May 11th, 2018 marked what would have been the hundredth birthday of theoretical physicist Richard Feynman. Many physicists name Feynman, who passed away in February 1988, as their primary inspiration in the field and science enthusiasts all over the world frequently quote Feynman’s dry wit and blunt wisdom. According to a poll of scientists conducted by Physics World in 1999, Feynman was amongst the top ten highest regarded physicists, sharing acclaim with Einstein, Galileo and Newton. But what is it about the man that captivates so many?

There are many valid responses, his undying curiosity, his naive wonder and desire to understand how things worked, his lack of deference to authority and rebellious spirit. Another common answer may surprise you as it involves a quality rarely associated with physics or science in general for that matter. Simplicity.

Feynman’s genius lay in his ability to understand and present complex ideas in an intuitive and natural way. It is the reason Feynman remains an inspiration. He would exemplify this concept many times during his career, but never more so than in the development of his Feynman Diagrams. Simple line drawings that depicted complex sub-atomic interactions.

Clearly, anyone who witnessed Feynman’s aptitude with Bongos, perhaps in one of the many strip clubs he played in, would agree that Richard, born in Queens during the Depression, did not fit the stereotypical image of a scientist. This extended to his escapades in japery such as picking the locks of both safes and filing cabinets at the Los Alamos-based Manhatten Project where he helped develop the atomic bomb. Whilst irritating to the base’s security team and many of his colleagues, to Feynman, there was a serious point to these pranks. It was his way of pointing out to his colleagues on the project that security at the base needed to improve.

Feynman’s Los Alamos security pass

“Los Alamos was a very cooperative place, and we felt it our responsibility to point out things that should be improved. I’d keep complaining that the stuff was unsafe, and although everybody thought it was safe because there were steel rods and padlocks, it didn’t mean a damn thing. To demonstrate that the locks meant nothing, whenever I wanted somebody’s report and they weren’t around, I’d just go in their office, open the filing cabinet, and take it out. When I was finished I would give it back to the guy: “Thanks for your report.”…” — Surely You’re Joking Mr Feynman, Richard Feynman.

A healthy disregard for authority

Such actions may well have indicated that Feynman wasn’t too enamoured with authority and this lack of deference would bring him to the public’s attention in 1986.

Feynman was determined to get to the root cause of the Challenger disaster. A passion which brought him into conflict with Washington officials

In the wake of the Challenger shuttle explosion which claimed the lives of seven astronauts on January 28th, Feynman was asked to serve on the Rogers Commission, an inquiry that proposed to discover the reasons behind one of the darkest days in the history of space exploration.

Feynman was reluctant to join, but his inquisitive nature won out. He wanted to know what happened to that space shuttle. Feynman set about asking questions, in particular of the people who constructed the rocket. These challenges brought him into direct conflict with Washington officials who had perhaps not envisioned such a deep investigation. In fact, according to Feynman himself in his second autobiography “What do you care what people think” efforts were made to water down his final conclusion in the report until he threatened to quit the project.

With a glass of ice water and a rubber ring, Feynman demonstrates the error which cost the lives of seven astronauts

What Feynman uncovered was a fundamental and deeply disturbing lack of communication between different departments within NASA. NASA management’s estimates of failure were vastly underestimated. Rather than 1 in 100,000 chance of failure, Feynman discovered by speaking to NASA engineers that the actual probability was closer to 1 in 100.

Delving deeper he uncovered what he believed was the fundamental reason for the explosion on that winter morning and he unveiled in a characteristic and devastatingly simple way. Feynman had discovered that the rubber O-rings which held together sections of the rocket were extremely vulnerable to changes in temperature.

He demonstrated this on live television on 11th February 1986, in a demonstration still available on YouTube, with nothing more than a glass of ice-water and one of these O-rings. He placed the O-ring in a clamp and in the ice water when he lifted it out the ring failed to stretch back to its original shape. This allowed gas to escape from a section of the rocket and heat the fuel tank which exploded.

The rocket had exploded simply because the morning of January 28th, 1986 was too cold for the launch.

Richard Feynman; the Nobel Laureate and the dinner plate

Feynman was awarded the Nobel in physics in 1965 alongside Sin-Itiro Tomonaga and Julian Schwinger, for their work in Quantum Electrodynamics (QED). QED was designed to make sense of the interactions between photons and other sub-atomic matter which arose from the development of quantum mechanics but as a theory it was incomplete, some interactions couldn’t be explained as a behaviour of a field and subsequently reconciled with Einstein’s theory of special relativity.

A dinner plate in a cabinet at Cornell signifies Feynman’s greatest discovery

In addition to this, there were unexplained infinities in the calculations of electromagnetic interaction, a warning sign to physicists that something is missing in their formulation. Whilst reading the work of Paul Dirac, one of the fathers of QED and quantum mechanics in general, Feynman was captivated by one particular statement made by the author:

“Some new ideas are needed,” Dirac wrote, throwing down the gauntlet to a generation of physicists.

