Theoretical physicist Brian Greene joined us for a Q&A today where he answered several of our most burning questions about string theory, starting with the most basic: Just what is string theory anyway?

In 10 words or less, what is string theory. Okay, 400,000 words or less.... GO!

It's an attempt to unify all matter and all forces into one mathematical tapestry.

(That is 10 words in base 14.)

Greene expounds further on the same subject in the 2-minute video above from his new World Science U project that launched today.

Of course, with the basic definition of string theory in place, there was plenty of room to segue into some of the deeper reaches of string theory, including what the future held for it:

So, the latest round of experiments from the LHC seem to blow up the idea of supersymmetry. Does string theory have any chance of surviving this?

This is an important question:

But first, for those who may have forgotten what supersymmetry is:

Supersymmetry is a potentially big step toward Einstein's dream of a unified theory. Supersymmetry brings together particles of matter and particles of forces into one unified whole.

Now, for your question:

You are right that there is as yet no evidence for supersymmetry at the Large Hadron Collider. Nevertheless, you need to bear in mind that the LHC can not rule out supersymmetry, at most it can show that supersymmetry can only be accessed by an even bigger collider. So string theory (which embraces supersymmetry) can not be rule out by the results of the LHC either.

Let me emphasize too that if we could rule out supersymmetry and rule out string theory I'd be thrilled. Which might sound strange coming form someone who has spent his adult life working on these ideas. But I'm not wedded to any one theory, I'm wedded to making progress toward the truth. And ruling out ideas is surely progress.

On the other hand, I'd also be thrilled if we could find evidence for supersymmetry and for string theory. And yes, more thrilled than I'd be to rule them out.

You can read Greene's whole Q&A, covering the relevance of string theory to the flat circle theory of time, black holes, and just which actress would book the coveted role of the fermion in *String Theory: The Movie,* right here.

## DISCUSSION

The last two paragraphs in the second quote-section is about the best summation of the proper attitude to have for scientific research that I think I've ever read.