We often wonder what the future would be like. Doris Day sang years ago, the future's not ours to see Que Sera, Sera. A good friend asked me only yesterday how I see the next five years. I wanted to think about the next Trillion years. After years of reading about the Big Bang theory, which as we know, purports to explain some of the earliest events in the universe - I wanted to shift my attention towards what might be the ultimate consequence this theory may hold about the fate of the universe in years to come.
Up to now
There is little consensus among physicists about the specific origins of the universe. According to the theory the universe was once in an extremely hot and dense state and that overtime time expanded causing the young universe to cool and form large scale structures.
The Big Bang Model rests on two theoretical pillars
The first key idea dates to the early 1900’s when Einstein developed his General Theory of Relativity suggesting that gravity is no longer described by a gravitational field but rather it is a distortion of space and time itself.
The second idea is that matter in the universe is homogeneous and isotropic when averaged over very large scales - the Cosmological Principle. The cosmic microwave background radiation (the afterglow) has a temperature which is highly uniform over the entire sky supporting the notion that the gas which emitted this radiation was uniformly distributed.
The Future
Hundred Trillion Years in the Future - Provided the universe continues to expand (doesn’t re-collapse under its weight) then it is assumed the universe will gradually wither away. During this period (10,000 years to 100 trillion years after the Big Bang) most of the energy generated by the universe is in the form of stars burning hydrogen and other elements in their cores.
Hundred Trillion to Ten Trillion Trillion Trillion Years in the Future - By now, most of the mass that we can see is locked up in that have blown up and then collapsed into black holes and neutron stars, or have withered into white dwarfs.
At Trillion Trillion Trillion Trillion Trillion Trillion Trillion years after the Big Bang the only stellar-like objects remaining are black holes of widely disparate masses, which are actively evaporating during this era.
Later again, black holes have evaporated and only photons of colossal wavelength, neutrinos, electrons, and positrons remain. For all intents the universe as we know it has dissipated.
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