How strange can space-time get?


AspaceTheoretical physicist Brian Greene admits that the world he describes in his new public-TV documentary series, “The Fabric of the Cosmos,” is nothing like everyday experience. He's not even sure some of the things he describes are for real. For example, how can we possibly know other universes exist? Believe it or not, there are ways to find out. The four-part “Nova” series makes its debut on PBS stations on Wednesday night with an episode that delves into the mysteriously substantial properties of empty space. “As it turns out, empty space is not nothing,” the Columbia University professor says at the start of the show. “It's something. … So real, that empty space itself helps shape everything in the world around us, and forms the very fabric of the cosmos.” That episode is already available for watching over iPhones, iPads and iPod Touch devices, as well as through Amazon Prime instant video. And if you miss seeing it on TV on Wednesday, you'll be able to catch up with it later online. Over succeeding weeks, Greene addresses not only space, but also the nature of time, the weird world of quantum mechanics and the possibility that our universe is just one bubble in the cosmic ocean (or raisin-bread loaf, or cheese wedge) of the multiverse. Most of the substance in “The Fabric of the Cosmos” comes from Greene's book of the same name — but the part about the multiverse is more speculative, and is derived from Greene's follow-up book titled “The Hidden Reality.” So of course that's where I had to start when I had a chat with Greene this week. Here's an edited transcript of the Q&A:

You must get this question all the time: What sort of proof do you have that any of this stuff is true?

Brian Greene: Well, the first three episodes — focusing on space, time and quantum mechanics — are much more closely tied to observations and experiments that have already been done. Much of what we describe in those programs is firmly rooted in science that is now largely accepted, even though it's weird. The fourth program is different in that regard, because as the last program in the series, it is looking beyond what we currently know, and surveying the landscape of possibilities that may in the future become accepted science. But not yet.

More here.