Physicists at the University of Birmingham have experimentally demonstrated that time can emerge within an isolated quantum system without the need for an external clock. By splitting a Bose-Einstein condensate of rubidium atoms, Giovanni Barontini observed how internal entropy exchanges between two system sectors create a measurable flow of time, providing the first laboratory verification of a concept rooted in the 60-year-old Wheeler-DeWitt equation.
The Wheeler-DeWitt Equation and the Problem of Time
For decades, the Wheeler-DeWitt equation has served as a cornerstone of quantum gravity while simultaneously presenting a profound paradox: it describes the universe as a global system that lacks an external temporal parameter. According to the research team at the University of Birmingham, this implies that no “cosmic clock” exists outside the boundaries of our universe to dictate the passage of events.
This theoretical void has long troubled physicists, as it contradicts the human perception of time as a fundamental, ever-ticking dimension. The “relational time” theory suggests that time is not a foundational ingredient of reality but an emergent property born from internal relationships between different parts of a system. Until the Birmingham experiment, this hypothesis remained largely speculative, lacking direct empirical validation in a controlled laboratory environment.
How a “Mini-Universe” Was Created in the Lab
To test if time could arise from within, Giovanni Barontini utilized a Bose-Einstein condensate—an exotic state of matter achieved by cooling atoms to temperatures near absolute zero. In this state, thousands of atoms merge into a single quantum entity. Barontini placed this condensate in a trap and used a laser beam to divide the system into two distinct parts.
The experimenters designated one half as the “bright sector,” which they monitored closely, and the other as the “dark sector,” which they intentionally left unobserved. This separation successfully simulated the conditions of a closed, isolated universe. According to the study published in Physical Review Research, the atoms within the bright sector oscillated across the laser barrier, creating periodic cycles that researchers labeled “Big Bang” and “Big Crunch” events.
The experiment revealed that when the two sectors reached thermodynamic equilibrium, the internal “clock” stopped completely, suggesting that the flow of time is inextricably linked to the exchange of disorder between system components.
The Role of Entropy in Temporal Flow
The emergence of time in the Birmingham experiment was measured through the exchange of entropy—the movement of disorder—between the two sectors. Barontini and his team constructed an internal “entropic time” based on these flux patterns. Their findings showed that the speed of this internal time was directly proportional to the rate of entropy exchange.
When entropy circulated rapidly between the sectors, the internal clock accelerated. Conversely, when the exchange slowed, the passage of time decelerated. This “entropic time” allowed the researchers to reconstruct a version of the Schrödinger equation that accurately predicted the observed atomic behaviors. This suggests that what we perceive as the “arrow of time” may be a byproduct of our partial knowledge of a larger system.
Future Implications for Quantum Physics
The conclusion that time emerges from the act of ignoring part of a system offers a radical shift in how scientists approach cosmology. As Barontini noted, the “arrow of time” may simply be a result of human ignorance regarding the total state of the universe. This experimental framework now provides a platform for future studies, including the simulation of black hole analogues and the conditions of the early universe.
Watch for future research using this condensate-splitting method, as it serves as a “proof of concept” for testing other deep-seated theories in quantum gravity that were previously thought to be untestable.
Frequently Asked Questions
- Does time exist independently of the universe?
According to the Wheeler-DeWitt equation, there is no external clock for the universe; time is likely an emergent property of internal system relationships. - What is “entropic time”?
It is a measurement of time derived from the exchange of disorder (entropy) between two halves of a closed quantum system. - Why did the researchers ignore the “dark sector”?
Leaving one sector unobserved was necessary to simulate a truly isolated, closed system, allowing the team to see if time would emerge naturally without outside influence.
What are your thoughts on time being a byproduct of entropy? Join the conversation in the comments section below or subscribe to our newsletter for the latest updates on quantum research.
