robphy

Last edited by a moderator: Jun 26, 2026

robphy said:

Does Lorentz Ether Theory have its own predictive power?
Or is it essentially a direct and straightforward (as opposed to convoluted) alternative-interpretation after Special-Relativity has predicted and established the result?

LET makes all of the same predictions as standard SR; it's just a different interpretation (and one we don't discuss here since there's no way to test any claims about LET vs. standard SR by experiment).

robphy said:

Does this extend to General Relativity?

GR has its own set of interpretations: spacetime curvature is one, "spin-2 field on a flat spacetime background" is another. (The latter is technically limited to spacetimes with topologies that can have a flat background put on them.) The second is kinda sorta LET-ish, I suppose (the flat background is in principle unobservable), but it has no historical lineage in common with LET that I'm aware of.

robphy said:

• Does Lorentz Ether Theory have its own predictive power?
  Or is it essentially a direct and straightforward (as opposed to convoluted) alternative-interpretation after Special-Relativity has predicted and established the result? ( McDonald's vs McDowell's ? )

There were different versions of LET.

• Early versions (between 1892 and 1895) explained the failure of the negative ether drift experiments (i.e. MM) to first order in v/c. So they did have limited predictive power.
• The final version (1904, with corrections in 1906), which is today usually referred to as "LET", is a convoluted alternative-interpretation to SR. Unlike SR, it does not follow Ockham's razor and does not provide additional predictive power.

robphy said:

• Does this extend to General Relativity?

Wikipedia refers to a related 2012 paper by Schmelzer, which I don't know.
There is no universally accepted "Lorentz Ether Theory for GR."

Source:
https://en.wikipedia.org/wiki/Lorentz_ether_theory

Sagittarius A-Star said:

Wikipedia refers to a related 2012 paper by Schmelzer

Whose claims were repeatedly and thoroughly discussed here at PF years ago. They didn't get any real traction here, and AFAIK they have not in the general physics community either.

Sagittarius A-Star said:

Note, btw, that his claimed "ether theory" including gravity does not make all of the same predictions as GR, so it is not just an interpretation of GR, it's a different theory.

Sagittarius A-Star said:

The final version (1904, with corrections in 1906), which is today usually referred to as "LET", is a convoluted alternative-interpretation to SR. Unlike SR, it does not follow Ockham's razor and does not provide additional predictive power.

To me, this sounds like SR just accepts the results of the speed of light in very precise experiments and sees what those results lead to, whereas LET tries to explain why those same experimental results happen. Therefore, LET is more complicated and leads to the same results.
Mathematically, with very simple and desirable assumptions, there are only two possible versions of relativity, Euclidean and Einsteinian (see @Ibix 's link in post#2). I don't see why one mathematical version needs some justification, beyond the experimental results. It is what it is. Would Euclidean relativity have needed justification?

FactChecker said:

Euclidean and Einsteinian

I think it is "Galilean and Einsteinian".

FactChecker said:

SR just accepts the results of the speed of light in very precise experiments and sees what those results lead to, whereas LET tries to explain why those same experimental results happen.

I'm not sure I would put it that way. SR explains the speed of light experimental results by saying they are a consequence of the geometry of spacetime. That's not the same as not explaining them at all.

robphy

robphy said:

Does LET make predictions on its own, using its own principles (whatever they may be) [without looking over the fence as to what SR is doing]?

Yes. It just postulates the Lorentz transform directly. Then it makes all the usual predictions.

robphy said:

Can LET get [on its own] to the spacetime geometry of GR

No. LET is equivalent to standard SR and fails to replicate GR in the same way that standard SR does.

robphy said:

Does LET make predictions on its own, using its own principles

What would that even mean? You don't make predictions using "principles". You make them using a well-defined mathematical model. LET's well-defined mathematical model is the same as that of standard SR.

robphy

Matterwave

robphy

Last edited by a moderator: Jun 26, 2026