Can String Theory Accommodate Inflation?

David Shiga writes "String theory is the leading contender for a "theory of everything" that could unite all the forces of physics. But a recent study suggests that it may be more difficult than scientists had hoped to square string theory with inflation — the widely accepted notion that the early universe had a period of especially rapid expansion. Some say this could even lead to the abandonment of either string theory or inflation, though no one is ruling out a possible resolution yet."

Comments

Ahem:

[Anonymous Coward]

It is said that papers in string theory are published at a rate greater than the speed of light. This, however, is not problematic since no information is being transmitted.

ObXKCD

[Eponymous Bastard]

Yet another post validating this argument

(yeah, yeah, it's old. So sue me)

Re:String Theory is Religon Not Science

[Anonymous Crowhead]

I've never understood how string theory could ever be validated, except through funky math invented for the purpose. It's my understanding that if you enlarged an atom to the size of the universe a string would be about 50 feet long (about a planck length). How is that ever going to be testable in practice? From all I've read, the energy required is just not possible, ever.

Re:String Theory is Religon Not Science

[kebes]

String theory should be discarded. It's a fanciful religion that explains nothing, but creates a lot of stuff that needs explaining.

String theory is often made fun of for being useless because it makes no predictions. In fact, string theorists are often the ones making these jokes. However, they are ultimately jokes, and not entirely true. The problem is that the public at large has gotten the impression that string theory isn't science because it doesn't make predictions. That's not really true.

The fact is that what string theory aims to explain (the very fundamental nature of the universe; the events just after the big bang; the reconciliation of quantum mechanics and general relativity) are effects that are inherently difficult to measure. (Otherwise these questions would have been asked long ago.) The fact is that we are not yet able to measure at the extreme energies where string theory becomes relevant. So, the fact is that string theory does make predictions, but it is difficult for us to test these predictions yet.

Efforts are being made, however. Increasingly sensitive measurements of large-scale cosmological phenomena, and ever-more-powerful particle accelerators may give us experimental information about string theory. Already, in fact, a wide variety of "string theories" have been discarded because they do not match the accelerator data. That is, we are placing bounds on the theories, based on experiments. This is how science works.

Also important to keep in mind is that string theory meshes with our currently established theories (which, it goes without saying, have been verified experimentally to a very high precision). The agreement is not yet perfect (as TFA points out), but it's important to keep in mind that of the millions of crazy theories you could write down to explain "the universe," very few of them can reproduce more conventional theories (e.g. electromagnetic interactions) in the appropriate limits. The fact that string theory meshes with established knowledge is the thing that keeps physicists "hopeful" that they are going down the right track. That doesn't mean the theory is right, but it shows that it fits in with our current scientific understanding. That's how science works: by developing more detailed theories that nevertheless reproduce the more basic theories.

String Theory is Religon Not Science

That kind of exaggeration isn't very useful. Ultimately string theory aims to explain the universe through verifiable (falsifiable) predictions. These observations are difficult to make, but are being attempted. If the observations contradict string theory, physicists will discard it. If a better theory comes along that explains observations, physicists will gladly use that theory instead. Until that happens, there is no reason to ignore our current "best guess."