What if time isn’t the steady, universal metronome we’ve always assumed it to be? What if, instead, it’s something that emerges from the chaos of relationships and changes within a system? This is the provocative question at the heart of a recent experiment led by Professor Giovanni Barontini at the University of Birmingham. Personally, I find this idea utterly fascinating because it challenges one of our most fundamental assumptions about the universe. We’ve always thought of time as an external force, ticking away independently of everything else. But Barontini’s work suggests that time might be more like a shadow—something that only exists in relation to the objects and processes around it.
In his experiment, Barontini created a ‘mini universe’ using 24,000 ultracold rubidium atoms, cooled to just a few billionths of a degree above absolute zero. This isn’t just a cool party trick (though it is that too); it’s a carefully designed system to test a radical idea from theoretical physics: that time might not be a built-in feature of the universe but rather an emergent property. What makes this particularly fascinating is how Barontini approached the problem. Instead of relying on a traditional clock, he defined time through entropy—the measure of disorder within the system. When entropy changes, time advances; when it doesn’t, time effectively stops.
This raises a deeper question: if time isn’t universal, how do we reconcile that with our everyday experience? After all, we all seem to agree on the direction of time—past to future. But Barontini’s experiment shows that time can flow at different rates, or even stall, depending on the dynamics of the system. From my perspective, this isn’t just a theoretical curiosity; it’s a potential paradigm shift. If time is emergent, it could mean that our understanding of causality, sequence, and even the arrow of time needs a serious rethink.
One thing that immediately stands out is how Barontini’s ‘entropic time’ aligns with thermodynamics, which has long been the odd one out in physics. Most fundamental laws are time-symmetric—they work the same forwards and backwards. But the second law of thermodynamics, which states that entropy tends to increase, gives us a clear direction for time. Barontini’s experiment leverages this asymmetry, suggesting that entropy might be the key to understanding why time seems to have a direction. What many people don’t realize is that this connection between time and entropy has been a philosophical puzzle for centuries. Barontini’s work turns it into a tangible, testable idea.
What this really suggests is that our intuition about time might be deeply flawed. We think of it as a linear, universal constant, but Barontini’s mini universe shows that time can be local, relative, and even stop-and-start. If you take a step back and think about it, this could have profound implications for how we understand the cosmos. Could the universe itself have periods where time effectively stands still? Could black holes or the early moments of the Big Bang operate under different time rules? These are the kinds of questions Barontini’s experiment opens up.
A detail that I find especially interesting is how Barontini rewrote the Schrödinger equation—the cornerstone of quantum mechanics—using entropic time instead of traditional time. This isn’t just a mathematical trick; it’s a demonstration that the system can still be described predictively without relying on an external clock. It’s as if the universe is saying, ‘You don’t need a watch to tell time; just look at how things change.’
Of course, this doesn’t solve all the mysteries of time in physics. But it does something equally important: it turns an abstract philosophical debate into a concrete experimental problem. Cold-atom experiments like Barontini’s are already being used to simulate black holes, false vacuum decay, and other exotic phenomena. Now, they’re giving us a way to test ideas from quantum gravity and cosmology in the lab, not just on paper.
In my opinion, the most exciting part of this research isn’t its immediate practical applications—though those are significant. It’s the way it forces us to rethink our most basic assumptions. Time, change, causality—these aren’t fixed truths but emergent properties that depend on the systems we’re studying. This experiment is a reminder that the universe is far stranger and more dynamic than we often give it credit for.
As we look to the future, Barontini’s work could pave the way for even more ambitious experiments. Could we simulate the early universe or the interior of a black hole using similar techniques? Could we test competing theories of emergent time? The possibilities are as vast as they are intriguing.
In the end, what Barontini’s mini universe teaches us is that time might not be the ruler of the cosmos—it might be one of its creations. And that, personally, is a thought that makes me look at the world in a whole new way.
