The Need for Interpretations of Relativity

I posted comments on a Sabine Hossenfelder video on relativity a few months ago. Now here is another:

The REAL Reason You Don't Understand Relativity

Think Relativity is confusing? Well, it's not just you -- even the experts can't seem to agree on its meaning, and often get basic facts about the formalism completely wrong. Here, we critique one such renowned professional who, in claiming to be clarifying the standardized theory of relativity, turns out to actually be promoting a misguided personal interpretation. What is this expert's confusion exactly, and why are such misconceptions so prevalent amongst the physics community?

Indeed, be cautious of posturers, gaslighters, stigmatizers, and Giordano-Bruno-burners who want to convince you that your inability to understand Relativity stems from your own deficient reasoning -- because when even the experts can't agree, you know there is something up...

It makes an argument that quantum mechanics is mysterious, so we have multiple interpretations, and we need the same for relativity.

You might say that the textbooks already provide two interpretations: Lorentzian and Einsteinian.

It points out that Einstein's interpretation is confused. He rejected the aether, and then endorsed it years later. He rejected geometrization of spacetime. He had a peculiar explanation of the twin paradox.

It also finds Hossenfelder\s explanation confusing.

I am not sure where this guy is going with this argument. He promises another video to explain.

The Wikipedia page on Lorentz ether theory says that it pre-dates Einstein and is experimentally indistinguishable from Einstein's special relativity. So you could say that these are two different interpretations of the same theory.

But then I would say that Minkowski's geometrical spacetime theory is another interpretation still. It is more different from Einstein's, as Einstein's is from Lorentz's. Maybe these should be understood as three different interpretations of the same theory.

Wikipedia says:

In the absence of any way to experimentally distinguish between LET and SR, SR is widely preferred over LET, due to the superfluous assumption of an undetectable aether in LET, and the validity of the relativity principle in LET seeming ad hoc or coincidental.

Einstein is indeed preferred over Lorentz, but I don't think that the reasoning is correct. Lorentz was the one to say that the aether was superfluous. And it was Einstein who made the relativity principle a postulate, instead of justifying it.

People don't like to talk about interpretations of relativity, because it undermines Einstein's genius. If all Einstein did was to find another interpretation of an accepted theory of Lorentz, then what is the big deal?
 

Sometimes the explanation is that Lorentz based his theory on Michelson-Morley and other experiments, and so his theory was "ad hoc or coincidental". Einstein based his on Lorentz's principles, and so his was paradigm shifting and revolutionary. At the time, everyone thought that Einstein's theory was just an elaboration of Lorentz's ideas.

Here is a Wikipedia explanation on why the FitzGerald contraction was ad hoc:

This hypothesis was partly motivated by Oliver Heaviside's discovery in 1888 that electrostatic fields are contracting in the line of motion. But since there was no reason at that time to assume that binding forces in matter are of electric origin, length contraction of matter in motion with respect to the aether was considered an Ad hoc hypothesis.

No reason to think? FitzGerald and Lorentz appear to have thought that, and it is true that the binding forces in solids are electric. I would call it brilliant reasoning, not ad hoc.

Minkowski spacetime is widly preferred over Einstein's interpretation, as it gives a coherent geometrical view that explains the paradoxes. It was based on Lorentz and Poincare, not Einstein.

The key principle that is usually used to distinguish Einstein from Lorentz is to say there is no aether, which means that there is no preferred frame. Both Lorentz and Einstein accept the relativity principle, so all inertial frames are equivalent, but Lorentz might prefer one somehow. Einstein would say that none can be preferred.

I am not sure that this reflects Lorentz's and Einstein's views accurately, but regardless, there is no scientific difference. It does not mean anything to say that there is no preferred frame. It is only meaningful to say that there is a symmetry between the frames.

The Cosmic Microwave Background radiation gives a preferred frame for what is motionless. It is not a counterexample to special relativity. So it is confusing to say that special relativity does not allow a preferred frame.

It is also said that Lorentz had an electromagnetic interpretation, while Einstein had a kinematic interpretation. Lorentz believed that electromagnetism underlies everything. Poincare wrote in 1905 that he was adopting an interpretation that relativity was about how we measure space and time, and that this was different from Lorentz's interpretation. So Poincare was the first with a spacetime interpretation.

The Minkowski geometrical interpretation says that all the special relativity mysteries derive from the non-euclidean geometry of spacetime. That has dominated the textbooks since about 1910, even though Einstein spoke out against it.

I guess that relativity has three interpretations. Lorentz relativity, based on Maxwell's equations and Michelson-Morley experiment. Einstein relativity, based on postulating what Lorentz and Poincare proved. Poincare-Minkowski relativity, based on a non-euclidean geometry on spacetime.

Here is a 2014 paper on Poincaré on clocks in motion, that was just posted online. It goes into Poincare's unpublished writings in detail, and argues that he had a somewhat different interpretation of relativity from Einstein and Minkowski.