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THERE is nothing quite so simultaneously familiar and enigmatic as time, the focus of this week’s issue. Which is perhaps what always makes it such a joy to indulge in our unique ability to explore the many ongoing mysteries of time – and to chase a better understanding of the most puzzling dimension of all.

We can’t even agree on what time is, though many people suspect answers could lie in the mismatch between how it manifests in general relativity – Einstein’s theory of gravity – and quantum mechanics, which describes the behaviour of subatomic particles and forces. Figuring that out could finally lead us to a quantum theory of gravity. That is proving to be a difficult quest, but fresh clues are arriving all the time. Just this week, researchers discovered a new kind of time crystal, strange oscillating materials that may offer a new window on events at the quantum scale.

We can’t physically go back in time – for now, at least. But that doesn’t stop us from venturing into the deep past through the fossil record, which is revealing that evolution happens on two timescales at once, or by studying stars and galaxies millions of light years away. This form of time travel has just received a boost with the latest release of data from the Gaia space telescope, featuring details on the chemical composition of almost 2 billion stars to help us build a better picture of our galaxy’s history. We can also speculate about the deep future, not least the ultimate question – will time ever end?

But arguably some of the most fascinating questions about time have to do with how we relate to it. In the past few years, neuroscientists have made strides in understanding how our brains measure time  and psychologists have demonstrated the role our bodies play in warping our perceptions of its passage. They even have surprising proposals for how we might rethink our relationship with time – for example, by tapping into the fact that each of us only enjoys a limited supply – to live more fulfilling lives.