What is the 11th dimension?

Answer 1

The one between the 10th and the 12th. Its like asking whats the 3rd dimension, you choose when you do the maths.
If you decide the Universe only needs 11 dimesions to describe it, then its the final one in your maths.

Answer 2

is a container for gravity and full of branes (so far)

branes are containers for other dimensions including ours

when the branes clash, they create big bangs inside of them, and bounce back off the other brane like a wave.

now take this 11d idea container idea and our dimension in a brane idea structure and turn the whole thing inside out making very very small instead of very very big.

Answer 3

Whaaaaaa???????
Three physical dimensions, commonly labeled as X,Y, and Z, with a fourth dimension commonly known as 'time'.

You're getting into string theory, here.

Answer 4

I believe it's something some physicist made up in order to put himself on the map. Others have ridden on its wake. Cryptic stuff like this allows them to postulate anything they want, like string theory. My bet: that it will all fizzle away one day, like the luminiferous ether.