- 500 million years from today
The Sun's increasing luminosity begins to disrupt the carbonate–silicate cycle; higher luminosity increases weathering of surface rocks, which traps carbon dioxide in the ground as carbonate. As water evaporates from the Earth's surface, rocks harden, causing plate tectonics to slow and eventually stop once the oceans evaporate completely. With less volcanism to recycle carbon into the Earth's atmosphere, carbon dioxide levels begin to fall. By this time, carbon dioxide levels will fall to the point at which photosynthesis is no longer possible. All plants that use photosynthesis (≈99 percent of present-day species) will die.

- 850 million years from today
Without plant life to recycle oxygen in the atmosphere, free oxygen and the ozone layer will disappear from the atmosphere allowing for intense levels of deadly UV light to reach the surface. Animals in food chains that were dependent on live plants will die shortly afterward. Mass extinction will start with large animals, then smaller animals and flying creatures, then amphibians, followed by reptiles, and finally, invertebrates.

- 1 billion years from today
The Sun's luminosity will have increased by 10%, causing Earth's surface temperatures to reach an average of around 47 °C (320 K, 116 °F) resulting in a runaway evaporation of the oceans.

- 1,2 billion years from today
Highest estimate until all plant life dies out. Rising temperatures will make any animal life unsustainable from this point on.

- 2 billion years from today
Earth's oceans evaporate when the atmospheric pressure decrease via the nitrogen cycle.

- 2,8 billion years from today
Earth's surface temperature will reach around 147 °C (420 K, 296 °F), even at the poles. Most positive estimate until all remaining Earth life goes extinct.

- 4 billion years from today
The Sun's luminosity will have increased by 35–40%, causing all water currently present in lakes and oceans to evaporate, if it had not done so earlier. Earth's surface temperature rises to 1,130 °C (1,400 K, 2,060 °F), hot enough to melt some surface rock.

- 5 billion years from today
The Andromeda Galaxy will have fully merged with the Milky Way forming an elliptical galaxy dubbed "Milkomeda". There is also a small chance of the Solar System being ejected into intergalactic space.

- 5,4 billion years from today
The sun, having now exhausted its hydrogen supply, leaves the main sequence and begins evolving into a red giant.

- 6,6 billion years from today
The Sun may experience a helium flash, resulting in its core becoming as bright as the combined luminosity of all the stars in the Milky Way galaxy combined.

- 22 billion years from today
The estimated time until the end of the universe in a Big Rip, assuming a model of dark energy is correct (w = −1.5) Thirty minutes before the Big Rip, planets, stars, asteroids and even extreme objects like neutron stars and black holes will evaporate into atoms. One hundred zeptoseconds before the Big Rip, atoms will break apart. Ultimately, once the Rip reaches the Planck scale, cosmic strings would be disintegrated as well as the fabric of spacetime itself.


But, assuming true density of dark energy is in reality less than −1 and that life continues without big rip, then the Universe's expansion will continue to accelerate and the Observable Universe will grow ever sparser. (observations of galaxy cluster speeds by the Chandra X-ray Observatory suggest that the true value of w is c. −0.991)


- 125 billion years from today
The Universe's expansion causes all galaxies beyond the former Local Group to disappear beyond the cosmic light horizon, removing them from the observable universe.

- 1 trillion years from today
Assuming a constant dark energy density, multiplies the wavelength of the cosmic microwave background by 1029, exceeding the scale of the cosmic light horizon and rendering its evidence of the Big Bang eternally undetectable.

- 1.05×1012 years from today
The estimated time by which the Universe will have expanded by a factor of more than 1026, reducing the average particle density to less than one particle per cosmological horizon volume. Beyond this point, particles of unbound intergalactic matter are effectively isolated, and collisions between them cease to affect the future evolution of the Universe.

- 10^14 years from today
A high estimate for the time by which normal star formation ends in galaxies. This marks the transition from the Stelliferous Era to the Degenerate Era. With too little free hydrogen to form new stars, all remaining stars slowly exhaust their fuel and die.

- 1.2×10^14 years from today
The time by which all stars in the universe will have exhausted their fuel. On average, about 100 stars will be shining in what was once the Milky Way.

- 1 nonillion years from today
The estimated time until all of the remaining stellar remnants not ejected from galaxies fall into their galaxies central supermassive black holes. By this point, with binary stars having fallen into each other, and planets into their stars, only solitary objects like stellar remnants, brown dwarfs, ejected planetary-mass objects and black holes will remain in the universe.

- 1 undecillion years from today
Estimated time for all remaining planets and stellar-mass objects, including the Sun, to disintegrate if proton decay can occur.

- 30 tredecillion years from today
Estimated time for all nucleons in the observable universe to decay. And assuming that the Big Bang was inflationary and that the same process that made baryons predominate over anti-baryons in the early Universe makes protons decay.


By this time, the Black Hole Era, in which black holes are the only remaining celestial objects, begins.


- 10^106–2.1×10^109 years from today
The estimated time until ultramassive black holes of 100 trillion solar masses that were formed during the gravitational collapse of galaxy superclusters, decay by Hawking radiation
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 in the heat death of the universe.

- 10^161–10^1383 years from today (95% confidence interval)
Estimate of Standard Model lifetime before collapse of a our universes false vacuum state. True vacuum bubble nucleation creates a cascade effect where more energy is released over and over again, releasing even more energy, creating a bubble like sphere that destroys everything it interacts with. Which means death of the universe as we know it. The end would be undetectable. Some true vacuum bubbles may exist already and be on its way towards us, though very unlikely.

- 10^10^50 years from today
The estimated time for a Boltzmann brain to appear in the vacuum via spontaneous entropy decrease.
The Boltzmann brain thought experiment suggests that it might be more likely for a single brain to spontaneously form in space, complete with a memory of having existed in our universe, rather than for the entire universe to come about in the manner cosmologists think it actually did.





- 10^10^10^56 Years from today. New beginning?
Quantum tunnelling in any isolated patch of the universe could generate new inflationary events, resulting in new Big Bangs.