. In any event, I welcome contributions on the working sub-page. As soon as I get a free day, I’ll pull the whole thing together nicely. Thanks for all the comments thus far. -- Sadi Carnot 01:00, 13 June 2007 (UTC)
The first paragraph says energy 'is not an object or a substance, but it is quantifiable in a way such that it cannot be created or destroyed.', but energy can be created as in nuclear energy.-- Jcvamp 02:51, 13 June 2007 (UTC)
I've not really sure what article on nuclear energy you're talking about-- if it's the one I've linked in this line, then it really says mass is converted to energy. But that's not really true. As has been argued here long and hard, in a chemical or nuclear reaction, the mass does not change until you let some of it out of the system (non-closed system). So there is no "conversion," just a release, like soda out of a soda bottle. What does happen is that one kind of energy is converted to another--- in both chem and nuclear reactions, potential energy locked up in fields is converted to "heat", which means (among other things) into kinetic energy of particles, and electromagnetic energy (various kinds of "light"). But when a chem reaction happens or even a nuclear bomb goes off, if the system is closed (hard to do with a nuke) the total energy doesn't change, either.
Is energy the capacity to do work? No, not when the energy is in the form of heat, in which case some of it is unavailable. So that definition is tempting, but wrong. Also, conservation of baryon number (which holds for most circumstances, though maybe not in in the Big Bang or in black hole evaporation) means that the energy a lot of the ordinary matter we're used to, which is made of protons and neutrons, it not available to do work. It just sits there, and you can't get it out. But we know it's in there, because if you have antiprotons or antineutrons, you can turn it into work. You just can't get antiprotons or antineutrons without making them, and that takes...... more work. So it's a good demo, but it means in practice that the energy is unavailable except as a demo. See the point? Anyway, this is not an easy topic, for the reason we're now discussing. All the easy and fascile ways to discuss energy are technically wrong. The ways which at least are not wrong, start out almost immediately as being somewhat technical (inertial observer? What's that?). But you have to know what an inertial observer is, even to define the kinetic energy of a baseball. So it's important even for simple problems. Where is the kinetic energy of a moving bullet "stored"? Answer: nowhere. It's a system property. It's like going into the brain and asking where is the personality-- point to it. Or going to Washington, DC and asking to see the "government". Where is the government LOCATED? Well, that's hard to say. That's not to say it has no reality. S B H arris 06:08, 13 June 2007 (UTC)
Sorry for not knowing too much on the subject, but I'm interested and I'd like to understand. So, you're basically saying that the energy is stored in the particles? Does that mean that, for example, in a fire, the thermal and light energy are being released from the particles of the fuel.
Also, if the energy is stored in the particles, what is it doing in the mean time? If it's inactive, does that put it on the same level as stuff like 'potential gravitational energy'? (oops forgot to sign)-- Jcvamp 00:58, 14 June 2007 (UTC)
I'm only fifteen years old, but we just learned about energy at school, I thought the sun created energy by fusion, or does the sun get the energy it sends to the earth from somewhere else? —Preceding unsigned comment added by 84.48.17.134 ( talk) 18:10, 26 September 2007 (UTC)
The history of the Energy pseudo-disambiguation page was lost in the (correct, I believe) move of Energy (physics) to the plain title. However, the contents of that page were needed for a merge into Energy (disambiguation), and since it will be part of a merge, it will be necessary to keep the page history under the GFDL. I'll be working for the next little while to sort out and restore the histories, and for a little bit it will appear that I'm undoing the move. The contents of the physics page will be back here again soon, so don't worry about it. I'm going to move the history of the old pseudo-disambiguation page to Energy (Disambiguation) (sic) and adding a mergeto tag to funnel the necessary contents to Energy (disambiguation). Please help out by merging entries and finally redirecting the page if you have the time. Dekimasu よ! 23:45, 13 June 2007 (UTC)
I see that there has been a serious attempt by SBHarris ans KSRoberts to undo all my edits on this page. I saw some merit in the way Sadi wanted to acheive a reformatting, but it appaears Roberts and Harris can't just wait to acheive their sole ambition in life Hallenrm 04:08, 14 June 2007 (UTC)
As edits can vary greatly in size and quality, it is important not to put too much weight into someone's edit count, and to avoid worrying too much about one's own edit count. Edit counts do not necessarily reflect the value of a user's contributions to the Wikipedia project. As the saying goes, "Quality, not quantity". Hallenrm 07:46, 17 June 2007 (UTC)
Furthermore, eight editors here disagree with your handing of this page (nine if you count Laura Scudder, who has made her opinion plain) and you can't get a single vote to support your point of view. Thus, it appears that in spite of the time you put in, the "quality" of your approach isn't apparent to any of the other people working here-- It's not just Robert and me who don't like what you did here. None of us do. S B H arris 07:51, 18 June 2007 (UTC)
Two quick things--(1) Was it not helpful to give the word's etymology right up front? Is there any reason it shouldn't be restored? (2) Is it helpful to include the qualifier "characteristic of the universe" in the definition of energy? Is there any non-theoretical-mathematical topic on Wikipedia that isn't "of the universe"? Does it impart useful information? Is there any reason "characteristic of the universe" shouldn't be deleted? Robert K S 19:32, 14 June 2007 (UTC)
See Wikipedia:Articles for deletion/Energy (chemistry). -- Itub 07:49, 20 June 2007 (UTC)
(I also nominated Energy (biology), Energy (cosmology), and Energy (earth science). -- Itub 08:18, 20 June 2007 (UTC))
The sentence: "Yet, energy is not simply a mathematical concept or a philosophical principle: it is a measurable quantity with definite properties." contradicts with Richard Feynman's statement few paragraphs below: "...That is a most abstract idea, because it is a mathematical principle; ... It is not a description of a mechanism, or anything concrete; it is just a strange fact..." What is the property of energy anyway? Also, what's the conclusion to this statement: "It was argued for some years whether energy was a substance (the caloric) or merely a physical quantity, such as momentum." So, is energy a substance or a physical quantity?
I really think that the section reading "electrical energy" should read "electromagnetic energy". Why? It includes magnetism and electromagnetic radiation inside it. We should just place the whole main part of the section "Electrical Energy", ehich is devoted to electricity, inside "electromagnetic energy", which would have subsections of "electrical energy", "magnetism", and "electromagnetic radiation" after an introuction listing the three subdivisions of this type of energy. Leaving it like this makes it look as though electricity is the phenomenon causing light and magetism, while, in fact, they are all just forms of Electromagnetic Energy. I really want some consensus before I make this change, so please state your opinions. Slartibartfast1992 15:44, 22 June 2007 (UTC)
Wow, I can't believe how many opinions I'm getting... Did somebody establish censorship? Slartibartfast1992 03:50, 14 July 2007 (UTC)
Is not the work one system can do on another, for only a fraction of heat energy in a system can be used to perform work in another, yet 100% of heat is energy. Thus, some heat energy does not fit this definition. Hence the definition is incorrect. Hence, Robert and I and multiple others have deleted it. Find another one. S B H arris 21:13, 22 June 2007 (UTC)
You'll note that none of this helps E-dude's proposed definition, since his definitional work is not a state function either (since it too, is not conserved) and the total energy in a object is obviously far more than the work it can do on other systems, unless you have a perfect heat-->work conversion machine, and also have a way to convert all the rest mass of an object at absolute zero, into work, too. You could maybe do that with a black hole, but then you have to get it into the other system as some kind of heat, and then you have the heat->work problem again.
I actually like Physchim62 (talk)'s proposal that we just define the energy of a system as the sum of all other other energies that go into it, that we can think of: rest energy of components, minus their bonding energy, plus the heat (and/or work) necessary to get it up to its temperature T and its volume V at its pressure P, and so on. That all turns out to be something like: enthalpy plus component rest energies minus component binding energies. Unless I've forgotten something. S B H arris 21:03, 24 June 2007 (UTC)
BTW, it seems to me that there are two kinds of differences between "real" and "theoretical" models. Some involve "infinitely long wires" or "perfectly strong spheres" or "infinitely long-lived astronauts". These gedanken changes tend to be OK because they can be approached as limits in the real world, and in theory all of them could be approached as closely as you like. It's quite a different thing, however, to simply toss out a major law of physics, and a relevant one, like the second law when talking about the first. Which is what we're talking about here. That's sort of like a gedanken in relativity, in which "we assume for the sake of this problem that the speed of light is infinite...." S B H arris 20:31, 23 June 2007 (UTC)
Even if protons evaporate, they evaporate into positrons and neutrinos, so after the positrons annihiliate with the electrons, you're still stuck with the neutinos, which do have some rest mass (when you say "all, or almost all," you know full well that it's "almost all"). And even when you annihiliate protons with antiprotons, the products are usually pi-mesons, which eventually decay back down to neutrinos and antineutrinos and photons. If there were enough antiparticles to let the leptons anihilate, you'd still get a universe full of photons and neutrinos. Thus, still one where you have neutrino rest mass that you can't get at. Can't convert your mu-neutrinos into e-neutrinos without neutrino oscillation, and you can't have that without neutrino rest mass. Can't have this both ways. Can't turn that last rest mass into work.
Of course you will have read Dyson's cosmology about what happens eventually, in that kind of universe (we're ignoring dark energy for now). Even black holes don't actually let you turn neutrinos into useful work. When a black hole evaporates, it evaporates into "heat" (a mix of paricles with higher entropy, by a small factor like 4/3rds, than the black hole of the same mass had-- see Beckenstein for details). First out comes gravity waves, then black body photons, then the first neutrinos, then (as it gets hotter) finally leptons and then hadrons and finally a flash where you get whole atoms and finally even old TV sets emitted. But that energy expands, dissipates, all the hadrons decay, and finally you're back down to photons and neutrinos at constant "temperature." Same energy, no way for life to get any useful work out of it, even if it did get a bit out of that last flash (and maybe watched a little TV).
As temperature falls and the universe expands, life will be faced with lower and lower black body radiation, and fewer and fewer pockets of space to dump it into, after making black holes for local fires. So life will have to slow down and slow down even more, in metabolism, to keep up the thinking processes. Add dark energy and the future isn't even that nice: the universe expands ever faster as it gets bigger. Finally you only have one last black hole for company. When it's gone, every neutrino sees the horizon expand, until all the photons are gone, and all other particles are outside its light-cone. So finally, each neutrino is all alone in the dark, without even a single photon for company.
What are you going to name that lone neutrino in your rest frame, E-dude? If it won't do any work for you, are you going to send it a pink slip? S B H arris 09:38, 27 June 2007 (UTC)
If we were free to pick our own definition (rather than finding one in a reference), I would go back to the history of energy for guidance. If I understand it correctly, energy was first recognized as a non-directional quantitative attribute of motion (i.e. classical kinetic energy) which tends to remain the same. From there it was expanded to include more and more forms of energy which were needed to maintain the conservation of energy. So I would define energy as the conserved quantity which includes classical kinetic energy . Right? JRSpriggs 06:17, 25 June 2007 (UTC)
1. How do I derive units of energy? As (total mass)/c^2. See Einstein or SR article for derivation of E = mc^2.
3. How do I derive kinetic energy? When I need to, system overall kinetic energy is (again) KE = (γ-1) * M where M is system rest mass, and the v in γ is the system center-of-mass velocity.
I'd much rather have a definition starting from than trying to cram relativity, cosmology, and particle physics in the first sentence of this article. Let's start from kinetic energy and relate that to potential energy and work before getting into modern physics. -- Itub 10:09, 27 June 2007 (UTC)
(added additional header above because this discussion is getting very long) Physchim62 (talk) 13:26, 28 June 2007 (UTC)
We should be writing the Energy intro so that it is generally true and has broad consensus. If that means eliminating some or other textbook definition because it does not apply in all cases, then that's what it takes: Wikipedia guidelines for leads ( WP:LEAD) state that significant controversies should be addressed in leads for a long article. Is definition of energy as the ability to do work a real and sourcable controversy? That's the important question that hassn't being addressed in this dicussion yet. Robert K S 23:49, 27 June 2007 (UTC)
There is indeed controversy over the definition of energy. Eugene Hecht wrote an article in the February 2007 issue of The Physics Teacher which stated that there is not a good definition of energy. It should be noted that Hecht is an author of a respected introductory physics text. See http://www.usna.edu/Users/physics/mungan/Publications/TPT13.pdf
These notions of potential and kinetic energy depend on a notion of length scale. For example, one can speak of macroscopic potential and kinetic energy, which do not include thermal potential and kinetic energy. Also what is called chemical potential energy (below) is a macroscopic notion, and closer examination shows that it is really the sum of the potential and kinetic energy on the atomic and subatomic scale. Similar remarks apply to nuclear "potential" energy and most other forms of energy. This dependence on length scale is non-problematic if the various length scales are decoupled, as is often the case ... but confusion can arise when different length scales are coupled, for instance when friction converts macroscopic work into microscopic thermal energy.
I have always thought of energy as a 'concept that is used to describe
change'. I do not see what is wrong with this simple explanation. Just to cite one textbook that uses this definition Lofts, G (2004). Jacaranda Physics 1.
