Talk:Scharnhorst effect: Difference between revisions

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Ati3414 added a link to his paper again, despite the fact that his musings on phase and group velocity are not related to this effect. The Scharnhorst efect is a quantum mechanical effect in which the vaccuum modes are less dense in one direction and therefore the light actually would travel faster in that direction. Trying to argue this away with classical mechanics arguements, not even taking the time to understand the physics here, and worst of all the self promotion ... must be stopped. Ati3414 I'd appreciate it if you stopped spamming your papers all over the physics topics. Thank you. Gregory9 00:26, 14 March 2006 (UTC)[reply]

Are you saying that there is no phase and group velocity in quantum mechanics? Remind that we must find the classical physics at different scale, no?Klinfran (talk) 19:58, 28 March 2009 (UTC)[reply]

Removed "Explanation" section

I removed this section because it's simply not correct. The speed of light in QED or the Standard Model is set by Lorentz invariance, and the Lorentz invariant speed c is the same as the speed of light c. Photons are not slowed by the vacuum. You could perhaps introduce a new physical theory in which they were, but Scharnhorst worked in the framework of QED, and QED doesn't work that way. Scharnhorst's 1998 paper (I don't have online access to the original one) certainly claims nothing of the sort. -- BenRG (talk) 15:37, 6 November 2009 (UTC)[reply]

Sounds like removal driven by OR, without an alternative explanation being available. What's your explanation of the effect then? --Michael C. Price ^talk 15:55, 6 November 2009 (UTC)[reply]

Have restored section. It had links to New Scientist which said essentially the same thing. By all means let's improve the explanation, but deletion isn't the answer.--Michael C. Price ^talk 16:03, 6 November 2009 (UTC)[reply]

I agree with rewriting the section. It is better to give the standard argument based on the effective coefficients of refraction for the photon moving parallel or perpendicular to the plates that one can derive from QED. The article by Visser et al. cited here gives these expressions. One can then discuss briefly how these expressions are derived from QED so that the assumptions that are made are clear.

As I understand it, the expressions for the effective indices of refractions are, strictly speaking, only valid in the limit of zero frequency. At finite frequency, diagrams of arbitrary high order in the loop expansion contribute to the leading 1/L power. Because one is interested in some given situation where the plates are at some fixed distance L, the frequency of the photon is necessarily finite. So you would need to do a non-perturbative computation to be 100% sure that the effect indeed exists. This was wrong. The issue is that you need the refractive index in the limit of infinite frequency to find out how the light front moves and that requires non-perturbative methods.Count Iblis (talk) 16:12, 6 November 2009 (UTC)[reply]

Remember WP:ESCA about alternative models -- both explanations are probably correct and thus both should be presented. The two restored links both explain the FTL effect via virtual pair supression.--Michael C. Price ^talk 16:20, 6 November 2009 (UTC)[reply]

It's fine with me if the section is rewritten rather than deleted, but it's not correct in its current form. New Scientist and Science News aren't reliable sources for information about quantum field theory. -- BenRG (talk) 17:41, 6 November 2009 (UTC)[reply]

They are good for accessible guides to QFT. And the fact that both sources give the same explanation should make us suspect that they are probably correct. Marcus Chown knows his oats, so to speak. --Michael C. Price ^talk 18:12, 6 November 2009 (UTC)[reply]

It rather makes me suspect that one copied it from the other. The Science News item has no byline.

Look. You can't assign a constant refractive index (other than 1) to the vacuum without breaking Lorentz invariance. Do you agree with that statement? Disagree with it? Not understand it? I'll continue based on your answer. -- BenRG (talk) 19:40, 6 November 2009 (UTC)[reply]

Sources?--Michael C. Price ^talk 21:03, 6 November 2009 (UTC)[reply]

Sources for what? -- BenRG (talk) 21:30, 6 November 2009 (UTC)[reply]

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 Ati3414 added a link to his paper ''again'', despite the fact that his musings on phase and group velocity are not related to this effect. The Scharnhorst efect is a quantum mechanical effect in which the vaccuum modes are less dense in one direction and therefore the light actually would travel faster in that direction.  Trying to argue this away with classical mechanics arguements, not even taking the time to understand the physics here, and worst of all the self promotion ... must be stopped.  Ati3414 I'd appreciate it if you stopped spamming your papers all over the physics topics.  Thank you. [[User:Gregory9|Gregory9]] 00:26, 14 March 2006 (UTC)