You know that "I'm an insignificant dot in the middle of this enormous universe" feeling you get when you stare up into the night sky a little too long? Well, some Oxford scientists think you might be a little more special than that - or at least, the planet you live on is. Their radical new theory would not only obviate the need for dark energy to explain observed patterns of galactic motion, it would overturn the centuries-old Copernican Principle. Not bad for a day's work.In the 16th century, Copernicus hypothesized that the Earth is not the center of the solar system, but rather the sun is. Later, cosmologists expanded this idea into the Copernican Principle: Earth is not in a special place in the universe, therefore our observations of local space can be used to infer data about the rest of the universe. When astronomers observed that the universe appears to be expanding at an accelerating rate, they needed to add something to their equations to make it all make sense. That something is dark energy, which would have to exist in massive quantities (as yet, pretty much undetectable) to explain this expansion. Here's the thing - the universe is really, really, really huge. Just the part we can see is almost incomprehensibly big, and there's a whole lot of universe we can't see. No one knows how big the whole universe is, but it's entirely possible that our part of the universe is just a tiny fraction of the whole. Physicists from Oxford University are considering the idea that the universe we can observe is actually anomalous, a giant void with a low density of matter. The rest of the universe may look substantially different. Doing some number crunching revealed that their model of the universe works without dark energy, but isn't quite as accurate as the current dark energy model. However, they need more observations of certain types of supernovae to refine their numbers - in a few months, their equations may look better with more data. What's particularly cool is that this maverick theory that tosses a very accepted tenet of astronomy right out the window is being published in Physical Review Letters, one of the most respected physics journals. It sure beats excommunication. Image by: NASA. Overturning Copernicus, eliminating dark energy. [Nobel Intent] Tsunami invisibility cloak, dark energy v. the void, sorting nanotubes with light, and more. [EurekAlert!]
It does make some sense insofar as we have yet to discover some scale on which the universe isn't at least partially granular, up to and including superclusters of thousands or millions of galaxies, and structures like the Great Wall. I'd see no reason why our observable universe couldn't happen to be in a pocket of relatively less dense space, with everything outside our visible universe drawing all the matter away.
It is a little disappointing though to have mysterious forces taken away and replaced with stuff that we know we can never see and never reach. I was so hoping for a dark energy drive to fuel my spaceship.