Richard Feynman

by John Gribbin

  His father earned about $5,000 a year in the early 1930s, which Richard knew because Melville would sometimes send him to the bank with a cheque for a week’s salary, about $100. It was Melville’s way of teaching Ritty the value of money, and it worked. Richard knew how much money the family had, and knew that they lived in reasonable comfort. He remembered thinking ‘that everything was all right, we lived fine, and my ambition was to earn that much money … I knew I wanted about $5,000 a year, that’s all I needed.’25 He worked part time for a printer while in high school, and in the summer after graduation at a hotel run by his aunt, giving rise to some of the stories recounted in Surely You’re Joking, Mr. Feynman! In many ways, this was a typical lifestyle for a bright Jewish kid in New York in the 1930s – it bears striking resemblances, for example, to the story Isaac Asimov tells in his autobiographical I Asimov (Doubleday).

  As a teenager, Feynman later said, he was interested in only two things, maths and girls (that’s one more thing than most teenage boys are interested in). He learned to dance, which was very useful for one of his interests, and he also quickly learned about the difference between social niceties and the truth.

  Richard was always uncomfortable with the phoney way many other people used language. He regarded English, as taught in high school, as ‘a kind of baloney’, had a lifetime disdain of philosophy, and dismissed religion, which seemed to him to be based purely on wishful thinking. He talked straight, meant what he said, and was genuinely confused if that seemed to upset other people. So when, at the end of his first date, the girl he had taken out said, ‘Thank you for a very lovely evening’, he thought she meant it. When the next girl he took out ended the evening with exactly the same words, he began to wonder. So the third time he took a girl out on a date, when the time came to say goodnight he got in first, saying the stock phrase before she could, and leaving her tongue-tied, unable to think what to say in response, because she had been just about to say the same thing.26 This was one of Feynman’s first encounters with this kind of empty formality, but he seldom bothered with such niceties himself.

  It wasn’t too long before he got to know a girl who would end up caring even less about social niceties than he did, and making him blissfully happy, as his first wife, in the process. When Richard first met Arline Greenbaum, when he was about thirteen, she was one of his wider circle of acquaintances, not a close friend. As they grew up together, he got to dance with her on occasion, but she soon had a regular boyfriend and to a large extent he admired her from a distance (Joan Feynman recalls Richard first mentioning this ‘wonderful girl’ to her when he was about fifteen and Joan was six). Arline was the most popular girl in the group, and everybody liked her. As Feynman recounted in What Do You Care What Other People Think?, she once made his day simply by coming over to him at a party and sitting on the arm of his chair to talk to him. ‘Oh boy!’, he thought, ‘somebody I like has paid attention to me!’ (his comments at home the next day may have been the occasion Joan remembers). He even joined an art group, something he had no ability at whatsoever at that time, simply because Arline was a member.

  Eventually, Arline’s steady relationship with her boyfriend ended, and during his final year in high school Richard got to know her better, although she was still dating other boys at that time. But Harold Gast, one of Richard’s contemporaries who also dated Arline, says that by then it was obvious to everyone in the group ‘that they were really very fond of each other and nobody was going to interfere’.27 Still rather shy and insecure socially, however, Richard imagined that Gast was a serious competitor, and was relieved when Arline chose to sit with Melville and Lucille at his graduation ceremony, a public acknowledgement of her interest in him.

  The graduation was, of course, a triumph for Feynman, who took top honours in just about everything, ironically including English. The reason for that particular triumph, also recounted in What Do You Care, was that, knowing his limitations, in the examination he had written an uncontentious essay about technology and aviation, designed to appeal to his teachers by ‘slinging the bull’ – saying simple things in an impressive way, using long words and technical terms. His friends with greater literary talent (including Gast) had been confident enough to spread their wings and take up more controversial themes, with which the examiners could take issue (another example, to Feynman, of the ‘baloney’ involved in English). So they ‘only’ scored 88 per cent, while Richard scored 91 per cent (in one of his worst subjects).

  In those days (Feynman graduated in the summer of 1935) many bright kids had to forgo a college education for financial reasons, but Melville and Lucille were determined to give Richard the best education they could. Even with his academic track record and his parents’ backing, though, getting into college wasn’t all plain sailing. He applied to Columbia University and the Massachusetts Institute of Technology (MIT). Columbia required an examination, and charged wouldbe students $15 for the privilege of taking it (at a time when the Feynman family income, remember, was about $100 per week); Richard took the exam, and presumably passed, but was denied a place at Columbia because they had already filled up their quota of Jewish students for that year. Feynman wasn’t bothered by the quota system, incredible though it seems to modern eyes; that was just the way things worked in the 1930s. But he would probably have appreciated it if the university had rejected him out of hand, without taking his $15 first.

  That left MIT. Apart from the academic requirements, they insisted upon a recommendation from an MIT graduate for all prospective freshmen. This did rankle, but it was a hoop that had to be jumped through, and Melville did the jumping, persuading an acquaintance whom he knew had gone to MIT to provide the recommendation. But the acquaintance really knew nothing about Richard, who later described the system,28 as ‘evil, wrong, and dishonest’, a falseness that was the only thing he disliked about applying to MIT. The unpleasant taste was eased somewhat when the college offered Richard a small scholarship – he had applied for a full scholarship, which he failed to get, but received the small award of about $100 per year, which would be a help.

