Distinguishing Convention and Empiricism

New paper:

Einstein's Hidden Scaffolding, with a Glance at Poincaré
Galina Weinstein

This paper reconstructs the derivations underlying the kinematical part of Einstein's 1905 special relativity paper, emphasizing their operational clarity and minimalist use of mathematics. Einstein employed modest tools-algebraic manipulations, Taylor expansions, partial differentials, and functional arguments-yet his method was guided by principles of linearity, symmetry, and invariance rather than the elaborate frameworks of electron theory. The published text in "Annalen der Physik" concealed much of the algebraic scaffolding, presenting instead a streamlined sequence of essential equations. Far from reflecting a lack of sophistication, this economy of means was a deliberate rhetorical and philosophical choice: to demonstrate that relativity arises from two simple postulates and basic operational definitions, not from the complexities of electron theory. The reconstruction highlights how Einstein's strategy subordinated mathematics to principle, advancing a new mode of reasoning in which physical insight, rather than computational elaboration, held decisive authority. In this respect, I show that Einstein's presentation diverges sharply from Poincaré's.

She analyzes Einstein's definition of time synchronization, which appears to be straight out of Poincare's 1898 paper, his formulas for the Lorentz transformation, which appear to be from Lorentz's 1904 paper, and his declaration of the Lorentz transformation forming a group, which seems to be from Poincare's earlier 1905 paper.

Einstein did not cite his sources, so there have been suspicions of plagiarism. Most scholars agree that there was some plagiarism, but disagree on how much.

She discusses a gap in Einstein's derivation of the Lorentz transformations, and whether Einstein worked backwards from a known result.

The "divergence" is mainly that Poincare is a mathematician, and is more mathematically precise in his papers. He shows that the Lorentz transformations form a symmetry group, and we observe the relativity principle because Maxwell's equations are invariant under the symmetry. One can choose particular coordinates for convenience, as they are equivalent to any other coordinates.

Einstein never really gets this point. He does show that composing a Lorentz boost with its inverse gives the identity, which is one of the steps in showing the transformations form a group. But he does not show that other Lorentz transformations can be composed, or appreciate the significance of being a group.

She acknowledges all this, but tries to spin it in Einstein's favor, as if using sloppy or plagiarized math meant he must have understood the physics better. She writes:

In reality, the gulf is structural. Poincaré’s framework remains tied to the ether and treats simultaneity as conventional fiction, whereas Einstein fuses convention and empiricism into a universal principle of relativity. Poincaré never crossed this threshold. In 1898, he recognized the conventionality of simultaneity and sketched the midpoint procedure, but only as a practical rule for determining longitude in astronomy. There is no invocation of c as a universal constant, no fusion of convention with empirical invariance, and no kinematical framework built upon it. In 1900, he linked the midpoint procedure to Lorentz’s local time: observers in uniform motion, ignorant of their drift through the ether, assume equal one-way propagation times. But for Poincaré, this was a fiction: in truth, only the ether rest frame contained the “true time,” and only there was the one-way velocity isotropic. He accepted the two-way constancy of light speed as an empirical fact, yet he relegated one-way isotropy to an illusion produced by convention.

She is wrong to say Poincare did not invoke c as a universal constant. Here is what he wrote, in his big 1905 relativity paper:

Lorentz had adopted a particular system of units, so as to eliminate the factors 4π in the formulas. I'll do the same, plus I choose the units of length and time so that the speed of light is equal to 1.

In his previous 1904 St. Louis lecture, he wrote:

an entirely new mechanics, which would be, above all, characterized by this fact, that no velocity could surpass that of light, any more than any temperature could fall below the zero absolute

Poincare did draw a distinction between conventional and empirical knowledge, and Einstein did not. This is a point that is obvious to mathematicians, and endlessly confusing to physicists. A mathematical truth is a theorem proved from axioms, and cannot be falsified. An empirical finding might be upset by a new experiment.

It is amazing how these Einstein scholars will do back flips to try to credit Einstein for relativity. She dedicates the paper to another Einstein scholar who did the same.

I have previously criticized her here and here. She has another new pro-Einstein paper, and I am about to post a rebuttal. Here is how she describes herself:

I am a scholar specializing in general relativity, black hole physics, and the philosophy of physics, with deep expertise in the theoretical, historical, and conceptual dimensions of Einstein’s work.

No, she is just an Israeli Einstein shill. I will have more to say in my next post.