Well, of course Stella shifts through Lorentz frames during the turn-around phase. During inertial motion the time-relationship of an object with its surroundings does not change, but during acceleration it does. I rather like the expression 'Lorentz boost' for the process of shifting from one Lorentz frame to another.
Recapitulating the basics: a shift from one Lorentz frame to another, does not only change the velocity of an object, it does not only change the space-wise relation with the surroundings, a Lorentz boost also changes time-wise relationship with the surroundings. (I didn't bother to recapitulate this before because it is so basic to relativity)
On the
Time dilation talk page you wrote:
I suspected this is your view of GR, but here is the first place that I see you state it explicitly.
That describes how I understand it in special relativity: if you draw planes of simultaneity in a space-time diagram then during acceleration the succesive planes of simultaneity are tilted with respect to each other.
I can see how this concept of accelerating with respect to the local inertial frame of reference can serve as a bridge between special relativity and general relativity. I have looked at that interpretation, but I found it on the whole unsatisfactory.
The Earth warps spacetime geometry. Because of this curvature of space-time geometry, an object that is stationary on the surface of Earth is accelerating with respect to the local inertial frame of reference. In other words: because of the curvature of space-time geometry, the local inertial frame of reference is accelerating towards the center of the Earth as seen from a frame of reference that is stationary with respect to the center of the Earth.
You describe that because of the acceleration with respect to the local inertial frame of reference, there is time dilation with respect to locations higher in the gravitational potential.
The warping of spacetime is mainly warping of time; in most circumstances the space-warping is negligable compared to the time-warping.
According to your description gravitational time warping is to be seen as the first cause, and you describe gravitational time dilation as a final effect of that. The question then is: is there a difference between gravitational time warping and gravitational time dilation? Can this differnce be measured?
--
Cleon Teunissen |
Talk
09:38, 26 May 2005 (UTC)
Yes, it was an error to use the expression 'time warping'. It's spacetime warping, space and time are equally affected.
I took the heuristic very literally. I equated the spacetime warping with its final effects. That is: I took the most symmetrical situation: a non-rotating planet, and clocks situated in towers of different heights, and I equated the spherically symmetrical time dilation pattern that can be measured in those circumstances with "time warping". That was incorrect.
Flow model
I came across a astrophysica article wit an intriguing interpretation of the Schwarzschild metric,
River model of the Schwarzschild metric by
Andrew J S Hamilton and Jason P. Lisle.
Professor Max Tegmark of MIT has incorporated the river model in his General relativity teaching MIT Course 8.033, Schwarzschild metric & black holes
The background philosophy, as I understand it, is that the mathematics of General Relativity does not intrinsically enforce one interpretation or the other, so the interpretation of the theory is seen as a heuristic tool. The demands on the interpretation are that the interpretation is consistent with the mathematics, and free of self-contradiction.
As I understand Hamilton and Tegmark, the flow model is a heuristic tool, it allows a set of features of curved spacetime to be arranged in a coherent picture. As I understand it the flow model heuristic tool is seen as equally suitable for interpretation of the theory as other heuristic tools that are currently in use.
I find the 'flowing space-time' interpretation quite satisfactory. Take two observers: Hugh, who is high in the gravitational potential, and Lowe, who is low in the gravitational potential of the same planet. This planet is their primary. If they want to calculate the rate of proper time of Lowe with respect to the rate of proper time of Hugh, then the river model describes that Lowe is traveling more distance than Hugh (as expressed in proper time of Hugh), which corresponds to less proper time for Lowe compared to the proper time of Hugh.
A flood of comments
I'm sorry about the way I have been flooding you with comments over the past months. Your Talk page is huge now. (My browser, Firefox, has problems displaying it.) I kept seeking contact because I just couldn't believe that communication can collapse so badly.
I will try hard to stay away from your Talk Page. Discovering that two leading astrophysicists endorse a flowing space-time interpretation resolves much of my uncertainties. I have a pretty good idea now of how I will explain the physics of general relativity to other people. (But not on wikipedia; I think explaining relativity is impossible on wikipedia, too many cooks spoil the broth.)
--
Cleon Teunissen |
Talk
14:08, 28 May 2005 (UTC)
Hi. I did not like that reference
at all, but I hesitated to delete something somebody put there. The reference seems, to me, to be largely someone's attempt to show how one can arrive at GR after exploring many alternate paths. But it is just a recasting of one person's experiences. It will not help others, most of whom can't follow the labyrinthine reasoning. Sorry you do not fully believe black holes have been discovered. Pdn 02:28, 17 Jun 2005 (UTC)
Well, I might delete that odd gabby reference. Back to black holes. They are old-hat now (nothing to do with the man who mistook his black hole for a hat). Where's a reference to something recent and non-crank against them, please?
By the way, the stuff higher up on your page about space or time being curved is a bit specialized, I'd say, 'cause I hate to say "wrong.". There are some cases like static solutions (Schwarzschild, Reissner-Nordstrom, ...) where you can uniquely split space and time and define a world-time.