  In the summer of 1935, before he left for MIT, Feynman worked in his aunt’s hotel (putting money aside ready for college) and spent a lot of time getting to know Arline better. It was at MIT that he would formally make the transition from being a mathematician to being a physicist, and he was lucky enough to arrive on the scene at a time when the physics textbooks had been completely rewritten by the development, in the 1920s, of quantum theory. The younger Feynman had read about some of this new work already, for pleasure; soon, it would become his vocation. In order to appreciate where Feynman was coming from when he began to make his own original contributions to science, it is time to take stock of the state physics was in just before Feynman came on the scene, in the aftermath of the quantum revolution and the slightly older revolution initiated by Albert Einstein with his two theories of relativity. Twentieth-century science was a very different world from the one in which physicists had operated for the previous 200 years, from the time of Isaac Newton (at the end of the 17th century), to the time of Max Planck (at the end of the 19th century).

  Notes

  1. Richard Feynman, interview with Jagdish Mehra, quoted in Mehra’s book The Beat of a Different Drum (hereafter referred to as Mehra; details in Bibliography).

  2. Feynman often recounted this anecdote. See, for example, What Do You Care What Other People Think?, by Richard Feynman & Ralph Leighton (hereafter referred to as What Do You Care; details in Bibliography). The widely recounted dinosaur, bird and wagon anecdotes can be found in the same source.

  3. What Do You Care.

  4. Leighton, interview with JG, April 1995.

  5. Quoted in No Ordinary Genius, edited by Christopher Sykes (see Bibliography).

  6. What Do You Care.

  7. The story of Johanna and Henry Phillips is told by Joan Feynman in No Ordinary Genius.

  8. What Do You Care.

  9. S
ee Joan Feynman’s contribution to the Feynman memoir Most of the Good Stuff, edited by Laurie Brown & John Rigden (see Bibliography).

  10. Joan Feynman’s comments taken from correspondence with JG, January/February 1996.

  11. Mehra.

  12. Most of the Good Stuff.

  13. There is no evidence that Lucille believed this. But she must have been aware of the extremely limited career opportunities for women in science at the time, and was probably trying to steer Joan away from the likelihood of a major disappointment.

  14. Interview with JG, April 1995; see also No Ordinary Genius.

  15. Most of the Good Stuff.

  16. Interview with JG, April 1995.

  17. No Ordinary Genius; see also note 10.

  18. Mehra.

  19. See also Six Easy Pieces (see Bibliography).

  20. See, for example, Surely You’re Joking, Mr. Feynman!, by Richard Feynman & Ralph Leighton (see Bibliography; hereafter referred to as Surely You’re Joking).

  21. Mehra.

  22. Mehra.

  23. No Ordinary Genius.

  24. Quoted by Hans Bethe, whom Kac described as an ordinary genius, in No Ordinary Genius.

  25. Mehra.

  26. What Do You Care.

  27. Mehra.

  28. Mehra.

  * The name is pronounced, rather appropriately, ‘Fine Man.’

  † Intriguingly, one of Feynman’s own insights into the nature of the world now provides us (although it was not appreciated in his lifetime) with one way of explaining what inertia ‘really is’; see Chapter 14.

  ‡ The famous ‘ultimate speed limit’ from relativity theory is the speed of light in a vacuum, which is greater still.

  2 Physics before Feynman

  The two revolutions that transformed physics in the 20th century, relativity theory and quantum mechanics, both developed from new understandings of the nature of light, and both had their roots in the 19th century. When Albert Einstein developed his Special Theory of Relativity early in the 20th century1 (it was published in 1905), the foundation stone on which he built was a discovery that had been made four decades earlier, in the 1860s, by the Scottish physicist James Clerk Maxwell.

  Maxwell, who was born in 1831 and died in 1879 (the year Einstein was born), was one of the great physicists of his day, who made many contributions to science. But he is best remembered for his work on electricity and magnetism, which led him to the discovery that light can be described as an electromagnetic wave travelling through space at a certain speed. He developed a set of four equations, now known as Maxwell’s equations, which can provide the answer to any question you want to ask about the ‘classical’ (that is, pre-quantum theory) behaviour of electricity and magnetism. Maxwell’s equations will tell you the force that operates between two electrical charges of a certain strength a certain distance apart; they will tell you how strong an electric current is generated in a nearby wire by a magnet moving past at a certain speed; and so on. Every problem involving electricity and magnetism, above the quantum level, can be solved by using Maxwell’s equations, which represented the greatest unifying discovery in science since Isaac Newton discovered the Universal Law of Gravitation.