ISBN
0 7016 3777 3. {{
cite book}}
: Unknown parameter |coauthors=
ignored (|author=
suggested) (
help). The change article needs a bit of work though. Thanks,
Monkeyblu
e
10:57, 29 June 2007 (UTC)
Yes, I know the last way is the way it's often done in popular explanations, and indeed is the way it's done in the Wikipedia article on the subject also. But don't mistake easy derivation for historical physics. Again, if you think that E = mc^2 for rest energy comes out of a "by-product of calculation of relativistic work to accelerate given mass from one speed to another," you're sadly mistaken, and you must learn some real physcis history, not "nice-story" history. S B H arris 23:23, 30 June 2007 (UTC)
As the article stands now, the lead reads In physics and other sciences, energy (from the Greek ενεργός, energos, "active, working")[1] is a scalar physical quantity used to describe a conserved property of objects and systems of objects, which is associated with the rest mass of the object or system, as well as any overall velocity which the object or system may have. Energy may come in many different forms... Robert K S 12:06, 29 June 2007 (UTC)
ED's definition is consistent with both Brittanica:
and Marrion-Webster:
The current lead is not wrong, but (a) it's not the usual way to define energy, (b) the phrasing "scalar physical quantity" seems unnecessarily abstract and vague, and (c) there's no need to mention E=mc^2 here. I suspect this discussion could have been resolved long ago if everyone stayed calm and polite and relied on references (and nothing else), as suggested by Robert. Make sure any edits have correct grammar and spelling. Gnixon 22:50, 6 July 2007 (UTC)
Wow, this is a long page, and I do not claim to have read it all.
ANYWAYS... I feel that the article is SEVERELY lacking in a mathematical definition of energy, and...
If SBHarris, et. all. deleted it, I feel (personally), that they shouldn't have done that, because they didn't replace it with a new one. I feel that the article NEEDS a mathematical definition of Energy, if one CAN be obtained (besides the rather esoteric E=mc^2 (IS THAT THE oNLY ONE???) and besides "the potential to do work")). Plus, it seems there was some sort of mass misunderstanding on the part of SBHarris (sorry i like you Mr. Harris, but misunderstandings happen to everyone..) and the quoted "Roberts and multiple others" between "HEAT" and "Thermal Energy."
It *SEEMS* to me that they just misunderstood... and I WOULD LIKE TO KNOW!!!!
WHAT WAS THE "DEFINITION" THAT THEY DELETED????
and i'll just add that... i think it should be put back.
- BriEnBest ( talk) 03:06, 22 January 2008 (UTC)
I have revamped the introduction ( diff):
Thanks, Monkeyblu e 11:50, 25 June 2007 (UTC)
There seems to have been some kind of edit war brewing over the last weeks at the heat and thermal energy articles between several editors, primarily User:The Way, that caused User: ScienceApologist to quit Wikipedia. In any event, the situation still continues; please review Talk:Heat (disambiguation) and Talk:Heat and give your opinion or vote: here . -- Sadi Carnot 04:08, 2 July 2007 (UTC)
Is energy material??? - Pat Peter 16:49, 2 July 2007 (UTC)
Neither this page nor the Village Pump are the place to ask knowledge questions. This page is only for discussing changes to the article, and the Village Pump is for discussing changes to Wikipedia. If people have questions about the content of the article, the best thing would be to look through the talk page and article history for someone who appears to be knowledgeable, then ask them a question on their user talk page. I've tried answering PP's question on his talk page. Cheers. Gnixon 14:50, 3 July 2007 (UTC)
I'm a little hesitant to add this comment but less hesitant not to. Question: Is this controversy a matter of encyclopedia content or one of physics? If the former, let's just defer to the standard texts and physicists noting important discrepancies where they occur. If the latter (that is if there really is controversy and confusion over the very definition of energy in the physics community), then this in itself is significant and should be included in the entry. I am not convinced there is such a controversy in the physics community; however, all of this lengthy and involved discussion here by many seemingly informed people and the fact that some pretty basic issues (one on transfer, another having to do with work capacity, and still others) remain unresolved has left me in doubt.
Is there really no basic consensus among physicists? If so, then this is just the kind of thing I would expect to learn from a good encyclopedia entry. -- Jcblackmon 06:22, 25 July 2007 (UTC)
I didn't mean to start a philosophical debate here; my question is now dated. I was responding to the intense debate between editors way back then. The article now addresses my concerns. I like.-- Jcblackmon ( talk) 18:22, 27 November 2008 (UTC)
I invite other editors to decide for themselves whether any of the links reinserted by Vig vimarsh enhance the article. Cripes, the first one isn't what it claims to be at all, i.e. it is not a discussion among physicsts, rather it's just a general forum discussion and clearly not a reliable source. A poorly chosen or unnecessarily large selection of external links greatly detracts from the value of an article. My consideration for picking links to be removed was based on these guidelines. Tim Shuba 09:13, 25 July 2007 (UTC)
You have the following equation in the page
C6H12O6 + 3O2 → 6CO2 + 6H2O
The amount of oxygen on the two sides do not balance. Shouldnt it be
C6H12O6 + 6O2 → 6CO2 + 6H2O
Cs1kh —Preceding comment was added at 15:37, 3 December 2007 (UTC)
At the beginning of the third paragraph of the section History, I can hardly identify who was represented by the pronoun "He".
In the same paragraph: "He amalgamated all of these laws...", the laws involved are not previously listed.
Chiloa ( talk) 20:06, 6 December 2007 (UTC)
[[]]-- 209.158.139.250 ( talk) 19:30, 10 December 2007 (UTC)
is there a latin word that is equivalent to energy? if so, what is it? and is there something like "energology," the study of energy? thanks. BriEnBest ( talk) 02:25, 22 January 2008 (UTC)
would it be physics? or physikas? (or whatever the latin word is)??? BriEnBest ( talk) 06:56, 1 February 2008 (UTC)
It's definitely navitas Gheta ( talk) 19:06, 22 July 2009 (UTC)
I see that there's a bit of tendency to see energy as stored in chemical bonds: it isn't. You only get energy stored as rearrangment of bonds from weak to strong. Thus energy in food is not IN the food, but only in the combo of food+oxygen. Similarly, the bonds in ATP don't store energy-- it's stored in the reaction of ATP + water --> AMP plus hydrated PP. ATP breakdown in vacuum would require energy (as the breakage of all chemical bonds does).
I've added a little vingette emphasizing that all energy releases are releases of various potentials stored since the Big Bang. Give me any spontaneous process and in a couple of steps I can show you how that energy was stored as usuable potential, from conditions after the Big Bang. That's the whole point of heat death. I've also added a point from an argument I had here earlier, which is that if you insist on energy being defined as work one system does to another, then heat death demands energy in the universe goes to zero, over time. Say what? We thought energy was conserved! The work one system can do on another is the FREE energy, not the simple energy. S B H arris 03:42, 22 January 2008 (UTC)
I've posted a long question at Talk:Wind power#Lopsided coverage? asking how best to fit the concepts of "Electricty generation from Wind" and "Wind energy" together. In brief I would like suggestions on which should be the parent and which the sub-articles. I can work with either but have a preference for an organization that matches the way Portal:Energy structures solar and hydro power. Thanks. - Wikianon ( talk) 22:25, 27 January 2008 (UTC)
Can somebody plz send me a list of what energy/electricity can travel along? thanks Sylvan wu ( talk) 22:45, 11 February 2008 (UTC)
Some people discourage the use of the term 'relativistic mass'. If we use the term 'invariant mass' as the sole definition of mass, we can derive a formula that relates mass, speed and kinetic energy. In order to conserve momentum in special relativity, we discover the definition of momentum which is different from classical mechanics.
Where m denotes mass, denotes velocity, v denotes speed and c denotes the speed of light in vacuum.
Kinetic energy of a object with mass possesses is equal to the amount of work to be done on it to accelerate it from rest to its current speed.
Where E denotes kinetic energy, m denotes mass, denotes displacement ,c denotes the speed of light, denotes velocity, v denotes speed and denotes a constant to be determined. Since an object has zero kinetic energy when its speed is zero, so we deduce that
From the above derivations, besides getting the equation of kinetic energy, we cannot conclude that mass is a form of energy or see any hint on it. However, if we use the notion of 'relativistic mass', we can see a suggestion on the equivalence of mass and energy. The reason is as the following. We define momentum is a product of relativistic mass and velocity. (This is actually the original definition of inertial mass, see inertia) As such, we get the relationship between relativistic mass and the rest mass.
Where m denotes relativistic mass, denotes rest mass, denotes kinetic energy and v denotes speed. We can conclude that the change of kinetic energy is equal to the change of relativistic mass, or simply mass. This implies that rest mass may be just a form of energy. We can further analyze if mass is really identical to energy.
As shown above, Special Relativity allows the possibility of the equivalence of the mass and energy. It suggests that way. However, the relationship cannot be derived directly from Special Relativity. It does not give a strict proof on the equivalence of mass and energy. We only see the suggestion when we use 'relativistic mass'.
After getting the relationship between momentum of a photon, its frequency and its energy, the equivalence of mass and energy can be proven. (This relationship is proven by Compton Scattering Experiment and photoelectric effect)
Where E denotes energy, m denotes (relativistic) mass, denotes momentum, h denotes plank constant and c denotes the speed of light in vacuum. We consider a thought experiment to see if mass is really equivalent to energy. In COM frame, an object is said to be at rest. It emits two photons in opposite direction with the same magnitude of momentum. As required in conservation of momentum, the object will remain at rest after the emission of two photons in COM frame. If an observer moves in the same direction as one of the photon in COM frame, he will see these photons carry different magnitude of momentum. The magnitude of momentum observed b the observer can be computed by using relativistic Doppler effect. According to the observer, the object does not change its speed after the emission, the only way to reduce momentum is to reduce mass.
In conclusion, the equivalence of mass and energy can be seen as a suggestion of special relativity. We can't really derive it from special relativity directly. We get a very clear hint however. See also mass-energy equivalence Thljcl ( talk) 03:49, 20 May 2008 (UTC)
There has been much debate over whether the 'physical quantity' meaning of the word "energy" is truly the primary meaning; alternatives might be one of the others on Energy (disambiguation) or perhaps there is no primary meaning, simply several relatively equal-weight meanings. This debate is ongoing and is quite heated. It seems to me that this talk page is the correct place for this debate rather than the dab talk page or the various other talk pages onto which it has spilled. If you decide there is no real primary meaning then this page should be moved to Energy (physics), or similar, and Energy used as the disambiguation page. I have no axe to grind here but I would appreciate it if editors familar with the topic could comment here. Thanks. Abtract ( talk) 12:06, 27 May 2008 (UTC)
remind only i cannot be so happy energy is transformed to another,the total energy remains the same.... —Preceding unsigned comment added by 125.60.241.190 ( talk) 02:05, 27 August 2008 (UTC)
The source at http://www.serve.com/herrmann/einpdf.pdf does not seem peer-reviewed and print-published, but it is well researched and it is not polemic. I quote it in the article for the convenience of not searching the web for other sources. I somebody else finds a better source, he/she may replace that source, or simply add an extra source. Tgeorgescu ( talk) 21:41, 9 October 2008 (UTC)
Some of these relate to power generation, or even tourism in sunny climates, rather than the subject of this article and are to a greater or lesser degree WP:SPAM. I'm suggesting that it's time for another modest clearout. -- Old Moonraker ( talk) 11:43, 23 January 2009 (UTC)
This article is about energy as a physical phenomenon. Americans for Balanced Energy Choices is an interest group for the coal industry. While it is true that they advocate the conversion of chemical energy into mechanical energy, their organization and mission is completely irrelevant to someone who would like to learn more about what energy is and how it works. Just to be absolutely clear, I am not removing the link because of the substance of their mission, but simply because their mission is irrelevant to the substance of the Energy article. -- 70.108.40.152 ( talk) 19:46, 16 February 2009 (UTC)
there is no such thing as 'magnetic energy', as Magnetism is not energy but is actually a push or a pull, and this makes magnetism a force. Energy can be converted from one form to another, but that is not the case with magnetism, or 'magnetic energy'.-- S9718483fb ( talk) 13:59, 10 March 2009 (UTC) —Preceding unsigned comment added by S9718483fb ( talk • contribs) 13:51, 10 March 2009 (UTC)
Either the work page or this should change definitions in the introductions. As it is, a curious individual, or perplexed student, comes to the energy page to see the definition of energy: Energy is a scalar physical quantity that describes the amount of work that can be performed by a force. Fair enough, so the inquisitive student will ask..."hmm, what's work?" being wikipedia one can conveniently click on the link, unfortunately one finds in the introduction: mechanical work is the amount of energy transferred by a force acting through a distance. It may make sense in the equations, but verbally it seems circular. 76.175.72.51 ( talk) 04:22, 18 October 2009 (UTC)
"Different forms of energy include kinetic, potential, thermal, gravitational, sound, elastic, light, and electromagnetic energy." Small correction: Light and electromagnetic energy are the same. —Preceding unsigned comment added by 86.176.242.199 ( talk) 13:25, 2 March 2010 (UTC)
I took out this table as potentially misleading. A form of energy doesn't have a magnitude. I guess it could be called "magnitudes of coefficients of equations for energy", but that doesn't seem like a meaningful or useful comparison. We already have the article Orders of magnitude (energy). -- Suffusion of Yellow ( talk) 08:24, 22 October 2009 (UTC)
This article begins In physics, energy is a scalar physical quantity that describes the amount of work that can be performed by a force. On 21 April 2009
User:Wisnuops (
talk) added the following comment:
(note: this is not the best definition. The word
work is also defined by referring to energy. It creates a
circular definition).
