Thus, by a thrilling convergence, two ancient problems were solved at the same time: the shining of stars, and the creation of the elements. Bohr had imagined an aufbau, a building up of all the elements starting from hydrogen, as a purely theoretical construct – but such an aufbau was realized in the stars. Hydrogen, element I, was not only the fuel of the universe, it was the ultimate building block of the universe, the primordial atom, as Prout had thought back in 1815. This seemed very elegant, very satisfying, that all one needed to start with was the first, the simplest of atoms.[71]
Bohr’s atom seemed to me ineffably, transcendently beautiful – electrons spinning, trillions of times a second, spinning forever in predestined orbits, a true perpetual-motion machine made possible by the irreducibility of the quantum, and the fact that the spinning electron expended no energy, did no work.
And more complex atoms were more beautiful still, for they had dozens of electrons weaving separate paths, but organized, like tiny onions, in shells and subshells. They seemed to me not merely beautiful, these gossamer but indestructible things, but perfect in their way, as perfect as equations (which indeed could express them) in their balancing of numbers and forces and shieldings and energies. And nothing, no ordinary agency, could upset their perfections. Bohr’s atoms were surely close to Leibniz’s optimum world.
‘God thinks in numbers’, Auntie Len used to say. ‘Numbers are the way the world is put together.’ This thought had never left me, and now it seemed to embrace the whole physical world. I had started to read a little philosophy at this point, and Leibniz, so far as I could understand him, appealed to me especially. He spoke of a ‘Divine mathematics’, with which one could create the richest possible reality by the most economical means, and this, it now seemed to me, was everywhere apparent: in the beautiful economy by which millions of compounds could be made from a few dozen elements, and the hundred-odd elements from hydrogen itself; the economy by which the whole range of atoms was composed from two or three particles; and in the way that their stability and identity were guaranteed by the quantal numbers of the atom itself – all this was beautiful enough to be the work of God.
25. The End of the Affair
It was ‘understood’, by the time I was fourteen, that I was going to be a doctor; my parents were doctors, my brothers in medical school. My parents had been tolerant, even pleased, with my early interests in science, but now, they seemed to feel, the time for play was over. One incident stays clearly in my mind. It was 1947, a couple of summers after the war, and I was with my parents in our new Humber touring the South of France. Sitting in the back, I was talking about thallium, rattling on and on and on about it: how it was discovered, along with indium, in the 1860s, by the brilliantly colored green line in its spectrum; how some of its salts, when dissolved, could form solutions nearly five times as dense as water; how thallium indeed was the platypus of the elements, with paradoxical qualities that had caused uncertainty about its proper placement in the periodic table – soft, heavy, and fusible like lead, chemically akin to gallium and indium, but with dark oxides like those of manganese and iron, and colorless sulphates like those of sodium and potassium. Thallium salts, like silver salts, were sensitive to light – one could have a whole photography based on thallium!
The thallous ion, I continued, had great similarities to the potassium ion – similarities which were fascinating in the laboratory or factory, but utterly deadly to the organism, for, biologically almost indistinguishable from potassium, thallium would slip into all the roles and pathways of potassium, and sabotage the now-helpless organism from within. As I babbled on, gaily, narcissistically, blindly, I did not notice that my parents, in the front seat, had fallen completely silent, their faces bored, tight, and disapproving – until, after twenty minutes, they could bear it no longer, and my father burst out violently: ‘Enough about thallium!’
But it was not sudden – I did not wake up one morning and find that chemistry was dead for me; it was gradual, it stole upon me bit by bit. It happened at first, I think, without my even realizing it. It came upon me sometime in my fifteenth year that I no longer woke up with sudden excitements – ’Today I will get the Clerici solution! Today I will read about Humphry Davy and electric fish! Today I will finally understand diamagnetism, perhaps!’ I no longer seemed to get these sudden illuminations, these epiphanies, those excitements which Flaubert (whom I was now reading) called ‘erections of the mind.’ Erections of the body, yes, this was a new, exotic part of life – but those sudden raptures of the mind, those sudden landscapes of glory and illumination, seemed to have deserted or abandoned me. Or had I, in fact, abandoned them? For I was no longer going to my little lab; I only realized this when I wandered down one day and saw a light layer of dust on everything there. I had scarcely seen Uncle Dave or Uncle Abe for months, and I had ceased to carry my pocket spectroscope with me.
