For decades, many scientists have criticized string theory, pointing out that it does not make predictions by which it can be tested. Now, researchers have developed a test of string theory. Their test involves measurements of how elusive high-energy particles scatter during particle collisions. Most physicists believe that collisions will be observable at the Large Hadron Collider (LHC), which is set to turn on later this year at the European Laboratory for Particle Physics, commonly known as CERN.

“The beauty of our test is the simplicity of its assumptions,” explained Benjamin Grinstein. “The canonical forms of string theory include three mathematical assumptions – Lorentz invariance (the laws of physics are the same for all uniformly moving observers), analyticity (a smoothness criteria for the scattering of high-energy particles after a collision) and unitarity (all probabilities always add up to one). Our test sets bounds on these assumptions.

“Since we don’t have a complete understanding of string theory, it’s impossible to rule out all possible models that are based on strings. However, most string theory models are based upon certain mathematical assumptions, and what we’ve shown is that such string theories have some definite predictions that can be tested,” Ira Rothstein said.

It’s not a proof — it’s a test. Failing the test would prove that string theory is incorrect. Passing the test still wouldn’t prove the theory correct; but — till the LHC, even running a test like this wasn’t possible.