Is Ann Arbor the center of the universe?
The answer may hinge on the existence of dark energy: the mysterious force that may or may not bind the cosmos together. U-M astronomer Philip Hughes admits dark energy is "an ad hoc and outrageous postulate" but says it's "just what is needed to explain the observed pattern of galaxies and to account for the geometry of space." U-M mathematician Joel Smoller disagrees. "No one has seen this stuff. It cannot be collected, and it does not change. It looks like a fudge factor."
Smoller offers another explanation. "Einstein's general relativity admits a family of expanding waves, and if our Milky Way just happened to lie near the center of a different wave in the family, then it would account for the anomalous acceleration of the galaxies without dark energy." That would mean our galaxy is special--and that, relatively speaking, Ann Arbor is, too.
Hughes, for one, isn't buying it. "Every step further into the universe in the half-millennium since Copernicus has shown us to be in no special place," he points out. "That the Earth would be at the center of much of the observable universe seems extraordinarily unlikely." In other words, Hughes says, "Ann Arbor is not at the center of the universe."
[Originally published in January, 2010.]