This Har­vard-pro­duced video has gone viral, and then some, hav­ing clocked more than 3,000,000 views. We’ve watched the pen­du­lum balls swirl, mov­ing almost impos­si­bly from pat­tern to pat­tern, and we’ve remained daz­zled all along. But the mechan­ics behind this chore­o­graphed action haven’t real­ly been brought to the fore. So let’s turn to Har­vard’s web site to under­stand how this kinet­ic art works:

The peri­od of one com­plete cycle of the dance is 60 sec­onds. The length of the longest pen­du­lum has been adjust­ed so that it exe­cutes 51 oscil­la­tions in this 60 sec­ond peri­od. The length of each suc­ces­sive short­er pen­du­lum is care­ful­ly adjust­ed so that it exe­cutes one addi­tion­al oscil­la­tion in this peri­od. Thus, the 15th pen­du­lum (short­est) under­goes 65 oscil­la­tions. When all 15 pen­du­lums are start­ed togeth­er, they quick­ly fall out of sync—their rel­a­tive phas­es con­tin­u­ous­ly change because of their dif­fer­ent peri­ods of oscil­la­tion. How­ev­er, after 60 sec­onds they will all have exe­cut­ed an inte­gral num­ber of oscil­la­tions and be back in sync again at that instant, ready to repeat the dance.

We’re adding this clip to our col­lec­tion of 125 Great Sci­ence Videos. You’ll also find a good num­ber of Physics cours­es in our big col­lec­tion of Free Online Cours­es.

Richard Feyn­man was a once in a gen­er­a­tion intel­lec­tu­al. He had no short­age of brains. (In 1965, he won the Nobel Prize in Physics for his work on quan­tum elec­tro­dy­nam­ics.) He had charis­ma. (Wit­ness this out­take from his 1964 Cor­nell physics lec­tures avail­able here.) He knew how to make sci­ence and aca­d­e­m­ic thought avail­able, even enter­tain­ing, to a broad­er pub­lic. (We’ve high­light­ed two pub­lic TV pro­grams host­ed by Feyn­man here and here.) And he knew how to have fun. The clip above brings it all togeth­er. Hope you enjoy, and don’t miss our col­lec­tion of Great Sci­ence Videos, or many free physics cours­es in our big col­lec­tion of Free Online Cours­es.

You would­n’t nec­es­sar­i­ly guess it, but astro­physics comes with occu­pa­tion­al risks. Try­ing to unrav­el the mys­ter­ies of the uni­verse, some physi­cists jour­ney to inhos­pitable parts of the world (Siberia, the Antarc­tic, deep mine shafts, etc.), search­ing for ide­al con­di­tions to per­form exper­i­ments into dark ener­gy, dark mat­ter, and beyond. This all gets detailed by Anil Anan­thaswamy, a soft­ware writer turned sci­ence writer, who recent­ly pub­lished a new book The Edge of Physics: A Jour­ney to Earth­’s Extremes to Unlock the Secrets of the Uni­verse. The talk above was pre­sent­ed at the INK Con­fer­ence last Decem­ber. You can also watch him give a fuller 50 minute talk at Google here.

We’re beam­ing you back to 1964. Richard Feyn­man, our favorite Bon­go-play­ing, Nobel Prize-win­ning physi­cist, reduces sci­ence to the barest essen­tials, to its most fun­da­men­tal truth. If a the­o­ry does­n’t square with exper­i­ment, it’s wrong. That holds true for clever the­o­ries, ele­gant the­o­ries, and all of the rest.

This clip is just a small out­take from a sev­en-part lec­ture series that Fey­man pre­sent­ed at Cor­nell in 1964, and the lec­tures are all now freely avail­able on the web thanks to Bill Gates. You can watch the full series on our site, or on a Mis­crosoft site, but be warned: if you choose the lat­ter, you’ll need to down­load Microsoft­’s Sil­verlight soft­ware to watch the lec­tures.

For more free physics lessons, don’t miss our col­lec­tion of Free Online Physics Cours­es, part of our larg­er col­lec­tion, 1,700 Free Online Cours­es from Top Uni­ver­si­ties.

Feyn­man fans will also want to see this oth­er open project: The Feyn­man Lec­tures on Physics, The Most Pop­u­lar Physics Book Ever Writ­ten, Now Com­plete­ly Online.

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