Science

Some signs of quantum gravity may be an illusion, study finds

A new theoretical framework shows that some proposed quantum gravity experiments can be explained by quantum particles in classical spacetime.

Updated Aug 30, 2026 · 15:19 UTC1 reports

The short version

Researchers have developed a theoretical framework called the "Relativity of Spacetime Superpositions," showing that some situations interpreted as gravity behaving in a quantum superposition can also be explained by quantum particles moving through ordinary, classical spacetime.
The study, published in npj Quantum Information, does not disprove quantum gravity, but it exposes a key ambiguity in how future experiments should be interpreted.
The findings will help physicists design more precise experiments by identifying which signatures genuinely require a quantum description of gravity.

Physicists from Kyushu University, the University of Waterloo, and Stockholm University published their findings in npj Quantum Information.[ScienceDaily]
The researchers established a theoretical framework showing that certain scenarios involving a supposed "superposition of gravity" can be described equally well as quantum particles moving through classical spacetime.[ScienceDaily]
Lead author Joshua Foo stated that some proposed experiments designed to reveal the quantum nature of gravity can actually be viewed from two equally valid mathematical perspectives.[ScienceDaily]
Co-author Magdalena Zych noted that the study does not rule out quantum gravity or prove that gravity is strictly classical, but rather helps differentiate between true quantum gravity signatures and familiar physics.[ScienceDaily]

Physicists still do not know how to fully unite quantum mechanics and Einstein's theory of gravity into a single, consistent theory of quantum gravity.[ScienceDaily]