Add Quote by Roger Penrose

If I take the theory as we have it now, literally, I would conclude that extra dimensions really exist. They're part of nature. We…

— Edward Witten

The theory has to be interpreted that extra dimensions beyond the ordinary four dimensions the three spatial dimensions plus time are sufficiently small that…

— Edward Witten

Technically you need the extra dimensions. At first people didn't like them too much, but they've got a big benefit, which is that the…

— Edward Witten

As you say, the way string theory requires all these extra dimensions and this comes from certain consistency requirements about how string should behave…

— Roger Penrose

String theory is not the only theory that can accommodate extra dimensions, but it certainly is the one that really demands and requires it.

— Brian Greene

Extra dimensional theories are sometimes considered science fiction with equations. I think that's a wrong attitude. I think extra dimensions are with us, they…

— Leonard Susskind

On the other hand, we don't understand the theory too completely, and because of this fuzziness of spacetime, the very concept of spacetime and…

— Edward Witten

In the book, I make the point that here we have string theory and here we have twistor theory and we don't know if…

— Roger Penrose

One of the weird things about modern physics is that we do find there are apparently these other dimensions that we don't directly experience…

— David Grinspoon

“For string theory to make sense, the universe should have nine spacial dimensions and one time dimension, for a total of ten dimensions.”

— Brian Greene

Having those extra dimensions and therefore many ways the string can vibrate in many different directions turns out to be the key to being…

— Edward Witten

As far as extra dimensions are concerned, very tiny extra dimensions wouldn't be perceived in everyday life, just as atoms aren't: we see many…

— Edward Witten