A new experiment to determine whether or not gravity is affected by the act of measurement has been proposed by theoretical physicists in the UK, India and the Netherlands. The experiment is similar to one outlined by the same group in 2017 to test whether or not two masses could become quantum-mechanically entangled by gravity, but the latest version could potentially be easier to perform.
An important outstanding challenge in modern theoretical physics is how to reconcile Einstein’s general theory of relativity – which describes gravity – with quantum theory, which describes just about everything else in physics.
“You can quantize gravity” explains Daniel Carney of the Lawrence Berkeley National Laboratory in California, who was not involved in this latest research. However, he adds, “Gravitational wave detection is extremely quantum mechanical…[Gravity is] a normal quantum field theory and it works fine: it just predicts its own breakdown near black hole singularities and the Big Bang and things like that.”
Multiple experimental groups around the world seek to test whether the gravitational field can exist in non-classical states that would be fundamentally inconsistent with general relativity. If it could not, it would suggest that the reason quantum gravity breaks down at high energies is that gravity was not a quantum field. Performing these tests, however, is extraordinarily difficult because it requires objects that are both small enough to be detectably affected by the laws of quantum mechanics and yet massive enough for their gravitation to be measured.
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