I have deleted the note from the article and transferred it here. It may stimulate debate. Dolphin51 ( talk) 03:58, 22 April 2009 (UTC)
At the beginning definition it mentions forms of energy and lists Kinetic, Potential, Light, Elastic, Electromagnetic etc. Isn't Light already Electromagnetic Energy via the Visible Light part of the spectrum? If so this is redundant. Gheta ( talk) 19:10, 22 July 2009 (UTC)
Currently the first sentence no longer has a reference to work. Though this avoids the circular definitions of energy and work, it leaves us with energy defined simply as "a quantity that can be assigned to every particle, object, and system of objects as a consequence of the state of that particle, object or system of objects". This definition doesn't seem satisfying. Does it distinguish energy from other state functions such as entropy? I'm not really convinced that the following two statements constitute a circular definition rather than merely reflecting the fact that energy and work are intertwined: Energy is the amount of work that can be performed by a force. Energy is transferred when work is performed. —Preceding unsigned comment added by Davidr222 ( talk • contribs) 18:54, 14 April 2010 (UTC)
If scalar means single dimensional Energy is not a single dimensional quantity. It is related as to how a quantity of matter is or potentially can be be made to be moved a certain spacial volume quantity within an interval of time. When the time period is over, a quantity of action will have occurred, involved with the matter's having been converted to the same quantity of a new kind of action. If the process is inefficient waste values of lost action will be created and lost, and the quantity of available future action is reduced. So Energy is action per unit time interval and action is Energy times time. So when you carry things upstairs to store in the attic, you're doing a lot of work without being able to regain any of the potential action contained in the stored materials due to their higher gravitational location. WFPM ( talk) 04:38, 15 April 2010 (UTC)
Coming up with a simple definition of "energy" is not possible, but I admire the author for trying. I agree with Davidr222 completely. The statement that energy is a quantity that can be "assigned" to various examples of matter is not helpful and does not make sense if you think about it. "Quantity" refers to a value that is used to describe the amount energy. The energy is not the quantity, just like me standing on the scales is not the weight. I also do not understand what "assigned" means in the context of the definition. Assigned is passive, meaning somebody has to do the assigning. But the energy is present regardless of any assigning body or person. So I don't think one can defend the statement that energy is " a quantity that can be assigned." BabelBoy ( talk) 01:30, 25 April 2010 (UTC)
Sorry to be so bothersome, but I am also having problems with this statement:
"As an example, when oil is reacted with oxygen, potential energy is released, since new chemical bonds are formed in the products which are more powerful than those in the oil and oxygen. "
First, grammatically, it should read either: ". . .products, which are more powerful. . ." (note the comma) or ". . .products that are more powerful. . ." They are two entirely different statements. In the original we can't tell whether it is the bonds or the products that are more powerful.
My second problem is I have no idea what the sentence is saying. "Oil" is awfully vague. Does the author mean hydro-carbons? The product of the sebaceous glands? Baby oil? Shouldn't "oil" be linked to the Wiki article "Oil?" Also, what is meant by "more powerful"? Contains more energy? But that's what we're defining.
Third, the phrase "potential energy is released" is set off by commas, which really distorts something. Is the author trying to say that the release of potential energy [whatever that means] is a consequence of reacting oil and oxygen? BabelBoy ( talk) 01:51, 25 April 2010 (UTC)
This sentence from the intro:
is, in my opinion, poorly worded - even if it is technically true that each of those words can describe some form of energy. Kinetic and potential are a totally separate categorization of energy - in its current shape, the sentence can easily convince someone that thermal is something completely different from kinetic. Or, taken with the next sentence The forms of energy are often named after a related force., it could be taken to suggest that some sort of a "kinetic force" exists.
I suggest we remove the 'kinetic' and 'potential' words from that particular sentence - if we want to have a reference to them in the intro, we can add a sentence along the lines of 'Energy is often split into kinetic and potential' Ivancho.was.here ( talk) 03:34, 11 December 2009 (UTC)
Kinetic and potential could be Mechanical. Grvitational could be removed, since gravity is a force and I'm pretty certain that it's called potential gravitational. Busha5a5a5 ( talk) 18:18, 15 February 2010 (UTC)
I suggest that semantically, the word energy can have a purely abstract non-physical meaning, as "something that moves" (something else or itself), in any kind of reference system.
For example, one could say that there are "energies" in the psyche, in the sense that there are psychological motives or mechanisms that activate/move the psyche in a certain direction, or which inhibit and block certain other tendencies in the psyche.
There is no reason why the notion of energy should be the exclusive property of physical sciences. The purely abstract use of that word in any kind of reference system is perfectly legitimate. —Preceding unsigned comment added by 161.53.149.242 ( talk) 15:36, 19 January 2010 (UTC)
I'm guessing you're answering me, so I am ranting about the use of the word Energy as a play on words. That's because Energy is connoted as being the result of an activity of matter or pseudomatter by causative factors and therefor is a resultave condition of the matter or pseudomatter. It doesn't cause anything in physics concepts, except for some activity to be initiated as the result of the accumulation of enough action to permit it. So matter (or pseudomatter) cannot receive energy and accumulate action and have something happen unless causative factors are considered. Thus the arguments about nuclear decay processes and chemical processes and Enzyme activity etc etc. In short I'm trying to keep the logic of cause and effect straight about the use of the word Energy. WFPM ( talk) 19:15, 15 April 2010 (UTC)
Well before Newton it was speculated the force was required to keep things moving. But He invented the idea that if the thing had energy or really action, it would keep moving on its own. But it still wasn't a separate thing from the involved matter but rather a physical motion property that the thing had acquired relative to space and time. So it's hard to dream up a concept of Energy apart from matter, or that it can do anything other than influence matter by its level of Energy delivery capability. WFPM ( talk) 21:12, 15 April 2010 (UTC)
And I appreciate your information about metaphors. But like Art Ls Pella said about stock trading, Understanding the words of science is serious business and it's getting harder and harder to rationalize and understand the complex details. And I'll bet that a PC using Boolean logic and algebra will never get it figured out. WFPM ( talk) 21:30, 15 April 2010 (UTC)
Does anyone object to me setting up automatic archiving for this page using MiszaBot? Unless otherwise agreed, I would set it to archive threads that have been inactive for 30 days and keep ten threads.-- Oneiros ( talk) 13:45, 24 January 2010 (UTC)
That reminds me that Dr Pauling commented about his arriving at opinions about chemical and other subject matters that "I think about things a lot!" So I admire your concise editorial capability to tell a computer program about how to judge the editorial importance of what it needs to keep printing about a subject matter. WFPM ( talk) 02:34, 16 April 2010 (UTC)
What is energy? —Preceding unsigned comment added by 218.103.199.177 ( talk) 14:32, 28 January 2010 (UTC)
Energy in itself is non-existing as explained by Richard Feynman in his Dennis the Menace blocks lecture; "There are no blocks!". Energy is born into existence once manifestated in a certain form, hence "different forms of energy". The law of conservation of energy does not formulate energy but is a law which relates to other theories in physics that do give a formulation of energy, hence the law of conservation of energy is a metatheoretical law. -- Knoxjohnson ( talk) 12:32, 21 March 2010 (UTC)
Energy is a 3 dimensional entity measurement of the relative magnitude of importance of the activity of matter within the spacetime continuum. In the dynamic sense, the measurement relates to the rate of displacement of the matter within the (3 dimensional) space continuum. In the static case the magnitude is predetermined by mathematical predictive calculations. One of the magnitude's dimensions is related to it's mass value, and the other two to a two dimensional value that is related to the volume of spacial displacement of the matter per unit of spacial distance. The equality equation for energy is therefor E is proportional to the mass value times S cubed divided by S. This concept of energy of course implies that in order for something to have energy, it must first have matter. WFPM ( talk) 12:58, 14 April 2010 (UTC)
Well, in this modern age of nonmaterial entities, it's hard to to explain to anybody, particularly a teenager about real physical entities. And so I'm trying to explain that there aren't any nonmaterial things and that every thing has to have matter and that its energy content is related to its rate of space volume displacement. And of course I'm getting shot full of holes by theorists who don't believe that. Like that the force of gravity is proportionate to the number of nucleons regardless of how they're arranged etc. And that each molecule of a gas is bouncing up and down within its container with a varying velocity such as to provide the differential atmospherical pressure causing buoyancy, etc. And the net result is that unless you look for and find someone who likes to explain things on a basic level, like Dr. Isaac Asimov used to do, you now have to be educated up to almost the college level before you can understand the explanations. WFPM ( talk) 14:36, 14 April 2010 (UTC)PS for a concept of what an atomic nucleus might look like as a real physical entity see Talk:Nuclear model.
So we've got this problem of dichotemy in physics that allows things like the photon to be described as a massless particle that transports "packets" of energy over long distances that keeps things confused even for the experts of which I am not one. And until that gets straightened out, I'm afraid that the teenager will have to muddle along with the rest of us. WFPM ( talk) 16:34, 14 April 2010 (UTC)
Exactly, you hit the nail on the head and as Feynman pointed out "it [conservation of energy] is a mathematical principle". So, for as long as mathematicians haven’t solved the conundrum of how to interpret mathematics, that is, what the foundation of mathematics is (which should have been solved a hundred years ago but for some strange reason remains unsolved) scientists will not really know what energy is and remain stuck on this dark side of the dichotomy. Hence, "It is important to realize that in physics today, we have no knowledge of what energy is." (italics by Feynman) Knoxjohnson ( talk) 11:18, 18 May 2010 (UTC)
To be incredibly simple, energy is just an idea. It is the relationship of how much any particular thing is able to do something (or is doing something) in comparison to any other thing from a reference frame. In other words, it is relative based on reference frame. However, it is also absolute, because although one can view something as having no energy in a particular reference frame, any change of energy that may take place is always the same. That is why it is both relative and absolute. From our point of view, it is relative to the number or amount that we place on any particular thing. Nature, however, only looks at the changes in energy, and in that sense, it is absolute. So, in essence, when one thinks about energy, it has to be relative when you put a quantity on it in comparison to other things, but it has to be absolute when energy changes. Pancakeface2 ( talk) 15:49, 4 June 2010 (UTC)
So we both agree that energy is just an idea. What remains open is whether this idea reflects anything that exists or does energy reflect not anything that exists, like a fairy from some fairy tale (here the fairy tale refers to the law of conservation of energy). Knoxjohnson ( talk) 16:27, 10 July 2010 (UTC)
Scientific knowledge consists in knowledge about things and their activities. This can be summarized as knowledge about Chemistry, (what things are), Physics, (what things do), and Mathematics, (the relative size of things). And this process of thought results in the necessity of quantizing everything and every idea as a means of consideration and discussion of these matters. But most people standing at the edge of a precipice have an innate understanding of the physical dangers related to the very real physical conversion process related to the falling of a physical object. WFPM ( talk) 12:29, 20 October 2010 (UTC)
Energy is of course a scalar quantity in classical (non-relativistic physics); but it special relativity it is the time-component of the momentum four-vector and obviousley not a scalar. I think the opening lines of the article should be corrected this way: " in non-relativistic physics, energy is a scalar quanity". We then need to say, somewhere else that in relativity energy is only a component of a vector This is directly related to the celeberated E=mc^2. 95.82.51.176 ( talk) 00:19, 1 February 2010 (UTC)
It is debatable about the energy needed to accomplish physical activity under the rules of special relativity. Which is to say that the rules involve the inclusion of a physical activity into the equation that is not absolutely known as to existence or quantity, whereas in classical physics it is not taken into consideration. And the concept of energy being related to the volumetric rate of displacement of matter through space would still be valid if we could keep our space-time coordinate measurement system under better conditions of knowledge and control. WFPM ( talk) 13:23, 20 October 2010 (UTC)
Converting chemical energy to thermal energy is exactly what does produce the work. For instance in an internal combustion engine it is the thermal energy that causes the gases to expand and move the pistons. Also in a thermoelectric system it is the thermal energy that gets converted into electrical energy. Only where there is very low grade heat energy, not much higher in temperature relative to its surroundings, is thermal energy no longer able to perform work. -- CharlesC ( talk) 12:07, 13 February 2010 (UTC)
This article is about the scalar physical quantity. For other uses, see Energy (disambiguation).
Lightning is the electric breakdown of air by strong electric fields and is a flow of energy. The electric potential energy in the atmosphere changes into heat, light, and sound which are other forms of energy.In physics, energy (from the Greek ἐνέργεια - energeia, "activity, operation", from ἐνεργός - energos, "active, working"[1]) is a scalar physical quantity that describes the amount of work that can be performed by a force, an attribute of objects and systems that is subject to a conservation law. Different forms of energy include kinetic, potential, thermal, gravitational, sound, elastic, light, and electromagnetic energy. The forms of energy are often named after a related force.
Any form of energy can be transformed into another form, e.g., from potential to thermal, and dissipated into the atmosphere. When oil, which contains high-energy bonds, is burned, the useful potential energy in the oil is converted into thermal energy, which can no longer be used to perform work (e.g., power a machine) and is lost. Although the thermal energy may not be a useful form of energy, the total energy has remained the same. The total energy always remains the same whenever energy changes from one form to another, even if the energy loses its ability to be used for performing work. This principle, the conservation of energy, was first postulated in the early 19th century, and applies to any isolated system. According to Noether's theorem, the conservation of energy is a consequence of the fact that the laws of physics do not change over time.[2]
Although the total energy of a system does not change with time, its value may depend on the frame of reference. For example, a seated passenger in a moving airplane has zero kinetic energy relative to the airplane, but non-zero kinetic energy relative to the Earth —Preceding unsigned comment added by 217.78.49.201 ( talk) 18:49, 22 February 2010 (UTC)
Energy in itself is non-existing as explained by Richard Feynman in his Dennis the Menace blocks lecture; "There are no blocks!". Energy is born into existence once manifestated in a certain form, hence "different forms of energy". The law of conservation of energy does not formulate energy but is a law which relates to other theories in physics that do give a formulation of a certain form of energy, hence the law of conservation of energy is a metatheoretical law. The article appears to remain a bit unclear about the relationship between "energy" and "forms of energy".-- Knoxjohnson ( talk) 12:45, 21 March 2010 (UTC)
"Any form of energy can be transformed into another form" or "Any form of energy can be transformed and can only be transformed into another form"? -- Knoxjohnson ( talk) 12:50, 21 March 2010 (UTC)
Hmmm… The analogy with money is quite interesting because it is capable of demonstrating two possibilities. An amount of gold can be melted and formed into a collection of coins. Each coin will, because of its shape and size, have a precise weight which determines the value of the coin and this value can be displayed upon the coin. In the end of the day it is the essence of the coin, the gold, which is responsible for its value and the form of the coin represents this value (assuming that the coin is not a collector’s item). Money nowadays appears to be almost virtual, just numbers on a screen which are empty from any essence. Can energy in itself be compared with the gold of the coin or can it be compared with the abstract numbers empty from essence?
