Science News: For all the hand wringing among physicists about the nature of dark energy, the invisible stuff that appears to be revving up the rate of cosmic expansion, a nagging possibility remains. Dark energy could be a cosmic mirage — if humans live in a special place in the universe with a peculiar distribution of matter.

But that scenario violates the Copernican principle, say theorists Robert Caldwell of Dartmouth College and Albert Stebbins of the Fermi National Accelerator Laboratory in Batavia, Ill. Named after the 16th century astronomer Nicolaus Copernicus, who made the then heretical proposal that Earth does not have a favored, central position in the solar system, the principle states that humans are not privileged observers in the universe, but have just as good — or bad — a vantage point as any other observer in the cosmos.

“Although the Copernican principle may be widely accepted by fiat, it is imperative that such a foundational principle be proven,” Caldwell and Stebbins assert in an upcoming Physical Review Letters. The researchers suggest a concrete way to check once and for all whether our neck of the cosmic woods is different from other parts of the universe. Their test relies on observations of the cosmic microwave background, the leftover radiation from the Big Bang that bathes all parts of the universe.