Is there more than one universe? Physicist Brian Greene shows how the unanswered questions of physics (starting with a big one: What caused the Big Bang?) have led to the theory that our own universe is just one of many in the "multiverse."
The SETI Institute's Jill Tarter wants to accelerate our search for cosmic company. Using a growing array of radio telescopes, she and her team listen for patterns that may be a sign of intelligence elsewhere in the universe.
What's six miles wide and can end civilization in an instant? An asteroid — and there are lots of them out there. With humor and great visuals, Phil Plait enthralls the TEDxBoulder audience with all the ways asteroids can kill, and what we must do to avoid them.
Physicist Brian Greene explains how the prevailing theories about the fabric of space changed dramatically in the last century — twice. The most recent shift in thinking came about from a strange mistake, and revealed hidden truths about the nature of our universe. Later in this episode, Greene talks more about why this discovery hints at the existence of other universes.
A man smokes marijuana outside Uruguay's parliament in Montevideo on Wednesday, where lawmakers in the lower house debated and passed a bill that would legalize marijuana and regulate its production and distribution.
The South American country's response to incessant drug-related violence in the region signals a quest for alternatives to the U.S.-led war on drugs, and a rethinking of official U.N. anti-drug policy, which has been in effect for more than half a century.