compactification

[meteor]

Hi, here are a pair of questions that I can't find the answer:
What's the difference between an orbifold and a Calabi-Yau manifold?
How many Calabi-Yau manifolds there exist for cubic meter of space?

[thed]

http://www.wikipedia.org/wiki/Calabi-Yau_spaces
http://www.wikipedia.org/wiki/Orbifold

Or alternatively

http://mathworld.wolfram.com/Calabi-YauSpace.html
http://mathworld.wolfram.com/Orbifold.html

Got to admit, I'm slightly out of my depth here.

[selfAdjoint]

Looks like Wikipedia and Mathworld are slightly out of their depthe too, at least on orbifolds.

[thed]

Problem is that both sites rely on volunteers to add new material. If no one has added anyhting, you won't find it.