These boxes are simulated snapshots of the growth of cosmic structure when the universe was 0.9 billion, 3.2 billion and 13.7 billion years old (now).
These boxes represent the growth of cosmic structure when the Universe was 0.9 billion, 3.2 billion and 13.7 billion years old (now). This shows how the Universe has evolved from a smooth state to a structured one. The yellow regions are stars and the brightest structures are galaxies and galaxy clusters. The growth of these structures was initially driven only by the attractive force of gravity, but then later there was competition with the repulsive force of dark energy.
For the last decade, researchers have been looking for evidence to confirm the existence of dark energy. Now they appear to have it.
Scientists have new clues about the behavior of dark energy, a mysterious force that makes up as much as 70 percent of the energy in the universe.
Researchers have known about dark energy for 10 years. They stumbled across it when a group of astronomers were studying the light from distant supernovae. The idea was to measure how gravity was slowing down the expansion of the universe. To their surprise, they found that the expansion wasn't slowing down at all — it was speeding up.
The best explanation for this observation was the existence of dark energy, a force that works counter to gravity.
New Evidence Of Dark Energy
Using NASA's Chandra X-ray observatory, astronomers have been exploring the growth of galaxy clusters. If there were no dark energy, these clusters would tend to grow and merge with other neighboring clusters. And that's not happening, which is providing new evidence of the existence of dark energy.
"Whatever is forcing the expansion of the universe to speed up is also forcing its development to slow down," says Alexey Vikhlinin of the Smithsonian Astrophysical Observatory (SAO) in Cambridge, Mass., who led the research.
The fact that these results are consistent with the existence of dark energy still doesn't explain what dark energy is or how it has the opposite effect of gravity
"It could be that all this talk about dark energy could be much ado about nothing," says cosmologist Michael Turner of the University of Chicago. It may just be that scientists just don't understand gravity, "and we need to find a substitute of Einstein's theory of relativity."
Turner says that's why it's so important to continue to study dark energy.
"Either we've found some really weird new form of energy that's nothing like anything we've ever seen before, or we're going to have to modify or find a new theory of gravity," says Turner.