
Last Word
When does a theory become a fact and who decides?
Regulars
New Å®ÉúСÊÓÆµ's popular Last Word series gives readers the opportunity to answer each other's questions about everyday science phenomena, from the shape of scones to the evolutionary history of toenails. To answer a question or ask a new one, email lastword@newscientist.com
Issue no. 3367 published 1 January 2022