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
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.
Robert is a science writer and visiting professor of science at Aston University.