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Questions and answers provided by Science Line's Dial-a-Scientist on 0345 600444

Q What is antimatter?

A Antimatter is matter that is in all respects the opposite to "ordinary" matter except mass. The charges of antimatter particles are the opposite of ordinary matter - so the equivalent of our negatively charged electron is positively charged (called the positron). An antihydrogen atom (one of which has been made on Earth) consists of a positron and an antiproton. Matter and antimatter interact through the same forces as matter and matter, but when they meet, the result is total annihilation.

Q Why don't woodpeckers get headaches?

A Woodpeckers have fluid surrounding their brains. They also have very large skulls and comparatively small brains, meaning their brain tissue doesn't have much momentum on impact - unlike, say, a human boxer. They also have shock absorbers in the beak and skull.

QHow do the widgets in beer cans work?

A Widgets - devices in the bottom of beer cans to give a frothy head - consist of a plastic container of nitrogen with a closed valve. The widget is placed in the can; then beer is added along with a small amount of nitrogen to fill the small gap between the top of the beer and the can. The beer is pasteurised, and the heat expands the widget and increases pressure in the can. When it's opened, the pressure bursts the valve in the widget and lets out the nitrogen. This gives smaller bubbles that last longer and look whiter.

QHow many slices of bread could you toast in a lightning strike?

A One lightning strike is a billion kW - the power of about 800 million toasters; it could toast 1.6 billion pieces of bread. Of course, lining up all those bits of bread and turning them over after five milliseconds could be tricky.

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