Atomic Universe Tracks Time Using Entropy
The research-stage experiment tests whether time can be measured without clocks, a question at the heart of the clash between relativity and quantum mechanics.
Updated on Nov. 2, 2026 in Physics
Giovanni Barontini, a scientist at the University of Birmingham, built a miniature atomic universe of roughly 24,000 rubidium atoms to test whether time can be tracked without clocks. The experiment is research-stage and has not been applied outside the laboratory.
Why it matters
Physics runs on two models, general relativity and quantum mechanics, that do not always agree on what time is. By letting the atomic system's own entropy serve as the timekeeper, the experiment offers a way to probe that disagreement directly rather than through external clocks.
The experiment is a laboratory measurement on about 24,000 rubidium atoms cooled near absolute zero, which behaved as one collective cloud. The internal clock progressed only as atoms crossed a laser barrier, and it diverged from the external clock when no atoms were exchanged, but the size of that divergence is not reported in the source.
The players
Giovanni Barontini
A physicist at the University of Birmingham who designed the miniature atomic universe experiment to test whether time can be tracked using entropy.
University of Birmingham
The UK university where Barontini works, with research in atomic and quantum physics.
The details
The rubidium atoms were enclosed in an inescapable trap that a specially configured laser split in half, and only one side was observed. Because the atoms acted as a collective cloud rather than as separate particles, the cloud's expansion, contraction, and the exchange of atoms across the barrier could be measured together. The changing entropy, a measure of disorder, on the observed side served as the timer, so the order of events was read from the system itself rather than from an external clock.
Timeline
The article describing the experiment was published on 2 November 2026.
The Tech Race
Efforts to build quantum simulators of cosmological conditions, such as the early universe after the Big Bang, are a growing research thread in atomic physics. This experiment adds a new approach by using entropy within an ultracold atom system as a timekeeper rather than an external clock.
This is a laboratory result with no announced product, availability, or pricing, so it does not yet reach everyday users. Any practical use of entropy-based timekeeping remains unannounced and would depend on follow-up research.
The takeaway
The experiment suggests time may be trackable from within a physical system without external clocks, a direction worth watching in future physics papers. Readers should watch for peer-reviewed follow-up work that reports the measured clock divergence and tests the approach at larger scales.
Further reading
For the wider field of how physicists probe the nature of time, explore the Physics section.
