Time May Be Fuzzy and Physics Can Now Test it

Quantum Collapse Models Reveal a Tiny Flaw in Time Itself

Estimated reading time: 10 minutes

Key Takeaways

• A new study shows that quantum collapse models suggest time itself has a hidden flaw: a tiny blur and a limit that cannot be crossed, no matter how good your clock is.
• The research offers a way to connect quantum mechanics and gravity through gravity-induced spacetime fluctuations.
• The predicted time uncertainty is many orders of magnitude smaller than what even the best atomic clocks can measure, so modern timekeeping remains unaffected.
• The work provides a quantitative, testable link between collapse models and gravitational spacetime fluctuations, giving future experiments a target to aim at.
• Support from the Foundational Questions Institute (FQxI) helped fund this kind of foundational research into time, space, and matter.

Physicists Demonstrate That Quantum Collapse Models Impose Fundamental Limits on Time Precision Through Gravity-Induced Spacetime Fluctuations

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Time seems simple. Clocks tick. Seconds pass. But deep inside the rules of physics, something strange is happening. A new study shows that quantum collapse models — special theories about how the quantum world becomes the everyday world — suggest time itself has a hidden flaw. A tiny blur. A limit that cannot be crossed, no matter how good your clock is.

This discovery does not break your watch or mess up your calendar. But it opens a door that physicists have been searching for: a way to connect quantum mechanics and gravity, two theories that have never fully agreed with each other.

Let’s break it down in plain terms.

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What Are Quantum Collapse Models and Why Do They Matter?

Understanding Quantum Collapse and Superposition

At the very small scale — atoms, electrons, particles — the rules of physics are strange. Things do not sit in one place or state. They exist in many possibilities at once. This is called superposition.

Physicists describe this using something called a wavefunction — a mathematical picture of all the possible states a particle could be in.

But here is the problem. When we look at the world around us, objects are not blurry. A ball sits in one spot. A cat is either awake or asleep. So how do all those fuzzy quantum possibilities become one clear, definite reality?

The traditional answer is: when you measure or observe a quantum system, the wavefunction collapses into one outcome.

This explanation works mathematically. But it raises a big question: What counts as a measurement? Does something have to be watching for reality to snap into place?

Quantum collapse models offer a different answer. They say collapse happens spontaneously — on its own, without needing an observer. These theories first appeared in the 1980s. Unlike other interpretations of quantum mechanics that just offer different ways of thinking about the same math, collapse models make real, testable predictions.

Two of the most studied collapse models are:

• Continuous Spontaneous Localization (CSL) — proposes that collapse happens randomly but continuously, preventing large objects from staying in superposition
• The Diósi-Penrose model — connects wavefunction collapse directly to gravity, suggesting gravity itself causes quantum possibilities to snap into one definite state

These are not just philosophical ideas. They can, in principle, be tested with real experiments.

Physical Review Research DOI: 10.1103/p6tj-lg8l

Diósi–Penrose model

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The New Research: How Quantum Collapse Models Blur Time

Spacetime Uncertainty and Fundamental Clock Precision Limits

An international team of physicists, led by Nicola Bortolotti — a PhD student at the Enrico Fermi Museum and Research Centre (CREF) in Rome, Italy — has published findings that take collapse models further than ever before.

Their study, published in Physical Review Research, asked a simple but bold question: If collapse models are real, what do they mean for time itself?

The team — including Catalina Curceanu, Kristian Piscicchia, Lajos Diósi, and Simone Manti — examined both CSL and the Diósi-Penrose model. What they found was surprising.

Here is what the research showed:

• They established a new mathematical relationship between the CSL collapse model and fluctuations in gravitational spacetime — something that had never been formally worked out before in this way
• These gravity-linked fluctuations mean that time itself cannot be perfectly precise
• Instead, time carries a tiny, built-in level of uncertainty — a kind of quantum fuzziness baked into the fabric of spacetime
• This creates a fundamental limit on clock precision — a ceiling no clock can ever break through, no matter how advanced it becomes

> “What we did was to take seriously the idea that collapse models may be linked to gravity,” said Bortolotti. “And then we asked a very concrete question: What does this imply for time itself?”

The answer was clear. If quantum collapse is real — and if it is linked to gravity — then spacetime uncertainty is unavoidable. Time is not perfectly smooth. It has a tremor, unimaginably small, but real.

The Numbers: How Small Is This Flaw in Time?

