Astronomy Buff

An Actual, Bona Fide Test for String Theory?

by Tony on February 7th, 2008

Long time readers know that I find string theory irritating. Very smart people have been studying this idea for decades and have yet to say something about it that I can understand. Of course I leave open the possibility that I’m an idiot, but I know I’m not the only one scrunching up their faces and cocking their heads to one side whenever someone tries to explain it.

Apparently, according to its evangelists (umm, I mean proponents), string theory will explain everything, unify physics and make French toast.

Don’t get me wrong, I love French toast, but I don’t think a “theory of everything” is anywhere close to what physicists are gonna end up with when the party’s over and the syrup dries on our plates.

I happen to think Einstein was dead wrong about there being one theory that the entire workings of the universe can be boiled down to. We’re even starting to question some of the basic forces of nature, like gravity. It’s entirely possible we’re wrong about what we think we already know.

Still, string theory is out there, for better or worse, as a possible explanation for everything that exists. Even if no one understands it.

Further, these guys right here at good old U of I have devised a test for it (I think I’m gonna stop by and ask a few questions).

Here’s how it goes (I think):

1. When the universe was 400,000 years old, matter in the universe consisted of a thick shell of neutral hydrogen atoms (one proton, one electron).
2. Neutral hydrogen easily absorbs photons with a wavelength of 21 centimeters.
3. The Cosmic Microwave Background (CMB) gave off these photons and the neutral hydrogen atoms absorbed them.
4. The effect of this absorption should be visible in the CMB
5. From 400,000 years old till the present day, the 21-centimeter radiation has stretched as the universe expanded to a wavelength of 21 meters, meaning you now need a radio telescope to look at it.

“Thanks Tony, I’m with you so far, but… ummm… what does this have to do with string theory?”

I really don’t know. Apparently there are characteristics of the absorption that relate to cosmic strings:

Cosmic strings are defects in space. A network of strings is predicted by string theory (and also by other supersymmetric theories known as Grand Unified Theories, which aspire to unify all known forces of nature except gravity) to have been produced in the early universe, but has not been detected so far. Cosmic strings produce characteristic fluctuations in the gas density through which they move, a signature of which will be imprinted on the 21-centimeter radiation. (Full Press Release).

So, there you go.

Oh. One more thing:

To precisely measure perturbations in the spectra would require an array of radio telescopes with a collective area of more than 1,000 square kilometers. Such an array could be built using current technology, Wandelt said, but would be prohibitively expensive.

Dammit. It’s always something.

Above photo credit: Katie Cowden

Technorati Tags: cosmic microwave background, cosmology, string theory

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POSTED IN: cosmology