Physics

What is time – and why does it move forward?

Imagine time running backwards. People would grow younger instead of older and, after a long life of gradual rejuvenation – unlearning everything they know – they would end as a twinkle in their parents' eyes. That’s time as represented in a novel by science fiction writer Philip K Dick but, surprisingly, time’s direction is also an issue that cosmologists are grappling with.

Corals, crochet and the cosmos: how hyperbolic geometry pervades the universe

Corals, crochet and the cosmos: how hyperbolic geometry pervades the universe

We have built a world of largely straight lines – the houses we live in, the skyscrapers we work in and the streets we drive on our daily commutes. Yet outside our boxes, nature teams with frilly, crenellated forms, from the fluted surfaces of lettuces and fungi to the frilled skirts of sea slugs and the gorgeous undulations of corals.

How Einstein’s general theory of relativity killed off common-sense physics

How Einstein’s general theory of relativity killed off common-sense physics

Gravity ties our bodies to planet Earth but it does not define the limits of the soaring human mind. In November 1915 – exactly one century ago – this was proven to be true when Albert Einstein, in a series of lectures at the Prussian Academy of Sciences, presented a theory that would revolutionise how we view gravity – and physics itself.