To understand just how tiny this effect is, consider the most accurate clocks ever made: atomic clocks. These clocks can measure time to about one part in 10¹⁸ — that is one second in 30 billion years.

The time uncertainty predicted by these collapse models is many orders of magnitude smaller than even that.

Key technical values from the research:

• CSL collapse rate parameter: λ ≈ 10⁻¹⁶ per second (standard proposal)
• Localization length: r_C ≈ 10⁻⁷ metres
• The time uncertainty grows cumulatively the longer a clock runs
• CSL model parameters are now constrained to viable ranges of λ ≈ 10⁻¹⁸ to 10⁻¹² per second based on data from gravitational wave detectors and X-ray emission experiments

> “The uncertainty is many orders of magnitude below anything we can currently measure, so it has no practical consequences for everyday timekeeping,” said Curceanu. “Our results explicitly show that modern timekeeping technologies are entirely unaffected,” added Piscicchia.

So your phone’s clock is safe. GPS satellites still work. This is physics at the very edge of what is real — well beyond what any current tool can touch.

> “Once you do the calculation, the answer is clear and surprisingly reassuring,” said Bortolotti.

Phys.org coverage

Interesting Engineering coverage

Physical Review Research DOI: 10.1103/p6tj-lg8l

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Quantum Gravity Unification: Why This Research Is a Big Deal

Bridging the Gap Between Quantum Mechanics and General Relativity

This research is not just about clocks. It sits right at the centre of one of physics’ greatest unsolved problems: how do quantum mechanics and gravity fit together?

Right now, physicists use two frameworks that each work brilliantly on their own but refuse to cooperate:

• Quantum mechanics — describes the behaviour of particles at microscopic scales, like atoms and electrons
• General relativity — describes how gravity bends and stretches space and time at large scales, like stars, planets, and galaxies

The problem is they treat time in completely opposite ways.

> “In standard quantum mechanics, time is treated as an external, classical parameter that is not affected by the quantum system being studied,” explained Curceanu.

In general relativity, by contrast, time is flexible. It stretches near massive objects. It slows down near black holes. It is woven into the fabric of spacetime itself.

These two pictures clash. And for decades, no one has been able to fully unite them into one consistent theory.

What Makes This Research a New Bridge

The Bortolotti team’s work is significant because it offers a quantitative, testable link between quantum collapse and gravitational spacetime fluctuations. That is rare.

Most attempts to connect quantum mechanics and gravity stay abstract or mathematical. This research produces specific, calculable predictions. It tells us:

• If collapse models are correct, then spacetime uncertainty is real
• That uncertainty affects time in a measurable (at least in principle) way
• The effect grows over time, giving future experiments a target to aim at

Bortolotti’s doctoral dissertation at the University of Rome also extends these predictions across systems of different sizes — from tiny molecules all the way to macroscopic structures. This provides a computational framework for future labs to test against.

The Kyushu University Connection

Interestingly, a parallel research effort at Kyushu University (April 2026) is working toward exactly the kind of experiment that could test these ideas.

Their approach uses momentum-squeezed mirror states inside cavity optomechanical systems. The idea is to amplify tiny signals of gravity-induced quantum entanglement, making them strong enough to detect in a lab setting.

If gravity can create quantum entanglement between objects, it suggests gravity itself is fundamentally quantum — a huge step toward quantum gravity unification.

Together, these two lines of research — theoretical predictions from Bortolotti’s team and experimental methods from Kyushu — are quietly building a bridge toward testing one of the deepest questions in all of physics.

Phys.org on Kyushu University experiment

arXiv: 2504.06109

Copernical coverage

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The Role of FQxI and Funding Frontier Science

Supporting Radical Ideas About the Universe, Space, Time, and Matter

This research was supported in part by the Foundational Questions Institute (FQxI), one of the few organizations in the world that funds research on the deepest and most unconventional questions in physics and cosmology.

Some key facts about FQxI’s role:

• FQxI has invested over $29 million across more than 234 grants since 2006
• The Bortolotti team received partial support through FQxI’s “Consciousness in the Physical World” program
• FQxI specifically funds ideas that are too radical or too foundational for traditional science funding bodies

> “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,” said Curceanu. “Our work shows that even radical ideas about quantum mechanics can be tested against precise physical measurements, and that, reassuringly, timekeeping remains one of the most stable pillars of modern physics.”

This matters. Foundational physics — the kind that asks what is time, really? or why does the quantum world become classical? — rarely gets funded through standard channels. Organizations like FQxI make it possible for researchers to pursue the deepest questions without the pressure of producing immediate commercial results.

