A report on CBS’ national news reported tonight on data from a deep-space telescope (in orbit far beyond the earth-moon system). Apparently, it has collected images from the farthest observations back into time yet. Along with this, the news claims we now know the universe is not going to collapse back upon itself (nor reach a steady-state), but it will expand forever. I thought we need to know more about the solving the “missing mass” problem before we can definitely make such a statement. Any SDopers have more info about how this is knows? (Or course, it could all change tomorrow, right?)
We did, and apparently now we do.
Here’s a link to the results from the Wilkinson Microwave Anisotropy Probe (WMAP) . There’s a pretty good discussion of the results going on over at the bad astronomy board.
Jinx is almost certainly talking about MAP, the data from which was just made public today, about more of which can be found in Squink’s links. As I understand it, MAP confirms the acceleration and some other things that we already knew about, and in general, offers no huge surprises. We’re just a lot more certain of these things now.
The basic idea is that there is a lot of mass in the Universe that cannot be seen, and in fact is most likely not made of “ordinary” matter (like protons, neutrons, etc.). This mass has gravity, which is how we know it’s there. It acts to slow the universal expansion.
But there is also some sort of energy permeating the Universe that is also not detected. This acts like a pressure, trying to increase the universal expansion. Energy is winning. The expansion is accelerating.
This creeps me out. As time goes on, more and more distant galaxies will appear to move away from us faster and faster. Eventually, as they approach the speed of light, they become undetectable. Sometime in the distant future, almost all galaxies will be “beyond our horizon”, and the Universe will be dark, cold, and empty.
It creeps me out too, but you know, we’ve got a few trillion years to come up with a plan to stop it. I think we’ll figure out a way to get around something as trivial as fundamental physics. I guess I’m just an optimist.
Basically, Einstein didn’t know the Universe was expanding when he formulated his theory (the expansion hadn’t been discovered). He assumed the Universe was static, unchanging. He realized that gravity would cause it collapse, so he added a term to the equation which counteracted garvity and kept the Universe from collapsing. This is called the Cosmological Constant.
When the expansion was discovered, Einstein realized the constant wasn’t needed, and called it his greatest mistake. This is ironic, as actually it looks now that removing it was an error!
As astronomer Bob Kirshner said: Einstein could have actually deduced the expansion of the Universe, predicted it was getting bigger. If he had done that, he’d have been famous!
