Physics

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Introducing the world's first solar-powered battery

A battery that runs on sunshine and fresh air sounds like something from a utopian novel, along with fusion-powered hover cars and cancer-curing breakfast cereals. But that is exactly what scientists at The Ohio State University have just invented: a solar cell that stores its own power.

Who is the greatest genius?

In the Summer issue of BBC Focus Magazine, we're asking you to choose your top genius of all time. But before you vote, read more about the 15 nominees.

Why does hair get darker when wet?

When light hits wet hair, some of the light reflecting off the surface of the hair strikes the inside surface of the water film at the right angle to be reflected or refracted back onto the hair again.

In search of the shadow universe

It makes up the vast majority of the matter in the Universe, but we have no idea what it is. Now, as Marcus Chown reveals, a hidden realm of dark matter could exist right under our noses.

How can we make antimatter?

It is one of the greatest mysteries in science: why does the Universe consist almost entirely of matter? Answering this question is the ultimate goal of scientists who are attempting to make antimatter in the lab.

What gives substances their scent?

Substances generate a smell when their molecules land on so-called olfactory neurones in our noses (which, for some things, is a pretty unpleasant thought). But the exact nature of the interaction is somewhat controversial.

Why do we need leap years?

The Earth takes about 365.25 days to complete an orbit around the Sun (one year). If you just round the calendar year down to the nearest whole number, the date recorded by the calendar will drift out of sync with the seasons.