Is anything actually 2D? © Getty Images

Is anything actually 2D?

Oil in puddles might provide a clue.

Asked by: Tom Storey, by email

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Nothing physical can exist with literally zero thickness, as its atoms have a finite size. But there are many examples of so-called ‘monolayers’ just one molecule – or a few tens of billionths of a metre – in thickness. The most familiar are monolayers of oil in puddles, which are so thin they split light into its constituent colours.


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