In more general cases, there is no global splitting possible and you would have no way to separate space curvature and curvature in the timelike dimension. Even in the Kerr metric, you have cross-terms between phi and t, so they are intertwined. Also remember any local observer can establish a "boost" to a local Lorentz frame of different velocity, and in that frame the constant-time sections are different. Wrong? Well, I mean that you are using one form of the Schwarzschild metric, but the are isotropic forms, and a form where the ingoing and outgoing null lines are used as axes (Kruskal-Szekeres metric [1]) Pdn 03:57, 17 Jun 2005 (UTC)
Sorry - I thought I was reading that you separated space and time curvature, but I guess it was someone else writing on your page. About that reference to a "web course" by Kevin Brown I think (as I wrote on Cleon Teunissen's page) it is mostly hogwash - so maybe someone will delete it. I changed the comments once and they were changed back so I am tired. Pdn 04:55, 18 Jun 2005 (UTC)
I do not find the link stale: [2] . Are we on the same page (no pun)? The same "mathpages.com"? We should be so lucky it goes stale. Or more stale. There is a lot of wrong science or at least very unlikely science out there and it attracts the innocent. For example there is something called The Wu-Li Dancing Masters which promotes a hidden agenda of the Bohm hidden variables "theory" (ruled out I believe by Alain Aspect and others). There is probably not much wrong in the "mathpages" link, just fluff. Well, there are some odd remarks:"The real content of Einstein's principles is that light is an inertial phenomena (despite its apparent wavelike nature). " Pdn 02:59, 19 Jun 2005 (UTC)
I think it is getting too far afield and I regret asking for a reference, but thanks (I looked up Earman a bit on the Web). Pdn 04:57, 18 Jun 2005 (UTC)
Hi EMS, I appreciate the trust that you put in my searching.
Web-searching is tedious business, it takes a lot of motivation. The 'black hole electron' doesn't get my blood racing, I'm afraid, so I guess I won't be looking into that matter.
The aspect of relativity that attracts my attention these days is time dilation. Keep watching the Talk:time_dilation page. -- Cleon Teunissen | Talk 18:51, 19 Jun 2005 (UTC)
Hi You wrote: "I assure you that the physics as viewed in a rotataing/accelerated frame of reference has meaning, even if the bottom line is that the same results are obtained in either case. The ability of use an accelerated viewpoint is especially important in GR, where you can be in a spaceship moving intertially, but the effects of gravitation are such that the objects distant from you are being accelerated, and effects such as gravitational time dilation and red/blue shifting are none-the-less revealing themselves.
Relatitivy fundamentally is about how perceptions of the same events are changed by virtue of being in different frames of reference. In essesnse, changing frames of reference is a gedanken is nothing more than putting yourself is someone else's shoes. In that regard their state of motion (be it inertial or not) should not matter. -"
By contrast: as seen from a point of view that is accelerating the speed of light appears to be non-isotropic, and I am rather suspicious about that.
I very much doubt that describing physics from an accelerating point of view has any meaning at all. EMS insisted that in the Sagnac effect article the physics should also be described as seen from a rotating frame of reference. I tend towards the opinion that describing physics from the point of view of a rotating frame of reference does not carry any physical meaning." was written by Teunisson, so it might be better to reply to him.
I will think more about the Michaelson-Morley experiment as related to acceleration. I think you are right - this cross dialogue is going too fast. But the idea was to detect differences in the "aether drift" as the apparatus turned (with the Earth). If it were in inertial motion the supposed drift would not show up as a fringe shift. A rotating reference frame is accelerated. Pdn 00:41, 21 Jun 2005 (UTC)
To some extend it is a moot point; the same results are obtained either way. That implies that the matter cannot be decided by experiment, and it is not clear whether a matter that cannot be decided by either logic or experiment is worth scratching one's head over.
I choose to apply Occam's Razor: in this particular area I restrict my hypotheses to the minimal set of hypotheses that suffices to account for the physics taking place.
I know what you mean by that, but personally I prefer to avoid any formulation that carries with it the suggestion that in relativity theory active participation of the observer matters for the physics taking place.
I prefer to formulate in such a way that it is clear that if the observers do not put themselves in the other guys shoes the same physics will take place. Whether the observer understands the physics or not, the same things will happen.
What I find intriguing about relativity is that there are the invariants, like the invariant space-time interval, that seem to suggest that there is an "arena" where these invariants exist, and that this is the true arena of physics. But every physical interaction, say a photon being detected and its frequency determined, occurs in such a way that space and time are split in a particular way. A photon may be emitted with an energy that corresponds to a light-wavelength of, say 400 nanometer, and the same photon can on absorption be detected to have an energy that corresponds to an 800 nanometer light-wavelength. For different observers space and time are split up differently, and we call that difference 'relative velocity'. I am inclined to think that the invariant qualities are closer to the true physics than the measurements, that are always subject to a particular split of space and time.
I am inclined to believe that relativity is fundamentally about the properties of Minkowski space-time, and more generally, about the properties of curved Minkowski space-time.
Yes, of course the ability to perform transformations between frames that are being accelerated with respect to each other is vital. In order to model the transmission of timing signals from a GPS satellite to a reciever on the ground, the following frame of reference is used: the non-rotating frame of reference that is co-moving with the Earth in its geodesic-following motion around the Sun. Both the GPS satellite and the reciever are moving with respect to that inertial frame of reference, so appropriate transformations need to be applied, and general relativity provides these transformations. -- Cleon Teunissen | Talk 08:18, 21 Jun 2005 (UTC)
I looked it up. As it turns out, it was
Pdn himself who mixed up the sentence,
Pdn's quote was garbled, the original sentence was correct.
By the way, I have never encountered any problem in browsing mathpages.com. I browse mathpages.com frequently, never a problem. It is unclear what makes the link appear stale to you.
