Mysterious Dark Energy: What Part in Early Universe

Light from distant galaxies is distorted by foreground matter. 

This so-called weak lensing can be used to characterize dark energy.

CREDIT: S. Colombi (IAP), CFHT Team

Scientists trying to understand dark energy, one of the weirdest things in the universe, have made a step forward in determining how much of it could have existed shortly after the Big Bang.

Dark energy is the mysterious force scientists think is responsible for pulling space apart at the seams, causing the expansion of the universe to accelerate. No one knows what dark energy is, and it hasn't been detected directly.

In the new study, researchers used the South Pole Telescope in Antarctica to observe the cosmic microwave background, the pervasive light left over from the Big Bang that is believed to have kick-started the universe. This radiation holds a record of many properties of the early universe, allowing scientists to deduce the maximum amount of dark energy that could have been present at the time.

Based on their measurements, the researchers found that dark energy could not have accounted for more than 1.8 percent of the total density of the universe. By contrast, dark energy dominates space today, accounting for about 74 percent of all the matter and energy in the universe.