Monday, February 20, 2023

Petkov on the Tragic History of Relativity

New paper:
Petkov, Vesselin (2023) The Quadruple Scientific Tragedy involved in the Discovery of Spacetime Physics. The Origin of Spacetime Physics (2nd ed.). pp. 257-276. ...

The advent of spacetime physics came at the price of four different scientific tragedies involving Hendrik Lorentz, Henri Poincaré Albert Einstein and Hermann Minkowski whose work essentially laid the foundations of spacetime physics. Lorentz' and Poincaré's scientific tragedies had the same cause - both Lorentz and Poincaré regarded the new theoretical entities they introduced in physics as pure mathematical abstractions that did not represent anything in the physical world. Einstein's rather subtle scientific tragedy has to do with his unclear and, in some cases, even incorrect views on a number of subjects that might have led to confusions and misconceptions some of which still persist.

Four men made some brilliant discoveries that changed our fundamental understanding of Physics. It is hard to understand what is tragic about this.

His statement about "pure mathematical abstractions" is just a misunderstanding. Lorentz and Poincare had physical interpretations for everything they did. Some people argue that Lorentz did not have a way of tying his concept of "local time" to the time of local clocks, but they all agree that Poincare did, and that Poincare credited Lorentz with a similar understanding. Poincare even nominated Lorentz to get a Nobel Prize in 1902 for his theory of local time. Of course they understood local time represented something in the physical world. Lorentz and Poincare wrote papers on how their relativity theory explained the Michelson-Morley and other experiments. It was Einstein who took the more abstract approach of relating the formulas to his postulates, instead of experiments.

It is just a slander on mathematicians when non-mathematicians complain they are just doing mathematics, as if that makes it not real.

Einstein is widely credited with geometrizing spacetime. Many say that was his most profound and important discovery. Petkov explains that Einstein did not do that, and even disagreed with it:

After Minkowski’s 1908 world-view-changing lecture “Space and Time” Einstein had apparently had difficulty realizing the depth of Minkowski’s ideas and his reaction to the developed by Minkowski four-dimensional physics had been rather hostile. Sommerfeld’s recollection of what Einstein said on one occasion provides an indication of Einstein’s initial attitude towards the work of his mathematics professor on the foundations of spacetime physics [6, p. 102]:
Since the mathematicians have invaded the relativity theory, I do not under- stand it myself any more.
However, later, in order to develop his general relativity, Einstein had to adopt Minkowski’s four-dimensional physics but it appears that the adoption has not been fully successful since he did not truly employ Minkowski’s program of geometrizing physics. ...

In a letter to Reichenbach from April 8, 1926 Einstein wrote [25]:

It is wrong to think that “geometrization” is something essential. It is only a kind of crutch for the discovery of numerical laws. Whether one links “geometrical” intuitions with a theory is an inessential private matter.
Twenty-two years later, on June 19, 1948, in a letter to Lincoln Barnett Einstein reiterated his (mis)understanding of his own theory [26]:
I do not agree with the idea that the general theory of relativity is geometrizing Physics or the gravitational field.
... if Einstein did not believe that spacetime represented a real four-dimensional world 22 (and were nothing more than a mathematical space), then, clearly, gravitational phenomena could not be manifestations of the curvature of some- thing that does not exist. So it seems even in 1948 Einstein seriously doubted whether spacetime represented a real four-dimensional world. ...

Einstein seems to have never been able to eliminate entirely his negative attitude towards the discovered by Minkowski spacetime structure of the world, which ultimately prevented him from accepting the most counter-intuitive result of his own general relativity – that gravitation is not a physical interaction 23 since it is nothing more than a manifestation of the non-Euclidean geometry of spacetime. `

This is the most startling thing I discovered about Einstein. Everybody knows he refused to credit his sources, and used ideas and formulas that had been previously published by others. But they always argue that Einstein had a superior understanding, and primarily a geometric view which came to dominate 20th century Physics. But in fact he rejected that view. We got that view from others.

Petrov is particularly critical of Einstein explaining the Ehrenfest paradox incorrectly. Consider a rotating disk of radius 1. The circumference is Lorentz contracted, and so has length less than 2π. Einstein argued that it is really bigger than 2π because the measuring rods will be contracted, so more rods will be needed to measure the circumference. He wrote about this several times over many years, and never seemed to accept that space itself is contracting, in the view of another frame. Time cannot be synchronized over all the frames.

This article has more info on the history of the paradox. The paradox was first published in 1909, and it convinced a lot of people that non-Euclidean geometry was needed for general relativity.

Petkov argues that Minkowski independently discovered some relativity ideas that are credited to others, but was slow to publish. This is possible, but the evidence for it is weak. Minkowski cited Poincare's big 1905 relativity paper, and seems to use a lot of ideas from it. Minkowski died soon after publishing, and that is tragic, and we do not know what he might have done with the theory.

The main evidence is that (1) Minkowski's 1907 paper has so many original ideas in it that it was probably several years of work; and (2) Max Born recounts taking a relativity course from Minkowski in 1905, before the Poincare and Einstein 1905 papers were published. Regardless, it is clear that Minkowski made a huge contribution.

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