The world’s best clocks keep improving. They lose less than a second over the entire age of the universe, and engineers keep finding ways to tighten that already-impossible margin.
Every year a new lab publishes a new record, and a small group of physicists is now asking whether the chase has a ceiling. Not from engineering limits, but from time itself.
Time may never tick perfectly
Nicola Bortolotti at the Enrico Fermi Museum and Research Centre (CREF) in Rome led a team that arrived at an unsettling conclusion.
They found that time, the very thing clocks measure, may carry a tiny built-in jitter no instrument will ever scrub away.
The jitter is small, almost laughably small. But the team argues it lives in the universe itself, not in some flaw of our equipment.
The strange nature of quantum
At very small scales, a particle does not sit at one place with one set of properties.
It exists as a smear of possibilities, each weighted by probability. Physicists describe that smear with a mathematical object called a wavefunction.
Then something interacts with the particle, or someone runs a measurement. The smear vanishes into a single outcome.
That sudden settling has a name, wavefunction collapse, and after nearly a century of debate, no one has fully agreed on what triggers it.
Two models in competition
Most interpretations of quantum mechanics shuffle the same equations and argue over meaning. In the 1980s, a few physicists tried something different.
They suggested that wavefunctions collapse on their own, spontaneously, with no observer required.
Two of those proposals stand out today. One is the Diósi-Penrose model, which has long argued that gravity itself drags quantum systems into definite states.
The other is Continuous Spontaneous Localization. Both predict subtle effects that careful experiments could, in principle, detect.
Linking gravity to time
Bortolotti and his colleagues went after a specific question. If spontaneous collapse really happens, would it leave a trace on the flow of time?
The Diósi-Penrose model already had a known connection to gravity. An older paper laid that groundwork decades ago. Continuous Spontaneous Localization showed no such bridge.
The two ideas had developed in parallel, addressing the same puzzle from different angles, and no one had tied the second one to the structure of spacetime in a quantitative way.
That is what the new calculation does. The team observed the random tiny disturbances of Continuous Spontaneous Localization.
If real, they would also produce tiny ripples in the gravitational field around that matter. Ripples in gravity become ripples in spacetime, thus creating ripples in time.
“What we did was to take seriously the idea that collapse models may be linked to gravity. And then we asked a very concrete question: What does this imply for time itself?” said Bortolotti.
Debating the importance of size
A wobble in spacetime translates into a wobble in the ticking of any clock. Bortolotti and his colleagues calculated how large that wobble must be if either model describes nature.
Their answer sits far below anything modern instruments can register. Even the best atomic clocks are nowhere near the predicted floor.
“The uncertainty is many orders of magnitude below anything we can currently measure, so it has no practical consequences for everyday timekeeping,” said Catalina Curceanu, a co-author on the team.
Bridging two differing physics
So why bother, if no clock will ever feel the effect? Because the result speaks to one of the deepest open problems in modern science: how to fit quantum mechanics together with gravity.
Quantum theory treats time as a fixed background, ticking along regardless of what particles do.
Einstein’s relativity treats time as something that bends and stretches under mass and energy. Those two views have refused to mesh for a century.
The new calculation hands physicists a small but very real bridge. It says one of the more speculative attempts to fix quantum mechanics, if correct, would reach into gravity’s territory and leave an imprint on time itself.
Future implications for time
Until this study, the connection between Continuous Spontaneous Localization and spacetime fluctuations had not been worked out. That gap is now closed, and a concrete prediction has taken its place.
The collapse models are no longer purely philosophical alternatives to standard quantum theory.
They make a numerical claim about the smallest possible uncertainty in time, one that could be tested if clock technology pushes deep enough into precision territory.
For the wider field of quantum gravity, the result offers a new entry point for researchers.
They can now ask whether other collapse-style theories also leave fingerprints on time, and whether any of those fingerprints sit closer to what an experiment might reach.
The everyday world keeps its trustworthy seconds. Wristwatches, GPS, all of it. The deeper question of what time really is just got a little sharper.
The study is published in the journal Physical Review Research.
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