Verrucchi now suspects this is key to how time works. The arrow of time, she says, might simply be a record of what has been measured. Like flicking through a cosmic flipbook, we reveal new pages by interacting with the elements of reality – or “making measurements” as a physicist might put it. The act of simply being in the world collapses our quantum reality into a definite state, leaving an irreversible record behind.

And if clocks are physical systems that record measurements – and we are, too – then perhaps we aren’t just observers of time, says Verrucchi, but participants in its making: “You create time when you ask what time it is.”

irreversible processes were missing one factor. Once they incorporate this factor, then these equations also do not distinguish between the future and the past anymore

Quantum entanglement is where two particles become interconnected and share a single state. But how and when do particles become entangled?

Physicists have struggled to understand the nature of time since the field began. But a new theoretical study suggests time could be an illusion woven at the quantum level.

When it comes to how we experience, interact with, and navigate our world, timing is everything.

There's also growing interest in how 'time blindness' – a symptom of ADHD and autism – arises. Understanding how time is mapped and recorded in the brain could help progress investigations there, too.

One of Alexander’s Macedonian generals, who would go on to win an enormous kingdom stretching from Bulgaria to Afghanistan, introduced a new system for reckoning the passage of time. It is known, after him, as the Seleucid Era. This was the world’s first continuous and irreversible tally of counted years.