a) you are so so so wrong...first of all it implies that we are in a 12-dimensional universe. Second it makes quantum gravity renormalizable (
http://en.wikipedia.org/wiki/Renormalization) which is HUGE.
b) thanks
That should be n-dimensional space where n is greater than I believe 9, since there are multiple string theories with many different possibilities for the number of dimensions.
in the theories current form of the Standard Model quantum gravity is not renormalizable. Meaning we have infinities turning up in places where they shouldn't, and we can't fix them with renormalization. Renormalization is what got the other 3 forces (electromagnetism, weak, and strong) to work with quantum field theory. To combine the electro-weak-strong force (they were combined in some theory) and quantum gravity it would need to be renormalizable
Put simply, you get really weird infinites when trying to combine the 2. I don't remember the exact ones, but it would be the equivalent of having infinite direction. It just does not make sense.
Guess this is now a XKCD thread.
Also: @
zemerick why do you think that Quantum Physics and Gravity can't exist together? Quantum Physics is just a more specialized field of Physics. Quantum is derived from the word Quanta, meaning single.
*
So Quantum Physics is just Physics but less diverse. My understanding is that it is based around the fact that light has mass and all the insanity attached to it is mainly sci-fi bullshit.
*Citation Needed
I didn't say Quantum Physics and Gravity can't exist together, but rather that the theories describing them do not work together. The problem is that they most certainly do exist together, meaning something somewhere in our theories is wrong. This is especially puzzling because both General/Special Relativity ( which describes Gravity ) and Quantum Mechanics have been tested to absolutely mind boggling accuracy, and both appear correct.
QM does not say photons have mass. We are pretty sure they are massless in fact, and it is required to travel at the speed of light. ( Interestingly, being massless also demands that you do travel at the speed of light. ) In fact, photons having a rest mass would actually break Quantum Mechanics. Of course, as I mentioned, there's something wrong somewhere between QM and Relativity, so there's always the possibility that's all wrong.
Depending on what "insanity" you're talking about, it usually is a real part of QM. It's a very weird system, and is why it is described separate from the "Classical" systems of every day life.
I highly recommend "The Elegant Universe" and "The Fabric of The Cosmos" by Brian Greene. There are PBS specials of both books, but naturally the books go into a little more detail. In fact, watching the videos and books both is best thanks to the visuals of the show, and detail of the books. They are all made for the general public, with virtually no math involved.