What is the current best-estimate for the number of dimensions required for a Theory-of-Everything?

You've got me too. o_o

Last I heard there were at least *three* competing theories:

--The most common one was one that held up that there were 10 spatial dimensions and *none* of time--that in the maths time variables had to cancel out for everything else to make sense. These ten dimensions are thought by some researchers to exist as multiple 9th-, 7th-, 5th-, and 3rd-dimensional universes that move and interact as "branes" upon the curve called "Calabi-Yau space". Last I checked, this was something of a majority theory.

--Some other researchers, however, hold that time isn't an imaginary construct, but that rather the *3rd dimension* itself is. Search the term "holographic universe" at one of the links below. Point of it is, it isn't *quite* as absurd as it seems once you consider that a) a "3rd dimension" could just as easily be represented in fact by the *thickening* of super-strings, and that b) the theory makes gravity VERY easily explained. Maybe too easily.

--And then more recently, one researcher in Europe suggested that a Theory of Everything would be best explained by having not *one* but *two* dimensions of time operating in close parallel. Essentially the "time" we know of is one dimension, where "time prime" would be something that at best we'd notice just at the ragged edges of our perception, or on a calculatory level, would estimate exists in parallel at the ragged edge of quantum probability.

I can understand why some folks get frustrated and want to dismiss it all as "so much numerology and not science". It's complex and terribly abstruse and not so terribly related to anything real-world, now is it?

Trouble is, some folks said much the same thing about Einstein and his "relativity", didn't they? And it ended up being what, 90-95% accurate once we figured out *ways* to test it experimentally? Okay then. And eventually, chemists, Wall Street, and (LED) clockmakers alike began to try and *rely on* some of Einstein's assumptions about molecular and atomic behavior, and probability. So it eventually did become a real world thing....nuclear weapons aside.

But in the meantime, I hear you, it's a pain to keep up with. Your links are below. ^_^ Have a good one!

Stephen Hawking said 11 in "A Brief History of Time" He has now gone back and said it would be possible with 10. trying to imagine anything beyond our 3-D world is almost impossible, and, even as a physicist myself, I find it impossible to think beyong the 4th dimmention of time. In fact, solving any of the equations one would first need to solve in anything above 3-D is difficult. The Schrodinger equation, I am told, has been solved in 4-D, and some chap at Oxford is close to solving it for 5-D, so there is still a long way to go to solve just one of the equations in 10 or 11-D. Thats just one, for the Theory of Everything, we would, as a minimum, need to relate quantum mechanics to relativity theory. I don't think we'll see it in Hawking's lifetime!

i think 11 too,thats what i read in A brief history of time,but dont try to imagine what these extra dimension look like cause its impossible

I believe it's 11 and wikipedia just confirmed that sort of. Some seem to believe it's 10.