In [
chapter 2, section 1] it is written:
-- Cleon Teunissen | Talk 23:23, 21 Jun 2005 (UTC)
Pdn wrote:
I get the impression that the reasoning of
Pdn goes as follows:
That is my tentative reconstruction of
Pdn's reasoning.
--
Cleon Teunissen |
Talk 07:41, 22 Jun 2005 (UTC)
Hi EMS,
About the credentials of Kevin Brown, the author of Reflections on Relativity
I did a Google search of Newsgroups with the following search terms: "Kevin Brown" "Chris Hillman"
There were several threads in which both Kevin Brown and a Chris Hillman had posted. One thread was started by Kevin Brown in the newsgroep sci.physics.relativity.
Datum: 1998/05/10
Onderwerp: Loxodromic Aliasing
A Chris Hillman replied:
From: Chris Hillman <hill...@math.washington.edu>
Datum: 1998/05/10
Onderwerp: Re: Loxodromic Aliasing
On Sun, 10 May 1998, Kevin Brown wrote:
> When describing the appearance of a sequence of states we sometimes
> need to account for the phenomenon of aliasing.
Good grief, this is even more subtle that my Paradox Resolved post
indicated! :-/ But, good point, Kevin, this is still another issue which
needs to be explained by anyone presenting a relativistic starflight
simulation.
This again shows the importance of superimposing on the star field say
yellow Steiner circles (or loxodromic spirals as the case may be) showing
the orbits of a given one parameter subgroup and say white circles of
constant red/shift blue shift (which vary with parameter).
[end quote of message by Chris Hillman]
Considering this reply by Chris Hillman, and other replies, my impression is that Chris Hillman has a pretty good idea of Kevin Brown's level of competence, and that he considers Kevin Brown to be on equal par to himself in the field of theoretical physics.
--
Cleon Teunissen |
Talk
21:33, 11 July 2005 (UTC)
i just threw a massive edit on that piece. please let me know what you think. Hamster Sandwich 00:23, 21 July 2005 (UTC)
Just left a comment for you on the VfD page. Summary is that I agree with everything you say about the need for copious citation and careful wording; apologize for not having the time to help out more right now; disagree with the claim that I'm ignorant of this material. Comment's still on the page. Take care. Babajobu 13:32, 21 July 2005 (UTC)
I'm understanding "religious persecution" as being the persecution of a minority religious group by a majority religious group. JDL doesn't qualify because a minority militant group is not capable of "persecution" as I'm defining it. The Kahane-ites were never part of the majority anywhere...except perhaps the ones in the West Bank, which would be covered under Israel. The Hasmoneans, as far as I know, could only qualify if they tried to Hellenize more traditional Jews. Even though they originally revolted against Hellenic occupation, they were pretty much Hellenized Jews themselves. That's my understanding. Babajobu 02:20, 22 July 2005 (UTC)
Hi Ems. You may have had this trivial remark before: do you want to write something on (or create) your user page ? It would get rid of the only red link on my user page :) Mpatel ( Talk).
Ril enlisted Persecution by Muslims for VfD again, just 24 hours after the article withstood the first VfD. You might be interested to watch it.
[3] --
Germen (
Talk |
Contribs
)
10:19, 30 July 2005 (UTC)
No confusion. I actually think that your overhaul of the GR article is cool. — AugPi 04:34, 2 August 2005 (UTC)
Dear EMS, following your boldness at Inertial frame of reference, I've done something simliar at Fictitious force. I'm pretty sure you know about this stuff, and would be grateful for your opinion. William M. Connolley 14:43:48, 2005-08-02 (UTC).
Currently, after the new edits, the coriolis effect article is contradicting itself badly. It is now a mosaic of fragments, written from incompatible points of view. William M Connolley acknowledges that the diagrams Image:Coriolis_effect10.png and the version Image:Coriolis_effect09.png are relevant for describing the formation of cyclonic flow, and his statements in the article indicate that he believes that the flow pattern is to be understood as a transformation from one frame of reference to another
, the second frame rotating with respect to the first. (In the case of meteorology the transformation is invariably from a fixed-to-the-stars frame to a frame that is co-rotating with Earth, rotating around the Earth axis.)
I disagree with William's assertions on this matter.
The diagrams are relevant, which is why I manufactured them along with the animations, but nothing in the diagrams is related to coordinate transformation.
On a more general level: the underlying assumption of William M Connolley is that GRT has shown there is a one-on-one correspondence between relativity of linear velocity and relativity of angular velocity.
Given William M Connolley's reasoning, he will reject the content of the
sagnac interferometer article, claiming that it violates GRT.
It has been months since William M Connolley and I have discussed this, his position may have altered since then. However, William's edits to the coriolis effect article do "breathe" the assumptions that also lead to the opinion that a Sagnac interferometer can only indicate a process of changing of angular velocity, but not angular velocity with respect to the local inertial frame of reference. --
Cleon Teunissen |
Talk
11:43, 3 August 2005 (UTC)
I may have stated in the past that a Sagnac interferometer measures absolute rotation, but I have since retracted from that position. I now state the following things:
Of course, it is meaningless to talk about such a thing as whether the universe as a whole rotates. Only what can be observed can be meaningfully discussed. There are no known instances of parts of space rotating with respect to the universe as a whole, and the cosmological models do not allow for such a possibility.--
Cleon Teunissen |
Talk
16:28, 3 August 2005 (UTC)
Yes, it would have been very strange indeed if that would have been your position.
So, for the umpteenth time we are back to square one, in a babylonian confusion of biblical proportion.
To understand that flow pattern there is no need to consider coordinate transformation, I just look at the physics. I am exclusively interested in the physics.
The mathematics of the coordinate transformation is obvious and transparent. I do not see why coordinate transformation should be discussed at all in discussing meteorology, the coordinate transformation is just a mathematical tool.
That has been my ongoing puzzlement. Why discuss coordinate transformation at all? As I said, the coordinate transformation involved is obvious and transparent, it is a mystery to me why William has kept explaining something that is A) glaringly obvious, and B) not involved in the physics.
It has now been confirmed that the red arrows in the diagrams on the right are unrelated to coordinate transformation.
For the coriolis effect article I have been writing about what physics the red arrows represent, for that is very interesting physics.-- Cleon Teunissen | Talk 17:01, 3 August 2005 (UTC)
I think the ring laser interferometer is the clearest demonstration of the Sagnac effect.
When a ring laser interferometer is not rotating with respect to the local inertial frame of reference, then then both counterpropagating flows of laserlight have the same frequency. When a ring laser interferometer is rotating with respect to the local inertial frame of reference, then there is a splitting of the frequencies, as described in the Sagnac effect article.
Some of the laserlight is diverted, and the two freqencies are brought to interference, leading to a beat frequency.
The university of Canterbury, new Zealand employs such a ring laser interferometer, one with a diameter large enough to measere the rotation of the Earth. The ring laser interferometer is in a deep cave, shielded as much as possible from any influence. The ring laser interferometer, is rotating with respect to space, so there is a splitting of the frequencies, resulting in a beat frequency of about 71 Hertz, consistent weith one rotation per sidereal day. The advantage of the ring laser interferometer for measuring the rotation of the Earth with respect to space is that small fluctuations in the beat frequency, related to Earth quakes, are picked up too.
Anyway, the point is: there are numerous ways to measure rotation with respect to local space, the ring laser interferomete is one of them, and because it works with light, I feel it is a bit more spectacular. -- Cleon Teunissen | Talk 17:24, 3 August 2005 (UTC)
So there is no calibration involved, it just works straight away.-- Cleon Teunissen | Talk 17:34, 3 August 2005 (UTC)
Months and months ago I mentioned the Sagnac interferometer to William, and he expressed doubts. --
Cleon Teunissen |
Talk
17:24, 3 August 2005 (UTC)
Of course there is no reason at all to invoke GR in discussing meteorology, the things I wrote for the coriolis effect article are strictly classical mechanics. I wouldn't have it any other way.
The
Ballistics section of the coriolis effect article is written by me, and other editers have left it the way it was. I wrote:
Anyway, that is all straightforward stuff.
The diagrams on the right, simplified as they are, are very relevant for understanding how cyclonic winds start, and the red arrows represent something, and the coriolis term in the equation of motion is unrelated to the red arrows in the diagrams.
The coriolis term is helpful when looking at motion that is a straight line as seen from one point of view (and thus curvilinear as seen from another, rotating point of view.) In the case of the diagrams on the right the motion with respect to the inertial frame of reference is curvilinear to begin with.
Reading the articles of the meteorologist Anders Persson made me aware of what the red arrows represent. It's really cool classical mechanics, worth looking into. -- Cleon Teunissen | Talk 02:10, 4 August 2005 (UTC)
EMS, I know you think you are only trying to help, but you must have assumed (since you didn't even ask me before making the change) that I had no good reason for not wanting to make this change, at least not right now, but in fact I do have good reason not to want you to monkey with this. TIA, CH (talk) 00:31, 6 August 2005 (UTC)
Not a problem EMS, oh and ty for creating a user page :). --- Mpatel (talk) 11:16, August 8, 2005 (UTC)
Hi, EMS, I have a wikicode question for you. Go to the "Exact solutions in general relativity" category and then follow the link to the article on "Aichelburg/Sexl ultraboost". While modifying another page, I noticed that I can't seem to get other articles to link correctly to this one. Looking at the url of the article, I see that the wikiserver may have interpreted the slash in the name as indicating a directory, which probably would not be good. Can you see how to link to this article? If not, can you see how to give it a name so that the slash appears to the reader, but the wikiserver can still link to it? If not, obviously, I'll have to change the name to "Aichelburg-Sexl ultraboost".
I have a preference for "Kerr/Newman" rather than "Kerr-Newman", and so forth, because hyphenated names are not unknown and can play havoc with the hyphen convention. However, if Wiki does not support this choice, I should know now, before I go and start trying to create lots of articles in the "Exact solutions in general relativity" category.--- CH (talk) 19:53, 9 August 2005 (UTC)
In response to your libelous false portrayal of my thoughtful and informative contributions to the cosmology article as NOT being thoughtful and informative, and furthermore as being mere diatribes, your use of a guise of being considerate so as to make your deceptions more convincing, and your act of giving small, nearly-insubstantial concessions in the guise of being considerare, so as to make more convincing the deception that other edits should not be allowed, thus demonstrating your malicious calculating nature, I have created a request for arbitration. Go ahead and make your statement on the arbitration page, not that it will make any difference. Your clever deceptions that I have pointed out are plain to see in the talk:cosmology page and the cosmology article history that they refer to, and the only way that the arbitrators will side with you is if they too have blind faith in the big bang belief, as well as the dominant temperament to suppress any facts that indicate that the big bang belief is anything less than a certain and obvious truth. --216.112.42.61
Well, of course Stella shifts through Lorentz frames during the turn-around phase. During inertial motion the time-relationship of an object with its surroundings does not change, but during acceleration it does. I rather like the expression 'Lorentz boost' for the process of shifting from one Lorentz frame to another.
