Earth Has No Special Place in the Universe: Cosmic Growth Explained

Earth apparently has no special place in the universe--at least not when it comes to the cosmic growth of the system. Scientists have ruled out a controversial theory that the accelerating expansion of the universe is an illusion.

Researchers have long known that the universe is expanding and over time, has sped up in this expansion. Yet there are those that believed that there could be another reason for what researchers observed.  A theory to explain the acceleration is that Earth, our solar system and Milky Way galaxy are at the center of the universe. This theory violates the standard assumption that the universe has no center. If true, though, the cosmic acceleration could potentially be explained without dark energy or any new laws of physics.

The standard idea for the expansion of the universe is that mysterious dark energy could be causing it. In order to find out whether the Earth is at the center or if dark energy is to blame, though, the scientists investigated the Cosmic Microwave Background, which is the glow of light left over from the Big Bang. More specifically, the scientists calculated how this glow would be affected by the different theories. In the end, they found that the model's prediction is completely contrary to the glow that has been measured.

"Essentially we held a mirror up to the universe and asked if the reflection was special," said Robert Caldwell, one of the researchers, in a news release. "The reflection shows that we do not appear to live in a special location, and decisively excludes this explanation for the universe's accelerating expansion. It would be a great relief to be able to understand a basic problem of cosmology within the known laws of physics, but our research is an important step in explaining the physics responsible for the cosmic acceleration."

The findings eliminate the possibility that our planet is at the center of the universe. Although further research is needed to explain the cosmic speed-up, this study represents an important step in narrowing down the possible outcomes.

The findings are published in the journal Physical Review D.