Physics

The maths behind ‘impossible’ never-repeating patterns

The maths behind ‘impossible’ never-repeating patterns

Remember the graph paper you used at school, the kind that’s covered with tiny squares? It’s the perfect illustration of what mathematicians call a “periodic tiling of space”, with shapes covering an entire area with no overlap or gap. If we moved the whole pattern by the length of a tile (translated it) or rotated it by 90 degrees, we will get the same pattern. That’s because in this case, the whole tiling has the same symmetry as a single tile. But imagine tiling a bathroom with pentagons instead of squares – it’s impossible, because the pentagons won’t fit together without leaving gaps or overlapping one another.

Graphene isn’t the only Lego in the materials-science toy box

Graphene isn’t the only Lego in the materials-science toy box

You may have heard of graphene, a sheet of pure carbon, one atom thick, that’s all the rage in materials-science circles, and getting plenty of media hype as well. Reports have trumpeted graphene as an ultra-thin, super-strong, super-conductive, super-flexible material. You could be excused for thinking it might even save all of humanity from certain doom.

Why lightsabers would be far more lethal than George Lucas envisioned

Why lightsabers would be far more lethal than George Lucas envisioned

Research is an unpredictable process. Sometimes you end up making a really cool discovery that you didn’t see coming. I recently uncovered a fundamental property of lightsabers (that’s right – the awesome weapons from Star Wars) while doing my regular plasma physics research. I found that, while it is in theory possible to build a lightsaber, it’s likely it would be the most dangerous weapon ever created – both for the perpetrator and the victim.

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.