Sixty Symbols

So what is the site about?

If you enjoyed The Periodic Table of Videos we profiled earlier this year (see “Web life: The Periodic Table of Videos“), but found it a bit too…well…chemical, then this is the website for you. Physics does not really have a periodic table, so a handful of scientists from Nottingham University in the UK worked with video-journalist Brady Haran to create one. The result is a 6 ×  10 matrix of important symbols in physics and astronomy, each linked to a 5–10 min video describing the symbol’s significance.

What symbols are included?

There are some self-evident ones, like Planck’s constant h, the speed of light c and the cryptic signs that represent planets in ancient (and modern) astronomy. For other symbols, part of the fun lies in guessing which of several meanings the team has elected to explore. Does µ represent the coefficient of friction? The chemical potential? Or maybe the magnetic moment? Some of the choices are far from obvious; the lower-case Greek letter delta, for example, is a ubiquitous symbol in many areas of physics, but here it signifies chaos theory’s Feigenbaum constant. A handful of entries – like Schrödinger’s cat, represented by a hieroglyphic feline – stretch the definition of “symbol” to breaking point, but it seems churlish to complain when the films supporting them are so intriguing.

Can you describe a typical video?

Since different disciplines within physics often concentrate on different aspects of a particular concept or symbol, many of the videos include contributions from two or more scientists. In the video on magnetic fields, for example, most of the eight minutes are spent following Richard Hill around his magnetic-levitation lab (at a respectful distance from the magnet for the sake of the camera’s magnetic tapes), but astronomer Michael Merrifield also makes a brief appearance to discuss the solar magnetic field. Some of the symbols lend themselves to experiments, while others – like the Schwarzschild radius, R_S, representing the characteristic size of a black hole – are described with equations and diagrams sketched on paper. These sketches are also posted on the site, so if you miss a detail, you can look it up later.

What are some of the highlights?

You could search LaTeX manuals and computer fonts in vain for the symbol in the bottom right-hand corner of the Sixty Symbols grid, which resembles a long-necked bird peering into a small cup. The “drinking bird” toy in the corresponding video has a head made of absorbent felt and a body filled with dichloromethane, and, at first glance, it looks like a perpetual-motion machine. The real explanation presented in the video is surprisingly simple (although apparently it eluded Einstein). Another high note – literally – is the video of a device called a Chladni plate. In one of the most beautiful demonstrations in physics, grains of powder sprinkled on this vibrating plate form patterns that trace out nodal points in the vibrations; the shape of the pattern depends on both the frequency of the sound and the size of the grains. The accompanying noise is annoying, but the video is marvellous.

Why should I visit?

Because this is what online physics should look like. The videos are professional but not too slick. The concepts are explained thoughtfully. The scientists skilfully avoid either confusing or patronizing their audience, and they are obviously keen without drifting into “hyperactive mad scientist” territory. Plus, the site has a sense of humour.

How often is it updated?

The matrix has been slowly filling up with symbols since spring 2009, with fresh videos appearing every few weeks. One recent addition discusses the “spots” that appeared on Jupiter and Venus this summer, and another includes footage of the team’s trip to China to view the solar eclipse in July. If you do not see your favourite symbol, then there is still time to request it (contact details are available on the site), but you had better hurry: as of mid-August, more than 50 of the planned 60 slots were already filled.

Can you give me a sample quote?

“The classic thing to ask at the end of a seminar is ‘Ah yes, but what about magnetic fields?’,” says Merrifield in one video. “The person you’re talking to won’t actually have an answer…but you’ll sound quite clever, because magnetic fields almost certainly affect a lot of things going on in the universe.”