Physicists have now managed to track the passage of time inside a quantum event without using anything that looks like a traditional clock. Instead of ticking gears or oscillating crystals, they read time directly from the behavior of electrons and the structure of atoms, on scales of around 140 to 175 attoseconds, a billion-billionth of a second. The result is not just a technical feat, it is a fresh way of thinking about what time even means when you zoom in far enough.
The work builds on a decade of ideas about extracting time from quantum systems themselves, rather than imposing an external stopwatch. From quantum interference patterns to entangled particles and exotic “Rydberg” atoms, researchers are converging on a striking conclusion: in the quantum world, time can be encoded in the ripples, correlations, and spins of matter, and in some cases it can be reconstructed the way you might recognize a song from only a few notes.
The EPFL experiment that timed an electron’s escape
The latest breakthrough comes from EPFL, where a team showed that quantum events take a measurable amount of time and that atomic structure shapes how fast electrons move. When an electron absorbs a photon and leaves a material, it does not simply teleport from point A to point B, it follows a path that can last roughly 140 to 175 attoseconds, and that duration depends sensitively on the environment inside the atom. By tracking how the electron’s spin changes as it exits, the researchers effectively turned the electron itself into a stopwatch, extracting a time interval without any external clockwork and tying it directly to the internal structure of the atom, as described in detail by EPFL.
To pull this off, the team relied on a sophisticated variant of photoemission spectroscopy that can read out the spin of electrons as they leave a surface. When electrons absorb a photon and leave a material, they carry information in the form of their spin, which changes depending on how long they spend inside, and that makes it possible to reconstruct the timing of the escape from the spin pattern alone. The method, known as spin and angle resolved photoemission spectroscopy, or SARPES, turns the material into its own timing device and shows that the internal quantum dynamics can be mapped with attosecond precision, as highlighted in a technical summary of quantum-level measurement.
Measuring time inside quantum events without a clock
What makes this result so striking is that it directly addresses a long standing challenge in physics: how to capture the timing of ultrafast quantum events from inside the process itself. When a photon of light hits an electron, that electron can explore several quantum paths at once before emerging, and the usual idea of a single, sharply defined trajectory breaks down. Researchers working on what has been described as Physicists Measure Time a Clock have emphasized that capturing these ultrafast processes requires tools that can resolve attosecond scale changes in both energy and spin, effectively turning quantum mechanics from a static snapshot into a high speed movie.
In a detailed explainer of the experiment, one description notes that when a photon hits an electron in the quantum realm, it can occupy a superposition of paths before it finally appears outside the material, and that the interference between those paths encodes how long the process took. A video breakdown of the work, shared in early Feb, walks through how the team used carefully tuned light pulses and spin sensitive detectors to read out that interference pattern and translate it into a time interval. The key point is that the “clock” is not an external device but the quantum system itself, with time emerging from how the electron’s properties change as it interacts with light and the atomic lattice.
From quantum ripples to a new definition of time
The EPFL result slots into a broader shift in how physicists think about time at the smallest scales. Earlier work on quantum interference showed that time can be inferred from the way probability waves overlap and create ripples in measurement outcomes, without any ticking mechanism in the background. In one widely shared summary, Measuring time without a clock relies on quantum interference patterns, with references to Moreva et al. in Physical Review A on time from quantum entanglement, Giovannetti et al. in Nature Photonics on quantum enhanced measurements, and Smith et al. in Nature Physics on quantum clocks and time estimation. Those studies collectively argue that correlations between quantum systems can serve as an internal reference, letting one part of the system act as a clock for another.
Another explanation of the same idea stresses that this approach challenges how physics treats time itself, since it no longer needs to be a universal background parameter that flows independently of what matter is doing. Instead, time becomes something that can be reconstructed from the evolution of a quantum state, much like reconstructing a melody from a few notes. A follow up post on Measuring time without a clock makes that philosophical point explicit, arguing that if time can be read from interference alone, then it is less like an external river and more like a pattern that emerges from the relationships between quantum systems.
Uppsala University and the “song from a few notes” analogy
Parallel work from Uppsala University pushes the concept even further, suggesting that in the quantum world, time does not need to be measured with clocks at all. A groundbreaking study from Uppsala University shows that time can be reconstructed from the way a quantum system evolves, with the details published in Physical Review Research, volume 4, article 043041. In that work, the researchers treat the system’s changing state as a kind of internal metronome, where each configuration is like a note in a sequence, and the order and spacing of those notes encode the passage of time.
Popular explanations of the Uppsala University result lean on a vivid analogy: just as you can recognize a song from hearing only a few notes, you can infer how much time has passed by sampling only part of a quantum evolution. One widely shared post on social media describes how Quantum physicists have discovered a new way to measure time without using a ticking clock or a starting point, with Researchers at Upp using that song analogy to explain the method. A related breakdown on Ins underscores that the key is not an external reference but the internal structure of the quantum state, which carries its own record of how long the system has been evolving.
“Entirely new” quantum clocks and the future of timekeeping
Alongside these conceptual advances, experimentalists are also building devices that behave like clocks but are rooted in quantum behavior rather than mechanical motion. Several reports describe how physicists have created what is described as an entirely new way to measure time, using quantum systems that resonate instead of tick. One popular science explainer notes that Physicists Just Found an Entirely New Way to Measure Time, urging readers to Forget ticking clocks and think instead of time as a resonance along a quantum line. In that picture, the “ticks” are replaced by oscillations in a carefully prepared quantum state, which can be read out with extreme precision.
Another strand of work focuses on Rydberg atoms, which are atoms with electrons excited to very high energy levels that orbit far from the nucleus and respond strongly to external fields. A detailed social media post explains that Physicists have created a clock based on Rydberg atoms, using their exaggerated properties to define a new kind of time standard, tagged with phrases like TimeRedefined, QuantumPhysics, and RydbergAtoms. Other posts frame this as part of a broader revolution, with repeated references to how Physicists Just Found an Entirely New Way to Measure Time and to Forget traditional clocks, and follow up coverage noting that Physicists Just Found an Entirely New Way to Measure Time linked directly to the Physical Review Research paper numbered 4.043041.
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*This article was researched with the help of AI, with human editors creating the final content.
