Astrophysicists mystified after noticing 80 per cent of the light in the universe appears to be missing.
The universe is a pretty dark place – but according to astrophysicists it is much too dark.
Scientists have been left scratching their heads after noticing there is a huge deficit of light.
The amount of light in the universe can be measured accurately by studying tendrils of hydrogen which become ionised, or charged, when they encounter ultraviolet light.
The more ionised hydrogen you can spot, the more light should exist.
But, according to a new study in Astrophysical Journal Letters, the hydrogen tendrils suggest there is far more ultraviolet light around than is being emitted by galaxies and quasars.
An astonishing five times too much, in fact, and it is leading astrophysicists to speculate that the photons could be coming from an "exotic new source", or even decaying dark matter.
It means that 80 per cent of light in the universe is effectively missing.
“It’s as if you’re in a big, brightly-lit room, but you look around and see only a few 40-watt light bulbs,” noted Carnegie’s Juna Kollmeier, lead author of the study. “Where is all that light coming from? It’s missing from our census.”