Science: Technoquest

Q: Why does static electricity affect water?

Everything is made up of atoms. But atoms aren't the smallest things in the world. There's a central bit called the nucleus and around that are lots of "electrons". An atom is a bit like a small solar system.

Static electricity is to do with electrons. Atoms usually have an equal number of electrons (which are negative) and protons (which are in the nucleus of the atom and are positive). So the electrons balance out the protons. This means the atom has no "charge" - it's balanced.

But you can remove electrons from or add electrons to atoms which means you've either got too many or too few electrons making atoms negative or positive. And just like opposite ends of magnets attract each other, so do opposite atoms. A negative atom will attract a positive one.

When you rub a comb or plastic ruler, you're taking electrons away from the atoms in the comb. So the comb becomes positive.

Water is a special material. Most things are balanced - with equal numbers of electrons and protons, so they wouldn't be attracted to the comb. But water is made up of oxygen and hydrogen. When these atoms join together, they share their electrons. This is often how things join together, by sharing electrons.

But they don't share them equally. The oxygen atom likes electrons more than the hydrogen atom so takes more than its fair share of electrons. This means the oxygen is slightly more negative than the hydrogen. So the comb will attract the oxygen and pull the rest of the water with it.

Q: Life, the universe and everything. The answer is 42, isn't it?

Yes - maybe! A recent report from some early results from a radio experiment in Cambridge to measure small temperature fluctuations in the cosmic microwave background (the heat left over from the big bang) suggests one of the answers to a puzzling question is 42.

The small fluctuations they observed are caused by very large clusters of galaxies as they are first forming. From the information gleaned it is possible to interpret the time it takes for such large things to form in terms of models of the formation of structure in the Universe. The group discovered one such cluster, the analysis of which produced a very uncertain value of the Hubble constant which is 42. However the uncertainty is very large. Correctly calculating what Hubble's constant is, is one of the bugbears of modern astronomy. The current consensus is somewhere close to 60.

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