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Shouldn't this article give an explanation as to the assumed contradiction that light cannot exert pressure because photons have zero mass? —Preceding unsigned comment added by 213.84.241.121 ( talk) 11:44, 3 February 2010 (UTC)
I am just guessing here - have you taken into account the radiation from the oscillating particle? The radiation from the oscillating particle will carry momentum and it could be that for the case you have mentioned, the momentum lost by the radiation of the oscillating particle is equal to the amount gained from the external EM field. PAR ( talk) 22:32, 25 January 2011 (UTC)
—Preceding unsigned comment added by 217.149.104.6 ( talk) 15:42, 12 April 2008 (UTC)
"In heaviest stars radiation pressure is the dominant pressure component." Can anyone explain why in heavy stars radiation pressure has a greater effect than gas pressure?
I know that this sort of question comes up from time to time when people discuss solar sails, but I'd like to ask it here for the possibility of getting different kinds of reply. It is always stated that the radiation pressure is doubled if the incident radiation is entirely reflected, but if the momentum change is transferred entirely to the object the radiation is incident on, then conservation of energy is violated. My question, then, is: "Is the solution simply that we cannot have perfect reflection?" or is there something more complicated going on? - MarkHudson 08:09, 29 July 2005 (UTC)
I'm moving this commentary out of the article and onto the talk page:
I don't know enough physics to know how to deal with this, so I'll just leave it here. :) -- Michael Kelly 09:57, 12 June 2006 (UTC)
I have a problem with the statement that the energy density for a black body is . It should be which is the radiation constant
The energy density of a black body per unit frequency is (see Planck's law of black body radiation or Hyperphysics)
Integrating this from ν=0 to infinity gives for the energy density
and the Stefan Boltzmann constant is (see Stefan-Boltzmann law and Stefan-Boltzmann constant)
substituting gives . Did I go wrong here or is the article wrong? PAR 00:17, 20 November 2006 (UTC)
Neat image. Would be cool to get permission for the image somehow. -- Eean 15:04, 29 March 2007 (UTC)
What is the total amount of light pressure of the Sun light on Earth? —Preceding unsigned comment added by 86.163.165.101 ( talk) 12:20, 27 August 2008 (UTC)
Useful for active ablative armor systems, feedback loops offer protection from bullets to explosions, as well rebreather filters can utilize this force given a sufficient power source. However verifiable sources of applied consumer goods as well as concepts are to be calculated and debated. Aditya.m4 ( talk) 03:16, 19 January 2010 (UTC)
The primary real world application of radiation pressure is in the two-stage thermonuclear warhead. In that case, the pressure is not slight, it is huge (140 TPa). You should mention it here.
/info/en/?search=Thermonuclear_weapon
Anorlunda (
talk) 13:27, 20 July 2014 (UTC)
hey i got a web http://www.blazelabs.com/f-g-rpress.asp that explain it quiet well for elementary level —Preceding unsigned comment added by ArielGenesis ( talk • contribs) 21:52, 9 June 2010 (UTC)
Including Casimir Effect as it is related... LucianSolaris ( talk) 07:53, 9 October 2010 (UTC)
"It may be shown by electromagnetic theory" is insufficient theoretical reference. Please, add more detailed explanations or derivations, or apropriate references. Especially useful will be direct derivation from Maxwell equations or Lorentz force equation. Softvision ( talk) 10:30, 22 January 2011 (UTC)
Yes. The article is good and the source is OK, but is the article referring to reflected or absorbed radiation pressure? Is the coefficient 1/3 or 2/3? Probably a combination of sources are needed here, some with simple and some with mathematical explanations.. 172.129.73.71 ( talk) 20:12, 8 September 2011 (UTC)BG.
This article doesn't have any explanation of WHY radiation exerts pressure. How about something that explains this in a sort of intuitive way, or if that is impossible, says that no one understands why it happens, but there is experimental proof that it does. Right now the article is very technical, pitched towards people who have degrees in physics rather than the average reader. It seems to assume that anyone reading it already has a basic understanding of what light pressure is and how it works. Which is what I was trying to find out when I looked it up. Can't you put in a top level section that is easy enough for most people to understand? Right now you are losing about 99% of the population. —Preceding unsigned comment added by 74.38.247.10 ( talk) 13:50, 21 May 2011 (UTC)
The article says "It may be shown by electromagnetic theory, by quantum theory, or by thermodynamics, making no assumptions as to the nature of the radiation, that the pressure against a surface exposed in a space traversed by radiation uniformly in all directions is equal to one third of the total radiant energy per unit volume within that space.[citation needed]". Is it really possible to derive it from thermodynamics alone, without any information about electromagnetic theory? I would be very interested to see the reference if so, but I suspect it's not possible. Planck derived most of the properties of radiation from thermodynamics alone, but he got the starting point of p=U/3V from Maxwell's equations. Nathaniel Virgo ( talk) 10:40, 2 January 2012 (UTC)
is apparently incorrect: for black bodies it yield zero force!
