# What's a conifold worth for?

1. Jan 8, 2004

### meteor

What's a conifold worth for?
My investigations have lead me to the conclusion that a conifold consist of two cones united by the vertex. What a strange construction! So what's the role of conifolds in superstring theory?
So, why there are so many constructions in superstring theory that end in -old (e.g. orientifold)?

2. Jan 8, 2004

### lethe

Re: conifold

i don t know what a conifold is, but i can tell you that all the -fold words come from constructions of manifolds. these are just different kinds of manifolds.

3. Jan 9, 2004

### meteor

Some of the jargon related to conifolds:
- conifold singularity
- conifold metric
- deformed conifold
- resolved conifold

I would like to know what are all these things

4. Feb 25, 2010

### thubsch

Re: conifold

The term "conifold" is a contraction of "cone" and the suffix "-fold", the latter of which derives from "manifold". Whereas a manifold (like the surface of a sphere or a donut) is smooth at every point, a conifold is allowed to have conically singular (non-smooth) points. Think of a sphere sprouting sharp quills like a porcupine, or imagine the surface of a donut being made more and more slender at one place until it pinches down to a point, so the result resembles a croissant the conical tips of which are brought together to touch.

The conifolds in string theory are complex 3-dimensional (real 6-dimensional), and are impossible to depict. Nevertheless the equations defining them allow us to identify the points where they are not smooth, and verify that the immediate neighborhood of those singular points are like a cone.

Check out also the Wikipedia article on conifolds.

Cheers, Tristan

5. Feb 26, 2010

### Demystifier

Re: conifold

Hi Tristan,

Wellcome to the Physics Forums!

As you are an expert for Calabi-Yau, could you update/correct my recent post #7 in