In part 5, humanity has either left the universe or have died off and the Sun, the bringer of all life to Earth, has begun to die. In today’s installment, the universe begins to the slip into chaos, which only serves as a precursor to a much more sinister fate.
14.4 billion A.D.: The Sun becomes a black dwarf as it’s luminosity falls below three-trillionths its current level. It’s temperature falls to 2,239 Kelvins (1,965.85 degrees Celsius/3,570.53 degrees Fahrenheit), rendering it invisible to human eyes.
20 billion A.D.: The universe ends in the Big Rip scenario, assuming a model of dark energy with w= -1.5. Studies conducted at the Chandra X-ray Conservatory — observations of galaxy cluster speeds — suggest this scenario will not occur.
50 billion A.D.: Assuming both survive the Sun’s expansion, the Earth and Moon become totally tidelocked, with each only showing one face to the other. Thereafter, the tidal action of the Sun will extract angular momentum from the system, causing the lunar orbit tyo decay and the Earth’s rotation to accelerate.
100 billion A.D.: The Universe’s expansion causes all galaxies outside of the Milky Way’s Local Group to disappear beyond the cosmic light horizon, removing them from the observable universe.
150 billion A.D.: The cosmic microwave background cools from its current temperature of 2.7 Kelvins (-270.45 degrees Celsius/-454.81 degree Fahrenheit) to 0.3 Kelvins (-272.85 degrees Celsius/-459.13 degrees Fahrenheit), rendering itself undetectable with present-day technology.
292,277,026,596 A.D.: At 15:30:08 UTC on December 4, the Unix time stamp will exceed the largest value that can be held in a signed 64-bit integer.
450 billion A.D.: Median point by which the galaxies of the Milky Way’s Local Group coalesce into a single large galaxy.
800 billion A.D.: Expected time when the net light emissions of the Milkomeda galaxy begins to decline as the red dwarf stars pass through their “blue dwarf” stage of peak luminosity.
1 trillion A.D.: Low estimate for the decline of star formation, as galaxies are depleted of the gas clouds necessary for stars to form. If humanity — or intelligent life in general — still exists at this time, they may decide to leave this universe through space-time rifts or black holes, assuming the technology is available. The Universe’s expansion, assuming a constant dark energy density, multiplies the wavelength of the cosmic microwave background by 10^29, exceeding the scale of the cosmic light horizon and rendering its evidence of the Big Bang undetectable. However, it may still be possible to determine the expansion of the universe through the study of hypervelocity stars.
30 trillion A.D.: Estimate time for the black dwarf Sun to undergo a close encounter with another star in the local Solar neighborhood. Whenever two stars (or stellar remnants) pass close to each other, their planets’ orbits can be disrupted, potentially ejecting them from the system entirely. On average, the closer a planet to its parent star, the longer it takes for them to be ejected in this manner, because stars rarely pass so closely.
100 trillion A.D.: High estimate for the time until normal star formation ends in galaxies. This marks the transition from the Stelliferous Era to the Degenerate Era of the universe, where a lack of free hydrogen to form new stars causes all existing stars to just slowly exhaust their fuel and die out.
110-120 trillion A.D.: All stars in the universe have exhausted their fuel. After this point, only stellar remnants remain, such as white dwarfs, neutron stars, and black holes. Brown dwarfs also remain. Collisions between brown dwarfs will create new red dwarf stars on a marginal level: on average, a few dozen at most will be present in the galaxy. Collisions between stellar remnants will create occasional supernovae.
1 quadrillion A.D.: Estimated time until stellar close encounters detach all planets in the Solar System from their orbits. By this point, the Sun will have cooled to five degrees above absolute zero (0.0 Kelvins/-273.25 degrees Celsius/-459.67 degrees Fahrenheit).