Oye - talk about reality being stranger than fiction. This topic is sure to give your head a spin, but will that spin be three halves (like a Graviton), or negative one half (like a Wino), or something in-between? And have I completely lost my mind? Let’s examine Superstring Theory and find out.
So, just what is Superstring Theory anyhow? Well Superstring Theory is one possible unified theory of all fundamental forces including quantum gravity which is the problem child (we will deal with him in a minute). In order for Superstring Theory to be what it is, it needs to reside in 10 dimensional spacetime or ghosts (quantum states with non physical negative probabilities) become part of the landscape. See, much stranger than fiction.
And keep in mind (appropriate term, no?) that Superstring Theory is "theoretical" right now since there is no direct evidence of strings - yet. And why is there no direct evidence of stings? Well, gravity, the problem child (we are dealing now), to be included in the theory makes the strings so small that no particle accelerator yet created can detect them. So to include a theory of everything and not leave out quantum gravity the theory predicts string lengths to be somewhere near the length scale of quantum gravity, better known as Planck’s length. Head rotating yet? Mine is.
Okay, so how long is Planck’s length? It is a mere millionth of a billionth of a billionth of a billionth of a centimeter. And you though short and curlies were small! Way too small in fact to be seen experimentally right now and nobody is going to finance a machine that can detect them - yet. So, what to do? Well, theorists are not to be denied, so they theorize what we would see if strings really exist in 10 dimensional spacetime by looking for their effects. Keep in mind this theory must result in the 4 dimensional world we observe and live in. (Although, I must admit to residing in one of the other 7 dimensions once in a while - and yes, Elvis is there.)
Two main contenders exist right now. In this corner we have Klauza Klein Compactification; seven dimensions rolled up (like the rim of a Tim Horton’s coffee cup) into an incredibly small strange, interesting little place all their own. And in the other corner we have Braneworlds; seven dimensions so unbelievably big but allowing matter and gravity to propagate in three dimensional space called a three brane (where we live). And the winner is - Tylenol helping millions overcome headaches. And right now my ‘brane’ is starting to hurt. . . .
Actually the winner is an attribute of either Superstring Theory contender called Supersymmetry. Supersymmetry states that the strings are closed loops (like necklaces or rubber bands) and have super partner pairs between bosons (force carrying particles) and fermions (particles that make up matter). And now for the head spinning conclusion.
Well, whether Braneworld (seven huge dimensions) or Klauza Klein Compactification (seven tiny dimension) Theory is the best is yet to be detected experimentally. And instead of definite answers, we are left with many more questions like - what is really the best theory? - why is the cosmological constant zero, or close to it? - what are the cosmological ramifications of the theories? - and why, after every laundry day, do we seem to lose one of a pair of socks?
It looks as though with all the work being done in the field of Superstring Theory, that the answers to these questions may come as soon as ten years. But until that time I am popping some Tylenol and trying not to think about it. Oye!