Why Size Makes All the Difference; A Wonderful Account of the Universe with the History of Science, Philosophy and Evolution Thrown In

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Byline: WILLIAM LEITH

YOU ARE HERE: A PORTABLE HISTORY OF THE UNIVERSE by Christopher Potter (Hutchinson, [pounds sterling]20)

IN THIS book, which is hugely fun to read, Christopher Potter, who is not a scientist by trade, tries to explain everything -- by which I mean everything in the universe -- in slightly less than 300 pages. I read it in an evening, with a sense of increasing excitement, and then vertigo, and finally a sort of stunned awe. Potter has written a wonderful account of the universe we live in, which is also a history of science, and touches, in some places, on a philosophical investigation.

Towards the beginning, he makes us familiar with the concept of size. The size we're most familiar with is our own, of course. But it's easy to grasp the size of the giraffe, which is slightly more than three times the height of a human, just as we can understand that a python can be five times as long as us. Neither did I have much trouble visualising a whale, Nelson's column or the Empire State Building. We can see five kilometres ahead of us on a flat landscape, and we might, one day, be able to build a skyscraper that is 18 kilometres high.

Next, Potter takes you into the atmosphere, the stratosphere, and beyond. It's dizzying. There are satellites thousands of kilometres above the earth.

One satellite, known as Vela 1A, orbits the earth at a distance of more than 100,000 kilometres. The moon is 400,000 kilometres away. The sun is 150 million kilometres distant from us, Jupiter more than a billion, Neptune more than four billion.

And these are just the really close things. The solar system extends "50,000 times the distance from the earth to the sun". And do you know the really spooky thing? At the edge of our solar system, we can't see much, because there's not much sunlight. What we see, when we look at the sky, are other solar systems, which are much, much further away than ours. For instance, the closest proper star, Alpha Centauri, is more than four light years away -- that's 40,000 billion kilometres. …