Ultimate fate of the universe

The ultimate fate of the universe is a valid question because according to all models on the universe, the universe is finite, and will end.^[1]^[2]^[3] The only question logically, is what will happen at the end of the universe. There are many different scientific scenarios, and religious scenarios as well. When the Big Bang theory became the foremost explanation for the current state of the universe, the fate of the universe became a valid question.

Backgroud

The universe is currently expanding at a rate of 73.8 ± 2.4/Megaparsecs per second. (A megaparsec is 3.08x10¹⁹ kilometers) Under the big bang model, expansion is currently accelerating.^[4] When catholic priest George LeMaitre proposed that the universe was born from a singularity, which was expounded on by Edwin Hubble, using the theory of relativity, it became clear that all theories implied an ultimate fate to the universe.

Scientific theories

There are three commonly accepted theories on how the universe will end. They are the Big crunch, where the universe collapses on itself, the Big Rip scenario, where acceleration destroys the bonding of atoms, and all matter decays, and the Heat death, where the universe reaches a maximum state of entropy.

Big Crunch

The Big Crunch theory is a symmetric view of the ultimate fate of the Universe. Just as the Big Bang started a cosmological expansion, this theory assumes that the average density of the universe is enough to stop its expansion and begin contracting. The end result is unknown; a simple estimation would have all the matter and space-time in the universe collapse into a dimensionless singularity, but at these scales unknown quantum effects need to be considered. This scenario allows the Big Bang to be immediately after the Big Crunch of a preceding universe. If this occurs repeatedly, we have a cyclic model which is also known as a oscillatory universe. The universe could then consist of an infinite sequence of finite universes, each finite universe ending with a Big Crunch that is also the Big Bang of the next universe. Theoretically, the cyclic universe could not be reconciled with the second law of thermodynamics: entropy would build up from oscillation to oscillation and cause heat death. Other measurements suggested the universe is not closed. These arguments caused cosmologists to abandon the oscillating universe model. A somewhat similar idea is embraced by the cyclic model, but this idea evades heat death, because of an expansion of the branes that dilutes entropy accumulated in the previous cycle. In the big crunch, the universe will end approximately 30 billion years from now.

Big Rip

In the special case of phantom dark energy, which has even more negative pressure than a simple cosmological constant, the density of dark energy increases with time, causing the rate of acceleration to increase, leading to a steady increase in the Hubble constant. As a result, all material objects in the universe, starting with galaxies and eventually, all forms, no matter how small, will disintegrate into unbound elementary particles and radiation, ripped apart by the phantom energy force and shooting apart from each other. The end state of the universe is a singularity, as the dark energy density and expansion rate becomes infinite. For a possible timeline based on current physical theories, see 1 E19 s and more. This universe will end approximately 100 billion years from now.

Heat death

After the Stelliferous Epoch, all hydrogen in the universe will be exhausted. Then, only remnants remain. After 10¹⁷ billion years from now, protons will decay into a positron, and a pion. All particles will decay, leaving behind nothing but simple particles. The rate of entropy will be at a maximum, and nothing will interact ever again.

References

↑ When he opened the sixth seal, I looked, and behold, there was a great earthquake, and the sun became black as sackcloth, the full moon became like blood, and the stars of the sky fell to the earth as the fig tree sheds its winter fruit when shaken by a gale. The sky vanished like a scroll that is being rolled up, and every mountain and island was removed from its place. (Revelation 6:12–14)
↑ ^ a b Lemaître, Georges (1927). "Un univers homogène de masse constante et de rayon croissant rendant compte de la vitesse radiale des nébuleuses extra-galactiques". Annales de la Société Scientifique de Bruxelles A47: 49–56. Bibcode 1927ASSB...47...49L translated by A. S. Eddington: Lemaître, Georges (1931). "Expansion of the universe, A homogeneous universe of constant mass and increasing radius accounting for the radial velocity of extra-galactic nebulæ". Monthly Notices of the Royal Astronomical Society 91: 483–490. Bibcode 1931MNRAS..91..483L
↑ Thomson, William. (1851). "On the Dynamical Theory of Heat, with numerical results deduced from Mr Joule’s equivalent of a Thermal Unit, and M. Regnault’s Observations on Steam." Excerpts. [§§1–14 & §§99–100], Transactions of the Royal Society of Edinburgh, March, 1851; and Philosophical Magazine IV. 1852, [from Mathematical and Physical Papers, vol. i, art. XLVIII, pp. 174]
↑ M. Stone (1976). "Lifetime and decay of excited vacuum states". Phys. Rev. D 14 (12): 3568–3573. Bibcode 1976PhRvD..14.3568S. doi:10.1103/PhysRevD.14.3568.

[religious-1] When he opened the sixth seal, I looked, and behold, there was a great earthquake, and the sun became black as sackcloth, the full moon became like blood, and the stars of the sky fell to the earth as the fig tree sheds its winter fruit when shaken by a gale. The sky vanished like a scroll that is being rolled up, and every mountain and island was removed from its place. (Revelation 6:12–14)

[bigbang-2] Lemaître, Georges (1927). "Un univers homogène de masse constante et de rayon croissant rendant compte de la vitesse radiale des nébuleuses extra-galactiques". Annales de la Société Scientifique de Bruxelles A47: 49–56. Bibcode 1927ASSB...47...49L translated by A. S. Eddington: Lemaître, Georges (1931). "Expansion of the universe, A homogeneous universe of constant mass and increasing radius accounting for the radial velocity of extra-galactic nebulæ". Monthly Notices of the Royal Astronomical Society 91: 483–490. Bibcode 1931MNRAS..91..483L

[static-3] Thomson, William. (1851). "On the Dynamical Theory of Heat, with numerical results deduced from Mr Joule’s equivalent of a Thermal Unit, and M. Regnault’s Observations on Steam." Excerpts. [§§1–14 & §§99–100], Transactions of the Royal Society of Edinburgh, March, 1851; and Philosophical Magazine IV. 1852, [from Mathematical and Physical Papers, vol. i, art. XLVIII, pp. 174]

[4] M. Stone (1976). "Lifetime and decay of excited vacuum states". Phys. Rev. D 14 (12): 3568–3573. Bibcode 1976PhRvD..14.3568S. doi:10.1103/PhysRevD.14.3568.

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