There had been times when I would sit in the Science Library, entranced for hours, totally oblivious to the passage of time. There were times when I seemed to see ‘lines of force’ or electrons dancing, hovering, in their orbitals, but now this half-hallucinatory power was gone too. I was less dreamy, more focused, school reports said – that, perhaps, was the impression I gave – but what I felt was wholly different; I felt that an inner world had died and been taken from me.
I often thought of Wells’s story about the door in the wall, the magic garden the little boy gets admitted to, and his subsequent exile or expulsion from it. He does not notice at first, in the press of life and outer achievement, that he has lost something, then the consciousness of this begins to grow on him, eroding and finally destroying him. Boyle had called his lab an ‘Elysium’; Hertz had spoken of physics as ‘an enchanted fairyland.’ I felt I was now outside this Elysium, that the doors of the fairyland were now closed to me, that I had been expelled from the garden of numbers, the garden of Mendeleev, the magic play realms to which I had had admittance as a boy.
With the ‘new’ quantum mechanics, developed in the mid-1920s, one could no longer see electrons as little particles in orbit, one had to see them now as waves; one could no longer speak of an electron’s position, only of its ‘wave function’, the probability of finding it in a particular place. One could not measure its position and velocity simultaneously. An electron, it seemed, could be (in some sense) everywhere and nowhere at once. All this set my mind reeling. I had looked to chemistry, to science, to provide order and certainty, and now suddenly this was gone.[72] I found myself in a state of shock, and I was past my uncles now, and in deep water, alone.[73]
71
The universe started, Gamow conceived, as almost infinitely dense – perhaps no larger than a fist. Gamow and his student Ralph Alpher went on to suggest (in a famous 1948 article that came to be known, after Hans Bethe was invited to add his name, as the alpha-beta-gamma paper), that this primal fist-sized universe exploded, inaugurating space and time, and that in this explosion (which Hoyle, derisively, was to call the Big Bang) all of the elements were created.
But here he was wrong; it was only the lightest elements – hydrogen and helium and perhaps a little lithium – that originated in the Big Bang. It was not until the 1950s that it became clear how the heavier elements were generated. It might take billions of years for an average star to consume all its hydrogen, but the more massive stars, far from extinguishing at this point, could contract, becoming hotter still, and start on further nuclear reactions, fusing their helium to produce carbon, fusing this in turn to produce oxygen, and then silicon, phosphorus, sulphur, sodium, magnesium – all the way up to iron. Beyond iron no energy could be released by further fusion, so this accumulated as an end point in nucleosynthesis. Hence its remarkable abundance in the universe, an abundance reflected in metallic meteorites and in the iron core of the earth. (The heavier elements, those beyond iron, remained a puzzle for longer; they only originate, apparently, with supernova explosions.)
72
This question again resonated for me when I read Primo Levi’s wonderful book
73
I was not quite alone. A most important guide to me at this point was George Gamow, a scientist-writer of great versatility and charm whose
I sometimes wondered whether any ‘macroquantal’ phenomena existed, whether one might ever be able to see, under extraordinary conditions, a quantal world with one’s own eyes. One of the unforgettable experiences of my life was exactly this, when I was introduced to liquid helium, and saw how this changed its properties suddenly at a critical temperature, turning from a normal liquid into a strange superfluid with no viscosity, no entropy whatever, able to go through walls, to climb out of a beaker, and with a thermal conductivity three million times that of normal liquid helium. This impossible state of matter could only be understood in terms of quantum mechanics: the atoms were now so close together that their wave functions overlapped and merged, so that one had, in effect, a single giant atom.