The broader scientific community views this work with cautious optimism. The predicted effects remain 15 or more orders of magnitude below current detection limits. But the fact that this gives us a testable framework at all — a way to distinguish collapse models from standard quantum theory — is seen as a genuine advance.

Phys.org coverage

Interesting Engineering coverage

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FAQ: 10 Questions About Quantum Collapse Models and Time Uncertainty

1. What is a quantum collapse model?

A quantum collapse model is a theory that explains how quantum superposition — the ability of particles to exist in many states at once — turns into a single definite outcome. Unlike standard quantum mechanics, collapse models say this happens spontaneously on its own, without needing an observer or a measurement. They make testable predictions, which makes them different from other interpretations of quantum theory.

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2. What is the Diósi-Penrose model?

The Diósi-Penrose model is one of the most studied quantum collapse models. It connects wavefunction collapse directly to gravity. The idea is that gravity itself causes quantum superpositions to break down into definite outcomes. This gives the model a natural connection to general relativity, making it a candidate for a unified theory of quantum mechanics and gravity.

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3. What is Continuous Spontaneous Localization (CSL)?

CSL is another major quantum collapse model. It proposes that all quantum systems experience a continuous, random process that nudges them toward definite states over time. For tiny particles, the effect is small. For large everyday objects, the accumulated nudges are enough to keep them in one definite place or state. The Bortolotti team established a new mathematical link between CSL and spacetime fluctuations caused by gravity.

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4. What does spacetime uncertainty mean?

Spacetime uncertainty refers to a kind of built-in fuzziness in the fabric of space and time. If quantum collapse models are correct, then the gravitational fluctuations linked to collapse processes would create tiny imprecisions in time measurements. These are not errors in our clocks — they are fundamental features of reality itself. Even a perfect clock could not escape them.

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5. Does this mean our clocks are wrong?

No. The time uncertainty predicted by these collapse models is far too small to affect any clock we have or can build in the foreseeable future. It is many orders of magnitude below even the best atomic clocks, which can already measure time to one part in 10¹⁸. Everyday timekeeping, GPS, and all modern technology remain completely unaffected.

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6. Why is it so hard to unite quantum mechanics and gravity?

Quantum mechanics and general relativity each work perfectly well in their own domain. But they describe time in fundamentally different ways. In quantum mechanics, time is a fixed background — a simple, external clock. In general relativity, time bends and stretches depending on mass and energy. Making one single theory that handles both has been one of physics’ greatest unsolved challenges for over a century.

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7. How could scientists test these collapse models?

Testing collapse models requires detecting their tiny effects experimentally. Current approaches include looking for unexpected noise in ultra-precise measurements, searching for small deviations in quantum systems that standard quantum mechanics cannot explain, and using advanced setups like the momentum-squeezed mirror states being developed at Kyushu University. The challenge is that the predicted effects are extremely small, making experiments very difficult.

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8. What is the Foundational Questions Institute (FQxI)?

FQxI is a scientific funding organization that supports research on the deepest and most fundamental questions in physics, cosmology, and related fields. Since 2006, it has provided over $29 million in funding across more than 234 grants. It specifically supports unconventional, high-risk ideas that traditional funding bodies tend to avoid. The Bortolotti team’s work was partially funded through FQxI’s “Consciousness in the Physical World” program.

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9. What makes this research different from previous work on collapse models?

Previous work on collapse models established the general idea that gravity could cause wavefunction collapse, but the quantitative connection between CSL and gravitational spacetime fluctuations had not been mathematically worked out in this way before. Bortolotti’s team formally calculated this relationship for the first time, producing specific, testable predictions about fundamental clock precision limits.

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10. What happens next in this area of research?

Researchers are working on two fronts. On the theoretical side, teams like Bortolotti’s are extending calculations across different system sizes — from molecules to large structures — to build a complete picture of how collapse models predict physical behaviour. On the experimental side, groups like Kyushu University are developing new techniques to amplify tiny quantum gravity signals to detectable levels. Over the coming years, it may become possible to directly test whether gravity is fundamentally quantum — and whether collapse models are real.

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Primary research source: Nicola Bortolotti, Catalina Curceanu, Lajos Diósi, Simone Manti, Kristian Piscicchia. “Fundamental limits on clock precision from spacetime uncertainty in quantum collapse models.” Physical Review Research, 2025; 7(4). DOI: 10.1103/p6tj-lg8l