science, video

Time Dilation with Carl Sagan

Google street-view mock-up of final scene of The Planet of the Apes.

Image created by Brook Boley

Remember the scene where Charlton Heston finds the remains of the Statue of the Liberty? In The Planet of the Apes, I mean. Sorry, I just gave the ending away. It’s a classic trope (the “Earth all along“). And it’s a classic pop culture reference to time dilation.


I recently ran across Carl Sagan’s explanation of time dilation, the phenomenon in which perspectives of time can vary–the concept of relativity that Einstein laid out. The most famous example being the relative slowing of time as you move faster—basically, the reason why Charlton Heston’s mission aboard the Icarus was 18 months for him but more than 2000 years back on Earth, during which time apes evolved, learned English, and took over.

Relative velocity isn’t the only cause of time dilation, but it’s the one Carl Sagan discusses here. The other big factor is gravity—the closer you are to a major source of gravity, like a planet, the slower time passes for you relative to objects farther from the planet.

This is from episode 8 of Sagan’s famous Cosmos series (which I’ve never actually seen). I like the pastoral Italian setting, and especially the opening scene in which Sagan uses a near-collision to illustrate his first point about the speed of light. And while the time dilation thought experiment has a certain poignance, I love the way Sagan supercharges his pronunciation of the Italian names Paolo and Vincenzo. He sounds more Italian than the Italian kids.


[Photo illustration by Brook Boley from Gizmodo’s “50 of the Most Insane Things Never Seen on Google Street View“]

journalism, science

Freeman Dyson and the Great Big World

Freeman Dyson is a global warming skeptic. This should not come as a surprise.

the cover of the new york times magazine with portrait of dysonLast Sunday, the New York Times Magazine featured a profile of the physicist, now in his 80s, as its cover story. He’s been ensconced at the Institute for Advanced Study for the last several decades.

I liked the piece. There are some questions, which I’ve heard a couple of editors express, about why he merited such a long profile, and the cover, no less. But that’s really a question of editorial inclinations.

The great strength of the article is the sensitive portrayal of Dyson himself. He is a character, a charming and sweet man whose life experience reads like fiction. Nicholas Dawidoff, who wrote the piece, describes Dyson’s smile, and his laugh, “so hearty it shakes him,” which is absolutely true. The global warming controversy seems secondary, though I’d guess it was originally the big reason this story was picked up by the magazine. Ultimately, we have this story of a man who is happy with his life, and has always done whatever suited him, rather than whatever the establishment expected. After all, he did switch from being an Englishman to being an American, and from mathematics to physics to activism and writing.

I interviewed Dyson almost nine years ago, in April 2001. As the years pass, I keep thinking how fortunate I am that my first in-depth, sit-down interview with anyone was with him.

You can see a kind of blueprint for the magazine story in my interview, from the series of Dyson’s greatest hits of applied scientific craziness (Project Orion, the so-called Dyson sphere, major genetic re-engineering), to his deep sense of humanity and obligation to the less fortunate.

I was also introduced to Dyson’s skepticism in that interview. He criticized people who were wary of genetically modified foods. He applauded gentrification. He recounted a story about NASA’s emphasis on public relations over science. He dismissed sustainability, “because what does it mean?” As far as Dyson was concerned, “sustainability” was—and, one could contend, still is—vague enough to mean whatever its promoters want.

You can download my interview, conducted for the Dartmouth Undergraduate Journal of Science, as a PDF here.

At the bottom of my web site, in the footer section, there is a phrase: “It is a great big world.” After my interview with Dyson, as I was about to leave, Dyson told me about flying to China, and sitting next to a boy who spent most of the trip staring out the window. At one point, the boy turned to him, and said, “It’s a great big world!.” Indeed, it is. Easy to forget.