Dimension in physics

I have a solid understanding of topological dimension. I heard that some string theororists think that the universe is >= 10-dimensional, but that the extra 7+ dimensions are too small for us to encounter. How can a dimension be small; is it just a model for what is observed, or is it based in theory?

small as in it is of length ~ 2pi h and compact (i.e. S^1). think of a really tiny circle.

Think of a piece of string, it's effectively 1 dimensional as you can move along it but that's all. But now think of it from the point of view of view of a dust mite, it can move along the string and around it, making it 2 dimensional to the mite. The second dimension is curled up tightly around the string so as we pull out it becomes negligable. The same is true in string theory, the extra dimensions are curled up on a very small scale and as we pull out to the length scales we exist on they are also negligable.

You probably think of our three spatial dimensions as infinite. Consider what would happen if they were finite (say, several lightyears across) and would loop back onto themselves. If you moved far enough in one direction, you would eventually return to somewhere near your starting point. Now consider what would happen if one of those three dimensions was really small; it loops back after only a millimeter or so. At larger scales, the universe would then appear to effectively have only two spatial dimensions.

>>3,4
thanks for rehashing my >>2 post except mixed with more stupid.

(op here)

So the universe is, on a big scale, a 3-manifold subset of 10/11/etc.-space, but when you go to microscopy you see that it has higher-dimensional places? Like a (conceptual) 2-dimensional piece of paper with a needle stuck through it is 3-d there?

fuck, I don't know

>>5
You mistyped "With more explanation", OP might be well versed in things like topology but other people read this and might be interested.

Basically what >>3,4 said.

Although I should add that these extra dimensions are recurring everywhere in space (as they each hold a 1 dimensional superstring that makes up a basic element of matter).

>>5
Bitter physicist is bitter. 

>>10
is it any wonder
I thought of going in physics then thought what job would i be able to get with that.

want fries with that?

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>>11

Retard, physicists are some of the most employ people in the world. A physics degree shows high numerical ability, logical thinking, problem solving and grounded in real world situations. Financial institutions that pay the big bucks, for example, are big employers of physicists.

I could facesit Moses to that response!

>>11
If you can get yourself a PhD in research for a specific field, then you're set for life, pretty much. 

Me.. I'm going into high energy physics.  I just have to try not to let education and learning blur out reality.  I still want to get laid. ;_;

>>13
Though it is true that financial institutions often employ physicsists, none of these jobs are related to physics.  I think >>11 was wondering about jobs that require physics, which is quite rare.  I'm doing physics as well, and I'm not very optimistic.

>>14
I've seen that expression elsewhere before, but what does it mean?

>>15
Not necessarily... a good number of people are enslaved as post docs for decades.  Even among the professors, the non tenured ones don't have job security.  I'm going for whatever can unify the standard model and gravity.

>>16
Yeah, that might be true.  I'm not too worried, though.. frankly, I'm fine with that.  As long as I have a clear understanding of our universe.

Oh, and good luck with that.   The standard model is starting to become less and less relevant in the most recent models of physics.

>>13
http://philip.greenspun.com/careers/women-in-science

>>18
lol

I CAN'T UNDERSTAND SHIT HERE.

hi maths forum

Divide by zero. Oh shi-

I'm feeling really keen, for some of that good ol' green

Marijuana MUST be legalized.