  One solution of Maxwell’s equations, a natural component of the unified whole, describes electromagnetic waves moving through space. The speed with which the waves move, usually denoted by the letter c, is a constant which emerges naturally from the equations, as a fundamental property of nature. It is not put in by hand. It was when Maxwell found that the value of c which automatically comes out of his theory is exactly the same as the speed of light measured in a vacuum (which was already quite well determined by the 1860s) that he realized that his equations also described the behaviour of light. In 1864, he wrote:

  The velocity is so nearly that of light that it seems we have strong reason to conclude that light itself … is an electromagnetic disturbance in the form of waves propagated through the electromagnetic field according to electromagnetic laws.2

  That word ‘field’ is one to watch out for. It is related to the idea of lines of force, which helps us to visualize, for example, what happens when two magnets are brought together. In this case, the lines of force are thought of as something like stretched elastic bands, which start out from the magnetic ‘north pole’ on a bar magnet and end up on the magnetic ‘south pole’. When a north pole and a south pole are brought together, the lines of force reach out across the gap and pull the two poles together; but when two north poles are pushed together, the lines of force are forced out of the gap, creating a resistance and holding the two north poles apart (see Figure 2). The region around the magnet where it exerts this influence is the region of its ‘magnetic field’. In a similar way, physicists think of massive objects, like the Sun and the Earth, as being surrounded by a ‘gravitational field’, filled with lines of force that tug on any object in that field. Of course, lighter objects, such as our desk, or your pen, also have their own gravitational fields, but these are so weak that they can only be detected using very sensitive equipment.

  Figure 2. The concept of a field is related to the idea of ‘lines of force’. (a) A north magnetic pole and a south magnetic pole attract each other as if they were being pulled together by stretched elastic bands. (b) Two north magnetic poles repel each other as if they were separated by a block of stiff, compressed rubber. The magnetic field is stronger where the lines of force are closer together.

  Field theory is an extremely successful way of describing the interactions between things like magnets, electrical charges and gravitating bodies. But don’t run away with the idea that it is the only way to describe these interactions. Without wishing to get too far ahead of our story, it’s worth warning you that one of the things that most intrigued Richard Feynman in later life was the way in which several different descriptions of the way things work can turn out to be equally effective in the right hands. Maxwell himself actually worked towards his field theory through an intermediate image which involved the forces of electricity and magnetism being conveyed by whirlpool-like vortices spinning in a fluid which filled all the space between material objects. The way the vortices interacted was like the cogs and wheels of some great piece of clockwork, and this early version of the theory looks totally bizarre to modern eyes – but it worked. The lesson to be drawn is that in some deep sense the truth about how the world works resides in the equations – in this case, Maxwell’s equations – and not in the physical images that we conjure up to help our limited imaginations to visualize what is going on.

  That was a point that was well appreciated by the young Einstein. One of the strangest things about the constant c that appeared in Maxwell’s equation was that it was just that – a constant. It represented the speed of light (and all other electromagnetic radiation, including radio waves), but it took no account of how fast the object producing the light was moving, or how fast the person measuring the speed of the light was moving. This didn’t match common sense, or the laws of motion based upon Newton’s work in the 17th century and held sacrosanct ever since.

  In the everyday world, if you ride in an open car that is travelling at 50 kilometres an hour (km/h) along a straight road, and you throw a ball straight out ahead of you at a speed of 5 km/h, then (if you could ignore wind resistance) you would expect the ball to be moving at 55 km/h relative to the road. But what Maxwell’s equations seemed to say was that if you rode in the same car and shone its headlights out in front of you, the speed of the light from the car would not only be c relative to the car (as you would expect) but also c (not c + 50 km/h) relative to the road! Even if you were in a spaceship travelling at half the speed of light, and you met a spaceship travelling the opposite way at half the speed of light, the light from the headlights on the other spaceship would be travelling at the same speed of light, c, relative to your measuring instruments and relative to the measuring instruments in the other spaceship.

  It was clear by the e
nd of the 19th century that there must be something wrong either with Maxwell’s equations or with common sense (and Newton’s equations). It was Einstein’s genius to take Maxwell’s equations at face value, and work out all the implications in his Special Theory of Relativity. Einstein’s theory explains how it can be that the speed of light (in a vacuum; it travels slightly more slowly in more dense media) is always measured to be the same no matter how the measuring instruments are moving relative to the light source. The implications include the fact that the faster an object moves, the more massive it gets; the fact that nothing can be accelerated from ‘ordinary’ speeds to travel faster than light (so that even if you are in a spaceship travelling at two-thirds of c relative to Earth, and you encounter a spaceship travelling in the opposite direction at two-thirds of c relative to Earth, the velocity of the other spaceship relative to yours is still less than c); and the famous relationship between mass and energy, E = mc2.

  All of these predictions, it cannot be overemphasized, have been tested many times to great precision. The Special Theory of Relativity passes every test, and has been proven to be a good description of the way the world works.3 But you only need to use the Special Theory to understand what is going on if you are dealing with things moving at very high speeds, a sizeable fraction of the speed of light. The difference between the predictions of the Special Theory and common sense are of no significance at all for speeds that are small compared with the speed of light, which is itself a huge 300,000 kilometres per second. Unfortunately for the physicists, though, there are things which move at these so-called ‘relativistic’ speeds that have to be taken account of in their attempts to describe the way the everyday world works. In particular, electrons whizzing around inside atoms have to be described taking proper account of the Special Theory of Relativity.*