Somewhere between the microscopic realm of elementary particles and the macroscopic world of human beings, something strange happens: The rules of quantum physics, which work so exquisitely for tiny atoms, seem to lose their grip as objects grow larger. Pondering where and how this shift from small-scale quantum fuzziness to everyday sharp certainty happens gives rise to thought-experiment oddities like Schrödinger's famous dead-and-alive cat. The process by which quantum phenomena like superposition—the paradoxical affliction of Schrödinger's cat—fade into the classical reality we experience is known as decoherence.
Now, a new experiment has narrowed the field of possible explanations for decoherence, in particular ruling out a prominent theory linking gravity to the process. The results appeared in a paper in the New Journal of Physics in June 2026.
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