20 June 2004

Railways and the roots of relativity

The young Einstein was not, of course, employed in the academic world but in the Swiss Patent Office. And Switzerland, as we know, was a centre of invention and innovation in clock technologies. The patent office at Bern was a clearing-house for new timing technologies, and Einstein's job afforded him a veritable grandstand seat from which to become acquainted with new electro-technological advances.

Moreover, every day Einstein saw an abundance of public clocks on his way to and from work - on storefronts, on baroque towers, at the train station. How to synchronize such clocks was a widespread concern all over Europe and America. Engineers, scientists and businessmen needed to synchronize clocks effectively in order to solve important problems, ranging from determining longitude at sea to preventing train crashes.

Galison's book is thus about the history of the problem of co-ordinating clocks, from the 1800s to the early 1900s. As he points out, this period was characterized by many efforts to unify, by convention, a plethora of standards of lengths and time. Geographical regions - even within a single country such as Germany - were distinguished by their own 'local times'. Railway lines defined and distributed time, bringing distant times into conflict with local times. Engineers struggled to pinpoint and unite locations and times. Chronometers transported aboard ships failed to keep the time of stationary clocks. Underwater telegraphic cables were laid across the Atlantic Ocean to transmit not only messages, but also time, from observatories in Europe to Africa, Newfoundland, Brazil and beyond. Poincar�? was even a member and sometime president of the French Bureau of Longitude, where he laboured to revise time-keeping conventions.

Local times, synchrony conventions, moving clocks that do not keep proper time, the diversity and unification of lengths and time. Were these remarkable coincidences? Or were there causal connections between breakthroughs in theoretical physics and prior techno-cultural developments? Galison's narrative implies a resounding 'yes', but he cautiously avoids any outright claims of historical causation. His aim is not to reduce the emergence of relativity to such developments, but to place it in a context where the interests of engineers, physicists, philosophers, entrepreneurs and even politicians converged.

Despite Galison's good intentions, his middle-of-the-road outlook does not counterbalance the direction of his research and the drift of his book. While claiming that special relativity emerged from physics, philosophy and technology, his book highlights the technological dimension, seemingly at the expense of the others. Readers who are not well acquainted with the roots of special relativity in optics and electrodynamics might therefore get the exaggerated impression that its crucial origins lay in the techno-culture of clock synchrony.

Be warned, moreover, that the patent offices were not the only possible source of technological imagery. Even before 1900, discussions of kinematics included references to clocks, observers, the measurement of length and time, and even trains. For example, in the 17th century, imagery of ships cruising rectilinearly served to illustrate the equivalence of physical processes on board to those on land, while by the late 19th century imagery of trains had become widespread. Such factors have to be subtracted before injecting Galison's circumstantial findings into a general history of physics. How much weight to give to the techno-cultural aspects will now challenge historians of special relativity.

Fortunately the young Einstein did not have to deal with the complex temporal leakages in the blogosphere where 'I'll just check my newsfeeds for a minute' can turn into several hours of densely (or loosely) argued post. Britain was the first government to make the time run on trains.

Britain was the first country to set the time throughout a region to one standard time. The railways cared most about the inconsistencies of local mean time, and they forced a uniform time on the country. The original idea was credited to Dr. William Hyde Wollaston (1766-1828) and was popularized by Abraham Follett Osler (1808-1903). The first railway to adopt London time was the Great Western Railway in November 1840; other railways followed suit, and by 1847 most (though not all) railways used London time. On September 22, 1847 the Railway Clearing House, an industry standards body, recommended that GMT be adopted at all stations as soon as the General Post Office permitted it. The transition occurred on 12-01 for the L&NW, the Caledonian, and presumably other railways; the January 1848 Bradshaw's lists many railways as using GMT. By 1855 the vast majority of public clocks in Britain were set to GMT (though some, like the great clock on Tom Tower at Christ Church, Oxford, were fitted with two minute hands, one for local time and one for GMT). The last major holdout was the legal system, which stubbornly stuck to local time for many years, leading to oddities like polls opening at 08:13 and closing at 16:13. The legal system finally switched to GMT when the Statutes (Definition of Time) Act took effect; it received the Royal Assent on August, 2, 1880.

At least that was easier than reforming the European calendar, where the retrograde Catholic south went Gregorian 170 years before the scientifically advanced Protestant north.

In an age of intense religious passion, the simple fact that the Pope instituted the reform was enough to make Protestant countries reject the change. The greater part of Protestant Germany did not switch to the Gregorian calendar until 1700, the Protestant Cantons of Switzerland and Protestant Netherlands until 1701. The Swedish dithered. In 1700 they began what was intended to be a gradual switch to the Gregorian calendar. They planned to stop observing leap years until their calendar was in line with the Gregorian one. They did omit the leap year in 1700, but observed the leap year in 1704 and 1708 (apparently they forgot the plan). Thus they were 10 days out of step with the Gregorian calendar and 1 day out from the Julian. Then, in 1712, they changed their minds, and went back to the Julian system by adding two leap days to February. Somewhere in Sweden, there are probably some unique baptismal records of people whose birthday was on a date never to be seen again: February 30. Lithuania and Latvia, which were under Polish rule at the time of the reform (and hence changed in 1582), actually reverted to the Julian calendar, so strong were the feelings. They did not change back again until the 20th century.

Now about that blogospheric temporal leakage...

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