A Physicist Builds a Miniature Universe and Watches Time Emerge Without a Clock
Written by AI from sciencedaily.com's report. Not checked by a person.
A University of Birmingham physicist used roughly 24,000 ultracold atoms to create a quantum system where time emerged internally from entropy changes, offering the first experimental evidence of how time itself may arise.
Professor Giovanni Barontini, a physicist at the University of Birmingham, built a miniature universe inside a laboratory and used it to observe the emergence of time. He cooled a cloud of approximately 24,000 atoms to just a few billionths of a degree above absolute zero, where quantum effects become especially prominent. The system was divided by two laser beams into a bright, observed region and a dark, unobserved region, and was designed to expand and contract — loosely mimicking a Big Bang and a Big Crunch. By tracking how atoms redistributed between the two regions of this isolated quantum system, Barontini identified an internal measure of progression he calls "entropic time," which moves in one consistent direction and can place events in the correct sequence without any reference to an external clock. Barontini said the work demonstrates that "time can be defined by changes within a system rather than as the external ticking clock we think of." The findings, published in Physical Review Research, provide the first controlled experimental evidence that time can be defined by internal changes within a system rather than by an outside clock — an idea that bears directly on theories of quantum gravity, where time does not appear as a built-in feature. The experiment does not rewrite physics overnight, but delivers one of the clearest laboratory demonstrations yet that time may ultimately be a consequence, not a cause, of physical processes.
