Plate Nº 64 · recorded October 10, 2026
PhysicsReported finding
Gravity Fails Test as the Killer of Schrödinger's Cat
Physicists spent 62 days under Gran Sasso mountain hunting faint radiation from gravity-driven spacetime fluctuations — the suspected killer of quantum superpositions — and found nothing.
By Nathan Brooks3 min read581 words
In brief
- Physicists measured for 62 days beneath Italy's Gran Sasso mountain and detected no signal.
- The experiment tested a theory that tiny spacetime fluctuations caused by gravity destroy quantum superpositions.
- The search used a highly shielded germanium detector looking for an extremely faint radiation signal.
- The null result is one of the toughest experimental tests yet for this decades-old gravity-based idea.
After 62 days of measurements deep beneath Italy's Gran Sasso mountain, physicists found no trace of the faint radiation signal that one gravity-based theory predicts should exist. The result puts a decades-old explanation for why quantum weirdness vanishes in the everyday world through one of its toughest experimental tests yet — and the theory did not pass.
The experiment targeted an idea that has circulated among physicists for decades: that gravity, through tiny fluctuations in the fabric of spacetime itself, gradually destroys quantum superpositions — the strange states where particles occupy multiple possibilities at once.
What is Schrödinger's cat, and why does it matter here?
Quantum mechanics allows objects to exist in superposition, holding several mutually exclusive states simultaneously. Erwin Schrödinger famously illustrated the oddness with a thought experiment: a cat in a box that is, by the rules of quantum theory, simultaneously alive and dead until someone looks.
Yet we never see chairs, coins, or cats in such blended states. Something makes the quantum rules fade at everyday scales. Explaining that transition remains one of the central open questions in physics, and gravity has long been one of the leading suspects.
The specific theory tested at Gran Sasso proposes a mechanism. Tiny fluctuations in spacetime — essentially microscopic ripples in gravity's own background — would constantly disturb quantum systems. Over time, this disturbance would smear out superpositions, converting quantum behavior into the definite, classical reality we experience. That would, in effect, kill Schrödinger's cat.
How do you test a theory about spacetime ripples?
The idea carries a testable consequence. If spacetime fluctuations steadily destroy quantum superpositions, they should also leave a fingerprint: an extremely faint burst of radiation, which a sensitive enough detector could pick up.
The team set up that search under Gran Sasso, the massive mountain in central Italy whose rock overhead shields experiments from cosmic rays and other background noise. They used a highly shielded germanium detector — a crystal that registers arriving radiation by producing tiny electrical signals — and collected data for 62 consecutive days.
The detector saw nothing. No signal appeared above background during the entire run.
What does the null result mean?
A null result is not a proof, and the physicists' finding should be read with care. The experiment shows that this particular gravity-based mechanism, if it operates at all, produces effects too weak for this detector to register — or that its predicted radiation signature does not exist in the form the theory anticipates.
What the result does establish is a boundary. The 62 days of Gran Sasso data now constrain how strong any gravity-driven destruction of superpositions could be, narrowing the space in which the theory can survive.
The outcome also illustrates a broader trend in physics. Questions once confined to thought experiments and philosophical debate — why the quantum world and the classical world look so different — are increasingly subject to direct laboratory measurement, with instruments sensitive enough to test proposals that were previously untestable.
What comes next?
The theory is not necessarily dead. Its proponents could revise the predicted signal strength or revisit assumptions about how spacetime fluctuations would couple to matter. More sensitive detectors, or longer measurement campaigns, could push the boundaries tighter still.
For now, gravity remains a suspect in the disappearance of quantum superpositions — but one of its most specific, long-standing alibis has just failed a 62-day interrogation under an Italian mountain. Schrödinger's cat, in other words, may need a different executioner.
via iopscience.iop.org (Original)
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