Some signs of quantum gravity may be an illusion

Quantum mechanics and Einstein’s theory of gravity explain almost everything we see in nature, yet physicists still do not know how to unite them. A new theoretical framework suggests that some experiments that appear to show gravity behaving quantum mechanically may have a much more ordinary explanation. Researchers found that scenarios involving a supposed “superposition of gravity” can sometimes be described equally well as quantum particles moving through classical spacetime.

Some signs of quantum gravity may be an illusion. Some signs of quantum gravity may be an illusion Science News from research organizations Some signs of quantum gravity may be an illusion A new study reveals that some supposed signs of quantum gravity may be illusions, sharpening the search for evidence that spacetime itself truly behaves quantum mechanically. Quantum mechanics describes the behavior of matter at very small scales, while Einstein’s theory of gravity explains how stars and black holes move and how the Universe expands.

Despite their enormous success, the two theories still do not fit neatly together. Physicists have spent decades searching for a theory of "quantum gravity" that could combine them into one consistent description of nature. The Challenge of Quantum Gravity A central expectation is that gravity itself should ultimately follow the rules of quantum mechanics.

That possibility quickly becomes difficult to visualize.