Another brilliant documentary from the BBC's 'Horizon' series.
There's something very odd going on in space, something that shouldn't be possible. It is as though vast swathes of the universe are being hoovered up by a gigantic and invisible celestial vacuum cleaner.
Sasha Kaslinsky, the scientist who discovered the phenomenon, is understandably nervous: 'It left us quite unsettled and jittery,' he says, 'because this is not something we planned to find.' The accidental discovery of what is ominously being called 'dark flow' not only has implications for the destinies of large numbers of galaxies but threatens to overturn our current understanding of the birth and evolution of the universe.
Does dark flow herald a new era of cosmological understanding, or does it simply mean that everything we know about the universe is wrong?
Run time: 00:58:56
Watch the full documentary streamed together here: