Until now, things have been gradually getting worse for the Universe. In today’s entry — the final entry in the seven-part exploration of the ultimate fate of existence — the Universe’s end game is put in motion.
10^19 to 10^20 A.D.: Estimated time in which 90% – 99% of brown dwarfs and stellar remnants are ejected from galaxies. When two objects pass close enough to each other, they exchange orbital energy, with lower-mass objects tending to gain energy. Through repeated encounters, the lower-mass objects can gain enough energy in this manner to be ejected from their galaxy. This process eventually causes the galaxy to eject the majority of its brown dwarfs and stellar remnants.
10^28 A.D.: Estimated time in which the Earth’s orbit around the Sun decays via emissions of gravitational radiation, assuming the Earth isn’t engulfed by the red giant sun or ejected from its orbit by a stellar encounter.
10^30 A.D.: Estimated time until those stars not ejected from galaxies (1% – 10%) fall into their galaxies’ central supermassive black holes. By this point, with binary stars having fallen into each other, and planets into their stars, via emissions of gravitational radiation, only solitary objects — stellar remnants, brown dwarfs, ejected planets, black holes — will remain in the universe.
2 x 10^36 A.D.: The estimated time in which all nucleons in the observable universe decay, if the proton half-life takes its smallest possible value (8.2 x 10^33 years).
3 x 10^43 A.D.: The estimated time in which all nucleons in the observable universe decay, if the proton half-life takes it largest possible value (10^41 years), and if the Big Bang was inflationary, and that the same process that made baryons predominate over anti-baryons in the early universe makes proton decay. By this time, if protons do decay, the Black Hole Era, in which black holes are the only remaining celestial objects, begins.
10^65 A.D.: Assuming that protons do not decay, estimated time for rigid objects like rocks to rearrange their atoms and molecules via quantum tunneling. On this timescale, all matter is liquid.
5.8 x 10^68 A.D.: Estimated time until a stellar mass black hole with a mass of three solar masses (approximately 998,838 Earths, by way of comparison) decays by the Hawking process.
1.9 x 10^98 A.D.: Estimated time until NGC 4889, the currently largest known supermassive black hole with a mass of 21 billion solar masses (approximately 6.991866 quadrillion Earths, by way of comparison) decays by the Hawking process.
1.7 x 10^106 A.D.: Estimated time until a supermassive black hole with a mass of 20 trillion solar masses (approximately 6.658920 quintillion Earths, by way of comparison) decays by the Hawking process. This marks the end of the Black Hole Era. Beyond this time, if protons do decay, the universe enters the Dark Era, in which all physical objects have decayed to subatomic particles, gradually winding down to their final energy state.
10^200 A.D.: Estimated high time for all nucleons in the observable universe to decay (assuming protons do not decay), through any one of many different mechanisms allowed in modern Particle physics (higher-order baryon non-conservation processes, virtual black holes, sphalerons, etc.), on time scales of 10^46 to 10^200.
10^1500 A.D.: Assuming protons do not decay, the estimated time until all baryonic matter has fused together to form iron-56 or decayed from a higher mass element into iron-56. This process creates an iron star.
10^10^26 A.D.: Low estimate for the time until all matter collapses into black holes, assuming no proton decay. Subsequent Black Hole Era and transition to the Dark Era are, on this timescale, instantaneous.
10^10^50 A.D.: Estimated time for a Botlzmann brain to appear in the vacuum via a spontaneous entropy decrease.
10^10^56 A.D.: Estimated time for random quantum fluctuation to generate a new Big Bang.
10^10^76 A.D.: High estimate for the time until all matter collapses into black holes, assuming there is no proton decay.
10^10^120 A.D.: High estimate for the time for the Universe to reach its final energy state.
10^10^10^76.66 A.D.: Scale of an estimated Poincare recurrence time for the quantum state of a hypothetical box containing an isolated black hole of stellar mass. This time assumes a statistical model subject to Poincare recurrence. A much simpler way of thinking about this time is that in a model where history repeats itself arbitrarily many times due to properties of statistical mechanics, this is the time scale when it will first be somewhat similar (for a reasonable choice of “similar”) to its current state again.
10^10^10^10^2.8 A.D.: Scale of an estimated Poincare recurrence time for the quantum state of a hypothetical box containing a black hole with the mass within the presently visible region of the universe.
10^10^10^10^10^1.1 A.D.: Scale of an estimated Poincare recurrence time for the quantum state of a hypothetical box containing a black hole with the estimated mass of the entire universe, observable or not, assuming Linde’s chaotic inflationary model with an inflation whose mass is 10^-6 Plancke masses.