Imagine you are a single atom of rubidium, trapped in a magnetic field, cooled until you barely move. You are part of a cloud of 20,000 siblings, all frozen into a state where nothing happens. There is no before, no after. You just are. Then, a laser hits you. You jump from your dark, quiet sector into a bright, noisy one. Suddenly, you have a history. You have a future. You have, for the first time, a sense of time.
This is a laboratory at the University of Birmingham, where physicist Giovanni Barontini built a miniature universe to ask a question that has haunted thinkers for centuries: is time real, or is it just a story we tell ourselves? [1]
The story of time is not a story about clocks. It is a story about change. Before Barontini’s experiment, the idea that time might be an illusion was a philosophical dream. Now, it is a measurable, repeatable phenomenon in a dish of cold atoms.
Let us start at the most accessible part of this story: the feeling of waiting. When you wait for a bus, time feels heavy, slow, real. But what if the bus never comes? What if nothing changes? Then, time would have no meaning. Barontini’s son, playing with toy blocks, understood this intuitively. He built a universe that was ‘boring’ because nothing happened “boring” because nothing happened. The boy’s insight was the seed of a revolution.
Barontini’s toy universe is simple. He takes rubidium atoms, chills them to near absolute zero, and divides them into two groups: one ‘bright’ and one ‘dark.’ This is like having two rooms in a house, with a door that is initially locked. Nothing moves “bright” and one “dark.” This is like having two rooms in a house, with a door that is initially locked. Nothing moves. The house is timeless.
Then, he opens the door. He uses lasers to coax atoms to jump from the dark room to the bright room. This is the first event. With that jump, something new appears: entropy. Entropy is a measure of disorder. In our universe, time flows in the direction of increasing disorder. An egg breaks, it does not unbreak. Ice melts, it does not refreeze on its own. Barontini’s atoms, by moving, create disorder. They create a direction. They create an arrow of time.
Once he has this arrow, Barontini can do something remarkable. He can define a new time for his toy universe, an internal time that is not borrowed from an external clock. He then plugs this internal time into the Schrodinger equation, the master equation of quantum mechanics. The equation works. It predicts the atoms’ behavior perfectly.
This is a ladder. At the bottom rung, we have the everyday experience of time. On the next rung, we have the classical physics of Newton, where time is a universal river. On the next rung, we have Einstein’s relativity, where time can stretch and shrink depending on speed and gravity. On the top rung, we have Barontini’s experiment, where time is not a given at all, but a property that emerges from quantum interactions.
This idea has a long history. In the 1930s, physicist Nevill Mott first suggested that time might arise from quantum correlations. It took until 2013 for Marco Genovese, at the National Metrology Institute of Italy, to offer the first experimental proof, using entangled particles of light. [2] Barontini’s cold-atom universe is more complex, more like our own. It is a bridge from the abstract to the concrete.
Think of it this way. Imagine a movie. The film reel has frames, one after another. The projector shows them in sequence. We see motion. But the frames themselves do not contain time. They are just still images. Barontini’s experiment suggests that our universe might be like that film reel. The quantum interactions are the frames. Our perception of time is the projector. Without the interactions, there is no movie.
This view of time connects to a deeper problem in physics: the search for a theory of quantum gravity. Quantum gravity is a single framework that would unite Einstein’s general relativity, which describes gravity and large-scale structure, with quantum mechanics, which describes the subatomic world. One of the biggest obstacles to this unification is time. In general relativity, time is a dynamic part of the fabric of spacetime. In quantum mechanics, time is a fixed background parameter. They do not fit together.
Some physicists, like Claus Kiefer at the University of Cologne, believe that in a true theory of quantum gravity, time would disappear at the most fundamental level. [3] It would be an illusion, an emergent property. Barontini’s experiment mimics this situation. In his toy universe, time is not fundamental. It emerges from the quantum dance of atoms.
