
#19
Feb710, 06:32 PM

P: 1,540





#20
Feb710, 06:40 PM

Sci Advisor
P: 8,004

Anyway, I happen to like the modern form of Lorentz's viewpoint much better than Einstein's spacetime view (but I almost always calculate with Einstein's view!), and found it interesting that Lorentz himself stated the need for a unique ground state, which classical electrostatics does not have, but which Swann later pointed out is potentially provided by quantum mechanics. I have to ask  even till this day, do we know if Swann's argument has an explicit instantiation? After all, our theories of solid bodies are all nonrelativistic, and are almost surely not any ground state of the standard model, which unlike classical special relativity, is not a consistent theory to arbitrarily high energies. 



#21
Feb710, 06:42 PM

P: 1,743

There is another approach, which is more logical in my opinion. It is based on wellknown postulates of Poincare symmetry and quantum mechanics. No extra assumptions are made. The main idea is contained in E. P. Wigner, "On unitary representations of the inhomogeneous Lorentz group", Ann. Math., 40 (1939), 149. Applications to interacting systems are in P. A. M. Dirac, "Forms of relativistic dynamics", Rev. Mod. Phys., 21 (1949), 392. In this approach, there is no need to make any assumption about transformation laws of physical observables. These laws follow automatically from the dynamical description of any given system. It appears that in the presence of interactions positions of particles (or events) do not transform by usual linear Lorentz formulas: E. V. Stefanovich, "Is Minkowski spacetime compatible with quantum mechanics?", Found. Phys., 32 (2002), 673. Eugene. 



#22
Feb710, 07:27 PM

Sci Advisor
P: 8,004





#23
Feb710, 08:03 PM

P: 1,743

This issue becomes very obscure in textbook (nondressed) presentations of QFT. Because in the traditional approach, QFT can be used only to obtain scattering amplitudes. So, the time evolution of particle observables and their boost transformations is simply not available. Eugene. 



#24
Feb710, 08:27 PM

P: 140

In regards to the thought experiments they I'll say for me it tended to distract from the unified space time. I don't have an educated background in physics, or math beyond geometry. I was able to see at least to me the unification of space time when I dispensed with the clocks and such and by taking a view that removing time in the picture since it was already a function of the velocity and distance against the limit set by c. the light went off (bad pun). I think and hopefully I'm not far off, that time is just as arbitrary as distance since it's defined by the ratio of your velocity to c. for each frame of reference the measurement of time and distance is set by that ratio. and I arrive at that from the view of space time as the velocity of c. I don't know how to explain the construct I see in my head. I'm going to work on the units and math to see if I can find problems with my view. Thankfully I do understand Cartesian coordinates as I've been doing 3d computer modeling and animation for 20yrs. 



#25
Feb710, 09:08 PM

Emeritus
Sci Advisor
P: 7,434

I'm not sure why the title contains the word "crank"? The title is rather unfortunate, fortunately the thread doesn't seem to be about what the title claims.
Anyway, my general view is that energy and momentum are core physical concepts, but the concept of "mass" is less well defined, particularly as it applies to GR. Many discussions would be better off if the word were avoided and the focus kept on what was well defined. See for instance http://adsabs.harvard.edu/abs/2006PhTea..44...40H The problem in my opinion isn't really that "There is no good concept of mass", as the above article purports, the problem is "There are too many good concepts of mass". For example, in GR we have Komar, Bondi, and ADM masses as the "top three", along with an uncertain number of other proposals. 



#26
Feb810, 05:17 AM

P: 1,540

The problem of 'what is mass' is open to experiment and discussion, as well as being a question that is clear to anyone. How to figure out which description of mass is more than a fun model is... painfully hard. 



#27
Feb810, 08:04 PM

P: 253

I found a recent book (+2000/2002) with a monograph of a candidate model of particles were masses are derived from first principles, on top of electromagnetism. Because I can not find any review, any reference or criticism, we can easily assume that the model is 'crank'. But now I have a clear representation, a concept, and some equations of what is 'mass' . The model also made predictions on the masses of new particles, that are distinct of the known predictions. The author is a retired electronic engineer with a career dedicated to light. 



#28
Feb910, 09:39 PM

P: 69

Although, I haven’t read Ohanian’s recent text, “Einstein’s Mistakes”. If it's an aggressive polemic, that would be unfortunate. 


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