Recently I heard a TED talk by Brian Greene where he was speaking about String Theory working on $(10+1)$ dimensions. Plus he said that we live in only in $(3 +1)$ dimensions. So where are others?
He explains that it is crippled to small sizes which we cannot perceive. Also, he gives the analogy of an ant and a man walking on the rope.
So my doubt is, what do physicists mean by saying word dimension? What do you mean by size of dimension? Thanks in advance for your help and support.
Edit: Any link to papers discussing philosophical aspects of the above mentioned is greatly welcome.