A new theory that unifies gravity with quantum mechanics

Image: Impression of an experiment in which heavy particles (pictured as the Moon) cause an interference pattern – a quantum effect – and at the same time distort space-time. (Isaac Young)

Physicists from University College London (UCL) have come up with a new theory that combines gravity and quantum mechanics, while retaining Einstein’s classical concept of space-time.

Modern physics is based on two pillars. One is quantum theory, which governs the smallest particles in the universe; The other is Einstein’s theory of general relativity, which explains gravity through the curvature of space-time. For more than a century, scientists have made frantic attempts to reconcile the two theories – so far to no avail.

The prevailing assumption is that Einstein’s theory of gravity must be modified or “quantified” to fit quantum theory. This is the approach taken by two leading candidates for the theory of quantum gravity: string theory and loop quantum gravity. The new theory, developed by Jonathan Oppenheim (UCL), takes an alternative approach by arguing that spacetime may be “classical” – that is, not governed by quantum theory at all.

Violent fluctuations

Instead of modifying spacetime, the theory — the so-called “post-quantum theory of classical gravity” — modifies quantum theory and predicts that spacetime produces intrinsic disorder. This leads to random and violent fluctuations in space-time that are larger than would be expected under quantum theory, making the apparent weight of objects unpredictable if measured with sufficient precision.

A paper published by former doctoral students at Oppenheim University addresses some of the implications of the theory and proposes an experiment to test the theory by measuring mass very precisely to see if its weight fluctuates over time.

He. She International Bureau of Measures and Measures For example, in France, a one-kilogram mass is routinely weighed which was previously the standard kilogram. If the fluctuations in measurements of this 1-kilogram mass are too little to achieve mathematical consistency, the theory can be ruled out. The concept of measurement is simple, but weighing the body must be done with unprecedented accuracy.