But not everyone is convinced. Carlo Rovelli, a leading physicist at Aix-Marseille University in France, argues that these experiments cannot discover something new about time because they are built using physics we already understand. [4] He compares them to a model of a volcano made from baking soda and vinegar. The model can teach you about eruptions, but it is not a real volcano.
Barontini’s toy universe is tiny, simple, and carefully controlled. It does not have gravity. It does not have complex interactions. It is not the cosmos. Yet, these experiments can provide inspiration. They can be a sandbox for testing ideas that might apply to the real universe.
Consider the parallel with another field: computer vision. In a recent paper from May 2025, researchers at a major university showed that machine vision systems are fooled by 3D visual illusions. A flat image can look three-dimensional to a computer, just as it does to a human. The computer’s depth estimation, its sense of space, is an illusion created by clever cues in the image. Our sense of time, like the computer’s sense of depth, might be an illusion created by quantum cues.
Now, consider another parallel: the Tianyan quantum cloud platform in China. This platform, announced in December 2025, gives researchers access to a 105-qubit quantum processor. It can solve a specific problem in 18 minutes that would take a classical supercomputer 16,000 years. Barontini’s experiment is a different kind of quantum advantage: it allows us to explore the nature of time itself.
The history of this idea is deeper than you might think. In 1998, a paper on ‘Space-time distributions’ explored the mathematical structure of time in general relativity. It showed that under certain conditions, time could be defined by a family of spacelike surfaces, like slices of a loaf of bread. This is a mathematical precursor to Barontini’s experiment “Space-time distributions” explored the mathematical structure of time in general relativity. It showed that under certain conditions, time could be defined by a family of spacelike surfaces, like slices of a loaf of bread. This is a mathematical precursor to Barontini’s experiment. The paper is abstract, but it lays the groundwork for the idea that time is not a fundamental dimension but a way of organizing events.
Then, in 2006, a paper on “Generalizing Quantum Mechanics for Quantum Spacetime” took the next step. It argued that quantum mechanics itself must be modified to account for a universe where time is not fixed. This is a radical idea. It suggests that the very laws of physics, as we know them, might be incomplete. Barontini’s experiment is a step towards testing this idea. By creating a system where time emerges, he is probing the boundary between quantum mechanics and a deeper, more fundamental theory.
Let us return to the lab. Barontini’s experiment is not just about time. It is also about entropy. Entropy is often described as the “arrow of time.” In our universe, entropy always increases. This is why we age, why stars burn out, why the universe is expanding. Barontini’s toy universe also has an arrow of time, defined by the flow of atoms from the dark sector to the bright sector. This flow increases entropy. It creates a direction.
But what if Barontini reversed the experiment? What if he coaxed atoms to flow from the bright sector back to the dark sector? Would time flow backwards? The answer is no. The second law of thermodynamics, which states that entropy always increases, is a statistical law. It is possible, in principle, for entropy to decrease, but it is astronomically unlikely. In Barontini’s tiny universe, the probability of reversing the arrow of time is so small that it is effectively zero. This is a powerful demonstration of why time seems to flow in only one direction.
Think about the implications for our own lives. We experience time as a river, carrying us from past to future. We remember the past, we anticipate the future. But if time is an illusion, then what about memory? What about anticipation? These might also be illusions, emergent properties of the quantum interactions that make up our brains.
This is not a comfortable thought. We are built to experience time as real. Our emotions, our plans, our regrets, all depend on a linear progression of time. But Barontini’s experiment suggests that this progression is not fundamental. It is a feature of the universe at our scale, not at the quantum scale.
Let us move to a more technical level. Barontini’s experiment uses ultracold atoms. These are atoms that have been cooled to temperatures near absolute zero, where they behave like a single quantum entity, a Bose-Einstein condensate. In this state, quantum effects become visible on a macroscopic scale. This is why Barontini can use them to study time. The quantum interactions between the atoms are the engine that generates time.
