End of the Universe

The ultimate fate of the universe is a topic in physical cosmology, whose theoretical restrictions can usefully and scientifically predict the future behaviour of the universe as it ages. Based on available observational evidence, deciding the fate and evolution of the universe now have become valid cosmological questions, being beyond the mostly untestable constraints of mythological or theological beliefs. Many possible futures have been predicted by rival scientific hypotheses, including that the universe might have existed for a finite and infinite duration, or towards explaining how and in what circumstances it was created.

Observations made by Edwin Hubble during the 1920s-1930s found that most galaxies appeared to be moving away from each other, leading to current accepted Big Bang Theory. This suggests that the universe began in the far distant past about 13.8 billion years ago and ever since, continues to expand. Confirmation of the Big Bang mostly depends on knowing the rate of expansion, average density of matter, and the physical properties of the mass/energy in the universe.

There is a strong consensus among cosmologists that the universe is flat and will continue to expand forever. Yet many other factors may influence the universe's origin and final destiny, including, for example: the average motions of galaxies, the shape and structure of the universe, or the amount of dark matter and dark energy the universe contains.

The theoretical scientific exploration of the ultimate fate of the universe became possible with Albert Einstein's 1916 theory of general relativity. General relativity can be employed to describe the universe on the largest possible scale. There are many possible solutions to the equations of general relativity, and each solution implies a possible ultimate fate of the universe.

Alexander Friedmann proposed several solutions in 1922, as did Georges Lemaître in 1927. In some of these solutions, the universe has been expanding from an initial singularity which was, essentially, the Big Bang.

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