It's a weird, weird, weird universe we live in. Cosmologists and astronomers know that only 5% of it consists of ordinary matter of the sort found in stars and planets. Another 23% consists of mysterious dark matter that (so far) manifests itself only through its gravity. And a whopping 72% of the universe consists of bizarre, space-stretching dark energy which is speeding up the expansion of the universe. Scientists don't know exactly what dark matter and dark energy are. But now they've pulled off a bit of black magic and used the subtle effects of one to study the other. Dark matter gives structure to the cosmos. Space is filled with a vast “cosmic web” of strands and clumps of dark matter, which have grown from microscopic variations in the original, nearly smooth distribution dark matter after the big bang. Through their gravity, the clumps draw in ordinary matter, so the galaxies form and reside within these clumps. Responding to their own gravity, the clumps and strands also grow denser and more compact. At the same time, dark energy stretches the very fabric of space. So if scientists can study the evolution of the cosmic web, they ought to be able to see the effects of dark energy setting in and slightly slowing the growth and coalescence of the clumps.
And that's what astrophysicist Tim Schrabback of the Leiden Observatory in the Netherlands, and colleagues have done.