Recapitulating the basics: a shift from one Lorentz frame to another, does not only change the velocity of an object, it does not only change the space-wise relation with the surroundings, a Lorentz boost also changes time-wise relationship with the surroundings. (I didn't bother to recapitulate this before because it is so basic to relativity)
On the
Time dilation talk page you wrote:
I suspected this is your view of GR, but here is the first place that I see you state it explicitly.
That describes how I understand it in special relativity: if you draw planes of simultaneity in a space-time diagram then during acceleration the succesive planes of simultaneity are tilted with respect to each other.
I can see how this concept of accelerating with respect to the local inertial frame of reference can serve as a bridge between special relativity and general relativity. I have looked at that interpretation, but I found it on the whole unsatisfactory.
The Earth warps spacetime geometry. Because of this curvature of space-time geometry, an object that is stationary on the surface of Earth is accelerating with respect to the local inertial frame of reference. In other words: because of the curvature of space-time geometry, the local inertial frame of reference is accelerating towards the center of the Earth as seen from a frame of reference that is stationary with respect to the center of the Earth.
You describe that because of the acceleration with respect to the local inertial frame of reference, there is time dilation with respect to locations higher in the gravitational potential.
The warping of spacetime is mainly warping of time; in most circumstances the space-warping is negligable compared to the time-warping.
According to your description gravitational time warping is to be seen as the first cause, and you describe gravitational time dilation as a final effect of that. The question then is: is there a difference between gravitational time warping and gravitational time dilation? Can this differnce be measured?
--
Cleon Teunissen |
Talk
09:38, 26 May 2005 (UTC)
Yes, it was an error to use the expression 'time warping'. It's spacetime warping, space and time are equally affected.
I took the heuristic very literally. I equated the spacetime warping with its final effects. That is: I took the most symmetrical situation: a non-rotating planet, and clocks situated in towers of different heights, and I equated the spherically symmetrical time dilation pattern that can be measured in those circumstances with "time warping". That was incorrect.
Flow model
I came across a astrophysica article wit an intriguing interpretation of the Schwarzschild metric,
River model of the Schwarzschild metric by
Andrew J S Hamilton and Jason P. Lisle.
Professor Max Tegmark of MIT has incorporated the river model in his General relativity teaching MIT Course 8.033, Schwarzschild metric & black holes
The background philosophy, as I understand it, is that the mathematics of General Relativity does not intrinsically enforce one interpretation or the other, so the interpretation of the theory is seen as a heuristic tool. The demands on the interpretation are that the interpretation is consistent with the mathematics, and free of self-contradiction.
As I understand Hamilton and Tegmark, the flow model is a heuristic tool, it allows a set of features of curved spacetime to be arranged in a coherent picture. As I understand it the flow model heuristic tool is seen as equally suitable for interpretation of the theory as other heuristic tools that are currently in use.
I find the 'flowing space-time' interpretation quite satisfactory. Take two observers: Hugh, who is high in the gravitational potential, and Lowe, who is low in the gravitational potential of the same planet. This planet is their primary. If they want to calculate the rate of proper time of Lowe with respect to the rate of proper time of Hugh, then the river model describes that Lowe is traveling more distance than Hugh (as expressed in proper time of Hugh), which corresponds to less proper time for Lowe compared to the proper time of Hugh.
A flood of comments
I'm sorry about the way I have been flooding you with comments over the past months. Your Talk page is huge now. (My browser, Firefox, has problems displaying it.) I kept seeking contact because I just couldn't believe that communication can collapse so badly.
I will try hard to stay away from your Talk Page. Discovering that two leading astrophysicists endorse a flowing space-time interpretation resolves much of my uncertainties. I have a pretty good idea now of how I will explain the physics of general relativity to other people. (But not on wikipedia; I think explaining relativity is impossible on wikipedia, too many cooks spoil the broth.)
--
Cleon Teunissen |
Talk
14:08, 28 May 2005 (UTC)
Hi. I did not like that reference
at all, but I hesitated to delete something somebody put there. The reference seems, to me, to be largely someone's attempt to show how one can arrive at GR after exploring many alternate paths. But it is just a recasting of one person's experiences. It will not help others, most of whom can't follow the labyrinthine reasoning. Sorry you do not fully believe black holes have been discovered. Pdn 02:28, 17 Jun 2005 (UTC)
Well, I might delete that odd gabby reference. Back to black holes. They are old-hat now (nothing to do with the man who mistook his black hole for a hat). Where's a reference to something recent and non-crank against them, please?
By the way, the stuff higher up on your page about space or time being curved is a bit specialized, I'd say, 'cause I hate to say "wrong.". There are some cases like static solutions (Schwarzschild, Reissner-Nordstrom, ...) where you can uniquely split space and time and define a world-time.