The correct one should be:
I am making an effort to tighten up the article. A lot of things have gotten into it that are out of scope and will be removed. An explanation of momentum is being added under the photon section. SpaceSailor 20:25, 31 July 2013 (UTC)
In the section Laser applications of radiation pressure there's a mention of laser radiation pressure being used for fusion research. The force on the pellet is primarily ablation of the surface. In fact in many cases, radiation pressure is confused with other effects involving the transfer of real mass - see the Crookes Radiometer for example.
I will revise this paragraph, and perhaps add a reference to Effects Commonly Confused With Radiation Pressure. Thomasonline ( talk) 15:39, 11 September 2014 (UTC)
This inserted topic is based on speculative, unsubstantiated pseudo-physics. A single source from 1968 without any experimental verification is not adequate, and not appropriate for this article--this article is not about speculative physics. Unless the author of the insert presents some hard evidence and shows acceptance by the physics community, it will be removed. SpaceSailor ( talk) 01:49, 17 March 2016 (UTC)
I took out the mass term since photons have no mass E= pc — Preceding unsigned comment added by 129.105.151.10 ( talk) 19:45, 4 June 2016 (UTC)
The vanes spin the same way as a Crookes Radiometer in the video, showing the greater force exerted on the black face rather than the reflective face. Vanes rotating the opposite direction would be expected with a radiation pressure demonstration because more momentum would be transferred to the reflective face on the vanes. I couldn't find a good video of a Nichols Radiometer, so I suggest this video should be removed or replaced with something which illustrates the concept described in this section. — Preceding unsigned comment added by 67.170.72.164 ( talk) 03:24, 10 October 2016 (UTC)
I may be wrong but in the optical tweezers section the force of a 30mW laser is 1E-10 and not 10E-10. A 1MW laser would give a force of 0.34 grams.
I expect that radiation pressure decreases by a factor greater than the square of the radius, because photons would not only spread-out, but also lose momentum or be red-shifted as they go against gravity. This effect would be very small in a low-gravity environment, but near a black-hole, it would be very significant. They pressure would also drop with distance as a result of interaction with interstellar medium. The pressure density would also be affected by dopler effects if the star or accretion disk is rotating, causing the peak-intensity to be offset from the centre of mass. MathewMunro ( talk) 00:33, 19 April 2020 (UTC)
The article, in particular the "Discovery" section, claims that Maxwell proposed radiation pressure in 1862. I cannot (easily) find a source for this claim. I briefly leafed through Maxwell's personal and scientific letters for 1862 and didn't find anything (although I may have just missed it), and the Nichols & Hunt paper references the treatise from 1873. If anyone knows the correct time and has a source for it, I think that would be beneficial. ChristofferOestfeldt ( talk) 15:48, 25 May 2022 (UTC)
We need an explanation for how radiation pressure is explained using the theory of general relativity. OpticalSystem ( talk) 17:24, 14 January 2024 (UTC)
It has been colonised by people having 'their own theory' and by students who are 'still studying'. No traditional encyclopedia would permit its readers to be confused by amateur opinions, so why should Wikipedia allow it? This is a very 'mature' topic, and no doubt concerning it exists in the minds of physicists. If Wikipedia readers do not understand the subtleties, they should seek out suitable textbooks rather than misleading others. One cannot help but think that the fatuous EmDrive propulsion device was proposed by Roger Shawyer simply because he confused himself by using some of the defective reasoning demonstrated here. 78.145.10.148 ( talk) 18:27, 18 May 2024 (UTC)
This is the
talk page for discussing improvements to the
Radiation pressure article. This is not a forum for general discussion of the article's subject. |
Article policies
|
Find sources: Google ( books · news · scholar · free images · WP refs) · FENS · JSTOR · TWL |
This
level-5 vital article is rated Start-class on Wikipedia's
content assessment scale. It is of interest to the following WikiProjects: | ||||||||||||||||||||||||
|
Shouldn't this article give an explanation as to the assumed contradiction that light cannot exert pressure because photons have zero mass? —Preceding unsigned comment added by 213.84.241.121 ( talk) 11:44, 3 February 2010 (UTC)
I am just guessing here - have you taken into account the radiation from the oscillating particle? The radiation from the oscillating particle will carry momentum and it could be that for the case you have mentioned, the momentum lost by the radiation of the oscillating particle is equal to the amount gained from the external EM field. PAR ( talk) 22:32, 25 January 2011 (UTC)
—Preceding unsigned comment added by 217.149.104.6 ( talk) 15:42, 12 April 2008 (UTC)
"In heaviest stars radiation pressure is the dominant pressure component." Can anyone explain why in heavy stars radiation pressure has a greater effect than gas pressure?
