Quantum Collapse Models Suggest Time Has Fundamental
New theoretical work indicates that certain quantum collapse models, if correct, imply a minuscule intrinsic uncertainty in time itself, setting an
An international team of physicists, supported by the Foundational Questions Institute (FQxI), has proposed that time itself may possess a tiny, fundamental uncertainty. Their calculations suggest this effect arises from certain alternatives to standard quantum mechanics known as quantum collapse models.
Nicola Bortolotti, a PhD student at the Enrico Fermi Museum and Research Centre in Rome who led the study, explains the motivation. "What we did was to take seriously the idea that collapse models may be linked to gravity," he says. "And then we asked a very concrete question: What does this imply for time itself?"
Exploring Spontaneous Collapse Models
The research examines models where the wavefunction of a quantum system collapses spontaneously, without needing an observer. This differs from standard quantum mechanics, where measurement causes collapse. The team analyzed two specific collapse frameworks.
One is the Diósi-Penrose model, which proposes gravity as the mechanism forcing quantum systems into definite states. The other is the Continuous Spontaneous Localization model. For the first time, the researchers established a quantitative link between this second model and gravitational fluctuations in spacetime.
The team included Catalina Curceanu of the National Institute for Nuclear Physics, Kristian Piscicchia, Lajos Diósi, and Simone Manti.
A Limit on Timekeeping Precision
The calculations yield a striking implication. If these collapse models accurately describe nature, then time itself contains an intrinsic uncertainty. This would place a fundamental limit on how precisely any clock could ever measure time.
The predicted effect is extraordinarily small. It is many orders of magnitude below the sensitivity of today's most advanced atomic clocks or any foreseeable future technology. "Our results explicitly show that modern timekeeping technologies are entirely unaffected," adds Kristian Piscicchia.
Catalina Curceanu emphasizes the scale. "The uncertainty is many orders of magnitude below anything we can currently measure, so it has no practical consequences for everyday timekeeping," she says.
A Path Toward Testing Quantum Gravity
This work touches on the long-standing challenge of unifying quantum mechanics with Einstein's theory of general relativity. The two theories treat time in fundamentally incompatible ways. In quantum mechanics, time is an external, classical parameter. In general relativity, time is part of a dynamic spacetime fabric.
The new analysis suggests collapse models might contain clues about how these disparate descriptions could fit together. By predicting physical effects that differ from standard quantum theory, these models also offer a potential experimental path forward.
Extremely precise future measurements could test whether the predicted spacetime uncertainty exists. Curceanu highlighted the value of investigating such foundational questions. "There are not many foundations in the world which are supporting research on these types of fundamental questions about the universe, space, time, and matter," she notes.
The research was partially supported by FQxI's Consciousness in the Physical World program.
