Physicists created a tiny universe where time emerged without a clock

Key Points:

• Professor Giovanni Barontini demonstrated experimentally that time can emerge naturally from the internal behavior of a quantum system, without relying on an external clock, using a cloud of ultracold atoms as a simplified quantum "universe."
• The experiment showed that the flow of time arises from changes in entropy—the distribution and disorder of atoms within the system—creating an "entropic time" that flows consistently and orders events even as the mini universe expands and contracts.
• This work provides the first controlled experimental evidence supporting theories in quantum gravity where time is not fundamental but emerges from relationships within the system, addressing how events can be ordered without a built-in universal clock.
• Researchers found that the Schrödinger equation, fundamental to quantum mechanics, can be expressed using entropic time, allowing predictions of quantum system evolution based on internal changes rather than external time.
• The miniature quantum universe offers a new platform for experimentally exploring quantum cosmology and gravity concepts, potentially enabling laboratory studies of phenomena like the Big Bang, Big Crunch, and black holes previously accessible only through theoretical models.