As The New York Times noted in a 2007 profile, Walter Lewin long had a cult following at MIT. But when his free courses went viral on the web (find them in the Physics section of our big collection of Free Online Courses), the physics prof became an “international Internet guru,” the first star of the open course movement. It’s a sign of his stardom that someone made a mashup of Lewin’s “best lines” (drawn, not spoken) from his Classical Mechanics course. For more great physics videos, don’t miss these items:
Think of it as the ultimate slow-motion movie camera. Researchers at M.I.T. have developed an imaging system so fast it can trace the motion of pulses of light as they travel through liquids and solids. To put it into perspective, writes John Markoff in The New York Times, “If a bullet were tracked in the same fashion moving through the same fluid, the resulting movie would last three years.”
We have built an imaging solution that allows us to visualize the propagation of light. The effective exposure time of each frame is two trillionths of a second and the resultant visualization depicts the movement of light at roughly half a trillion frames per second. Direct recording of reflected or scattered light at such a frame rate with sufficient brightness is nearly impossible. We use an indirect ‘stroboscopic’ method that records millions of repeated measurements by careful scanning in time and viewpoints. Then we rearrange the data to create a ‘movie’ of a nanosecond long event.
You can learn more by watching the video above by Melanie Gonick of the M.I.T. News Office, or by visiting the project website.
Cambridge University has had many famous graduates, but perhaps none is more famous than Isaac Newton (class of 1665). This week, Cambridge continues to honor Newton by opening a digital archive of Newton’s personal papers, which includes an annotated copy of the Principia, the landmark work where the physicist developed his laws of motion and gravity. The initial archive features 4,000 pages of scanned materials (roughly 20% of the complete Newton archive), and eventually Cambridge will add material from Charles Darwin, another famous alum, and other scientific figures.
Bonus: If you’re looking to bone up on Physics, you can find many free physics courses in our big collection of Free Online Courses. Leonard Susskind’s class on Classical Mechanics may be of particular interest here.
With a fast-moving mixture of comedy and seriousness, an interview on The Colbert Report is something of an improvisational flying trapeze act. “Stephen Colbert is an amazingly good interviewer,” writes physicist Sean Carroll, “managing to mix topical jokes and his usual schtick with some really good questions, and more than a bit of real background knowledge.”
Beneath the humor there is a sense that Colbert understands and respects science. The sad thing, writes Carroll, “is that more people are exposed to real scientists doing cutting-edge research by watching Comedy Central than by watching, shall we say, certain channels you might have thought more appropriate venues for such conversations.” But the exposure is all too brief. An interview on The Colbert Report typically lasts only a few minutes.
So it was interesting when Colbert stepped away from his comedic character for a more in-depth conversation with one of his frequent guests, astrophysicist Neil deGrasse Tyson. The interview took place last year at Montclair Kimberley Academy in Montclair, New Jersey. Earlier this week Tyson uploaded the video to the website of the Hayden Planetarium, where he is director, but the server was overwhelmed by the resulting surge in traffic. So someone placed the version above on YouTube. It’s an interesting, and witty, one-hour-and-19-minute conversation. For more of Tyson with Colbert, you can watch his appearances on The Colbert Report at the Hayden Planetarium site.
Infinity. It’s a puzzling concept. Is it real, or a mathematical fiction?
Aristotle believed infinity could only be potential, never actual. To speak of an actual infinity, he argued, is to fall into logical contradiction: “The infinite turns out to be the contrary of what it is said to be,” Aristotle wrote in the Physics. “It is not what has nothing outside it that is infinite, but what always has something outside it.”
Aristotle’s logic rested on common sense: the belief that the whole is always greater than the part. But in the late 19th Century, Georg Cantor and Richard Dedekind turned common sense upside down by demonstrating that the part can be equal to the whole. Cantor went on to show that there are many orders of infinity–indeed, an infinity of infinities.
