A(nother) potential test for the string model?

[Wolverine]

This press release prompted me to begin a new thread. I'd come across several others in a cursory search of this sub-forum on the same topic, but they each appeared to be bogged down by tangental banter. I'd like to respectfully request that all interested participants stay on topic here.

Anyway, out of curiosity, I'm most interested to see reactions from regular participants here with expertise in physics and/or cosmology. This is the third or fourth such proposed test I've read about in recent memory, and I'm wondering about its feasibility and potential.

I omitted from the thread title but begrudgingly included in the tags for ease of searching the phrase "string theory", because I still greatly dislike - no matter how promising - the usage of "theory" (in the strict sense) to describe what's an admittedly elegant mathematical model but has yet to provide testable predictions let alone suitable explanations for existing data.

So, how does this rate?

Scientists propose test of string theory based on neutral hydrogen absorption

Ancient light absorbed by neutral hydrogen atoms could be used to test certain predictions of string theory, say cosmologists at the University of Illinois. Making the measurements, however, would require a gigantic array of radio telescopes to be built on Earth, in space or on the moon.

String theory – a theory whose fundamental building blocks are tiny one-dimensional filaments called strings – is the leading contender for a “theory of everything.” Such a theory would unify all four fundamental forces of nature (the strong and weak nuclear forces, electromagnetism, and gravity). But finding ways to test string theory has been difficult.

Now, cosmologists at the U. of I. say absorption features in the 21-centimeter spectrum of neutral hydrogen atoms could be used for such a test.

“High-redshift, 21-centimeter observations provide a rare observational window in which to test string theory, constrain its parameters and show whether or not it makes sense to embed a type of inflation – called brane inflation – into string theory,” said Benjamin Wandelt, a professor of physics and of astronomy at the U. of I.

[Continued...]

Thoughts? Thanks in advance.

 

[sol invictus]

Using fluctuations in 21 cm radiation as a probe of structure is a great idea. It's going to be a while before it happens, but when it does it will open a whole new window on cosmology. There's potentially far more information there than there is in the cosmic microwave background.

It's also true that cosmology may be the best hope of testing string theory. There are some very interesting ideas out there along those lines.

So the general idea is solid, but I haven't looked at the details to see how it works. One thing to be aware of is that things like the density of cosmic strings have large theoretical uncertainties. In other words no one understands string theory well enough to be able to say, the density of cosmic strings is X. They can only say, in many models it's between X and Y, but in some other models it's smaller. So a negative result from this will not rule out the theory - it will only constrain it. On the other hand a positive result would be one of the most important in the history of science, so it's worth doing!

 

[edd]

Anyway, out of curiosity, I'm most interested to see reactions from regular participants here with expertise in physics and/or cosmology. This is the third or fourth such proposed test I've read about in recent memory, and I'm wondering about its feasibility and potential.

There's a couple of what smell like misconceptions in that article (talk of a 'shell' of hydrogen for example, I can sort of see how you'd get to that kind of description but it's not one I'd use as it probably gives the wrong impression of the universe as a whole) but the essence seems quite sound. I don't know how strong the predictions of cosmic strings are - if you failed to detect cosmic strings would that rule out string theory? However, certainly it sounds like a quite plausible route to detecting such cosmic strings (and probably not the only one either).

They're hoping for a thousand square kilometre radio array though. We're only just working on a one square kilometre array (http://www.skatelescope.org/) and I don't see a thousand square kilometre one as being remotely practical on any near time scale (on a mainly economic basis) - which is pretty much what the researchers are saying.

 

[mijopaalmc]

wrong thread