If we were to look at the Universe as a whole, what state of matter would we say it’s in?

This is a tricky one because around 85 per cent of the matter that we know exists in our Universe has not yet been seen, and so scientists don’t know what state this ‘dark matter’ is in.

However, of the matter that we can see, the vast majority is in the form of plasma – an ionised gas in which atoms have been partially or fully stripped of their electrons. About 10 per cent of this plasma exists in stars, and the rest as diffuse clouds of ionised hydrogen.

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