But what relation does the Platonic realm of pure mathematics have to the physical world? Physics is an empirical science, but that hasn’t stopped theorists from imagining the mind-boggling consequences of an infinite universe. To Infinity and Beyond, a one-hour BBC Horizon special featuring interviews with leading mathematicians and physicists, is an entertaining exploration of a subject which, by definition, you won’t be able to wrap your mind around.
Theoretical physicist Brian Greene returns to PBS, this time presenting The Fabric of the Cosmos, a four-part look at the “mind-boggling reality beneath the surface of our everyday world.” The first segment, “What Is Space?,” airs tonight at 9pm. Then come the remaining installments — “The Illusion of Time” (11/9), “Quantum Leap” (11/16), and “Universe or Multiverse?” (11/23). If you can’t catch the episodes on TV, they will be streamed online too at video.pbs.org.
Bonus: At 10 pm eastern time tonight, PBS will host a live, interactive webcast with Brian Greene and some special guests: renowned theoretical physicist Leonard Susskind (watch his theoretical physics courses online) and Saul Perlmutter, winner of the 2011 Nobel Prize in Physics. Together, they will “explore how scientists are piecing together the most complete picture yet of space, time, and the universe.” Get more details on the live event here.
Unrelated bonus: Tonight, at 6 pm eastern time, MoMA will stream online “The Language of Objects,” a conversation featuring Kenneth Goldsmith, poet; Ben Greenman, author and editor, The New Yorker; Leanne Shapton, illustrator, author, and publisher; and Cintra Wilson, culture critic. Get more information and watch here.
You may have seen levitation tricks performed by magicians, but rest assured that they can’t beat this: quantum levitation. The video above was captured at the 2011 ASTC conference, a gathering of scientists in Baltimore, Maryland, with the purpose of demonstrating “how science centers and museums are putting new ideas to practical use to serve their communities.” The School of Physics and Astronomy at Tel-Aviv University has put together this physics experiment showcasing quantum superconductors locked in a magnetic field.
While the video fails to explain the science of what is happening here, the complementary website is helpful. The white round disk (essentially a sapphire wafer coated with a thin layer of yttrium barium copper oxide) is cooled to below negative 185 degrees C. At that temperature (dubbed the critical temperature), the material becomes superconductive, meaning that it has zero electrical resistance. From the website:
Superconductivity and magnetic field do not like each other. When possible, the superconductor will expel all the magnetic field from inside. This is the Meissner effect. In our case, since the superconductor is extremely thin, the magnetic field DOES penetrate. However, it does that in discrete quantities (this is quantum physics after all! ) called flux tubes.
Inside each magnetic flux tube superconductivity is locally destroyed. The superconductor will try to keep the magnetic tubes pinned in weak areas (e.g. grain boundaries). Any spatial movement of the superconductor will cause the flux tubes to move. In order to prevent that, the superconductor remains “trapped” in midair.
And in case you’re wondering: are there practical applications for quantum levitation? The answer, of course, is yes!
Find free physics courses in our big collection of Free Courses from top universities — 400 great courses and growing.
Eugene Buchko is a blogger and photographer living in Atlanta, GA. He maintains a photoblog, Erudite Expressions, and writes about what he reads on his reading blog.
The Open University strikes again. In June, they released The History of English, a series of witty animated videos that covered 1600 years of linguistic history in ten minutes. Now, they’re back with 60-Second Adventures in Thought, another animated sequence that highlights six famous thought experiments. It all starts with Zeno’s ancient Paradox of the Tortoise and Achilles. (Watch above.) Then we head straight to the 20th century, to five famous thought experiments in physics, math and computer science.
The Grandfather Paradox (time travel)
Chinese Room (artificial intelligence)
Hilbert’s Infinite Hotel (the concept of infinity)
The Twin Paradox (special relativity)
Schrödinger’s Cat (quantum mechanics)
You can watch the full series on YouTube and iTunes.
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