In more general cases, there is no global splitting possible and you would have no way to separate space curvature and curvature in the timelike dimension. Even in the Kerr metric, you have cross-terms between phi and t, so they are intertwined. Also remember any local observer can establish a "boost" to a local Lorentz frame of different velocity, and in that frame the constant-time sections are different. Wrong? Well, I mean that you are using one form of the Schwarzschild metric, but the are isotropic forms, and a form where the ingoing and outgoing null lines are used as axes (Kruskal-Szekeres metric [1]) Pdn 03:57, 17 Jun 2005 (UTC)
Sorry - I thought I was reading that you separated space and time curvature, but I guess it was someone else writing on your page. About that reference to a "web course" by Kevin Brown I think (as I wrote on Cleon Teunissen's page) it is mostly hogwash - so maybe someone will delete it. I changed the comments once and they were changed back so I am tired. Pdn 04:55, 18 Jun 2005 (UTC)
I do not find the link stale: [2] . Are we on the same page (no pun)? The same "mathpages.com"? We should be so lucky it goes stale. Or more stale. There is a lot of wrong science or at least very unlikely science out there and it attracts the innocent. For example there is something called The Wu-Li Dancing Masters which promotes a hidden agenda of the Bohm hidden variables "theory" (ruled out I believe by Alain Aspect and others). There is probably not much wrong in the "mathpages" link, just fluff. Well, there are some odd remarks:"The real content of Einstein's principles is that light is an inertial phenomena (despite its apparent wavelike nature). " Pdn 02:59, 19 Jun 2005 (UTC)
I think it is getting too far afield and I regret asking for a reference, but thanks (I looked up Earman a bit on the Web). Pdn 04:57, 18 Jun 2005 (UTC)
Hi EMS, I appreciate the trust that you put in my searching.
Web-searching is tedious business, it takes a lot of motivation. The 'black hole electron' doesn't get my blood racing, I'm afraid, so I guess I won't be looking into that matter.
The aspect of relativity that attracts my attention these days is time dilation. Keep watching the Talk:time_dilation page. -- Cleon Teunissen | Talk 18:51, 19 Jun 2005 (UTC)
Hi You wrote: "I assure you that the physics as viewed in a rotataing/accelerated frame of reference has meaning, even if the bottom line is that the same results are obtained in either case. The ability of use an accelerated viewpoint is especially important in GR, where you can be in a spaceship moving intertially, but the effects of gravitation are such that the objects distant from you are being accelerated, and effects such as gravitational time dilation and red/blue shifting are none-the-less revealing themselves.
Relatitivy fundamentally is about how perceptions of the same events are changed by virtue of being in different frames of reference. In essesnse, changing frames of reference is a gedanken is nothing more than putting yourself is someone else's shoes. In that regard their state of motion (be it inertial or not) should not matter. -"
By contrast: as seen from a point of view that is accelerating the speed of light appears to be non-isotropic, and I am rather suspicious about that.
I very much doubt that describing physics from an accelerating point of view has any meaning at all. EMS insisted that in the Sagnac effect article the physics should also be described as seen from a rotating frame of reference. I tend towards the opinion that describing physics from the point of view of a rotating frame of reference does not carry any physical meaning." was written by Teunisson, so it might be better to reply to him.
I will think more about the Michaelson-Morley experiment as related to acceleration. I think you are right - this cross dialogue is going too fast. But the idea was to detect differences in the "aether drift" as the apparatus turned (with the Earth). If it were in inertial motion the supposed drift would not show up as a fringe shift. A rotating reference frame is accelerated. Pdn 00:41, 21 Jun 2005 (UTC)
To some extend it is a moot point; the same results are obtained either way. That implies that the matter cannot be decided by experiment, and it is not clear whether a matter that cannot be decided by either logic or experiment is worth scratching one's head over.
I choose to apply Occam's Razor: in this particular area I restrict my hypotheses to the minimal set of hypotheses that suffices to account for the physics taking place.
I know what you mean by that, but personally I prefer to avoid any formulation that carries with it the suggestion that in relativity theory active participation of the observer matters for the physics taking place.
I prefer to formulate in such a way that it is clear that if the observers do not put themselves in the other guys shoes the same physics will take place. Whether the observer understands the physics or not, the same things will happen.
What I find intriguing about relativity is that there are the invariants, like the invariant space-time interval, that seem to suggest that there is an "arena" where these invariants exist, and that this is the true arena of physics. But every physical interaction, say a photon being detected and its frequency determined, occurs in such a way that space and time are split in a particular way. A photon may be emitted with an energy that corresponds to a light-wavelength of, say 400 nanometer, and the same photon can on absorption be detected to have an energy that corresponds to an 800 nanometer light-wavelength. For different observers space and time are split up differently, and we call that difference 'relative velocity'. I am inclined to think that the invariant qualities are closer to the true physics than the measurements, that are always subject to a particular split of space and time.
I am inclined to believe that relativity is fundamentally about the properties of Minkowski space-time, and more generally, about the properties of curved Minkowski space-time.
Yes, of course the ability to perform transformations between frames that are being accelerated with respect to each other is vital. In order to model the transmission of timing signals from a GPS satellite to a reciever on the ground, the following frame of reference is used: the non-rotating frame of reference that is co-moving with the Earth in its geodesic-following motion around the Sun. Both the GPS satellite and the reciever are moving with respect to that inertial frame of reference, so appropriate transformations need to be applied, and general relativity provides these transformations. -- Cleon Teunissen | Talk 08:18, 21 Jun 2005 (UTC)
I looked it up. As it turns out, it was
Pdn himself who mixed up the sentence,
Pdn's quote was garbled, the original sentence was correct.
By the way, I have never encountered any problem in browsing mathpages.com. I browse mathpages.com frequently, never a problem. It is unclear what makes the link appear stale to you.