Feynman had a great respect for Dirac, which is understandable given that Dirac always asserted that theories in physics should be based on “simplicity and beauty”. Thus displaying a similar outlook on knowledge of the world as Feynman. So it is little surprise that Feynman was drawn to build on Dirac’s work. What may be more surprising is the source of Feynman’s “eureka moment” that led him to this exploration.

Feynman had found himself at Cornell University at a particularly desperate time. Both the death of his first wife, Arlene, as a result of tuberculosis in June 1945 and the detonation of the atomic bombs on Hiroshima and Nagasaki, had left Feynman bereft. His love of physics gone.

As he tells it, in typically unceremonious fashion in his autobiography:

“…I was in the cafeteria and some guy, fooling around, throws a plate in the air. As the plate went up in the air I saw it wobble, and I noticed the red medallion of Cornell on the plate going around. It was pretty obvious to me that the medallion went around faster than the wobbling. I had nothing to do, so I start to figure out the motion of the rotating plate. I discover that when the angle is very slight, the medallion rotates twice as fast as the wobble rate — two to one. It came out of a complicated equation! Then I thought, ``Is there some way I can see in a more fundamental way, by looking at the forces or the dynamics, why it’s two to one?’’ I don’t remember how I did it, but I ultimately worked out what the motion of the mass particles is, and how all the accelerations balance to make it come out two to one. I went on to work out equations of wobbles. Then I thought about how electron orbits start to move in relativity. Then there’s the Dirac Equation in electrodynamics. And then quantum electrodynamics. And before I knew it (it was a very short time) I was ``playing’’ — working, really — with the same old problem that I loved so much, that I had stopped working on when I went to Los Alamos: my thesis-type problems; all those old-fashioned, wonderful things. It was effortless. It was easy to play with these things. It was like uncorking a bottle: Everything flowed out effortlessly. I almost tried to resist it! There was no importance to what I was doing, but ultimately there was. The diagrams and the whole business that I got the Nobel Prize for came from that piddling around with the wobbling plate.” Surely you’re joking, Mr Feynman Richard Feynman,

This simple observation of a spinning plate led Feynman to develop the idea that on a subatomic level particles interact via the exchange of ‘virtual photons’ and that these exchanges can be modelled in a disarmingly deceptive way. The Feynman Diagram.

The Feynman Diagram, complexity hidden in simplicity

Though the Feynman diagram is now a stable and familiar part of the theoretical physicist’s chalkboard, they were initially met with some scepticism upon their introduction to the scientific world at a private meeting for 28 of his fellow theorists in 1948, held at Pocono Manor Inn in rural Pennsylvania. Even Feynman’s sister, Joan Feynman, born in 1927 and herself an accomplished astrophysicist, told in the documentary “The Fantastic Mr Feynman” that she had just believed the diagrams to be “silly little squiggles” when she had first seen them. But the simple aesthetic appeal of the diagram hides a series of complex rules for the interaction of particles.

A simple Feynman diagram showing the electromagnetic force of repulsion between two electrons: http://www.vivaxsolutions.com/physics/feynman-diagrams.aspx

The diagrams, show incoming particles about to crash into each other or otherwise interact in some way. At the top, we have out-going particles the result of this interaction. But it is the internal wavy lines that are of particular interest. These are virtual photons, particles which cannot be measured or observed and exist only to allow a particular interaction to exist.

A Feynman diagram of electron/positron annihilation and the subsequent release of energy via two photons

Feynman Diagrams allowed physicists to side-step complex numerical calculations to some extent and describe the intricacies of QED in a brilliantly intuitive way whilst avoiding the infinities that had been so troubling and construct a meaningful model of particle interactions.

Richard Feynman, the greatest teacher

Perhaps the greatest quality of a great teacher is the ability to influence a student to think not what they think, but to think as they think. Feynman’s contributions to the sciences do exactly that. His Feynman diagrams teach students to picture events which will never be seen with the naked eye. His masterworks The Feynman Lectures on Physics are a manual that instructs students to think as Feynman does.

Richard Feynman wasa gifted and intuitive teacher

Feynman’s greatest teaching is the physics student should view physics in a natural and intuitive way. Despite this, examples from Feynman’s life demonstrate that authority should be questioned and that one’s own teachers can be honoured by the improvement of their work. Feynman’s contributions to physics belie a mischievously maverick spirit.

As Feynman stated himself in a self-narrated series of videos, with regards to his Nobel Prize award.

“I don’t see that it makes any point that someone in the Swedish Academy decides that the work is noble enough to receive a prize… The prize is the pleasure of finding the thing out, kick in the discovery, the observation that other people use it. those are the real things. The honours are unreal,”

Clearly, Feynman’s greatest lesson and his simplest was that the pursuit of knowledge is ultimately its own reward.