The page 'energy' gives a description of what energy is and then the page talks about "Different forms of energy". If the understanding of the term "Different forms of energy" is derived from substituting the definition of the term 'energy' into the term "Different forms of energy" for the word 'energy' then the following result can be attained: Different forms of a quantity that can be assigned to every particle, object, and system of objects as a consequence of the state of that particle, object or system of objects. This shows that the relationship between the concepts 'energy' and 'forms of energy' is not straight forward and the attentive reader is therefore left in doubt of how these two concepts relate to each other. I started the subject 'energy in itself' a bit rough and I would like to reformulate the question, which to my opinion remains unanswered by the energy-page, but this time in a more gentle way:
- Is energy in itself a form of energy like gold in itself (i.e., unformed gold) which also can be seen as a form of money or currency and is in fact a kind of supreme form of money because it used to be in many cases the foundation of a monetary system and nowadays is almost more fundamental than any monetary system, or,
- Is energy in itself only an abstract representative (without any essence like the numbers on a screen) of the collection of forms of energy which determine the state of a quasi enclosed system (i.e., particle, object or system of objects)?
If both formulations are incorrect than I’m very eager to learn how 'energy' and 'form of energy' relate to each other. -- Knoxjohnson ( talk) 08:16, 7 April 2010 (UTC)
If you want Energy and Action let's look at a lot of Energy and Action, like in the Whirlpool Galaxy. There we see a large manifestation of matter with action and emitting Energy. And the matter is being consolidated by a natural accumulation process that we're still trying to understand. And could the matter be condensed action? I don't know. But I don't think so. I'm like the Grandma described by Dr. Asimov. I think it's turtles (er matter) all the way down into protomatter. And how do we receive information about this action? Well some part of the matter gets to us carrying amounts of energy perceptible to a nerve ending in our sense of sight. And our sense of sight is not involved with looking at a modulated wavefront, but rather with a nerve ending's being able to accumulate enough action (of matter) to result in biological nerve action in our body. WFPM ( talk) 06:12, 15 April 2010 (UTC)
So when you start talking about energy without matter, it's like trying to talk about a ghost of somebody who never existed. WFPM ( talk) 14:13, 15 April 2010 (UTC)
That's where I'm getting lost reading Feynman's QED. He says that light is energy that can go through holes in an opaque surface, but that if the holes are spaced correctly, the light will cancel itself out. Any Explanations? WFPM ( talk) 04:11, 20 October 2010 (UTC)
The formila in Gravitational energy section should be: E = -G*m1*m2/r^2 92.247.247.23 ( talk) 23:00, 16 May 2010 (UTC)
{{editsemiprotected}} My science teacher said that everything has energy. I didn't see that at all in the details of or about energy.
I was wondering if you could add that in there in big bold letters! 99.13.123.215 ( talk) 00:31, 20 May 2010 (UTC)
{{
editsemiprotected}}
The current page starts with:
In
physics, energy (from the
Greek ἐνέργεια -
energeia, "activity, operation", from ἐνεργός - energos, "active, working"
[1]) is a quantity that can be assigned to every particle, object, and system of objects as a consequence of the state of that particle, object or system of objects.
I suggest the following change:
In physics, energy (from the Greek ἐνέργεια - energeia, "activity, operation", from ἐνεργός - energos, "active, working" [2]) is a scalar dimensional quantity that can be assigned to every particle, object, and system of objects as a consequence of the state of that particle, object or system of objects. Its dimension is M L2T -2.
141.155.107.173 (
talk)
03:40, 8 June 2010 (UTC)
Under the subheading Kinetic Energy:
Regarding the last expression for kinetic energy Ek=mc2((1-(v/c)2)-1-1)
For v=0 the given expression becomes Ek=0. But the next line after this equation is:
A mathematical by-product of this work (which is immediately seen in the last equation) is that even at rest a mass has the amount of energy equal to: Erest = mc2
Though not incorrect readers will expect the expression for Ek to become Ek=mc2 for v=0. Maybe an intermediate expression using a symbol for rest mass is needed.
-- Phononcondensate ( talk) 14:32, 1 July 2010 (UTC)
A number of physical concepts and quantities do not have "universally valid" or "generally agreed" definitions (possibly none at all), after they are analyzed to "the ultimate depth". However, this understanding comes only after a systematic and thourough study of the subject, which begun with some simplified, or limited, or particular definitions. Amateur opinions on impefection of definitions, which are not based on serious study and understanding of the problem, disregard the fact that these "imperfect" concepts have lead to great cognitive advances and technological developments in recent centuries. It therefore seems rather unreasonable to limit the article on energy to roundabout statements that it "is a quantity that can be assigned to every particle, object, and system of objects as a consequence of the state of that particle, object or system of objects. Different forms of energy include... etc". Even if the same could not be said about some other quantities, it hardly helps a lay person to get any clue on "what this energy thing is about". Therefore, I dare suggest that some simplified highschool definition should be inserted somewhere at the beginning of the article (such as "the ability of an object to do some work; it has so much energy as much work it can do"), preferably somewhat better worded. Of course, together with a note that this is not the "general" definition. And then you can proceede with other details and explanations. —Preceding unsigned comment added by 89.201.201.125 ( talk) 00:58, 16 July 2010 (UTC) Levanat
This proposal looks more appealing than the present intro. Perhaps something like "a quantity that is conserved in isolated systems due to translational invariance of time" should be immeditelly followed by a reference to work (e.g. as a note on the pioneering role of kinetic energy) and a reference to mass, keeping all "chatty" simple at this first round (e.g. "particle physicists specify mass in energy units"), no links yet. To be honest, I do not quite feel up to writing a full specific proposal, and my main concern was that an average reader might give up before reading all fine points in the rest of the article if he could not find something "tangible" in the intro. As for physicists, if any visit this topic, they will molest you in the discussion page anyway. —Preceding unsigned comment added by 178.160.22.100 ( talk) 01:57, 17 July 2010 (UTC) Levanat
I find this to be an appropriate improvement of the intro. It looks much more tangible now, and yet opened towards the rest of the article without unnecessary claims about formal definition.
Ilevanat (
talk)
02:01, 21 August 2010 (UTC)
What is the defenition of chemical energy? —Preceding unsigned comment added by 98.114.166.229 ( talk) 21:16, 27 September 2010 (UTC)
Processes are generally categorized as energy conversion processes, whereby energy is changed from one container to another, (at a higher existence of entropy). And Chemical energy, like from an electrochemical battery cell, is energy that is derived from the internal energy of a chemical compound. WFPM ( talk) 11:56, 20 October 2010 (UTC)
I agree that the opening could be simplified. Why start with Einstein's mass-energy equivalence? That could be taken up in another section below. The article should start simply with Newtonian mechanics. 152.228.124.234 ( talk) 13:41, 10 May 2011 (UTC)
In physics, energy (Ancient Greek: ἐνέργεια energeia "activity, operation"[1]) is a quantity that is often understood as the ability a physical system has to do work on other physical systems.[2][3] Since work is defined as a force acting through a distance (a length of space), energy is always equivalent to the ability to exert pulls or pushes against the basic forces of nature, along a path of a certain length.
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Perhaps it is inevitable, but the addition of explanatory text to this disambiguation page is beginning to change it into an unnecessary and redundant re-incarnation of the old "Energy" article (before it was subdivided). Is that really what you guys want? Let us remove the overview text and keep this just a list of pointers! JRSpriggs 08:00, 5 May 2007 (UTC)
Why do we need an intermediate length article on "real" energy? Because there needs to be some introductory article to the transformations of that sort of energy which is quantified in joules, whether in the natural or biological sciences or in technology. There's a certain sweeping story of how that kind of energy makes the universe work, which has really (by now) been totally butchered and distributed among subarticles, on energy in the sciences and technologies. So the story is really gone. If you want to read about how initial Big Bang energy, together with newly created space and quantum states to expand into, makes the universe run-- i.e., how the low entropy energy showed up at universe creation, and it is even now stored and filtered and suddenly released to give us all the phenomena that makes stuff "go," even now-- THEN you have to read all those subarticles. Too long. But now, there's no other choice. S B H arris 20:13, 9 May 2007 (UTC)
I just clicked on this page and found it with one sentence, so I wrote a quick history overview, without first looking at the talk page or knowing that it was a disambig. Anyway, the history section gives the reader a good springboard with which to dig into the numerous related links. -- Sadi Carnot 17:35, 19 May 2007 (UTC)
From the content forking page: "The generally accepted policy is that all facts and major Points of View on a certain subject should be treated in one article. Hence, whoever decided to change this page into a disambig was doing so in opposition to good encyclopedia writing protocol. Both Encarta and Britannica, for example, have overview articles on energy. Basically, we need to have at least the top 10 uses of the term "energy" defined on this page in the form of stubby header sections with "see main" links above each overview paragraph. The average reader isn't going to know how to wade through all the various links as they are now. -- Sadi Carnot 09:24, 20 May 2007 (UTC)
To Sadi Carnot: If you really think that this should be undone, I would suggest that the proper procedure would be to propose a merger of Energy (physics) back into Energy using the merger template. Otherwise, perhaps you should consider moving the history section which you created from this article to the Energy (physics) article or make it a separate article (if History of energy does not already exist) and link to it from here. JRSpriggs 08:22, 23 May 2007 (UTC)
All the other aspects of the scientific view of energy which once formed part of a great article ( See the last combined version) are now languishing in orphaned and almost meaningless isolation ( See Energy (Earth science) as an example. We need to bring them back together into one article , something under a name like Energy (science) , or Energy in science. We don’t want to perpetuate the idea that they are somehow different things. - Lumos3 23:15, 25 May 2007 (UTC)
I heartily support this perspective. But here's a question. Don't all the other sciences' concept of energy resolve to the physics concept? And thus shouldn't the unifying article be Energy (physics)? And how would this article differ from the Energy article prior to the "grand redesign" commenced by Hallenrm circa May 1, 2007? Robert K S 10:35, 5 June 2007 (UTC)
Just to forewarn everybody on this page, I plan on doing a full-rewrite on this page, so that Wikipedia as a decent approximately 32kb article on energy, on all the main topics, not just energy (physics). I will write it similar in style (header and section-size wise) to that of the thermodynamics article, which is the science of energy transformations. I’m short on time presently, but unless someone else does for me, I will then do it. I would appreciate outline suggestions below. I hope we can all work together on this. Thanks: -- Sadi Carnot 17:20, 9 June 2007 (UTC)
Looking at the above discussion, I can see that the physicists editors on the wikipedia, atleast the people participating in the above discussion are really paranoid? After all, what are they grudging about when they indeed have a full article dealing with energy in physics. I think, I have an answer, they want to dominate any article on energy, and that is the reason why scientist editors of other desciplines seldom contributed to the other article, because the number of physicists editors outnumber and try to dominate. The main advantage of the present form of energy page, is that it gives space to all sectore of human endaveour that deals with energy. Can, dear Sadi Carnot ever cover all these aspects in a single article of 32k. Let him. come up with an article that gets critical acclaim from all the scientist editors, and not just the disgrunted few who participated in the above discussion, only then hi should try to change the present format Hallenrm
Why are there two disambig pages, Energy and Energy (disambiguation). And why isn't the article Energy (physics) not here, as it would be in any real encyclopedia? -- Pjacobi
Yes, JH you are missing the big picture. Hallen has pawned off a lot of material to subpages, e.g. energy (physics), energy (biology) (the correct article is biological thermodynamics (which I wrote)), energy (chemistry) (the correct article is chemical thermodynamics (which I wrote)), energy (earth science) (the correct article would be geological thermodynamics (which I own two textbooks on)), etc. Basically, the whole thing is a big mess and is going to require more than a simple merge tag. Thanks for the words of encouragement. Talk soon: -- Sadi Carnot 01:23, 12 June 2007 (UTC)
Hallenrm, I see that you are the one who is causing all the problems here. I suggest you take a Wikibreak, for at least two weeks, from editing. Come back with a clear head and then work with us. Again this is a community project. Talk soon: -- Sadi Carnot 00:08, 12 June 2007 (UTC)
I still won't be able to do a full dig into the article for a bit, but in the mean time maybe we can vote on a good intro pic to use for the new article to represent all the related energy articles equally? Please visit: Wikipedia:Commons or upload a free-content image if you have one. I have put the previous gallery on a sub-page ( Talk:Energy/Photo-gallery) for the moment. -- Sadi Carnot 08:26, 12 June 2007 (UTC)
I suggest we come up with and agree on a proposal for the structure for all of the Energy articles. Get a consensus and then implement it.
Comments please. Lumos3 08:29, 12 June 2007 (UTC)
The info box next to http://en.wikipedia.org/wiki/Energy#Energy_and_the_laws_of_motion needs to be removed. It shows a picture of force being the derivative of momentum. These two quantities are completely different than energy, and referencing a completely different physics concept without explanation is misleading to someone trying to understand energy in classical mechanics.
