College of Liberal Arts & Science

Arizona State University, Goldwater Building

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Office: (480) 965-7381

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© 2017 Frank Wilczek, All Rights Reserved

Feynman Project

Feynman Project

 

Teenage Frank devoured The Feynman Lectures, and a few years later Feynman diagrams changed his life.  Frank had the pleasure to write about a memorable personal encounter with Richard Feynman, and the honor of writing an introduction to The Character of Physical Law, his popular science masterpiece. 

 

2018 will mark the 100th anniversary of Feynman’s birth.  Since Feynman himself was an artist and a charismatic public figure, Betsy Devine (Frank’s wife), assisted by Frank and others, promoted the idea of an art/science outreach to the public, in commemoration.  That concept has matured into a virtual exhibit under development at the Nobel Museum and a conference in Singapore – with more in the works.  
 

Betsy Devine

 

Betsy Devine works as a Guest curator at the Nobel Museum in Stockholm. Betsy is also working on with Nobel Museum in Stockholm and now with ArtScience Museum in Singapore.
  

About three years ago, Frank started helping Betsy create this exhibition for Feynman's 100th birthday in 2018. The exhibition was inspired by Feynman diagrams, especially those related to eight different Nobel Prizes. They also use Prize-related Feynman diagrams to explore eight kinds of "stories" that inspire both scientists and artists.

 

The Nobel Museum's plan is primarily to create a Feynman website that teachers can use to motivate discussions about creativity, art, science, and career choices. The prototype of this website is online at feynman.daresay.io

 

The exhibition is a series of eight stations for the 8 Nobel Prizes and has an introductory station about Feynman, his diagrams, his science, and his art. The theme of that station is “Representation.”

 

Each of the eight Nobel-Prize stations shows information about that year's Laureates, the relevant Feynman diagram, the science "story" behind their prize, and some example of artworks telling a similar story.

 

To sharpen the focus, they reduced the number of Nobel Prizes in Physics from 16 to 8, each associated with a Feynman diagram and with a story-telling metaphor that also applies to many works of art. For example, the 1965 Prize (Tomonaga, Schwinger, Feynman) is associated with the idea of “Light.” So, in addition to talking about the science behind the prize, the website shows artworks that make light a major focus of viewer experience.

 

 

How Feynman Diagrams Almost Saved Space - Frank Wilczek

 

Richard Feynman’s famous diagrams embody a deep shift in thinking about how the universe is put together.

 

Richard Feynman looked tired when he wandered into my office. It was the end of a long, exhausting day in Santa Barbara, sometime around 1982. Events had included a seminar that was also a performance, lunchtime grilling by eager postdocs, and lively discussions with senior researchers. The life of a celebrated physicist is always intense. But our visitor still wanted to talk physics. We had a couple of hours to fill before dinner.

 

I described to Feynman what I thought were exciting if speculative new ideas such as fractional spin and anyons. Feynman was unimpressed, saying: “Wilczek, you should work on something real.” (Anyons are real, but that’s a topic for another post.)

 

Looking to break the awkward silence that followed, I asked Feynman the most disturbing question in physics, then as now: “There’s something else I’ve been thinking a lot about: Why doesn’t empty space weigh anything?”

 

Feynman, normally as quick and lively as they come, went silent. It was the only time I’ve ever seen him look wistful. Finally he said dreamily, “I once thought I had that one figured out. It was beautiful.” And then, excited, he began an explanation that crescendoed in a near shout: “The reason space doesn’t weigh anything, I thought, is because there’s nothing there!”

 

To appreciate that surreal monologue, you need to know some backstory. It involves the distinction between vacuum and void.

 

Vacuum, in modern usage, is what you get when you remove everything that you can, whether practically or in principle. We say a region of space “realizes vacuum” if it is free of all the different kinds of particles and radiation we know about (including, for this purpose, dark matter — which we know about in a general way, though not in detail). Alternatively, vacuum is the state of minimum energy.

 

Intergalactic space is a good approximation to a vacuum. Void, on the other hand, is a theoretical idealization. It means nothingness: space without independent properties, whose only role, we might say, is to keep everything from happening in the same place. Void gives particles addresses, nothing more.

 

Aristotle famously claimed that “Nature abhors a vacuum,” but I’m pretty sure a more correct translation would be “Nature abhors a void.” Isaac Newton appeared to agree when he wrote:... that one Body may act upon another at a Distance thro’ a Vacuum, without the Mediation of anything else, by and through which their Action and Force may be conveyed from one to another, is to me so great an Absurdity, that I believe no Man who has in philosophical Matters a competent Faculty of thinking, can ever fall into it.

 

But in Newton’s masterpiece, the Principia, the players are bodies that exert forces on one another. Space, the stage, is an empty receptacle. It has no life of its own. In Newtonian physics, vacuum is a void.

 

That Newtonian framework worked brilliantly for nearly two centuries, as Newton’s equations for gravity went from triumph to triumph, and (at first) the analogous ones for electric and magnetic forces seemed to do so as well. But in the 19th century, as people investigated the phenomena of electricity and magnetism more closely, Newton-style equations proved inadequate.

 

In James Clerk Maxwell’s equations, the fruit of that work, electromagnetic fields — not separated bodies — are the primary objects of reality.

 

Quantum theory amplified Maxwell’s revolution. According to quantum theory, particles are merely bubbles of froth, kicked up by underlying fields. Photons, for example, are disturbances in electromagnetic fields.

 

As a young scientist, Feynman found that view too artificial. He wanted to bring back Newton’s approach and work directly with the particles we actually perceive. In doing so, he hoped to challenge hidden assumptions and reach a simpler description of nature — and to avoid a big problem that the switch to quantum fields had created.

 

In quantum theory, fields have a lot of spontaneous activity. They fluctuate in intensity and direction. And while the average value of the electric field in a vacuum is zero, the average value of its square is not zero. That’s significant because the energy density in an electric field is proportional to the field’s square. The energy density value, in fact, is infinite.

 

The spontaneous activity of quantum fields goes by several different names: quantum fluctuations, virtual particles, or zeropoint motion. There are subtle differences in the connotations of these expressions, but they all refer to the same phenomenon. Whatever you call it, the activity involves energy. Lots of energy — in fact, an infinite amount.

 

For most purposes we can leave that disturbing infinity out of consideration. Only changes in energy are observable. And because zero-point motion is an intrinsic characteristic of quantum fields, changes in energy, in response to external events, are generally finite. We can calculate them. They give rise to some very interesting effects, such as the Lamb shift of atomic spectral lines and the Casimir force between neutral conducting plates, which have been observed experimentally. Far from being problematic, those effects are triumphs for quantum field theory.

 

The exception is gravity. Gravity responds to all kinds of energy, whatever form that energy may take. So the infinite energy density associated with the activity of quantum fields, present even in a vacuum, becomes a big problem when we consider its effect on gravity.

 

In principle, those quantum fields should make the vacuum heavy. Yet experiments tell us that the gravitational pull of the vacuum is quite small. Until recently — see more on this below — we thought it was zero. Perhaps Feynman’s conceptual switch from fields to particles would avoid the problem.

 

Feynman started from scratch, drawing pictures whose stick-figure lines show links of influence between particles.

 

The first published Feynman diagram appeared in Physical Review in 1949.

 

 

 

 

 

 

 

 

 

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