In [
chapter 2, section 1] it is written:
-- Cleon Teunissen | Talk 23:23, 21 Jun 2005 (UTC)
Pdn wrote:
I get the impression that the reasoning of
Pdn goes as follows:
That is my tentative reconstruction of
Pdn's reasoning.
--
Cleon Teunissen |
Talk 07:41, 22 Jun 2005 (UTC)
Hi EMS,
About the credentials of Kevin Brown, the author of Reflections on Relativity
I did a Google search of Newsgroups with the following search terms: "Kevin Brown" "Chris Hillman"
There were several threads in which both Kevin Brown and a Chris Hillman had posted. One thread was started by Kevin Brown in the newsgroep sci.physics.relativity.
Datum: 1998/05/10
Onderwerp: Loxodromic Aliasing
A Chris Hillman replied:
From: Chris Hillman <hill...@math.washington.edu>
Datum: 1998/05/10
Onderwerp: Re: Loxodromic Aliasing
On Sun, 10 May 1998, Kevin Brown wrote:
> When describing the appearance of a sequence of states we sometimes
> need to account for the phenomenon of aliasing.
Good grief, this is even more subtle that my Paradox Resolved post
indicated! :-/ But, good point, Kevin, this is still another issue which
needs to be explained by anyone presenting a relativistic starflight
simulation.
This again shows the importance of superimposing on the star field say
yellow Steiner circles (or loxodromic spirals as the case may be) showing
the orbits of a given one parameter subgroup and say white circles of
constant red/shift blue shift (which vary with parameter).
[end quote of message by Chris Hillman]
Considering this reply by Chris Hillman, and other replies, my impression is that Chris Hillman has a pretty good idea of Kevin Brown's level of competence, and that he considers Kevin Brown to be on equal par to himself in the field of theoretical physics.
--
Cleon Teunissen |
Talk
21:33, 11 July 2005 (UTC)
i just threw a massive edit on that piece. please let me know what you think. Hamster Sandwich 00:23, 21 July 2005 (UTC)
Just left a comment for you on the VfD page. Summary is that I agree with everything you say about the need for copious citation and careful wording; apologize for not having the time to help out more right now; disagree with the claim that I'm ignorant of this material. Comment's still on the page. Take care. Babajobu 13:32, 21 July 2005 (UTC)
I'm understanding "religious persecution" as being the persecution of a minority religious group by a majority religious group. JDL doesn't qualify because a minority militant group is not capable of "persecution" as I'm defining it. The Kahane-ites were never part of the majority anywhere...except perhaps the ones in the West Bank, which would be covered under Israel. The Hasmoneans, as far as I know, could only qualify if they tried to Hellenize more traditional Jews. Even though they originally revolted against Hellenic occupation, they were pretty much Hellenized Jews themselves. That's my understanding. Babajobu 02:20, 22 July 2005 (UTC)
Hi Ems. You may have had this trivial remark before: do you want to write something on (or create) your user page ? It would get rid of the only red link on my user page :) Mpatel ( Talk).
Ril enlisted Persecution by Muslims for VfD again, just 24 hours after the article withstood the first VfD. You might be interested to watch it.
[3] --
Germen (
Talk |
Contribs
)
10:19, 30 July 2005 (UTC)
No confusion. I actually think that your overhaul of the GR article is cool. — AugPi 04:34, 2 August 2005 (UTC)
Dear EMS, following your boldness at Inertial frame of reference, I've done something simliar at Fictitious force. I'm pretty sure you know about this stuff, and would be grateful for your opinion. William M. Connolley 14:43:48, 2005-08-02 (UTC).
Currently, after the new edits, the coriolis effect article is contradicting itself badly. It is now a mosaic of fragments, written from incompatible points of view. William M Connolley acknowledges that the diagrams Image:Coriolis_effect10.png and the version Image:Coriolis_effect09.png are relevant for describing the formation of cyclonic flow, and his statements in the article indicate that he believes that the flow pattern is to be understood as a transformation from one frame of reference to another
, the second frame rotating with respect to the first. (In the case of meteorology the transformation is invariably from a fixed-to-the-stars frame to a frame that is co-rotating with Earth, rotating around the Earth axis.)
I disagree with William's assertions on this matter.
The diagrams are relevant, which is why I manufactured them along with the animations, but nothing in the diagrams is related to coordinate transformation.
On a more general level: the underlying assumption of William M Connolley is that GRT has shown there is a one-on-one correspondence between relativity of linear velocity and relativity of angular velocity.
Given William M Connolley's reasoning, he will reject the content of the
sagnac interferometer article, claiming that it violates GRT.
It has been months since William M Connolley and I have discussed this, his position may have altered since then. However, William's edits to the coriolis effect article do "breathe" the assumptions that also lead to the opinion that a Sagnac interferometer can only indicate a process of changing of angular velocity, but not angular velocity with respect to the local inertial frame of reference. --
Cleon Teunissen |
Talk
11:43, 3 August 2005 (UTC)
I may have stated in the past that a Sagnac interferometer measures absolute rotation, but I have since retracted from that position. I now state the following things:
Of course, it is meaningless to talk about such a thing as whether the universe as a whole rotates. Only what can be observed can be meaningfully discussed. There are no known instances of parts of space rotating with respect to the universe as a whole, and the cosmological models do not allow for such a possibility.--
Cleon Teunissen |
Talk
16:28, 3 August 2005 (UTC)
Yes, it would have been very strange indeed if that would have been your position.
