GUY RAZ, HOST:
Albert Einstein better be watching his back. Physicists have added fuel to a fire that could destroy one of Einstein's fundamental notions: Nothing travels faster than the speed of light.
Well, back in September, a team of scientists first claimed that a sub-atomic particle called the neutrino could travel faster than the speed of light. Needless to say, there were skeptics. Now, physicists have done it again with a fine-tuned experiment that matches the previous results.
To explain just how earth-shaking this could be, we're joined by Brian Greene. He's professor of physics and mathematics at Columbia University, and author most recently, of "The Hidden Reality."
Brian Greene, welcome.
BRIAN GREENE: Thank you.
RAZ: Okay, so the idea of that nothing travels faster than the speed of light, that obviously is part of Einstein's Theory of Relativity, this is a foundation of physics. These new experiments have truly rocked the scientific community. Explain why.
GREENE: Well, no one anticipated that a particle could go faster than the speed of light. And, frankly, I should say at the outset, most physicists don't believe that any particle does go faster than the speed of light.
RAZ: Still - they still don't believe it.
GREENE: No, I mean these are very difficult experiments when you're trying to calculate the precise speed of this little ghostly particle called the neutrino. And many of us think that it will take an independent
RAZ: Still? They still don't believe it?
GREENE: ...than a gigabyte. No. I mean, these are very difficult experiments when you're trying to calculate the precise speed of this little ghostly particle called a neutrino. And many of us think that it will take an independent experiment, doing it a different way, getting the same answer before we believe it.
RAZ: So you're one of those skeptics?
GREENE: Hugely so.
RAZ: All right.
GREENE: And I think, if you were to do a survey of most physicists, we'd all pretty much say the same thing. An extraordinary result like this, in the words of Carl Sagan, requires extraordinary evidence and we don't have that extraordinary evidence yet.
RAZ: Okay. Can you explain, first of all, what neutrinos actually are?
GREENE: They're little, tiny particles of matter that are the most standoffish, if you will, of the particles that we know of. They can pass through trillions of miles of lead without being deflected, just pass right through. So they're ghostly particles that we require in order to make sense of data from particle accelerators around the world, to make sense of observations of astrophysical phenomenon.
So we know that the neutrinos are certainly real, but their speed is what is at question here.
RAZ: So these physicists at CERN, this lab in Switzerland - can you explain how they came to this conclusion that they have managed to send particles traveling faster than the speed of light?
GREENE: In principle, it's quite straightforward. They take these particles and they fire them from Switzerland to another receptor at another laboratory in Gran Sasso in Italy. And what they do is they calculate how long it took the neutrinos to get there and they calculate how long the journey is and that's all you need to figure out speed.
RAZ: So why all the skepticism if they've basically shown that it's faster?
GREENE: Well, it's very hard to precisely measure the distance between two places. These particles are passing through the earth's crust, so it isn't as though you can just lay out a tape measurer...
GREENE: ...from one location to the other. Moreover, you have to make sure that the clocks at the two positions where the particles begin and end, they must be synchronized to fantastic precision. You know, if someone runs a marathon and you're going to time how long it takes them, the clock at the finish line better be in synch with the clock at the starting line. And it's very hard to get clocks into sync.
RAZ: If this is actually true, I mean, this could change the way you all and then, of course, we all, think about time and space, right?
GREENE: Yes and no. So let me just point out that the idea that this would somehow throw Einstein out the window...
GREENE: That's just not true.
GREENE: E equals MC squared will still be with us. All of the wonderful features of relativity will still be with us. We'll just have a more refined version of relativity to accommodate these results if they are true.
RAZ: 'Cause you actually really want to believe this. You're not being a skeptic just to be difficult.
GREENE: Well, we live for things which change our understanding of reality. And that's what being a physicist is all about, so we want this to be true, but we don't think it is. We're waiting for the proof.
RAZ: That's Brian Greene. He's a professor of physics and mathematics at Columbia University, talking about experiments with neutrinos that may or may not prove they can travel faster than the speed of light. Brian Greene, thanks.
GREENE: My pleasure. Transcript provided by NPR, Copyright NPR.