I would remove it myself, but my lack of editing skills might result in some other part of the article being damaged.
I agree, I was just studying and noticed this error. Specifically I was looking for the difference between work, energy and momentum, this just confused everything! —Preceding
unsigned comment added by
142.244.161.13 (
talk)
18:31, 7 December 2008 (UTC)
Just a question that arose when reading about meteorological phenomena: what about ocean currents? For your reference:
(...)meteorological phenomena like wind, rain, hail, snow, lightning, tornadoes and hurricanes, are all a result of energy transformations brought about by solar energy on the planet Earth.
I realized that ocean currents are mainly caused by the gravity of the moon, as well as solar heating, and winds. The latter two of them are a result of solar energy, but moon gravity is not solar energy...
Ocean currents are not included in this article about energy, which is not directly the point here, but don't you think that many of those meteorological phenomena listed are caused by solar energy as well as gravity forces from the moon? Or is the moon not an energy source on earth like the sun is? The ocean currents caused by it can generate electricity as is done in the Norwegian fjords...
However, I can't see how this would work mechanically. I mean, the moon pulls on the water masses and causes the water to rise where the earth surface faces the moon, as well as on the opposite side, while the earth surfaces moves underneath the water mass. The resulting water currents would slow down the rotation of the earth, wouldn't they? And then
I found this page helpful about moon gravity: http://howthingswork.virginia.edu/print.php?title=The%20Sea%20and%20Surfing&startdate=0&enddate=99999999&topic=the%20sea%20and%20surfing
I hope this is not too much off-topic :-) -- Lindenlion ( talk) 08:23, 28 November 2007 (UTC)
A user has asked at an administrative noticeboard if this page belongs here or at the original location Energy. The content that it currently at the page called Energy should be merged into the page Energy (disambiguation); the final location of that page also needs to be discussed. What opinions do others have about the correct names for these pages? CMummert · talk 13:41, 1 May 2007 (UTC)
Not many people have commented here, but of those who have, only Charlie (Hallenrm) seems to favor the new arrangement, which has separate pages for energy in physics, chemistry, biology, etc. Others have said there's only one concept of energy being discussed in those fields, that all the pages except Energy (physics) are just stubs, and that there are already pages which address the applications of energy that are relevant to each field (e.g., biological thermodynamics). Charlie has said he hopes pages like Energy (Chemistry) will grow now that they've been created. Gnixon 16:42, 9 May 2007 (UTC)
Charlie, since you seem to be in the minority, maybe you could take some space here to lay out your arguments for the changes in a clear, concise way. So far it looks like people prefer the old way, but maybe there's some point that hasn't been appreciated. Gnixon 16:42, 9 May 2007 (UTC)
I would like to propose that a section about Energy Problems, is created to discuss issues about Global Warming, oil depletion,etc. we can not go on pretending those issues do not exist.
I have sent the following text, to Hillary Clinton,and would like to know your opinion.
Proposal about Public Policies. THEME: Energy.
The world requires, under the leadership of the U.S.A. a reform in energy policies:
The world needs, new Energy policies, based in energies that do not pollute, and do not create increases in the prices of corn or sugar (bio-fuels) for the poor people of the world, considering that bio-fuels do contain Carbon and therefore still generate CO2.
The only energy that does not pollute is Hydrogen (produced by algae), or hydraulic plants (like Hoover Dam), solar, wind, sea waves, geothermic, etc.
Nuclear energy is dangerous,as seen in history.
It is necessary that the rich countries, promote the creation of Alternative Energy Research Institutes, to research and promote solutions.
Mexico, Aguascalientes, Dagoflores -- 189.166.5.98 ( talk) 03:21, 3 April 2008 (UTC)
OK I understand Sadi Carnot's proposal is something like this. Lumos3 09:18, 12 June 2007 (UTC)
I suggest that as many editors as possible agree to this by stating so below or give counter proposals. Lumos3 10:12, 12 June 2007 (UTC)
Hallen states:
i would grant that he is a genius, but I will wait till he accomkplishes the task successfully, and applies himself to the task seriously rather than just giving warnings that have ni meaning, by the very nature of wikipedia.
COMMENT: People are banned all the time from article when they are insulting or nonconstructive. And I don't just mean sarcastically naming somebody a genius, as Hallen does, above. In the short time (since May 1) that this article has been in its present form, Hallen has left at least one insulting edit summary in the main article: [2] ("edits by sadi Carnot seem to lead nowhere except grunting in frustration") And not less than 3 insulting comments in the TALK section. [3] (Editors are lazy) [4] (Editors are paranoid) [5] (Two editors can hardly write sensible lines)
Nor is this odd behavior for him. There are a huge number of examples from Hallen's posts of this nature going back for more than a year, for he's insulted dozens of people, some many times. I'm quite capable of going back, collecting them all, and laying them before ArbCom. It surely will get Hallen banned in some way, because that is NOT how Wikipedia works. I hope I don't have to do this, as I don't want to do the work. And Hallen won't like the result if I do have to do it. But I will do it, if this behavior doesn't change. I hereby promise it. S B H arris 20:10, 12 June 2007 (UTC)
This is not the proper place to decide whether to ban a user, that's what Wikipedia:Requests for arbitration and other similar channels are for. -- Itub 07:49, 13 June 2007 (UTC)
Energy should be an article about energy in the sciences. A summary mention of industrial energy conversion would be fine too. E.g. da:Energi and es:Energía look OK, de:Energie generally speaking also, but it has grown a bit messy. I assume they all derive from a rather old version of the English article. -- Pjacobi 16:42, 12 June 2007 (UTC)
There seems to be momentum in the consensus (8-to-1); hence, for the moment, I’ll start a working subpage here: Talk:Energy/Energy (template). Although, it will still take me another week or two to really dig in. In any event, I welcome contributions on the working sub-page. As soon as I get a free day, I’ll pull the whole thing together nicely. Thanks for all the comments thus far. -- Sadi Carnot 01:00, 13 June 2007 (UTC)
The first paragraph says energy 'is not an object or a substance, but it is quantifiable in a way such that it cannot be created or destroyed.', but energy can be created as in nuclear energy.-- Jcvamp 02:51, 13 June 2007 (UTC)
I've not really sure what article on nuclear energy you're talking about-- if it's the one I've linked in this line, then it really says mass is converted to energy. But that's not really true. As has been argued here long and hard, in a chemical or nuclear reaction, the mass does not change until you let some of it out of the system (non-closed system). So there is no "conversion," just a release, like soda out of a soda bottle. What does happen is that one kind of energy is converted to another--- in both chem and nuclear reactions, potential energy locked up in fields is converted to "heat", which means (among other things) into kinetic energy of particles, and electromagnetic energy (various kinds of "light"). But when a chem reaction happens or even a nuclear bomb goes off, if the system is closed (hard to do with a nuke) the total energy doesn't change, either.
Is energy the capacity to do work? No, not when the energy is in the form of heat, in which case some of it is unavailable. So that definition is tempting, but wrong. Also, conservation of baryon number (which holds for most circumstances, though maybe not in in the Big Bang or in black hole evaporation) means that the energy a lot of the ordinary matter we're used to, which is made of protons and neutrons, it not available to do work. It just sits there, and you can't get it out. But we know it's in there, because if you have antiprotons or antineutrons, you can turn it into work. You just can't get antiprotons or antineutrons without making them, and that takes...... more work. So it's a good demo, but it means in practice that the energy is unavailable except as a demo. See the point? Anyway, this is not an easy topic, for the reason we're now discussing. All the easy and fascile ways to discuss energy are technically wrong. The ways which at least are not wrong, start out almost immediately as being somewhat technical (inertial observer? What's that?). But you have to know what an inertial observer is, even to define the kinetic energy of a baseball. So it's important even for simple problems. Where is the kinetic energy of a moving bullet "stored"? Answer: nowhere. It's a system property. It's like going into the brain and asking where is the personality-- point to it. Or going to Washington, DC and asking to see the "government". Where is the government LOCATED? Well, that's hard to say. That's not to say it has no reality. S B H arris 06:08, 13 June 2007 (UTC)
Sorry for not knowing too much on the subject, but I'm interested and I'd like to understand. So, you're basically saying that the energy is stored in the particles? Does that mean that, for example, in a fire, the thermal and light energy are being released from the particles of the fuel.
Also, if the energy is stored in the particles, what is it doing in the mean time? If it's inactive, does that put it on the same level as stuff like 'potential gravitational energy'? (oops forgot to sign)-- Jcvamp 00:58, 14 June 2007 (UTC)
I'm only fifteen years old, but we just learned about energy at school, I thought the sun created energy by fusion, or does the sun get the energy it sends to the earth from somewhere else? —Preceding unsigned comment added by 84.48.17.134 ( talk) 18:10, 26 September 2007 (UTC)
The history of the Energy pseudo-disambiguation page was lost in the (correct, I believe) move of Energy (physics) to the plain title. However, the contents of that page were needed for a merge into Energy (disambiguation), and since it will be part of a merge, it will be necessary to keep the page history under the GFDL. I'll be working for the next little while to sort out and restore the histories, and for a little bit it will appear that I'm undoing the move. The contents of the physics page will be back here again soon, so don't worry about it. I'm going to move the history of the old pseudo-disambiguation page to Energy (Disambiguation) (sic) and adding a mergeto tag to funnel the necessary contents to Energy (disambiguation). Please help out by merging entries and finally redirecting the page if you have the time. Dekimasu よ! 23:45, 13 June 2007 (UTC)
I see that there has been a serious attempt by SBHarris ans KSRoberts to undo all my edits on this page. I saw some merit in the way Sadi wanted to acheive a reformatting, but it appaears Roberts and Harris can't just wait to acheive their sole ambition in life Hallenrm 04:08, 14 June 2007 (UTC)
As edits can vary greatly in size and quality, it is important not to put too much weight into someone's edit count, and to avoid worrying too much about one's own edit count. Edit counts do not necessarily reflect the value of a user's contributions to the Wikipedia project. As the saying goes, "Quality, not quantity". Hallenrm 07:46, 17 June 2007 (UTC)
Furthermore, eight editors here disagree with your handing of this page (nine if you count Laura Scudder, who has made her opinion plain) and you can't get a single vote to support your point of view. Thus, it appears that in spite of the time you put in, the "quality" of your approach isn't apparent to any of the other people working here-- It's not just Robert and me who don't like what you did here. None of us do. S B H arris 07:51, 18 June 2007 (UTC)
Two quick things--(1) Was it not helpful to give the word's etymology right up front? Is there any reason it shouldn't be restored? (2) Is it helpful to include the qualifier "characteristic of the universe" in the definition of energy? Is there any non-theoretical-mathematical topic on Wikipedia that isn't "of the universe"? Does it impart useful information? Is there any reason "characteristic of the universe" shouldn't be deleted? Robert K S 19:32, 14 June 2007 (UTC)
See Wikipedia:Articles for deletion/Energy (chemistry). -- Itub 07:49, 20 June 2007 (UTC)
(I also nominated Energy (biology), Energy (cosmology), and Energy (earth science). -- Itub 08:18, 20 June 2007 (UTC))
The sentence: "Yet, energy is not simply a mathematical concept or a philosophical principle: it is a measurable quantity with definite properties." contradicts with Richard Feynman's statement few paragraphs below: "...That is a most abstract idea, because it is a mathematical principle; ... It is not a description of a mechanism, or anything concrete; it is just a strange fact..." What is the property of energy anyway? Also, what's the conclusion to this statement: "It was argued for some years whether energy was a substance (the caloric) or merely a physical quantity, such as momentum." So, is energy a substance or a physical quantity?
I really think that the section reading "electrical energy" should read "electromagnetic energy". Why? It includes magnetism and electromagnetic radiation inside it. We should just place the whole main part of the section "Electrical Energy", ehich is devoted to electricity, inside "electromagnetic energy", which would have subsections of "electrical energy", "magnetism", and "electromagnetic radiation" after an introuction listing the three subdivisions of this type of energy. Leaving it like this makes it look as though electricity is the phenomenon causing light and magetism, while, in fact, they are all just forms of Electromagnetic Energy. I really want some consensus before I make this change, so please state your opinions. Slartibartfast1992 15:44, 22 June 2007 (UTC)
Wow, I can't believe how many opinions I'm getting... Did somebody establish censorship? Slartibartfast1992 03:50, 14 July 2007 (UTC)
Is not the work one system can do on another, for only a fraction of heat energy in a system can be used to perform work in another, yet 100% of heat is energy. Thus, some heat energy does not fit this definition. Hence the definition is incorrect. Hence, Robert and I and multiple others have deleted it. Find another one. S B H arris 21:13, 22 June 2007 (UTC)
You'll note that none of this helps E-dude's proposed definition, since his definitional work is not a state function either (since it too, is not conserved) and the total energy in a object is obviously far more than the work it can do on other systems, unless you have a perfect heat-->work conversion machine, and also have a way to convert all the rest mass of an object at absolute zero, into work, too. You could maybe do that with a black hole, but then you have to get it into the other system as some kind of heat, and then you have the heat->work problem again.
