Ask dcr: String Theory
String Theory: It’s What Did Captain Kirk In. Er, I Guess that was the Nexus. String Theory is Easier to Understand…
Today, I received an interesting question from Speedy: “Does string theory work better on the 10 dimensional model?”
That’s an easy one: Yes, depending upon the circumstances.
If you have a question, send it to: askdcr@dcrblogs.com. That address, of course, may change one day if I start getting a bunch of “Official [insert name of little blue pill]” junk mail.
Superstring theory sometimes requires a 10 dimensional spacetime, or else bad quantum states called ghosts with unphysical negative probabilities become part of the spectrum … depending upon the circumstances of course as DCR has pointed out
Now, this creates a problem in d=10 string theory: how to get the d=4 world as we know it out of the theory
So far there are two main proposals
1. Roll up the extra dimensions into some very tiny but nonetheless interesting space of their own. This is called Kaluza Klein compactification.
2. Make the extra dimensions really big, but constrain all the matter and gravity to propagate in a three dimensional subspace called the three brane. (For an analogy, your computer screen could be said to be a two brane of three dimensional space) These types of theories are called braneworlds.
All of this means there is a lot of computations in my own Brain World
I’m sorry that they never brought back Captain Kirk from the dead. I think he is stuck in the 11th dimension.