Sub-titled 'The Hidden 95% of the Universe', all the matter and light we can see in the universe makes up a trivial 5% of everything. The rest is hidden. This could be the biggest puzzle that science has ever faced. Since the 1970s astronomers have been aware that galaxies have far too little matter in them to account for the way they spin around. They should fly apart, but something concealed holds them together and that 'something' is dark matter - an invisible material in five times the quantity of the familiar stuff of stars and planets. By the 1990s we also knew that the expansion of the universe was accelerating. Something named dark energy was pushing it to expand faster and faster. Across the universe this requires enough energy that the equivalent mass would be nearly 14 times greater than all the visible material in existence. Brian Clegg explains this major conundrum in modern science and looks at how scientists are beginning to find solutions to it. From the Hot Science series of Icon Books. 164 page illustrated paperback.
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