Trains held a special place in the heart of Albert Einstein. Read his book Relativity: The Special and the General Theory. There they are: not only described but illustrated in neat diagrams.
In his thought experiments he has you standing on a station platform as they hurtle towards you and past you. He has them speeding away from each other in opposite directions (but never, he notes, at more than the speed of light).
Then he has you on the trains, holding lights aloft so that they may be discerned by those others now fulfilling your former role on the platform.
One imagines the trains with which Einstein’s imagination had to work in that era before the First World War: fussy Middle-European steam trains of the sort that are nowadays confined to chugging up and down mountains so that the tourists inside can exclaim, not at men on platforms with lights, but at snow-topped peaks. These are infinitely more picturesque than men with lights but, in terms of the physics, straight-forward and dull.
Then one imagines the lights that were to be inspected as they came and went (though never, as he would caution, at a speed greater than that of light). What sort would they have been? Probably they were not electric lights. Those were very rare then and confined to the drawing rooms of the quality. They would not have been made available for scientific experiments, even thought experiments. Perhaps the lights were naphtha flares.
I am not entirely sure what naphtha flares are but I seem to remember their featuring gloomily in the visuals for the catastrophe that was to come, the Great War which replaced the gemütlich, pleasantly bourgeois world in which Einstein’s ideas first occurred to him. No doubt there came a point when they needed something that would cast a baleful light over No Man’s Land, and some bright spark remembered. Naphtha flares! Wasn’t there was a man, the bright spark might have exclaimed, who used to stand on the platform at Zurich Central holding naphtha flares when the trains went past. It was a scientific experiment apparently. He’s probably in the trenches now but the flares will be there still, in a cupboard owned by the railway company or something.
And so they would have been, though, being Swiss, the man on the platform had probably avoided the trenches and was peacefully awaiting the outcome underneath his home mountain in hobbit-like tranquility.
Einstein’s’ world may have been gemütlich and pleasantly bourgeois but there was nothing gemütlich about what went on inside his head. In there the little Swiss steam trains flashed past at impossible speeds (though never, as he noted, at more than the speed of light) and, almost buckling under the more extreme provocations of his thought experiments, elongated themselves to multiples of their length when at rest (whatever, as Einstein would have said, looking at things relatively, ‘at rest’ means – ‘at rest’ vis-à-vis what exactly?).
One thinks of the immense trains of the imagination of the old, weird America, the mystery trains, multiply-coached, implacably bearing the singer’s baby away (although, to be fair, they never, unless Alan Lomax was careless in what he recorded, even approached the speed of light).
When I think of Einstein looking out between his nice lace curtains, with all of that strange stuff going on inside his head, gazing onto the streets of Zurich with its good burghers going about their business at very much less than the speed of light, I remember George Harrison in that scene in the film Yellow Submarine: in his head all the weirdness that state of the art graphics could suggest and quotidian Liverpool all about him.
I love the idea of relativity, the idea, as it is in my no doubt fatuous arts-education mind, that motion is not absolute but relative, and that when we plunge towards the centre of the Earth in the broken lift the centre of the Earth is also plunging towards us.
And I have a mental picture of the General Theory of Relativity, with the universe bent around its mass like Richard III bent around his kingship. Sometimes I think that I understand it and then I lose it all again.
I have a secret idea. If at the point of the Big Bang the universe was all bent around its own mass, and nothing existed except the singularity that was about to explode and become our universe, what changed when the Big Bang happened? It’s still bent around its own mass, beetling away. Only the scale is different.
My theory: the Big Bang never happened.
I also love the idea of Schrödinger’s Cat, the much later thought experiment where the single photon goes through one of two holes and it’s not that we don’t know which hole it goes through, it’s that the Principle of Uncertainty has it that it goes through both holes until a later event (the death or survival of the hypothetical cat in the late Professor Erwin Schrödinger’s nasty imagination) establishes, after the event, which hole it was.
I always think of Professor Schrödinger when I travel on the Tube.
Use all available doors, they instruct me.
The good burghers on the streets of Zurich before the Great War would have found that a meaningless instruction. ‘How precisely can I use all available doors?’ would have been their sensible Swiss response. We know better. The uncertainty of the struggle to get in is succeeded by the realisation of the actual carriage that one has penetrated and its actual occupants with whom one has become a fellow traveller. Admittedly their identity is rarely critical, though if Professor Schrödinger is prepared to poison a cat in the interests of science he is quite capable of sending a terrorist to bomb the Underground, occupying and demolishing with his little bomb this carriage and its occupants but not that.
Some time ago the whole business of relativity was brought home to me graphically on the Tube. It was Piccadilly Circus in the rush hour. I was on the east-bound Piccadilly Line. I was already in the carriage and a father and his child were trying to force their way on. (They thought that they were using all available doors, but I, inside and cat-like, knew better. That however is a different thought experiment.)
The father fought his way in. The son was still on the platform when the doors started to close. The son screamed. The father seized him and dragged him in, the other passengers, being only human, making room. The father soothed his distraught child. He said:
Don’t worry. Daddy’s not going anywhere.
The good burghers on the streets of Zurich before the Great War would have said, possibly unfeelingly:
Yes he is: he’s going to Leicester Square.
But we know better, thanks to Einstein. I gazed paternally at the couple, a little singularity, half of it whimpering but all of it almost fully recovered from its crisis. I knew the right answer:
No, Daddy isn’t going anywhere. Leicester Square’s coming to him.
(But not at more than the speed of light.)