Physicists are Using Lasers to Test Quantum Gravity Theories

Since Soviet scientist Matvei Bronstein pioneered its study in the 1930s, quantum gravity is still one of the most interesting unsolved mysteries of the universe.

However, Bronstein (1906-38) fell victim to Stalin’s Great Purge and was executed at a young age before he could conclude his research on quantum gravity.

Why is Quantum Gravity Hard to Crack?

The theoretical physicists after Bronstein have been attempting to come up with “theories” of quantum gravity for many decades, which they have, but there’s still no tangible conclusions.

A large community of physicists is working on different models of a quantum gravity theory, in an attempt to find a “theory of everything”, one that brings Einstein’s relativity and quantum physics together and ushers in “new physics”.

String theory is one of the most studied quantum gravity models at present. Loop quantum gravity is another theory that’s touted as a viable model of quantum gravity.

Although very promising, these theories are hard to test.

But for the phenomena of quantum gravity to manifest itself, it requires high energy scales, so that researchers can observe and study its effects.

What’s more, quantum gravity prevails at tiny length scales, close to Planck, which is about 15 orders of magnitude smaller than what is currently available at CERN’s Large Hadron Collider.

And while there’s no shortage of such theories, they need to be tested to get approved or ruled out.

Laser-Based Available Tech to Test Theories of Quantum Gravity.

A multinational team of seven physicists has come up with a novel approach to check the predictions of quantum gravity theories without the need of very high energy scales.

If proved to be successful, this will allow physicists to devise a correct theory of quantum gravity, which would, hopefully, unify general relativity and quantum mechanics.

To get around this difficulty (Plank high scale energy and tiny length), the team focused on the property known as “non-commutativity”: a characteristic of most of the proposed variants of quantum gravity, including string theory and loop quantum gravity. Non-commutative geometry is a generalization of geometry, inspired by quantum physics, whose purpose is to study spaces mathematically.

A paper on the proposed test was published in the journal Nuclear Physics B.

The test “is within the reach of current technology and, thus,” said authors of the paper, “it could uncover a feasible route towards the realization of quantum gravitational phenomena through a simple table-top experiment.”