“It is impossible to assign, in any meaningful way, a universal time to the totality of inertial systems.”
AT THE HEIGHT OF AN ANTI-RELATIVITY CAMPAIGN, EINSTEIN ADDRESSES PERHAPS HIS MOST PUBLIC CRITIC, REMINDING HIM OF ONE OF THE ESSENTIAL ELEMENTS OF THE THEORY: THAT THERE CAN BE NO MEANINGFUL NOTION OF “UNIVERSAL TIME” FOR “THE TOTALITY OF INERTIAL SYSTEMS”.
Even though “Einstein achieved worldwide fame in late 1919, when the scientific breakthrough of his general theory of relativity, as tested by British astronomers in South America and Africa during a total eclipse of the sun, was trumpeted to all corners of the globe” there still were influential and strident critics of his theory and “in 1920, a series of events took place that were directed against Einstein and relativity theory. They were thinly veiled anti-Semitic attacks instigated by physicist Philipp Lenard and right-wing publicist Paul Weyland, who accused Einstein of having a ‘particular press, a particular congregation’ that took it upon itself to promote Einstein as something more than he was... On August 24, the first of a lecture series intended to expose Einstein as a propagandist and fraud took place at the Berlin Philharmonic Hall... Einstein, who was in the audience, responded on August 27, with an article in the newspaper Berliner Tageblatt. In it, he denounced their campaign, refuted the assertions of the speakers point by point, and documented the acceptance of his theories by the most respected physicists. Still, he was rattled enough to consider leaving Germany, and received offers to work in other countries.”
In the midst of this anti-relativity fervor of 1920, Edouard Guillaume, a fierce critic of relativity for much of the decade, saw an opportunity to renew his attacks on Einstein’s theory. Guillaume was “an old colleague from Einstein’s days in the patent office in Bern. (He should not be confused with his relative Charles-Edouard Guillaume, a Swiss inventor who was awarded the Nobel Prize the year before Einstein.) The Guillaume with whom Einstein was friendly became determined to oppose relativity theory, especially in the period after the publication of general relativity (though his objections were related more to the special theory). Einstein devoted a long correspondence to patiently trying to explain to Guillaume that his arguments against the theory were invalid. Guillaume’s objections were based on his failure to properly comprehend the theory, as was the case with so many other anti-relativists”; a reminder of just how radical and counter-intuitive much of Einstein’s theory must have seemed to community of scientists in the early days of the theory. (Calaprice, et al., An Einstein Encyclopedia, pp.216-218).
In the present letter - one of the last Einstein wrote to Guillaume - Einstein hopes to finally dismiss Guillaume’s objections by making one of his clearest statements of the core of relativity thoery, namely that “[I]t is impossible to assign, in any meaningful way, a universal time to the totality of inertial systems.”
The full letter from December 16, 1920 - translated from the original German - reads in full:
I have so much obligatory work to do at present that I cannot think of writing a longer paper. Thus I am unfortunately not in a position to accept the friendly challenge. You might write Mr. Xavier Léon that he could address himself to Langevin, who is an outstanding expert in the theory. Grossmann recently asked me for an assessment of your papers in the area of relativity theory because it was supposedly necessary to take an official position on it, finally. I asserted that despite diligent attempts I was unable to make any progress toward comprehension and that I personally was convinced that there is no clear theoretical idea behind it. Don’t be cross with me; it was no longer appropriate to keep silent about my opinion on this point. It is impossible to assign, in any meaningful way, a universal time to the totality of inertial systems.
Amicable greetings to you and your wife,
[signed] A. Einstein
[Translation from The Collected Papers of Albert Einstein, Volume 10, #233.]
One page (8.5x11 inches), signed “A. Einstein” in ink. Usual folds. Very slight wear at extreme edges, otherwise fine. With the original typed and post-marked mailing envelope.
A REVEALING LETTER AFFIRMING THE CENTRAL TENET OF RELATIVITY DURING A PERIOD OF STRONG PUBLIC CRITICISM OF THE THEORY.