I would call for @TokoyamiSenshi !

Oh man. I don't even know where to start. That's partly because there is not one but I dunno, five or so string theories. I'll assume you know a bit about the elementary particles.

Here's what a string theory, in a nutshell is(and I like it for that).

So we built accelerators 'n stuff, and greatly expanded our horizon from the three subatomic particles most people know about. In fact, it went a bit overboard and now there are more subatomic particles then there are elements in a periodic table. That's a lot, mind you!

The only logical(note: there is no hard proof from which to conclude this, it's kind of "this is how it worked out so far" thingy) thing for a physicist to think is that there has to be some simpler underlaying mechanism which gives birth to such complexity. Compare it to language; there are only so many signs in a writing system but you have no problems expressing much more information by simply lining those signs together.

So the scientists assumed that subatomic particles are a tad too big of an alphabet and instead assumed they are in fact words. The natural thing to do was to look for 'the alphabet' of subatomic particles then. And that's basically what strings are.

So here's an overused analogy of what strings are.

Imagine a string. Stretch it and pluck it. It will make a sound. Now stretch it harder. It makes a higher pitched sound now. The sounds in this analogy are what we see as elementary particles. The strings are what actually creates them, depending on how tense they are, in other words, how fast they vibrate. So obviously, one string can play an entire array of elementary particles. That makes the atom an orchestra. Fun, right?

The only thing left to do is push this analogy into as many dimensions as you need to make mathematical sense out of what we observe as the real world and voilá, string theory.

p.s. the last paragraph is what gave birth to several string theories. As you may or may not know, the equations of motion are differential equations and you solve them by choosing the boundary conditions(just some numbers, nothing scary). But what happens is, depending on your choice of boundary conditions, you get different sets of solutions. It's just a mathematical guessing game. Also, you get to choose the dimensionality of space. So far, popular(as in, solved) spaces are 10 and 26 dimensional. In both spaces there are several legit solutions, but this is all math. It's not fit for storytelling.

@TokoyamiSenshi So it ties up the quantum theory with the big bang theory and the theory of relativity together, huh?

Hmm yes that there are multiple string theories. I think one is called the M theory and another is the F theory. From the Youtube videos I've watched, it seems that the M theory is the leading theory and from Michio Kaku's interview, the Math works best on 11 currently. There are still a lot of work to be done it seems since it still hasn't unified all the theories.

But of course, I'm not really in the science field (though I really wish I had chosen to go there. welp, life's long) so I don't know if having only Michio Kaku as source is wise. Which is why I created this thread. If it's okay, I'd like to know the obstacles for string theory.

@eterno: Well, it's a shot at unifying all theories, yes. But it's a new theory, not a patchwork of older ones. As for the number of possible legit string theories, I haven't really done any research on that so I can't even tell if it's finite or not. Not enough data to speak about that just yet, sorry :)

As with any theory dealing with really small, it's the experiments. Proving that there are extra dimensions packed within a ridiculously small volume of space is science fiction at it's best.

The only hope to prove or disprove string theories is using them to predict something on a measurable scale and then trying that out. Which is not as simple as it sounds. Basically, you need a wild, yet unseen prediction and means to see if it's right. If it's right, you're doing it right. But since string theory deals with things so small, it's not easy to come up with measurable predictions.

The problem with new theories is, every next theory has to explain all the things observed thus far, plus add something that can't be explained with existing theories.

tl;dr: The main obstacle is actually trying it out to see if it works.

@TokoyamiSenshi

Umm yeah, I learned about 11 from this video

And here, he explains about Higgs-Boson being the missing subatomic particle

&list=PLE73E48C4D227E053&index=7&feature=plpp_video

And I just watched this one and it kinda started out like you said but in the end, they settled with M theory and 11.

&feature=relmfu

this is the part where they figured that string theory is actually just one theory.

http://www.youtube.com/watch?v=nN7C22u74sQ&feature=relmfu

But yeah, as it stands now, there is but 1 sting theory and the true number of the multiverse is 11. The LHC is currently testing the theory (after all, it's in the name, the Large Hadron Collider). But of course, this is all mostly from Michio Kaku and his colleagues and even though he's the leading expert in string theory, I wonder if there are any opposition to this theory.

@eterno: As long as the M theory remains a theory, there will be an opposition. Whether opposing theories are worthy rivals to the M theory is a different story.

A possible rival, but with much less media publicity is the quantum loop gravity. It may not be as elegant as the string theory, (it's a patchwork of GR and QM, and a good one at that), but it's certainly not disproveable.

I prefer string theory though, because it's poetic. And whoever created the universe, I think was more of an artistic type.

There are also really wild alternative theories which range from outrageously idiotic to too philosophical(as in undescribable in a consistent way), but since they come from people outside the acknowledged scientific groups, and often due to their inability to represent their theories mathematically, aren't given much attention. Also note that though mathematics is beautiful and omnipotent as a description tool and all that, it's not like we know all there is to know about mathematics, so the mathematics needed to describe our universe correctly may not even be known at the moment.

tl;dr

@Flywalker37: It's okay, you wouldn't understand anyway.

@TokoyamiSenshi: Very nice. Touche. ;D

I find string theory very interesting and, as you said, poetic, but I can't help but think of this every time it's mentioned:

@Decae: Me too. It's too mathematical, not physical enough. Still, poetic :)

Big news! Higgs Boson is confirmed to exist!

http://www.smh.com.au/world/science/confirmed-the-higgs-boson-does-exist-20120704-21hac.html

Suddenly, the Unified Field Theory seems closer than ever!

"It could be a gateway to the next phase of exploring the deepest parts of the fabric of the universe," Mr Incandela said. It could be a portal to a exotic world of new particles and new dimensions.

I think the most interesting thing as far as the newly observed Higgs Boson, is to see if it's characteristics match what the Standard Model predicts, and then if so, immediately been working to either prove or disprove super symmetry.