Death of the Universe

Everything in the universe dies at some or the other point of time, right? Yeah, now what about the universe as a whole? Will the universe ever die? or ends up with some steady state? or any kind of  evaporation? Many questions arise when one thinks about this but no single answer as of date can answer all these questions. Experiments have been conducted and analysis are being done since 1931, when Edwin Hubble published that the universe was expanding. How the universe is going to end up actually depends on many factors like size of the universe, expansion rate and the shape of the universe. And if the final energy is positive, the university expands foever and if it is negative, it starts expanding and collapses back. Along with these, dark matter is given highest priority in predicting the fate of the universe as it is doubted to play a major role. Anyways, lets go into the main theories suggested for the end of the universe till date. They are:

1. Big Freeze
2. Big Crunch
3. Big Rip
4. Evaporation 

The first three theories are been suggested by the scientists and the fourth one is actually the idea that came stuck my mind when I started writing this blog. May be that is going to be proven wrong but still let me put the idea in front of you guys so that I get it cleared at least.

Big Freeze:  Big Freeze is a condition when the universe may keep on expanding resulting in an absolute zero temperature. Here the entropy will continuously increase, leading to even distribution of everything in the universe. As the entire heat dies, this theory is also called as "Heat death". Big freeze takes place if the measured density of the universe is less than the critical density. But you never know when it's going to attain this state just from the study of today's universe. Theoretical work by Eric Chaisson and David Layzer concluded that the space time is expanding and thus it gives rise to an increasing entropy-gap saying the universe may end up with a Heat death.

Big Crunch: Big Crunch is a state when the gravitational force exceeds the expansion pressure and the entire universe falls into a singularity (single point). This will happen if the density of the universe exceeds the critical density and no other force would be able to counter act the resulting gravitational attraction.This theory is obtained as a result of the idea of Big Bang by which the universe is expected to evolve from a singularity and thus there is a chance of the same universe ending up with that singularity. Therefore the universe may end up even by collapsing back.

Big Rip: is a state where the universe and every thing present in the universe are going to get ripped into small elementary particles due to the Phantom dark energy. According to the present expansion studies of the nearby supernovae, its been known that the universe is expanding at an accelerating rate and the dark energy is filling the space resulting in this expansion. So as the increase in the quantity of the dark energy speeds up the expansion, and will continue to expand forever.

The Fourth one, I call it the Evaporation, as stated at the very beginning. Whats bothering me is why it can't end up evaporating the whole matter into the medium around it and leaving just the vacuum in place of the present universe. May be you call it a wrong one just because the matter exists somehow in the evaporated state but again I have something to state at this point. Why are the other three theories been called possible when according to those theories also, the matter exists, even though in singularity and spread-up.

Thus there are evidences to say that each and every theory is a valid one and none is yet been proved. Lets wait till someone's gonna find it out or wait till the end of the universe ;)

Pranu :)