The Überverse beyond the horizon
A new study by Alexander Kashlinsky (Goddard Space Flight Center) and coworkers examines the velocities of some of the largest structures in the known universe; galaxy clusters. By looking at the Doppler shifts of massive galactic clusters out near the edge of the cosmic horizon, Kashlinsky and his team found evidence that a large section of the sky out there is flowing out toward some even-larger unseen concentration of mass beyond the horizon… beyond the maximum distance light could have traveled to us since the Big Bang 13.7 billion years ago.
Why is this interesting? The inflationary model of cosmic expansion posits that in the first infinitesimal moments of our Big Bang, the material of spacetime expanded wholesale, much faster than the speed that light can move inside spacetime. So fast, in fact, that now the entire observable universe – a volume encompassing roughly 13.4 billion light years in every direction from Earth – is itself only an infinitesimal little speck of space in the phantasmagorical Über-ultra-hella-volume of space that really makes up our cosmos. If that’s true, then we should expect to see evidence that there are lots of other galaxies and dark matter and whatnot beyond the farthest distance we can peer. Way farther.
This new study provides such evidence. Apparently, huge clusters of galaxies out in one direction are sliding away from us at some weird tangent that can’t be explained by the recession velocity imposed by the expanding universe. Something else is tugging these galaxies along… something farther away than it would be possible to be, if cosmic inflation didn’t happen. If inflation didn’t happen, there can’t be anything out there because there can’t be a there.
What lies out there unseen, fishing up the galaxies by the millions? Probably just a much bigger galactic supercluster. There may not be any reason to invoke anything more exotic, because lots of galaxies and galaxy clusters that are well within our horizon already zoom around each other according to the rules of gravity and mass.
These new findings raise an interesting question: is our visible universe just an average sector of the Überverse, or are we in a thin spot? We know that the distribution of mass in the universe is patchy, with large regions containing almost no mass – voids of truly horrendous size – separated by a webwork of higher-mass regions that are full of galaxies and galaxy clusters. Within the visible universe, there are voids and thickets, and by looking at the whole thing we can figure out whether the universe is going to just keep exploding forever or will eventually reverse into a Big Crunch. The Crunch seems to be impossible, because there doesn’t seem to be enough mass-energy in the universe to allow it. But what if there is, just beyond the horizon?
It’s a nagging problem; if our visible universe is only a little piece of a huge inflationary Überverse, might we just happen to be in a mediocre place, or perhaps even a fairly empty place? What if we’re living inside a kind of mega void, and there are regions beyond our horizon that are much more densely packed with galactic clusters? This would be interesting, and it might require us to revise some of our expectations about the long term fate of the cosmos. This one new study doesn’t give us that kind of smoking gun, but it is very intriguing, and it gives us a new line of astronomical evidence that inflation really happened. That by itself is Überamazing.