I actually like Physchim62 (talk)'s proposal that we just define the energy of a system as the sum of all other other energies that go into it, that we can think of: rest energy of components, minus their bonding energy, plus the heat (and/or work) necessary to get it up to its temperature T and its volume V at its pressure P, and so on. That all turns out to be something like: enthalpy plus component rest energies minus component binding energies. Unless I've forgotten something. S B H arris 21:03, 24 June 2007 (UTC)
BTW, it seems to me that there are two kinds of differences between "real" and "theoretical" models. Some involve "infinitely long wires" or "perfectly strong spheres" or "infinitely long-lived astronauts". These gedanken changes tend to be OK because they can be approached as limits in the real world, and in theory all of them could be approached as closely as you like. It's quite a different thing, however, to simply toss out a major law of physics, and a relevant one, like the second law when talking about the first. Which is what we're talking about here. That's sort of like a gedanken in relativity, in which "we assume for the sake of this problem that the speed of light is infinite...." S B H arris 20:31, 23 June 2007 (UTC)
Even if protons evaporate, they evaporate into positrons and neutrinos, so after the positrons annihiliate with the electrons, you're still stuck with the neutinos, which do have some rest mass (when you say "all, or almost all," you know full well that it's "almost all"). And even when you annihiliate protons with antiprotons, the products are usually pi-mesons, which eventually decay back down to neutrinos and antineutrinos and photons. If there were enough antiparticles to let the leptons anihilate, you'd still get a universe full of photons and neutrinos. Thus, still one where you have neutrino rest mass that you can't get at. Can't convert your mu-neutrinos into e-neutrinos without neutrino oscillation, and you can't have that without neutrino rest mass. Can't have this both ways. Can't turn that last rest mass into work.
Of course you will have read Dyson's cosmology about what happens eventually, in that kind of universe (we're ignoring dark energy for now). Even black holes don't actually let you turn neutrinos into useful work. When a black hole evaporates, it evaporates into "heat" (a mix of paricles with higher entropy, by a small factor like 4/3rds, than the black hole of the same mass had-- see Beckenstein for details). First out comes gravity waves, then black body photons, then the first neutrinos, then (as it gets hotter) finally leptons and then hadrons and finally a flash where you get whole atoms and finally even old TV sets emitted. But that energy expands, dissipates, all the hadrons decay, and finally you're back down to photons and neutrinos at constant "temperature." Same energy, no way for life to get any useful work out of it, even if it did get a bit out of that last flash (and maybe watched a little TV).
As temperature falls and the universe expands, life will be faced with lower and lower black body radiation, and fewer and fewer pockets of space to dump it into, after making black holes for local fires. So life will have to slow down and slow down even more, in metabolism, to keep up the thinking processes. Add dark energy and the future isn't even that nice: the universe expands ever faster as it gets bigger. Finally you only have one last black hole for company. When it's gone, every neutrino sees the horizon expand, until all the photons are gone, and all other particles are outside its light-cone. So finally, each neutrino is all alone in the dark, without even a single photon for company.
What are you going to name that lone neutrino in your rest frame, E-dude? If it won't do any work for you, are you going to send it a pink slip? S B H arris 09:38, 27 June 2007 (UTC)
If we were free to pick our own definition (rather than finding one in a reference), I would go back to the history of energy for guidance. If I understand it correctly, energy was first recognized as a non-directional quantitative attribute of motion (i.e. classical kinetic energy) which tends to remain the same. From there it was expanded to include more and more forms of energy which were needed to maintain the conservation of energy. So I would define energy as the conserved quantity which includes classical kinetic energy . Right? JRSpriggs 06:17, 25 June 2007 (UTC)
1. How do I derive units of energy? As (total mass)/c^2. See Einstein or SR article for derivation of E = mc^2.
3. How do I derive kinetic energy? When I need to, system overall kinetic energy is (again) KE = (γ-1) * M where M is system rest mass, and the v in γ is the system center-of-mass velocity.
I'd much rather have a definition starting from than trying to cram relativity, cosmology, and particle physics in the first sentence of this article. Let's start from kinetic energy and relate that to potential energy and work before getting into modern physics. -- Itub 10:09, 27 June 2007 (UTC)
(added additional header above because this discussion is getting very long) Physchim62 (talk) 13:26, 28 June 2007 (UTC)
We should be writing the Energy intro so that it is generally true and has broad consensus. If that means eliminating some or other textbook definition because it does not apply in all cases, then that's what it takes: Wikipedia guidelines for leads ( WP:LEAD) state that significant controversies should be addressed in leads for a long article. Is definition of energy as the ability to do work a real and sourcable controversy? That's the important question that hassn't being addressed in this dicussion yet. Robert K S 23:49, 27 June 2007 (UTC)
There is indeed controversy over the definition of energy. Eugene Hecht wrote an article in the February 2007 issue of The Physics Teacher which stated that there is not a good definition of energy. It should be noted that Hecht is an author of a respected introductory physics text. See http://www.usna.edu/Users/physics/mungan/Publications/TPT13.pdf
These notions of potential and kinetic energy depend on a notion of length scale. For example, one can speak of macroscopic potential and kinetic energy, which do not include thermal potential and kinetic energy. Also what is called chemical potential energy (below) is a macroscopic notion, and closer examination shows that it is really the sum of the potential and kinetic energy on the atomic and subatomic scale. Similar remarks apply to nuclear "potential" energy and most other forms of energy. This dependence on length scale is non-problematic if the various length scales are decoupled, as is often the case ... but confusion can arise when different length scales are coupled, for instance when friction converts macroscopic work into microscopic thermal energy.
I have always thought of energy as a 'concept that is used to describe
change'. I do not see what is wrong with this simple explanation. Just to cite one textbook that uses this definition Lofts, G (2004). Jacaranda Physics 1.
ISBN
0 7016 3777 3. {{
cite book}}
: Unknown parameter |coauthors=
ignored (|author=
suggested) (
help). The change article needs a bit of work though. Thanks,
Monkeyblu
e
10:57, 29 June 2007 (UTC)
Yes, I know the last way is the way it's often done in popular explanations, and indeed is the way it's done in the Wikipedia article on the subject also. But don't mistake easy derivation for historical physics. Again, if you think that E = mc^2 for rest energy comes out of a "by-product of calculation of relativistic work to accelerate given mass from one speed to another," you're sadly mistaken, and you must learn some real physcis history, not "nice-story" history. S B H arris 23:23, 30 June 2007 (UTC)
As the article stands now, the lead reads In physics and other sciences, energy (from the Greek ενεργός, energos, "active, working")[1] is a scalar physical quantity used to describe a conserved property of objects and systems of objects, which is associated with the rest mass of the object or system, as well as any overall velocity which the object or system may have. Energy may come in many different forms... Robert K S 12:06, 29 June 2007 (UTC)
ED's definition is consistent with both Brittanica:
and Marrion-Webster:
The current lead is not wrong, but (a) it's not the usual way to define energy, (b) the phrasing "scalar physical quantity" seems unnecessarily abstract and vague, and (c) there's no need to mention E=mc^2 here. I suspect this discussion could have been resolved long ago if everyone stayed calm and polite and relied on references (and nothing else), as suggested by Robert. Make sure any edits have correct grammar and spelling. Gnixon 22:50, 6 July 2007 (UTC)
Wow, this is a long page, and I do not claim to have read it all.
ANYWAYS... I feel that the article is SEVERELY lacking in a mathematical definition of energy, and...
If SBHarris, et. all. deleted it, I feel (personally), that they shouldn't have done that, because they didn't replace it with a new one. I feel that the article NEEDS a mathematical definition of Energy, if one CAN be obtained (besides the rather esoteric E=mc^2 (IS THAT THE oNLY ONE???) and besides "the potential to do work")). Plus, it seems there was some sort of mass misunderstanding on the part of SBHarris (sorry i like you Mr. Harris, but misunderstandings happen to everyone..) and the quoted "Roberts and multiple others" between "HEAT" and "Thermal Energy."
It *SEEMS* to me that they just misunderstood... and I WOULD LIKE TO KNOW!!!!
WHAT WAS THE "DEFINITION" THAT THEY DELETED????
and i'll just add that... i think it should be put back.
- BriEnBest ( talk) 03:06, 22 January 2008 (UTC)
I have revamped the introduction ( diff):
Thanks, Monkeyblu e 11:50, 25 June 2007 (UTC)
There seems to have been some kind of edit war brewing over the last weeks at the heat and thermal energy articles between several editors, primarily User:The Way, that caused User: ScienceApologist to quit Wikipedia. In any event, the situation still continues; please review Talk:Heat (disambiguation) and Talk:Heat and give your opinion or vote: here . -- Sadi Carnot 04:08, 2 July 2007 (UTC)
Is energy material??? - Pat Peter 16:49, 2 July 2007 (UTC)
Neither this page nor the Village Pump are the place to ask knowledge questions. This page is only for discussing changes to the article, and the Village Pump is for discussing changes to Wikipedia. If people have questions about the content of the article, the best thing would be to look through the talk page and article history for someone who appears to be knowledgeable, then ask them a question on their user talk page. I've tried answering PP's question on his talk page. Cheers. Gnixon 14:50, 3 July 2007 (UTC)
I'm a little hesitant to add this comment but less hesitant not to. Question: Is this controversy a matter of encyclopedia content or one of physics? If the former, let's just defer to the standard texts and physicists noting important discrepancies where they occur. If the latter (that is if there really is controversy and confusion over the very definition of energy in the physics community), then this in itself is significant and should be included in the entry. I am not convinced there is such a controversy in the physics community; however, all of this lengthy and involved discussion here by many seemingly informed people and the fact that some pretty basic issues (one on transfer, another having to do with work capacity, and still others) remain unresolved has left me in doubt.
Is there really no basic consensus among physicists? If so, then this is just the kind of thing I would expect to learn from a good encyclopedia entry. -- Jcblackmon 06:22, 25 July 2007 (UTC)
I didn't mean to start a philosophical debate here; my question is now dated. I was responding to the intense debate between editors way back then. The article now addresses my concerns. I like.-- Jcblackmon ( talk) 18:22, 27 November 2008 (UTC)
I invite other editors to decide for themselves whether any of the links reinserted by Vig vimarsh enhance the article. Cripes, the first one isn't what it claims to be at all, i.e. it is not a discussion among physicsts, rather it's just a general forum discussion and clearly not a reliable source. A poorly chosen or unnecessarily large selection of external links greatly detracts from the value of an article. My consideration for picking links to be removed was based on these guidelines. Tim Shuba 09:13, 25 July 2007 (UTC)
You have the following equation in the page
C6H12O6 + 3O2 → 6CO2 + 6H2O
The amount of oxygen on the two sides do not balance. Shouldnt it be
C6H12O6 + 6O2 → 6CO2 + 6H2O
Cs1kh —Preceding comment was added at 15:37, 3 December 2007 (UTC)
At the beginning of the third paragraph of the section History, I can hardly identify who was represented by the pronoun "He".
In the same paragraph: "He amalgamated all of these laws...", the laws involved are not previously listed.
Chiloa ( talk) 20:06, 6 December 2007 (UTC)
[[]]-- 209.158.139.250 ( talk) 19:30, 10 December 2007 (UTC)
is there a latin word that is equivalent to energy? if so, what is it? and is there something like "energology," the study of energy? thanks. BriEnBest ( talk) 02:25, 22 January 2008 (UTC)
would it be physics? or physikas? (or whatever the latin word is)??? BriEnBest ( talk) 06:56, 1 February 2008 (UTC)
It's definitely navitas Gheta ( talk) 19:06, 22 July 2009 (UTC)
I see that there's a bit of tendency to see energy as stored in chemical bonds: it isn't. You only get energy stored as rearrangment of bonds from weak to strong. Thus energy in food is not IN the food, but only in the combo of food+oxygen. Similarly, the bonds in ATP don't store energy-- it's stored in the reaction of ATP + water --> AMP plus hydrated PP. ATP breakdown in vacuum would require energy (as the breakage of all chemical bonds does).
I've added a little vingette emphasizing that all energy releases are releases of various potentials stored since the Big Bang. Give me any spontaneous process and in a couple of steps I can show you how that energy was stored as usuable potential, from conditions after the Big Bang. That's the whole point of heat death. I've also added a point from an argument I had here earlier, which is that if you insist on energy being defined as work one system does to another, then heat death demands energy in the universe goes to zero, over time. Say what? We thought energy was conserved! The work one system can do on another is the FREE energy, not the simple energy. S B H arris 03:42, 22 January 2008 (UTC)
I've posted a long question at Talk:Wind power#Lopsided coverage? asking how best to fit the concepts of "Electricty generation from Wind" and "Wind energy" together. In brief I would like suggestions on which should be the parent and which the sub-articles. I can work with either but have a preference for an organization that matches the way Portal:Energy structures solar and hydro power. Thanks. - Wikianon ( talk) 22:25, 27 January 2008 (UTC)
Can somebody plz send me a list of what energy/electricity can travel along? thanks Sylvan wu ( talk) 22:45, 11 February 2008 (UTC)
Some people discourage the use of the term 'relativistic mass'. If we use the term 'invariant mass' as the sole definition of mass, we can derive a formula that relates mass, speed and kinetic energy. In order to conserve momentum in special relativity, we discover the definition of momentum which is different from classical mechanics.
Where m denotes mass, denotes velocity, v denotes speed and c denotes the speed of light in vacuum.
Kinetic energy of a object with mass possesses is equal to the amount of work to be done on it to accelerate it from rest to its current speed.
Where E denotes kinetic energy, m denotes mass, denotes displacement ,c denotes the speed of light, denotes velocity, v denotes speed and denotes a constant to be determined. Since an object has zero kinetic energy when its speed is zero, so we deduce that
From the above derivations, besides getting the equation of kinetic energy, we cannot conclude that mass is a form of energy or see any hint on it. However, if we use the notion of 'relativistic mass', we can see a suggestion on the equivalence of mass and energy. The reason is as the following. We define momentum is a product of relativistic mass and velocity. (This is actually the original definition of inertial mass, see inertia) As such, we get the relationship between relativistic mass and the rest mass.
