# Special & General Relativity Questions and Answers

## What are P-branes?

The folks that are studying super string theory for clues to the 'Theory of Everything' say that P-branes are 'p-dimensional subspaces in the 10- dimensional string manifold' which apparently serve the mathematical function of 'anchoring' the endpoints of the strings which represent the fundamental particles. Evidently by mathematically manipulating these objects instead of the strings themselves, you can investigate how the strings interact in ways that a direct approach doesn't let you. I personally have not the foggiest idea what they are talking about, and I view all of these elements as computational tools, not necessarily a statement of what is actually going on in a physical way. Ultimately, they are studying the geometric properties of space-time, and this in turn represents the gravitational field itself. These mathematical representations are simply the tools we are now using to motivate certain kinds of calculations we would most like to perform.

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All answers are provided by Dr. Sten Odenwald (Raytheon STX) for the NASA Astronomy Cafe, part of the NASA Education and Public Outreach program.