Re: A little challenge for relativists.

Bilge wrote:
shevek:
>Tom Roberts wrote:
>> I do not "defend" LET, I _explain_ it. As many of my writings have
>> shown, it is not useful, and its foundations are seriously flawed. SR is
>> experimentally indistinguishable from LET and does not share its
>> theoretical flaws.
>Which are the seriously flawed theoretical foundations?
List the theoretical foundations. 

1. There is an ether which permeates all of space and everywhere
   defines a unique intertial frame.

2. Clocks and rulers in motion wrt the ether frame behave as
   described by a Lorentz transform from the ether frame.

The problem with these assumptions is that because of the structure of the Lorentz transforms, _ANY_ inertial frame can be selected as "the ether frame" without changing the theoretical predictions for any measurement. So "the ether frame" becomes a mere label, of no physical significance whatsoever.

SR, of course, avoids that problem completely.

	Those are the aspects of LET that correspond to SR.
	Lorentz developed a complete _Theory_of_Electrons_,
	which is essentially the same as modern "classical
	electrodynamics" (in his 1904 paper he made a
	mistake in defining charge density, but corrected it
	in his 1915 monograph with that title).


I also disagree that the two are experimentally indistinguishable. 

The structure of the Lorentz group ensures it.


Consider the following coordinate transformation:
x^0 = ct - x With the metric tensor given by,
x^1 = ct + x g_01 = g_10 = 1/2, g_22 = g_33 = -1
x^2 = y x^3 = z

I think most people do not consider such null coordinates to be on the SR side of the boundary between SR and GR. That is, the semi-Riemannian geometry needed to justify them seems more in the spirit of GR than SR.


x^0 is the time coordinate and x^1 is the space coordinate.

No. Neither is timelike and neither is spacelike, they are both NULL. That is, the norm of d/dx^0 and the norm of d/dx^1 are both zero (NULL), because as you said, g_00 = g_11 = 0. That's why these are called "null coordinates".

	In GR such null basis vectors always come in pairs, as
	the signature of the metric is -2 and cannot be modified
	by a mere change of coordinates.


One of the assumptions of LET is the existence of absolute
simultaneaty, i.e., an absolute time which can be defined
for every observer,

Yes (it's not really "defined for every observer", it's just defined once and everybody uses it; or better, it just _is_).


and that time really slows down, lengths
really contract, etc.,

I don't think Lorentz would agree -- I have seen no such statements in any of his writing. He considers the moving coordinates {x',y',z',t'} as merely mathematical convieniences. But since the Maxwell's equations are identical in the ether and moving coordinates, it's clear that in a moving frame electromagnetic phenomena behave _exactly_ the same as in the ether frame when using those moving coordinates (that was the whole point of his 1904 paper). That's why I stated #2 above in terms of clocks and rulers (governed by electromagnetic phenomena), not space and time or distance and time-intervals.


LET doesn't tell me how to even imagine a way to construct a theory
of the weak interaction without reverse engineering it from relativity.

Yes. Today this is probably the bigest drawback of LET -- it lacks the essential Lorentz symmetry that has permitted the discovery of all modern fundamental theories of physics. Rather ironic, isn't it....


Tom Roberts	tjroberts@xxxxxxxxxx
.

Relevant Pages

  • Re: A little challenge for relativists.
    ... >> List the theoretical foundations. ... There is an ether which permeates all of space and everywhere ... Clocks and rulers in motion wrt the ether frame behave as ... > described by a Lorentz transform from the ether frame. ...
    (sci.physics.relativity)
  • Re: What is LET?
    ... that the coordinates are related to those of the ether frame by a Lorentz transform. ... Because of the structure of the Lorentz group, the choice of ether frame is completely arbitrary, the ether frame is completely unobservable, and LET is experimentally indistinguishable from SR. ... a theory consists of some postulates, the theorems derived from ... select the theoremthat applies to the experimental measurement ...
    (sci.physics.relativity)
  • Re: A little challenge for relativists.
    ... There is an ether frame that is inertial and global. ... relating moving coordinates to ether coordinates by a Lorentz transform. ... Later knowledge of the properties of the Lorentz group show that this robs the ether frame of its uniquenss, except for the label. ... really part of special relativity, though Einstein's presentation of them in 1905 *used* SR. ...
    (sci.physics.relativity)