Just as science nearly universally agrees that time BEGAN, there’s near universal agreement that
Time will end
…but how? Experts say “In one of 6 ways.”
(Which one? Not sure. Kind of hard to predict and defend something all agree is so far off…)
1) with a “BIG CRUNCH” (now more doubtful)
2) in a “BIG WHIMPER”
3) with a “BIG RIP”
4) in a “BIG FREEZE”
5) with a “BIG BREAK” (new in 2004)
6) in a “BIG LURCH” (new in 2004)
…But “end” it will…
[This and what follows is adapted from Scientific American (Sept. 2010)]
For more use the DOOR.
Here’s a quick summary, so buckle up and be ready for bumps:
1) BIG CRUNCH Cosmic expansion slows down as the gravity of matter holds it back. Eventually it stops and goes into reverse, culminating with collapse back into a singularity that marks time’s end. Once thought likely, this fate now seems doubtful. Expanding matter seems too sparse to brake, and dark energy, presently unseen, appears to be speeding things up.
2) BIG WHIMPER The universe expands forever, becoming ever “emptier” and “gloomier.” Astronomers now consider this fate the likeliest. Although time never exactly ends, it becomes increasingly “pointless.“ The universe suffers “heat death”–a state of equilibrium in which every process is quickly undone, so that time has no forward progression…
3) BIG RIP The universe tears itself to pieces, which happens as dark energy begins to gain in power. Hypothesized in 1999, the extra potent dark energy goes by the name “phantom energy.” It drives the universe to expand by an infinite amount–even atoms get shredded–and finishes off time. Occurs about 20 billion years from now.
4) BIG FREEZE The universe fills up with phantom energy and reaches infinite density, while expanding only a finite amount. Surviving pieces of matter are locked in place unable to move, and time seizes up. A “localized” big freeze can occur if our universe is a membrane that is moving in a higher dimensional space, postulated by string theory and begins to whip around violently.
5) BIG BRAKE Dark energy shifts from driving cosmic expansion to retarding it, bringing the growth of the universe to a screeching halt, with the rate of deceleration becoming infinite. First hypothesized in 2004, the event is traumatic, with cosmic structures subjected to tidal forces of infinite strength. Although other quantities remain infinite, time in some way suffers, or ends.
6) BIG LURCH Hypothesized also in 2004, a so-called singularity does not require dark energy. All it takes is for ordinary matter to “work itself up into a frenzy.” Pressure forces become infinite, while the density and cosmic expansion rate remain in safe territory. Time might or might not “carry on.“ Astronomical observations cannot rule out such a possibility about 9 million years from now.
So what to make of all this? First, recognize that this is a summary (by Scientific American *) of work of serious card-carrying astronomers and physicists on the highest level who agree on many things, but frequently dramatically disagree, or misunderstand each other. The card I carry should should give me a wisp of respectability to discuss these to a certain extent on a secondary level that’s worth hearing. (Maybe.)
That I will do in the next post, tentively called “God, Starbucks.” (Sticking to those 2-word titles…)
I will also mention religious concerns, and summarize.
And I reserve the right to be wrong–although I’ll try hard not to be.
[* Listing of 6 ways TIME may end comes from Scientific American (Sept. 2010). In a few cases I’ve slightly rephrased their very tight summary statements for–what I see as–better clarity.]