Where m denotes relativistic mass, denotes rest mass, denotes kinetic energy and v denotes speed. We can conclude that the change of kinetic energy is equal to the change of relativistic mass, or simply mass. This implies that rest mass may be just a form of energy. We can further analyze if mass is really identical to energy.
As shown above, Special Relativity allows the possibility of the equivalence of the mass and energy. It suggests that way. However, the relationship cannot be derived directly from Special Relativity. It does not give a strict proof on the equivalence of mass and energy. We only see the suggestion when we use 'relativistic mass'.
After getting the relationship between momentum of a photon, its frequency and its energy, the equivalence of mass and energy can be proven. (This relationship is proven by Compton Scattering Experiment and photoelectric effect)
Where E denotes energy, m denotes (relativistic) mass, denotes momentum, h denotes plank constant and c denotes the speed of light in vacuum. We consider a thought experiment to see if mass is really equivalent to energy. In COM frame, an object is said to be at rest. It emits two photons in opposite direction with the same magnitude of momentum. As required in conservation of momentum, the object will remain at rest after the emission of two photons in COM frame. If an observer moves in the same direction as one of the photon in COM frame, he will see these photons carry different magnitude of momentum. The magnitude of momentum observed b the observer can be computed by using relativistic Doppler effect. According to the observer, the object does not change its speed after the emission, the only way to reduce momentum is to reduce mass.
In conclusion, the equivalence of mass and energy can be seen as a suggestion of special relativity. We can't really derive it from special relativity directly. We get a very clear hint however. See also mass-energy equivalence Thljcl ( talk) 03:49, 20 May 2008 (UTC)
There has been much debate over whether the 'physical quantity' meaning of the word "energy" is truly the primary meaning; alternatives might be one of the others on Energy (disambiguation) or perhaps there is no primary meaning, simply several relatively equal-weight meanings. This debate is ongoing and is quite heated. It seems to me that this talk page is the correct place for this debate rather than the dab talk page or the various other talk pages onto which it has spilled. If you decide there is no real primary meaning then this page should be moved to Energy (physics), or similar, and Energy used as the disambiguation page. I have no axe to grind here but I would appreciate it if editors familar with the topic could comment here. Thanks. Abtract ( talk) 12:06, 27 May 2008 (UTC)
remind only i cannot be so happy energy is transformed to another,the total energy remains the same.... —Preceding unsigned comment added by 125.60.241.190 ( talk) 02:05, 27 August 2008 (UTC)
The source at http://www.serve.com/herrmann/einpdf.pdf does not seem peer-reviewed and print-published, but it is well researched and it is not polemic. I quote it in the article for the convenience of not searching the web for other sources. I somebody else finds a better source, he/she may replace that source, or simply add an extra source. Tgeorgescu ( talk) 21:41, 9 October 2008 (UTC)
Some of these relate to power generation, or even tourism in sunny climates, rather than the subject of this article and are to a greater or lesser degree WP:SPAM. I'm suggesting that it's time for another modest clearout. -- Old Moonraker ( talk) 11:43, 23 January 2009 (UTC)
This article is about energy as a physical phenomenon. Americans for Balanced Energy Choices is an interest group for the coal industry. While it is true that they advocate the conversion of chemical energy into mechanical energy, their organization and mission is completely irrelevant to someone who would like to learn more about what energy is and how it works. Just to be absolutely clear, I am not removing the link because of the substance of their mission, but simply because their mission is irrelevant to the substance of the Energy article. -- 70.108.40.152 ( talk) 19:46, 16 February 2009 (UTC)
there is no such thing as 'magnetic energy', as Magnetism is not energy but is actually a push or a pull, and this makes magnetism a force. Energy can be converted from one form to another, but that is not the case with magnetism, or 'magnetic energy'.-- S9718483fb ( talk) 13:59, 10 March 2009 (UTC) —Preceding unsigned comment added by S9718483fb ( talk • contribs) 13:51, 10 March 2009 (UTC)
Either the work page or this should change definitions in the introductions. As it is, a curious individual, or perplexed student, comes to the energy page to see the definition of energy: Energy is a scalar physical quantity that describes the amount of work that can be performed by a force. Fair enough, so the inquisitive student will ask..."hmm, what's work?" being wikipedia one can conveniently click on the link, unfortunately one finds in the introduction: mechanical work is the amount of energy transferred by a force acting through a distance. It may make sense in the equations, but verbally it seems circular. 76.175.72.51 ( talk) 04:22, 18 October 2009 (UTC)
"Different forms of energy include kinetic, potential, thermal, gravitational, sound, elastic, light, and electromagnetic energy." Small correction: Light and electromagnetic energy are the same. —Preceding unsigned comment added by 86.176.242.199 ( talk) 13:25, 2 March 2010 (UTC)
I took out this table as potentially misleading. A form of energy doesn't have a magnitude. I guess it could be called "magnitudes of coefficients of equations for energy", but that doesn't seem like a meaningful or useful comparison. We already have the article Orders of magnitude (energy). -- Suffusion of Yellow ( talk) 08:24, 22 October 2009 (UTC)
This article begins In physics, energy is a scalar physical quantity that describes the amount of work that can be performed by a force. On 21 April 2009
User:Wisnuops (
talk) added the following comment:
(note: this is not the best definition. The word
work is also defined by referring to energy. It creates a
circular definition).
I have deleted the note from the article and transferred it here. It may stimulate debate. Dolphin51 ( talk) 03:58, 22 April 2009 (UTC)
At the beginning definition it mentions forms of energy and lists Kinetic, Potential, Light, Elastic, Electromagnetic etc. Isn't Light already Electromagnetic Energy via the Visible Light part of the spectrum? If so this is redundant. Gheta ( talk) 19:10, 22 July 2009 (UTC)
Currently the first sentence no longer has a reference to work. Though this avoids the circular definitions of energy and work, it leaves us with energy defined simply as "a quantity that can be assigned to every particle, object, and system of objects as a consequence of the state of that particle, object or system of objects". This definition doesn't seem satisfying. Does it distinguish energy from other state functions such as entropy? I'm not really convinced that the following two statements constitute a circular definition rather than merely reflecting the fact that energy and work are intertwined: Energy is the amount of work that can be performed by a force. Energy is transferred when work is performed. —Preceding unsigned comment added by Davidr222 ( talk • contribs) 18:54, 14 April 2010 (UTC)
If scalar means single dimensional Energy is not a single dimensional quantity. It is related as to how a quantity of matter is or potentially can be be made to be moved a certain spacial volume quantity within an interval of time. When the time period is over, a quantity of action will have occurred, involved with the matter's having been converted to the same quantity of a new kind of action. If the process is inefficient waste values of lost action will be created and lost, and the quantity of available future action is reduced. So Energy is action per unit time interval and action is Energy times time. So when you carry things upstairs to store in the attic, you're doing a lot of work without being able to regain any of the potential action contained in the stored materials due to their higher gravitational location. WFPM ( talk) 04:38, 15 April 2010 (UTC)
Coming up with a simple definition of "energy" is not possible, but I admire the author for trying. I agree with Davidr222 completely. The statement that energy is a quantity that can be "assigned" to various examples of matter is not helpful and does not make sense if you think about it. "Quantity" refers to a value that is used to describe the amount energy. The energy is not the quantity, just like me standing on the scales is not the weight. I also do not understand what "assigned" means in the context of the definition. Assigned is passive, meaning somebody has to do the assigning. But the energy is present regardless of any assigning body or person. So I don't think one can defend the statement that energy is " a quantity that can be assigned." BabelBoy ( talk) 01:30, 25 April 2010 (UTC)
Sorry to be so bothersome, but I am also having problems with this statement:
"As an example, when oil is reacted with oxygen, potential energy is released, since new chemical bonds are formed in the products which are more powerful than those in the oil and oxygen. "
First, grammatically, it should read either: ". . .products, which are more powerful. . ." (note the comma) or ". . .products that are more powerful. . ." They are two entirely different statements. In the original we can't tell whether it is the bonds or the products that are more powerful.
My second problem is I have no idea what the sentence is saying. "Oil" is awfully vague. Does the author mean hydro-carbons? The product of the sebaceous glands? Baby oil? Shouldn't "oil" be linked to the Wiki article "Oil?" Also, what is meant by "more powerful"? Contains more energy? But that's what we're defining.
Third, the phrase "potential energy is released" is set off by commas, which really distorts something. Is the author trying to say that the release of potential energy [whatever that means] is a consequence of reacting oil and oxygen? BabelBoy ( talk) 01:51, 25 April 2010 (UTC)
This sentence from the intro:
is, in my opinion, poorly worded - even if it is technically true that each of those words can describe some form of energy. Kinetic and potential are a totally separate categorization of energy - in its current shape, the sentence can easily convince someone that thermal is something completely different from kinetic. Or, taken with the next sentence The forms of energy are often named after a related force., it could be taken to suggest that some sort of a "kinetic force" exists.
I suggest we remove the 'kinetic' and 'potential' words from that particular sentence - if we want to have a reference to them in the intro, we can add a sentence along the lines of 'Energy is often split into kinetic and potential' Ivancho.was.here ( talk) 03:34, 11 December 2009 (UTC)
Kinetic and potential could be Mechanical. Grvitational could be removed, since gravity is a force and I'm pretty certain that it's called potential gravitational. Busha5a5a5 ( talk) 18:18, 15 February 2010 (UTC)
I suggest that semantically, the word energy can have a purely abstract non-physical meaning, as "something that moves" (something else or itself), in any kind of reference system.
For example, one could say that there are "energies" in the psyche, in the sense that there are psychological motives or mechanisms that activate/move the psyche in a certain direction, or which inhibit and block certain other tendencies in the psyche.
There is no reason why the notion of energy should be the exclusive property of physical sciences. The purely abstract use of that word in any kind of reference system is perfectly legitimate. —Preceding unsigned comment added by 161.53.149.242 ( talk) 15:36, 19 January 2010 (UTC)
I'm guessing you're answering me, so I am ranting about the use of the word Energy as a play on words. That's because Energy is connoted as being the result of an activity of matter or pseudomatter by causative factors and therefor is a resultave condition of the matter or pseudomatter. It doesn't cause anything in physics concepts, except for some activity to be initiated as the result of the accumulation of enough action to permit it. So matter (or pseudomatter) cannot receive energy and accumulate action and have something happen unless causative factors are considered. Thus the arguments about nuclear decay processes and chemical processes and Enzyme activity etc etc. In short I'm trying to keep the logic of cause and effect straight about the use of the word Energy. WFPM ( talk) 19:15, 15 April 2010 (UTC)
Well before Newton it was speculated the force was required to keep things moving. But He invented the idea that if the thing had energy or really action, it would keep moving on its own. But it still wasn't a separate thing from the involved matter but rather a physical motion property that the thing had acquired relative to space and time. So it's hard to dream up a concept of Energy apart from matter, or that it can do anything other than influence matter by its level of Energy delivery capability. WFPM ( talk) 21:12, 15 April 2010 (UTC)
And I appreciate your information about metaphors. But like Art Ls Pella said about stock trading, Understanding the words of science is serious business and it's getting harder and harder to rationalize and understand the complex details. And I'll bet that a PC using Boolean logic and algebra will never get it figured out. WFPM ( talk) 21:30, 15 April 2010 (UTC)
Does anyone object to me setting up automatic archiving for this page using MiszaBot? Unless otherwise agreed, I would set it to archive threads that have been inactive for 30 days and keep ten threads.-- Oneiros ( talk) 13:45, 24 January 2010 (UTC)
That reminds me that Dr Pauling commented about his arriving at opinions about chemical and other subject matters that "I think about things a lot!" So I admire your concise editorial capability to tell a computer program about how to judge the editorial importance of what it needs to keep printing about a subject matter. WFPM ( talk) 02:34, 16 April 2010 (UTC)
What is energy? —Preceding unsigned comment added by 218.103.199.177 ( talk) 14:32, 28 January 2010 (UTC)
Energy in itself is non-existing as explained by Richard Feynman in his Dennis the Menace blocks lecture; "There are no blocks!". Energy is born into existence once manifestated in a certain form, hence "different forms of energy". The law of conservation of energy does not formulate energy but is a law which relates to other theories in physics that do give a formulation of energy, hence the law of conservation of energy is a metatheoretical law. -- Knoxjohnson ( talk) 12:32, 21 March 2010 (UTC)
Energy is a 3 dimensional entity measurement of the relative magnitude of importance of the activity of matter within the spacetime continuum. In the dynamic sense, the measurement relates to the rate of displacement of the matter within the (3 dimensional) space continuum. In the static case the magnitude is predetermined by mathematical predictive calculations. One of the magnitude's dimensions is related to it's mass value, and the other two to a two dimensional value that is related to the volume of spacial displacement of the matter per unit of spacial distance. The equality equation for energy is therefor E is proportional to the mass value times S cubed divided by S. This concept of energy of course implies that in order for something to have energy, it must first have matter. WFPM ( talk) 12:58, 14 April 2010 (UTC)
Well, in this modern age of nonmaterial entities, it's hard to to explain to anybody, particularly a teenager about real physical entities. And so I'm trying to explain that there aren't any nonmaterial things and that every thing has to have matter and that its energy content is related to its rate of space volume displacement. And of course I'm getting shot full of holes by theorists who don't believe that. Like that the force of gravity is proportionate to the number of nucleons regardless of how they're arranged etc. And that each molecule of a gas is bouncing up and down within its container with a varying velocity such as to provide the differential atmospherical pressure causing buoyancy, etc. And the net result is that unless you look for and find someone who likes to explain things on a basic level, like Dr. Isaac Asimov used to do, you now have to be educated up to almost the college level before you can understand the explanations. WFPM ( talk) 14:36, 14 April 2010 (UTC)PS for a concept of what an atomic nucleus might look like as a real physical entity see Talk:Nuclear model.
