Theoretical Physicist Sean Carroll asks why does time exist? Marla Aufmuth/Courtesy of TED hide caption

itoggle caption Marla Aufmuth/Courtesy of TED

"Human beings are works in progress that mistakenly think they're finished," says psychologist Dan Gilbert. Ryan Lash/Courtesy of TED hide caption

itoggle caption Ryan Lash/Courtesy of TED

An artist's conception of how Saturn's immense Phoebe ring might appear to eyes sensitive to infrared wavelengths. NASA/JPL/Space Science Institute hide caption

itoggle caption NASA/JPL/Space Science Institute

The new spacecraft, called LightSail, is orbiting Earth. Future versions could travel to the moon and beyond. The Planetary Society hide caption

itoggle caption The Planetary Society

The Two-Way

Solar Sail Unfurls In Space

A nonprofit has successfully tested technology that could one day be used to explore the solar system on a budget.

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