Universe to end sooner/weirder than expected.

Dark Energy is the theoretical construct that makes a lot of modern cosmological theories work. Dark energy is theorized as a repulsive effect that started out weak but gets stronger as the universe gets older. Recent number crunching on this theoretical construct shows a universe weirder and more endangered than we imagined.

Via Io9:

The ultimate fate of the universe

It's worth noting that, given this timescale, and assuming that the big rip will hold as theory, the Universe will never go through the much-considered heat death phase, which was scheduled to start 10100 years from now. And what's particularly disturbing about all of this is, stars and planets will very much be still in existence at the time of the big rip. It's going to be a universe-wide catastrophe, that words cannot even begin to describe.

When considering their data, the cosmologists are fairly convinced that w will continue to exhibit a value less than -1 well into the future — which, in the words of the study's authors, "will lead to a strange future for the Universe."

And the picture they paint is very strange indeed. The cosmologists suggest that dark energy's gravitational repulsion will continually increase until it overcomes all forces holding objects together, causing every structure in the Universe to be torn apart. Nothing will be immune to this cataclysmic event — including those atomic-scale objects that are more tightly bound (they'll be the last to go).

Now, it's very unlikely that our solar system will exist in its current form at that time, but it's worth considering what would happen if it did.

Zhang and Li write that the the Milky Way will be torn apart 32.9 million years before the big rip. The Earth will be ripped away from the Sun two months before the end, and we'll lose our moon with five days left. The Sun itself will be destroyed 28 minutes before the end of time, and the Earth will explode a mere 12 minutes later.

Fun times.

This is going to be a blow to the faith of atheists.

Mathematics shows that universe had a beginning no matter what kind of ad hoc rationalizations are asserted.

In recent years, however, cosmologists have begun to study a number of new ideas that have similar properties. Curiously, these ideas are not necessarily at odds with the notion of a Big Bang.

For instance, one idea is that the universe is cyclical with big bangs followed by big crunches followed by big bangs in an infinite cycle.

Another is the notion of eternal inflation in which different parts of the universe expand and contract at different rates. These regions can be thought of as different universes in a giant multiverse.

So although we seem to live in an inflating cosmos, other universes may be very different. And while our universe may look as if it has a beginning, the multiverse need not have a beginning.

Then there is the idea of an emergent universe which exists as a kind of seed for eternity and then suddenly expands.

So these modern cosmologies suggest that the observational evidence of an expanding universe is consistent with a cosmos with no beginning or end. That may be set to change.

Today, Audrey Mithani and Alexander Vilenkin at Tufts University in Massachusetts say that these models are mathematically incompatible with an eternal past. Indeed, their analysis suggests that these three models of the universe must have had a beginning too.

Their argument focuses on the mathematical properties of eternity--a universe with no beginning and no end. Such a universe must contain trajectories that stretch infinitely into the past.

However, Mithani and Vilenkin point to a proof dating from 2003 that these kind of past trajectories cannot be infinite if they are part of a universe that expands in a specific way.

They go on to show that cyclical universes and universes of eternal inflation both expand in this way. So they cannot be eternal in the past and must therefore have had a beginning. "Although inflation may be eternal in the future, it cannot be extended indefinitely to the past," they say.

They treat the emergent model of the universe differently, showing that although it may seem stable from a classical point of view, it is unstable from a quantum mechanical point of view. "A simple emergent universe model...cannot escape quantum collapse," they say.

The conclusion is inescapable. "None of these scenarios can actually be past-eternal," say Mithani and Vilenkin.

Since the observational evidence is that our universe is expanding, then it must also have been born in the past. A profound conclusion (albeit the same one that lead to the idea of the big bang in the first place).

Ref: arxiv.org/abs/1204.4658: Did The Universe Have A Beginning?