So we've got this problem of dichotemy in physics that allows things like the photon to be described as a massless particle that transports "packets" of energy over long distances that keeps things confused even for the experts of which I am not one. And until that gets straightened out, I'm afraid that the teenager will have to muddle along with the rest of us. WFPM ( talk) 16:34, 14 April 2010 (UTC)
Exactly, you hit the nail on the head and as Feynman pointed out "it [conservation of energy] is a mathematical principle". So, for as long as mathematicians haven’t solved the conundrum of how to interpret mathematics, that is, what the foundation of mathematics is (which should have been solved a hundred years ago but for some strange reason remains unsolved) scientists will not really know what energy is and remain stuck on this dark side of the dichotomy. Hence, "It is important to realize that in physics today, we have no knowledge of what energy is." (italics by Feynman) Knoxjohnson ( talk) 11:18, 18 May 2010 (UTC)
To be incredibly simple, energy is just an idea. It is the relationship of how much any particular thing is able to do something (or is doing something) in comparison to any other thing from a reference frame. In other words, it is relative based on reference frame. However, it is also absolute, because although one can view something as having no energy in a particular reference frame, any change of energy that may take place is always the same. That is why it is both relative and absolute. From our point of view, it is relative to the number or amount that we place on any particular thing. Nature, however, only looks at the changes in energy, and in that sense, it is absolute. So, in essence, when one thinks about energy, it has to be relative when you put a quantity on it in comparison to other things, but it has to be absolute when energy changes. Pancakeface2 ( talk) 15:49, 4 June 2010 (UTC)
So we both agree that energy is just an idea. What remains open is whether this idea reflects anything that exists or does energy reflect not anything that exists, like a fairy from some fairy tale (here the fairy tale refers to the law of conservation of energy). Knoxjohnson ( talk) 16:27, 10 July 2010 (UTC)
Scientific knowledge consists in knowledge about things and their activities. This can be summarized as knowledge about Chemistry, (what things are), Physics, (what things do), and Mathematics, (the relative size of things). And this process of thought results in the necessity of quantizing everything and every idea as a means of consideration and discussion of these matters. But most people standing at the edge of a precipice have an innate understanding of the physical dangers related to the very real physical conversion process related to the falling of a physical object. WFPM ( talk) 12:29, 20 October 2010 (UTC)
Energy is of course a scalar quantity in classical (non-relativistic physics); but it special relativity it is the time-component of the momentum four-vector and obviousley not a scalar. I think the opening lines of the article should be corrected this way: " in non-relativistic physics, energy is a scalar quanity". We then need to say, somewhere else that in relativity energy is only a component of a vector This is directly related to the celeberated E=mc^2. 95.82.51.176 ( talk) 00:19, 1 February 2010 (UTC)
It is debatable about the energy needed to accomplish physical activity under the rules of special relativity. Which is to say that the rules involve the inclusion of a physical activity into the equation that is not absolutely known as to existence or quantity, whereas in classical physics it is not taken into consideration. And the concept of energy being related to the volumetric rate of displacement of matter through space would still be valid if we could keep our space-time coordinate measurement system under better conditions of knowledge and control. WFPM ( talk) 13:23, 20 October 2010 (UTC)
Converting chemical energy to thermal energy is exactly what does produce the work. For instance in an internal combustion engine it is the thermal energy that causes the gases to expand and move the pistons. Also in a thermoelectric system it is the thermal energy that gets converted into electrical energy. Only where there is very low grade heat energy, not much higher in temperature relative to its surroundings, is thermal energy no longer able to perform work. -- CharlesC ( talk) 12:07, 13 February 2010 (UTC)
This article is about the scalar physical quantity. For other uses, see Energy (disambiguation).
Lightning is the electric breakdown of air by strong electric fields and is a flow of energy. The electric potential energy in the atmosphere changes into heat, light, and sound which are other forms of energy.In physics, energy (from the Greek ἐνέργεια - energeia, "activity, operation", from ἐνεργός - energos, "active, working"[1]) is a scalar physical quantity that describes the amount of work that can be performed by a force, an attribute of objects and systems that is subject to a conservation law. Different forms of energy include kinetic, potential, thermal, gravitational, sound, elastic, light, and electromagnetic energy. The forms of energy are often named after a related force.
Any form of energy can be transformed into another form, e.g., from potential to thermal, and dissipated into the atmosphere. When oil, which contains high-energy bonds, is burned, the useful potential energy in the oil is converted into thermal energy, which can no longer be used to perform work (e.g., power a machine) and is lost. Although the thermal energy may not be a useful form of energy, the total energy has remained the same. The total energy always remains the same whenever energy changes from one form to another, even if the energy loses its ability to be used for performing work. This principle, the conservation of energy, was first postulated in the early 19th century, and applies to any isolated system. According to Noether's theorem, the conservation of energy is a consequence of the fact that the laws of physics do not change over time.[2]
Although the total energy of a system does not change with time, its value may depend on the frame of reference. For example, a seated passenger in a moving airplane has zero kinetic energy relative to the airplane, but non-zero kinetic energy relative to the Earth —Preceding unsigned comment added by 217.78.49.201 ( talk) 18:49, 22 February 2010 (UTC)
Energy in itself is non-existing as explained by Richard Feynman in his Dennis the Menace blocks lecture; "There are no blocks!". Energy is born into existence once manifestated in a certain form, hence "different forms of energy". The law of conservation of energy does not formulate energy but is a law which relates to other theories in physics that do give a formulation of a certain form of energy, hence the law of conservation of energy is a metatheoretical law. The article appears to remain a bit unclear about the relationship between "energy" and "forms of energy".-- Knoxjohnson ( talk) 12:45, 21 March 2010 (UTC)
"Any form of energy can be transformed into another form" or "Any form of energy can be transformed and can only be transformed into another form"? -- Knoxjohnson ( talk) 12:50, 21 March 2010 (UTC)
Hmmm… The analogy with money is quite interesting because it is capable of demonstrating two possibilities. An amount of gold can be melted and formed into a collection of coins. Each coin will, because of its shape and size, have a precise weight which determines the value of the coin and this value can be displayed upon the coin. In the end of the day it is the essence of the coin, the gold, which is responsible for its value and the form of the coin represents this value (assuming that the coin is not a collector’s item). Money nowadays appears to be almost virtual, just numbers on a screen which are empty from any essence. Can energy in itself be compared with the gold of the coin or can it be compared with the abstract numbers empty from essence?
The page 'energy' gives a description of what energy is and then the page talks about "Different forms of energy". If the understanding of the term "Different forms of energy" is derived from substituting the definition of the term 'energy' into the term "Different forms of energy" for the word 'energy' then the following result can be attained: Different forms of a quantity that can be assigned to every particle, object, and system of objects as a consequence of the state of that particle, object or system of objects. This shows that the relationship between the concepts 'energy' and 'forms of energy' is not straight forward and the attentive reader is therefore left in doubt of how these two concepts relate to each other. I started the subject 'energy in itself' a bit rough and I would like to reformulate the question, which to my opinion remains unanswered by the energy-page, but this time in a more gentle way:
- Is energy in itself a form of energy like gold in itself (i.e., unformed gold) which also can be seen as a form of money or currency and is in fact a kind of supreme form of money because it used to be in many cases the foundation of a monetary system and nowadays is almost more fundamental than any monetary system, or,
- Is energy in itself only an abstract representative (without any essence like the numbers on a screen) of the collection of forms of energy which determine the state of a quasi enclosed system (i.e., particle, object or system of objects)?
If both formulations are incorrect than I’m very eager to learn how 'energy' and 'form of energy' relate to each other. -- Knoxjohnson ( talk) 08:16, 7 April 2010 (UTC)
If you want Energy and Action let's look at a lot of Energy and Action, like in the Whirlpool Galaxy. There we see a large manifestation of matter with action and emitting Energy. And the matter is being consolidated by a natural accumulation process that we're still trying to understand. And could the matter be condensed action? I don't know. But I don't think so. I'm like the Grandma described by Dr. Asimov. I think it's turtles (er matter) all the way down into protomatter. And how do we receive information about this action? Well some part of the matter gets to us carrying amounts of energy perceptible to a nerve ending in our sense of sight. And our sense of sight is not involved with looking at a modulated wavefront, but rather with a nerve ending's being able to accumulate enough action (of matter) to result in biological nerve action in our body. WFPM ( talk) 06:12, 15 April 2010 (UTC)
So when you start talking about energy without matter, it's like trying to talk about a ghost of somebody who never existed. WFPM ( talk) 14:13, 15 April 2010 (UTC)
That's where I'm getting lost reading Feynman's QED. He says that light is energy that can go through holes in an opaque surface, but that if the holes are spaced correctly, the light will cancel itself out. Any Explanations? WFPM ( talk) 04:11, 20 October 2010 (UTC)
The formila in Gravitational energy section should be: E = -G*m1*m2/r^2 92.247.247.23 ( talk) 23:00, 16 May 2010 (UTC)
{{editsemiprotected}} My science teacher said that everything has energy. I didn't see that at all in the details of or about energy.
I was wondering if you could add that in there in big bold letters! 99.13.123.215 ( talk) 00:31, 20 May 2010 (UTC)
{{
editsemiprotected}}
The current page starts with:
In
physics, energy (from the
Greek ἐνέργεια -
energeia, "activity, operation", from ἐνεργός - energos, "active, working"
[1]) is a quantity that can be assigned to every particle, object, and system of objects as a consequence of the state of that particle, object or system of objects.
I suggest the following change:
In physics, energy (from the Greek ἐνέργεια - energeia, "activity, operation", from ἐνεργός - energos, "active, working" [2]) is a scalar dimensional quantity that can be assigned to every particle, object, and system of objects as a consequence of the state of that particle, object or system of objects. Its dimension is M L2T -2.
141.155.107.173 (
talk)
03:40, 8 June 2010 (UTC)
Under the subheading Kinetic Energy:
Regarding the last expression for kinetic energy Ek=mc2((1-(v/c)2)-1-1)
For v=0 the given expression becomes Ek=0. But the next line after this equation is:
A mathematical by-product of this work (which is immediately seen in the last equation) is that even at rest a mass has the amount of energy equal to: Erest = mc2
Though not incorrect readers will expect the expression for Ek to become Ek=mc2 for v=0. Maybe an intermediate expression using a symbol for rest mass is needed.
-- Phononcondensate ( talk) 14:32, 1 July 2010 (UTC)
A number of physical concepts and quantities do not have "universally valid" or "generally agreed" definitions (possibly none at all), after they are analyzed to "the ultimate depth". However, this understanding comes only after a systematic and thourough study of the subject, which begun with some simplified, or limited, or particular definitions. Amateur opinions on impefection of definitions, which are not based on serious study and understanding of the problem, disregard the fact that these "imperfect" concepts have lead to great cognitive advances and technological developments in recent centuries. It therefore seems rather unreasonable to limit the article on energy to roundabout statements that it "is a quantity that can be assigned to every particle, object, and system of objects as a consequence of the state of that particle, object or system of objects. Different forms of energy include... etc". Even if the same could not be said about some other quantities, it hardly helps a lay person to get any clue on "what this energy thing is about". Therefore, I dare suggest that some simplified highschool definition should be inserted somewhere at the beginning of the article (such as "the ability of an object to do some work; it has so much energy as much work it can do"), preferably somewhat better worded. Of course, together with a note that this is not the "general" definition. And then you can proceede with other details and explanations. —Preceding unsigned comment added by 89.201.201.125 ( talk) 00:58, 16 July 2010 (UTC) Levanat
This proposal looks more appealing than the present intro. Perhaps something like "a quantity that is conserved in isolated systems due to translational invariance of time" should be immeditelly followed by a reference to work (e.g. as a note on the pioneering role of kinetic energy) and a reference to mass, keeping all "chatty" simple at this first round (e.g. "particle physicists specify mass in energy units"), no links yet. To be honest, I do not quite feel up to writing a full specific proposal, and my main concern was that an average reader might give up before reading all fine points in the rest of the article if he could not find something "tangible" in the intro. As for physicists, if any visit this topic, they will molest you in the discussion page anyway. —Preceding unsigned comment added by 178.160.22.100 ( talk) 01:57, 17 July 2010 (UTC) Levanat
I find this to be an appropriate improvement of the intro. It looks much more tangible now, and yet opened towards the rest of the article without unnecessary claims about formal definition.
Ilevanat (
talk)
02:01, 21 August 2010 (UTC)
What is the defenition of chemical energy? —Preceding unsigned comment added by 98.114.166.229 ( talk) 21:16, 27 September 2010 (UTC)
Processes are generally categorized as energy conversion processes, whereby energy is changed from one container to another, (at a higher existence of entropy). And Chemical energy, like from an electrochemical battery cell, is energy that is derived from the internal energy of a chemical compound. WFPM ( talk) 11:56, 20 October 2010 (UTC)
I agree that the opening could be simplified. Why start with Einstein's mass-energy equivalence? That could be taken up in another section below. The article should start simply with Newtonian mechanics. 152.228.124.234 ( talk) 13:41, 10 May 2011 (UTC)
In physics, energy (Ancient Greek: ἐνέργεια energeia "activity, operation"[1]) is a quantity that is often understood as the ability a physical system has to do work on other physical systems.[2][3] Since work is defined as a force acting through a distance (a length of space), energy is always equivalent to the ability to exert pulls or pushes against the basic forces of nature, along a path of a certain length.