So, for the umpteenth time we are back to square one, in a babylonian confusion of biblical proportion.
To understand that flow pattern there is no need to consider coordinate transformation, I just look at the physics. I am exclusively interested in the physics.
The mathematics of the coordinate transformation is obvious and transparent. I do not see why coordinate transformation should be discussed at all in discussing meteorology, the coordinate transformation is just a mathematical tool.
That has been my ongoing puzzlement. Why discuss coordinate transformation at all? As I said, the coordinate transformation involved is obvious and transparent, it is a mystery to me why William has kept explaining something that is A) glaringly obvious, and B) not involved in the physics.
It has now been confirmed that the red arrows in the diagrams on the right are unrelated to coordinate transformation.
For the coriolis effect article I have been writing about what physics the red arrows represent, for that is very interesting physics.-- Cleon Teunissen | Talk 17:01, 3 August 2005 (UTC)
I think the ring laser interferometer is the clearest demonstration of the Sagnac effect.
When a ring laser interferometer is not rotating with respect to the local inertial frame of reference, then then both counterpropagating flows of laserlight have the same frequency. When a ring laser interferometer is rotating with respect to the local inertial frame of reference, then there is a splitting of the frequencies, as described in the Sagnac effect article.
Some of the laserlight is diverted, and the two freqencies are brought to interference, leading to a beat frequency.
The university of Canterbury, new Zealand employs such a ring laser interferometer, one with a diameter large enough to measere the rotation of the Earth. The ring laser interferometer is in a deep cave, shielded as much as possible from any influence. The ring laser interferometer, is rotating with respect to space, so there is a splitting of the frequencies, resulting in a beat frequency of about 71 Hertz, consistent weith one rotation per sidereal day. The advantage of the ring laser interferometer for measuring the rotation of the Earth with respect to space is that small fluctuations in the beat frequency, related to Earth quakes, are picked up too.
Anyway, the point is: there are numerous ways to measure rotation with respect to local space, the ring laser interferomete is one of them, and because it works with light, I feel it is a bit more spectacular. -- Cleon Teunissen | Talk 17:24, 3 August 2005 (UTC)
So there is no calibration involved, it just works straight away.-- Cleon Teunissen | Talk 17:34, 3 August 2005 (UTC)
Months and months ago I mentioned the Sagnac interferometer to William, and he expressed doubts. --
Cleon Teunissen |
Talk
17:24, 3 August 2005 (UTC)
Of course there is no reason at all to invoke GR in discussing meteorology, the things I wrote for the coriolis effect article are strictly classical mechanics. I wouldn't have it any other way.
The
Ballistics section of the coriolis effect article is written by me, and other editers have left it the way it was. I wrote:
Anyway, that is all straightforward stuff.
The diagrams on the right, simplified as they are, are very relevant for understanding how cyclonic winds start, and the red arrows represent something, and the coriolis term in the equation of motion is unrelated to the red arrows in the diagrams.
The coriolis term is helpful when looking at motion that is a straight line as seen from one point of view (and thus curvilinear as seen from another, rotating point of view.) In the case of the diagrams on the right the motion with respect to the inertial frame of reference is curvilinear to begin with.
Reading the articles of the meteorologist Anders Persson made me aware of what the red arrows represent. It's really cool classical mechanics, worth looking into. -- Cleon Teunissen | Talk 02:10, 4 August 2005 (UTC)
EMS, I know you think you are only trying to help, but you must have assumed (since you didn't even ask me before making the change) that I had no good reason for not wanting to make this change, at least not right now, but in fact I do have good reason not to want you to monkey with this. TIA, CH (talk) 00:31, 6 August 2005 (UTC)
Not a problem EMS, oh and ty for creating a user page :). --- Mpatel (talk) 11:16, August 8, 2005 (UTC)
Hi, EMS, I have a wikicode question for you. Go to the "Exact solutions in general relativity" category and then follow the link to the article on "Aichelburg/Sexl ultraboost". While modifying another page, I noticed that I can't seem to get other articles to link correctly to this one. Looking at the url of the article, I see that the wikiserver may have interpreted the slash in the name as indicating a directory, which probably would not be good. Can you see how to link to this article? If not, can you see how to give it a name so that the slash appears to the reader, but the wikiserver can still link to it? If not, obviously, I'll have to change the name to "Aichelburg-Sexl ultraboost".
I have a preference for "Kerr/Newman" rather than "Kerr-Newman", and so forth, because hyphenated names are not unknown and can play havoc with the hyphen convention. However, if Wiki does not support this choice, I should know now, before I go and start trying to create lots of articles in the "Exact solutions in general relativity" category.--- CH (talk) 19:53, 9 August 2005 (UTC)
In response to your libelous false portrayal of my thoughtful and informative contributions to the cosmology article as NOT being thoughtful and informative, and furthermore as being mere diatribes, your use of a guise of being considerate so as to make your deceptions more convincing, and your act of giving small, nearly-insubstantial concessions in the guise of being considerare, so as to make more convincing the deception that other edits should not be allowed, thus demonstrating your malicious calculating nature, I have created a request for arbitration. Go ahead and make your statement on the arbitration page, not that it will make any difference. Your clever deceptions that I have pointed out are plain to see in the talk:cosmology page and the cosmology article history that they refer to, and the only way that the arbitrators will side with you is if they too have blind faith in the big bang belief, as well as the dominant temperament to suppress any facts that indicate that the big bang belief is anything less than a certain and obvious truth. --216.112.42.61