The experiment is precise. Barontini uses lasers to create a potential landscape, like a series of hills and valleys, for the atoms. He then uses a second set of lasers to drive the atoms from one sector to another. The rate of this transfer is controlled by the laser intensity. By adjusting the lasers, he can change the flow of time in his toy universe. He can make it faster or slower. He can even, in principle, make it stop.
This is a remarkable degree of control. It is like being able to turn the clock of the universe on and off. Barontini is not just observing time; he is manipulating it. This opens up new possibilities for research. For example, he could study what happens to quantum entanglement when time is turned off. He could study how information flows in a universe without time. He could test the limits of the Schrodinger equation.
Now, consider the bridge to another field: cosmology. Cosmologists study the entire universe. They have their own ideas about time. Some believe that time began with the Big Bang. Others believe that time is cyclic, with no beginning and no end. Barontini’s experiment cannot answer these questions, but it can provide a model. It can show how time might emerge from a timeless state, like the one that might have existed before the Big Bang.
Barontini is aware of this connection. He says that cosmologists are likely to have objections to his work. They will point out that his toy universe is too simple. It does not have gravity. It does not have dark matter. It does not have the complexity of the real cosmos. But Barontini is not trying to build a perfect model of the universe. He is trying to isolate a single phenomenon: the emergence of time. In this, he has succeeded.
What is next for Barontini? He wants to explore further. He wants to use lasers to create regions that atoms cannot escape from, like the event horizon of a black hole. This would allow him to study the relationship between time and gravity. He could see if time behaves differently near a simulated black hole. This is a bold idea. It brings us one step closer to understanding the nature of time in extreme environments.
Let us take stock. Barontini’s experiment is a confirmation of ideas that have been around for decades. It is not a proof that time is an illusion in our universe. It is a demonstration that time can be an illusion in a simplified system. This is a significant step forward. It moves the debate from theory to experiment. It gives physicists a tool to test their ideas about time.
Think of it as a bridge. On one side, we have the classical view of time as a universal, absolute quantity. On the other side, we have the quantum view of time as an emergent, relational quantity. Barontini’s experiment is a bridge between these two worlds. It shows that we can travel from one to the other, at least in a laboratory.
Now, let us list the things that are now obsolete because of this finding.
First, the idea that time is a fundamental, irreducible property of nature is obsolete, at least for toy universes. We now know that time can emerge from simpler ingredients.
Second, the belief that the Schrodinger equation requires an external, absolute time is obsolete. Barontini has shown that the equation works with an internal, emergent time.
Third, the notion that the arrow of time is a mysterious, unexplained feature of the universe is obsolete, at least in principle. We can now create an arrow of time in the lab.
Fourth, the distinction between time and entropy is obsolete. Barontini’s experiment shows that they are intimately linked. Time is the direction of increasing entropy.
Fifth, the idea that quantum mechanics and gravity are completely separate is obsolete. Barontini’s experiment provides a model for how time might emerge in a theory of quantum gravity.
Sixth, the belief that experiments cannot shed light on the nature of time is obsolete. Barontini has shown that they can.
Seventh, the notion that time is a human construct, a product of our consciousness, is obsolete, at least as a complete explanation. Barontini’s experiment shows that time can exist without a conscious observer.
Eighth, the idea that the past and future are fundamentally different is obsolete. Barontini’s experiment shows that they are both products of quantum interactions.
Ninth, the belief that time travel is impossible is not obsolete, but it is now seen in a new light. If time is an illusion, then time travel is not about moving through a dimension, but about manipulating quantum correlations.
Tenth, the assumption that our everyday experience of time is a reliable guide to the nature of reality is obsolete. Barontini’s experiment shows that reality is stranger than we imagine.
Barontini’s experiment is a small step in a long journey. It is a single data point in a vast, unexplored landscape. But it is a step forward. It reminds us that the universe is not what it seems. It reminds us that the most fundamental questions, like the nature of time, are still open. And it reminds us that we have the tools to answer them. The next time you look at a clock, remember the atoms in Birmingham. They are dancing to a different tune. They are telling us that time is not a given. It is a gift, born from the quantum dance of the cosmos.