An Experimental Test Of String Theory?

The biggest and major criticism against string theory is that it is untestable, or make predictions that is beyond the capability of it being tested. For a theory that has existed for this long, and grown this popular, not being able to test any part of its development is a serious shortcoming. No other theory in the history of physics has gone this long without producing a shred of empirical verification. Because of that, string theory comes in multiple different flavors, each one vying for attention and being accepted or rejected simply based on a matter of taste.

However, now comes a rather interesting proposal. A team out of Imperial College and Stanford has proposed a way to test an aspect of string theory using 4-qubit entangled particles. The paper is reported to appear in Phys. Rev. Lett. this week, but you can get a preprint at the link above.

Professor Duff recalled sitting in a conference in Tasmania where a colleague was presenting the mathematical formulae that describe quantum entanglement: “I suddenly recognised his formulae as similar to some I had developed a few years earlier while using string theory to describe black holes. When I returned to the UK I checked my notebooks and confirmed that the maths from these very different areas was indeed identical.”

The discovery that string theory seems to make predictions about quantum entanglement is completely unexpected, but because quantum entanglement can be measured in the lab, it does mean that at last researchers can test predictions based on string theory. There is no obvious connection to explain why a theory that is being developed to describe the fundamental workings of our universe is useful for predicting the behaviour of entangled quantum systems. “This may be telling us something very deep about the world we live in, or it may be no more than a quirky coincidence”, concluded Professor Duff. “Either way, it’s useful."

Hum... let's see if the many different labs that are doing Bell-type experiments might jump into this.

Edit: This paper has now appeared in print. The exact reference is:

L. Borsten et al., Phys. Rev. Lett. v.105, p.100507 (2010).

Zz.