What is the Universe made of? © Getty Images

What is the Universe made of?

Aside from conventional matter, the actual composition of the universe is one of the biggest mysteries facing 21st-century science.

Asked by: Adam Smith, York

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This is one of the biggest mysteries facing 21st-century science. Recent studies of the heat left over from the Big Bang have revealed that conventional matter made from atoms accounts for just a few per cent of the matter in the Universe. Most of it is in the form of so-called cold dark matter (CDM), whose enigmatic name reflects the awkward fact that astronomers don’t know what it is.


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