… and I feel fine :-)
We've known for quite a while that the Earth has an expiration date, but for a lot of that time, the assumption was that we had about 5 billion years
until the sun turned into a red giant and swallowed the planet. Some consolation could be found in the expectation that, were we still around at that
point, we could just up and move somewhere else.
Well, turns out that the universe itself has an expiration date, and I ran across a fascinating paper this morning that details it.
There was a belief at one time that the universe is cyclical -- an eternal cycle of birth (the Big Bang), expansion, contraction and back to birth.
That has been shown to be in error, as if that were the case, the motion of the universe would be in one of two states -- a slowing expansion, or a
retraction, but observation has shown that the expansion is, in fact, increasing in speed.
The increase in expansion rate is believed to be due to something called Dark Energy, a theorized form of energy that underlies all space (making up
about 70% of all the "stuff" in the universe.) Dark energy accounts for the increase, and projecting things forward, we wind up with a very different
view of the end of reality, referred to colloquially as "The Big Rip".
The original Dartmouth paper that proposed The Big Rip (found here
) laid out the mathematics,
and noted that the key value for determining what that expiration date might be, "w", had to be smaller than -1/3 (to account for the fact that we
were in an expanding universe,) but they couldn't say for sure how much smaller "w" actually was. It should be noted, however, that the smaller the
number, the more dire the eventual consequences.
The dark energy is usually described by an “equation- of-state” parameter w ≡ p/ρ, the ratio of the spatially- homogeneous dark-energy
pressure p to its energy density ρ. A value w < −1/3 is required for cosmic acceleration. The simplest explanation for dark energy is a
cosmological constant, for which w = −1. However, this cosmological constant is 120 orders of magnitude smaller than expected from quantum gravity.
Thus, although we can add this term to Einstein’s equation, it is really only a placeholder until a better understanding of this negative pressure
(Source: Caldwell, Kamionkowski and Weinberg, "Phantom Energy and Cosmic Doomsday")
Well, the paper I ran across this morning (found here
) was by a
group of Chinese physicists, who believed that they were able to get a bit closer in nailing down a value for "w". Using an analysis of redshifts,
they determined that the actual rate of expansion merited a value closer to -1.5 which, as noted above, represents a pretty dire future.
Well, by their calculations, about 32.9 million years before the Big Rip, the Milky Way will be torn apart, as the gravitational attraction that holds
it together is negated. Two months before the end, the solar system suffers a similar fate. The moon leaves our orbit five days out, 28 minutes
before the end, the sun explodes, at the 16 minute mark, the Earth follows, and the very atoms that make up our physical reality are ripped apart at
3x10(-17) seconds. It's all pretty much downhill from there. (Source: XiaoDong, Shuang, QingGuo, Xin, Miao "Dark energy and fate of the
Now THAT'S real wrath of God stuff, lol.
You're not likely to be around for the end, projected to be anywhere from 16.7 billion to 103.5 billion years into the future, but it's a little
sobering to recognize that, no matter what, it's all going to come crashing down someday. By the 16.7 billion year mark, we're only about 2 billion
years from reaching the halfway point in the life of the universe.
edit on 24-7-2012 by adjensen because: added some words to keep "-1/3"