"Look up the trains [to
Little Purlington], Watson,"
said Holmes.
"There is one at 5:20
from Liverpool Street," he replied.[1]
Our son, Mark, gave me a copy of Alan Lightman’s The Discoveries for Christmas. This book contains reproductions of twenty two scientific papers from the 20C together with a preface to each one explaining what it says and its significance. Two of them, not surprisingly are by Albert Einstein from his Annus Mirabilis. In the year 1905 the then obscure, young clerk, working in the Swiss patent office in Bern, published four diverse works in the Annalen der Physik, any one of which would have earned him a Nobel Prize. If you have ever wanted to see how science is made, these are excellent examples.
One of these is the original article on what became known as
Special Relativity. I had first become
aware of Special Relativity as a high school student – almost half way back to
1905 – in books by some of the great British astronomers and cosmologists, such
as Arthur Eddington and James Jeans. It
is a hard work out for the mind to accommodate such seemingly irrational ideas,
as I was to discover again a few years later when I encountered quantum
mechanics. And thinking back to the
glory years of classical Physics it seems truly astonishing that Einstein, working
essentially in isolation, would have had such purity of thought to arrive at
such remarkable insights.
I came to grips with this work originally through his thought experiment and only later through the mathematics and I have found such thought experiments enormously valuable in my own (much lesser) work.
At some point in the last few years I was struck by the thought that perhaps there was an association between trains – which feature so often in these thought experiments – and Special Relativity itself. Actually the thought was that the invention of the train timetable – presumably sometime in the mid-19C – is a rather unsung innovation of major proportions. The concept of a train timetable must itself have been quite a break through, since never before had there been a need to think about events that happened at precise times in remote places.
The need for train timetables arises not simply to enable passengers to know when they can catch a train or when they will arrive at a destination. Rather it is required to enable multiple trains to share portions of tracks safely by keeping them separated in time. Today of course this is all worked out by computers, but until quite late in the 20C it was a manual process based on drawing the movement of every train on large pieces of paper and noting where and when they needed to pass. No previous human had activity had required us to think of the coincidence of remote events. The development of coordinated regional, national, and international train timetables seems to me to be a considerable intellectual achievement with no historical precedent.
Moreover, the printing of train timetables as pocket books - such as the Bradshaw’s Railway Guide employed by Sherlock Holmes and Dr. Watson - surely represents one of the first steps into the Information Age. The existence of such books is a first indication, perhaps only preceded by the concept of a map, of a world of information abstracted from the physical world and made portable and accessible. While the map and compass enable navigation in the spatial world, the train timetable and a watch allow navigation in the temporal world.
Einstein was certainly familiar with the well-developed Swiss railway system, but I have no way of knowing whether thinking about train timetables directly influenced him. Still, it struck me that it would have been far less likely for anyone to conduct the thought experiments underlying Special Relativity if the thinking underlying train timetables had not been already invented.
[1] The Adventure of the Retired Colourman, Sir Arthur Conan Doyle
