What kills Schrödinger’s cat? Gravity may not be the answer
Physicists have conducted an experiment at the Gran Sasso National Laboratory that challenges the theory that gravity causes quantum decoherence. The study suggests that spacetime fluctuations, as proposed by Frigyes Károlyházy, may not be the primary reason quantum behavior disappears in the macroscopic world.
Why it matters
Understanding why quantum effects fade in the everyday world is a fundamental challenge in physics; ruling out gravity as a cause narrows the search for the true mechanism.
At some point between the tiny world of particles and atoms and the much larger world we experience every day, quantum behavior appears to fade away.
Quantum mechanics allows particles to exist in combinations of possible states, a phenomenon known as superposition. That strange feature inspired Schr dinger's famous thought experiment involving a cat that is both alive and dead until it is observed. Yet objects in the everyday world do not behave that way.
Physicists call the loss of these distinctly quantum effects decoherence. Exactly why decoherence happens, and whether gravity plays a role, remains one of the major open questions in fundamental physics.
Now, a new experiment supported by FQxI has eliminated one prominent explanation involving gravity. The findings were published in the New Journal of Physics in June 2026.
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