
Is anything actually 2D?
Oil in puddles might provide a clue.
Asked by: Tom Storey, by email
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.
Subscribe to BBC Focus magazine for fascinating new Q&As every month and follow @sciencefocusQA on Twitter for your daily dose of fun science facts.
Authors

Robert is a science writer and visiting professor of science at Aston University.
Subscription offer
Subscribe and save 50% on the shop price. Pay just £16.50 every 6 issues by Direct Debit. Receive every issue delivered direct to your door with FREE UK delivery.