Free Radicals - Michael Brooks [12]
Not that Kekulé said anything about his dreams to these colleagues – he revealed his sources only a few years before his death. This seems to be a recurring theme. Einstein, too, kept the strange inspiration for special relativity locked away until he had finished in science. Only in his autobiography, written in his final decade, did Einstein reveal that, at the tender age of sixteen, he had experienced a vision. He saw himself running alongside a beam of light, an experience that conjured up a puzzle in the young Einstein’s mind. He visualised the light as an electromagnetic wave composed of two oscillating fields – one electric and one magnetic – just as most physicists of the time would have done. Normally, such a wave would rush past him at great speed – the speed of light – but in the vision it merely stretched out in front of him.
Two things struck him immediately. First, if you run alongside a light beam, you see the waves as stationary. Such a stationary electromagnetic field would not correspond to anything we would experience as light. Second, Einstein instinctively knew that he ought to experience nothing different in his interactions with the world around him, just because of motion.
The situation is no different to finding yourself inside a train carriage, travelling through a pitch-black night at an unwavering speed. There can be no way for you to know that you are even moving – there is no experiment you can carry out that will reveal your motion relative to the landscape outside the window. Moving with the light beam, with nothing else around, Einstein saw that there would be no way for him to tell that he was travelling at the speed of light – or at any other speed, for that matter: ‘everything would have to happen according to the same laws as for an observer who, relative to the earth, was at rest’, he said.
But the implications of his vision said otherwise. According to the standard electromagnetic theory, the laws of physics would depend on your speed: if you travelled fast enough, you would experience something as nonsensical and resistant to analysis as a stationary light wave. Einstein wrote in his autobiography that ‘the germ of special relativity theory was already present in that paradox’. When he constructed the theory a decade later, he resolved the problem entirely by declaring the speed of light to be constant, whatever the speed of the source of the light. All the strangeness of relativity – the elastic nature of time and distance, for example – follow from this insight.
In revealing his sources only at the last minute, Einstein was following a grand tradition. Is the fact that the sources of ideas are so ‘unscientific’, so irrational, somehow embarrassing to scientists? The truth is, for most scientists there is nothing to be gained from revealing the inspiration. And there is much to lose: the joy of bamboozling your colleagues, for instance. The Renaissance scientist Girolamo Cardano, for one, took great pleasure in deceiving his colleagues into thinking he was much cleverer than they.
Cardano was born in Pavia, Lombardy in 1501, the illegitimate child of a lawyer friend of Leonardo Da Vinci. He arguably contributed even more to science than Da Vinci. The driveshaft of your car employs a pivoting joint that allows rotary power to be transmitted at an angle. This joint is known as a Cardan joint in honour of its inventor. Cardano also published more than a hundred books that ranged across mathematics, natural sciences, medicine, engineering and philosophy. It was he who came up with the mechanical gimbal that made high-speed printing possible. He also originated the study of probability – largely because of his interest in gambling. Perhaps most impressively, he developed the concept of imaginary numbers, a vital part of the theories of electromagnetism, quantum physics