Is it possible to create light without heat? © Getty Images

Is it possible to produce light without heat?

This phenomenon requires generating photons with visible, UV wavelengths rather than hot, infra-red wavelengths, and it happens in nature.

Asked by: Anonymous

Advertisement

Yes – and many living organisms, such as fireflies, the angler fish and some jellyfish, do precisely that, via luminescence. This involves generating photons with wavelengths mainly in the visible region, rather than in the shorter, infrared region corresponding to heat. Some chemical reactions can do this – for example, phosphorus exposed to the air – and also so-called phosphors, which absorb ultraviolet light and re-emit it as ‘cold’ light.


Advertisement

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.