I know that this sort of question comes up from time to time when people discuss solar sails, but I'd like to ask it here for the possibility of getting different kinds of reply. It is always stated that the radiation pressure is doubled if the incident radiation is entirely reflected, but if the momentum change is transferred entirely to the object the radiation is incident on, then conservation of energy is violated. My question, then, is: "Is the solution simply that we cannot have perfect reflection?" or is there something more complicated going on? - MarkHudson 08:09, 29 July 2005 (UTC)
I'm moving this commentary out of the article and onto the talk page:
I don't know enough physics to know how to deal with this, so I'll just leave it here. :) -- Michael Kelly 09:57, 12 June 2006 (UTC)
I have a problem with the statement that the energy density for a black body is . It should be which is the radiation constant
The energy density of a black body per unit frequency is (see Planck's law of black body radiation or Hyperphysics)
Integrating this from ν=0 to infinity gives for the energy density
and the Stefan Boltzmann constant is (see Stefan-Boltzmann law and Stefan-Boltzmann constant)
substituting gives . Did I go wrong here or is the article wrong? PAR 00:17, 20 November 2006 (UTC)
Neat image. Would be cool to get permission for the image somehow. -- Eean 15:04, 29 March 2007 (UTC)
What is the total amount of light pressure of the Sun light on Earth? —Preceding unsigned comment added by 86.163.165.101 ( talk) 12:20, 27 August 2008 (UTC)
Useful for active ablative armor systems, feedback loops offer protection from bullets to explosions, as well rebreather filters can utilize this force given a sufficient power source. However verifiable sources of applied consumer goods as well as concepts are to be calculated and debated. Aditya.m4 ( talk) 03:16, 19 January 2010 (UTC)
The primary real world application of radiation pressure is in the two-stage thermonuclear warhead. In that case, the pressure is not slight, it is huge (140 TPa). You should mention it here.
/info/en/?search=Thermonuclear_weapon
Anorlunda (
talk) 13:27, 20 July 2014 (UTC)
hey i got a web http://www.blazelabs.com/f-g-rpress.asp that explain it quiet well for elementary level —Preceding unsigned comment added by ArielGenesis ( talk • contribs) 21:52, 9 June 2010 (UTC)
Including Casimir Effect as it is related... LucianSolaris ( talk) 07:53, 9 October 2010 (UTC)
"It may be shown by electromagnetic theory" is insufficient theoretical reference. Please, add more detailed explanations or derivations, or apropriate references. Especially useful will be direct derivation from Maxwell equations or Lorentz force equation. Softvision ( talk) 10:30, 22 January 2011 (UTC)
Yes. The article is good and the source is OK, but is the article referring to reflected or absorbed radiation pressure? Is the coefficient 1/3 or 2/3? Probably a combination of sources are needed here, some with simple and some with mathematical explanations.. 172.129.73.71 ( talk) 20:12, 8 September 2011 (UTC)BG.
