Physics Help Forum What's the secret behind v < c

 Special and General Relativity Special and General Relativity Physics Help Forum

 Jun 23rd 2019, 04:49 PM #11 Senior Member   Join Date: Mar 2019 Location: cosmos Posts: 583 fascinating @dragon: How did Einstein transform permittivity and permeability to be relativistic in his SR? ... In the ancient Chinese fiction Travelling to the West, Monk pig often was fascinated by beautys and wanted to station. It's the brothers that pulled his big ears all the way to the West... Attached Thumbnails
Jun 23rd 2019, 05:45 PM   #12

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 Originally Posted by neila9876 @dragon: How did Einstein transform permittivity and permeability to be relativistic in his SR?
I doubt he bothered. As far as I know he didn't apply electrodynamics at any point, except with reference to the Lorentz transformations. He just used that c is constant between any two reference frames.

Here's a link to his 1905 SR paper, "On the Electrodynamics of Moving Bodies." (Go to the first post and you can download the paper in pdf format.)

-Dan
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Last edited by topsquark; Jun 23rd 2019 at 05:48 PM.

 Jun 25th 2019, 06:55 AM #13 Senior Member     Join Date: Jun 2016 Location: England Posts: 1,011 Maxwell's equations gave the speed of EM radiation, but they did not indicate relative to what reference frame. This was noted at the time, and many physicists thought there must be a hole in the equations, that needed to be plugged. Many experiments were performed (Michelson-Morley) to identify the influence of the reference frame, None was found. Einstein embraced the implications of this, that there is no preferred reference frame, and "c" is the same for all observers. Making this assumption pretty much forces the mathematics toward his relativity theories. topsquark and neila9876 like this. __________________ ~\o/~
 Jun 25th 2019, 04:49 PM #14 Senior Member   Join Date: Mar 2019 Location: cosmos Posts: 583 SR vs SR When objects move in velocity v < c, their matter states do not change. You remain you, electron remains electron, etc. When something moves in velocity of c, it will be released photon only. The matter state of released photon is obviously different from you, electron, etc… The traditional 3D space SR contains a hidden condition: matter state does not change. (Actually, the so called “rest frame” or “moving frame” is attached to substantial object.) That’s why v < c is the premise of traditional 3D space SR. When people use SR to analyze space – time transformation, etc, concerning released photon, an element denoting matter state should be added. Moreover, anti matter, dark matter, etc, are different matter states…The traditional 3D space SR should be expanded with the element denoting matter states and then it will be sufficient to represent cosmos. With regard to the question of “light speed in photon frame”, I think that the traditional Lorentz transformation of speed is not applicable anymore because the observer and released photon are in different matter states. People have to find another way to do that.
Jun 25th 2019, 06:33 PM   #15

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 Originally Posted by neila9876 When objects move in velocity v < c, their matter states do not change. You remain you, electron remains electron, etc. When something moves in velocity of c, it will be released photon only. The matter state of released photon is obviously different from you, electron, etc… The traditional 3D space SR contains a hidden condition: matter state does not change. (Actually, the so called “rest frame” or “moving frame” is attached to substantial object.) That’s why v < c is the premise of traditional 3D space SR. When people use SR to analyze space – time transformation, etc, concerning released photon, an element denoting matter state should be added. Moreover, anti matter, dark matter, etc, are different matter states…The traditional 3D space SR should be expanded with the element denoting matter states and then it will be sufficient to represent cosmos. With regard to the question of “light speed in photon frame”, I think that the traditional Lorentz transformation of speed is not applicable anymore because the observer and released photon are in different matter states. People have to find another way to do that.
A few points:
1) v < c is not a premise, it's a prediction that SR makes. (Or you could also say v < c is a feature of the Lorentz transformations, which are a form of an invariance principle, similar to Galilean Relativity.)

2) For all we know dark matter is not matter at all. We don't know.

3) For particles moving at the speed of light, yes, the Lorentz transformations make little sense. We need QM to describe photons properly. (But we can always use $\displaystyle E = h \nu$ to do SR dynamics with.)

To wrap this up:
I probably shouldn't mention this but possible matter states can be predicted by merging SR and QM. This leads to the general categorization of particles with different spin states. For example, an electron is a spin 1/2 particle and is a member of the $\displaystyle ( 1/2, 0 ) \oplus ( 0, 1/2 )$ spinor representation. This also means that the relevent wave equation is the Dirac equation, which is specific to spin 1/2 spinor particles. We don't need to specify the "matter state" in order to get information about the particle in question. The "matter state" is already attached to the particle description by simply calling it an electron, or quark, or whatever.

I can provide more information about the representations and how to derive them if you like but it's not at the "layman" level of study and it would require a new thread.

-Dan

Addendum: What the heck is the "traditional 3D space SR?" Any form of SR is 4D and you always need to include the time component. SR really doesn't apply to spatial subgroups.
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Last edited by topsquark; Jun 25th 2019 at 06:38 PM.

 Jun 25th 2019, 07:23 PM #16 Senior Member   Join Date: Mar 2019 Location: cosmos Posts: 583 @dragon: !
 Jun 27th 2019, 10:03 AM #17 Senior Member   Join Date: Mar 2019 Location: cosmos Posts: 583 pig vs dog @dragon: Why should the expansion (development) of SR itself have something to do with QM, Dirac, etc? SR < QM, Dirac? Last edited by neila9876; Jun 27th 2019 at 10:12 AM.
Jun 27th 2019, 11:57 AM   #18

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 Originally Posted by neila9876 @dragon: Why should the expansion (development) of SR itself have something to do with QM, Dirac, etc? SR < QM, Dirac?
The assumption is that SR holds even on the quantum scale. So we go ahead and combine SR and QM. This leads to Quantum Field Theory.

As far as the wave equations:
The Schrodinger equation deals with non-relativistic particles and only spin 0 particles work well. For example, the S equation does not predict or use spin. On the other hand we can use the S equation for anything non-relativistic.

The Klein-Gordon equation deals with relativistic particles with spin 0.

The Dirac equation deals with relativistic partles with spin 1/2. The particles involved (like electrons but not massless particles like neutrinos) are called spinors.

The Weyl equation deals with massless relativistic particles with spin 1/2.

The Proca equation deals with relativistic particles with spin 1. (The Maxwell equations also hold in QM and deals with massless relativistic particles with spin 1.)

There are other wave equations, like for spin 3/2 particles and gravitons (spin 2) but I don't know the names of them. There is a procedure to derive the equations of particles with spins other than these. As you can see the spin of the particles is just as important as whether they have mass or not.

-Dan
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Last edited by topsquark; Jun 27th 2019 at 05:32 PM.

 Jun 27th 2019, 05:00 PM #19 Senior Member   Join Date: Mar 2019 Location: cosmos Posts: 583 pig vs dog @dragon: Does combination always prohibit individual expansion (development, freedom)? Attached Thumbnails
Jun 27th 2019, 05:34 PM   #20

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 Originally Posted by neila9876 @dragon: Does combination always prohibit individual expansion (development, freedom)?
Sorry, I don't know what you are asking?

-Dan
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