This article doesn't have any explanation of WHY radiation exerts pressure. How about something that explains this in a sort of intuitive way, or if that is impossible, says that no one understands why it happens, but there is experimental proof that it does. Right now the article is very technical, pitched towards people who have degrees in physics rather than the average reader. It seems to assume that anyone reading it already has a basic understanding of what light pressure is and how it works. Which is what I was trying to find out when I looked it up. Can't you put in a top level section that is easy enough for most people to understand? Right now you are losing about 99% of the population. —Preceding unsigned comment added by 74.38.247.10 ( talk) 13:50, 21 May 2011 (UTC)
The article says "It may be shown by electromagnetic theory, by quantum theory, or by thermodynamics, making no assumptions as to the nature of the radiation, that the pressure against a surface exposed in a space traversed by radiation uniformly in all directions is equal to one third of the total radiant energy per unit volume within that space.[citation needed]". Is it really possible to derive it from thermodynamics alone, without any information about electromagnetic theory? I would be very interested to see the reference if so, but I suspect it's not possible. Planck derived most of the properties of radiation from thermodynamics alone, but he got the starting point of p=U/3V from Maxwell's equations. Nathaniel Virgo ( talk) 10:40, 2 January 2012 (UTC)
is apparently incorrect: for black bodies it yield zero force!
The correct one should be:
I am making an effort to tighten up the article. A lot of things have gotten into it that are out of scope and will be removed. An explanation of momentum is being added under the photon section. SpaceSailor 20:25, 31 July 2013 (UTC)
In the section Laser applications of radiation pressure there's a mention of laser radiation pressure being used for fusion research. The force on the pellet is primarily ablation of the surface. In fact in many cases, radiation pressure is confused with other effects involving the transfer of real mass - see the Crookes Radiometer for example.
I will revise this paragraph, and perhaps add a reference to Effects Commonly Confused With Radiation Pressure. Thomasonline ( talk) 15:39, 11 September 2014 (UTC)
This inserted topic is based on speculative, unsubstantiated pseudo-physics. A single source from 1968 without any experimental verification is not adequate, and not appropriate for this article--this article is not about speculative physics. Unless the author of the insert presents some hard evidence and shows acceptance by the physics community, it will be removed. SpaceSailor ( talk) 01:49, 17 March 2016 (UTC)
I took out the mass term since photons have no mass E= pc — Preceding unsigned comment added by 129.105.151.10 ( talk) 19:45, 4 June 2016 (UTC)
The vanes spin the same way as a Crookes Radiometer in the video, showing the greater force exerted on the black face rather than the reflective face. Vanes rotating the opposite direction would be expected with a radiation pressure demonstration because more momentum would be transferred to the reflective face on the vanes. I couldn't find a good video of a Nichols Radiometer, so I suggest this video should be removed or replaced with something which illustrates the concept described in this section. — Preceding unsigned comment added by 67.170.72.164 ( talk) 03:24, 10 October 2016 (UTC)
I may be wrong but in the optical tweezers section the force of a 30mW laser is 1E-10 and not 10E-10. A 1MW laser would give a force of 0.34 grams.
I expect that radiation pressure decreases by a factor greater than the square of the radius, because photons would not only spread-out, but also lose momentum or be red-shifted as they go against gravity. This effect would be very small in a low-gravity environment, but near a black-hole, it would be very significant. They pressure would also drop with distance as a result of interaction with interstellar medium. The pressure density would also be affected by dopler effects if the star or accretion disk is rotating, causing the peak-intensity to be offset from the centre of mass. MathewMunro ( talk) 00:33, 19 April 2020 (UTC)
The article, in particular the "Discovery" section, claims that Maxwell proposed radiation pressure in 1862. I cannot (easily) find a source for this claim. I briefly leafed through Maxwell's personal and scientific letters for 1862 and didn't find anything (although I may have just missed it), and the Nichols & Hunt paper references the treatise from 1873. If anyone knows the correct time and has a source for it, I think that would be beneficial. ChristofferOestfeldt ( talk) 15:48, 25 May 2022 (UTC)
We need an explanation for how radiation pressure is explained using the theory of general relativity. OpticalSystem ( talk) 17:24, 14 January 2024 (UTC)
It has been colonised by people having 'their own theory' and by students who are 'still studying'. No traditional encyclopedia would permit its readers to be confused by amateur opinions, so why should Wikipedia allow it? This is a very 'mature' topic, and no doubt concerning it exists in the minds of physicists. If Wikipedia readers do not understand the subtleties, they should seek out suitable textbooks rather than misleading others. One cannot help but think that the fatuous EmDrive propulsion device was proposed by Roger Shawyer simply because he confused himself by using some of the defective reasoning demonstrated here. 78.145.10.148 ( talk) 18:27, 18 May 2024 (UTC)