Timeline of the far future

While the future cannot be predicted with certainty, present understanding in various scientific fields allows for the prediction of some far-future events, if only in the broadest outline. These fields include astrophysics, which studies how planets and stars form, interact and die; particle physics, which has revealed how matter behaves at the smallest scales; evolutionary biology, which studies how life evolves over time; plate tectonics, which shows how continents shift over millennia; and sociology, which examines how human societies and cultures evolve.
These timelines begin at the start of the 4th millennium in 3001 CE, and continue until the furthest and most remote reaches of future time. They include alternative future events that address unresolved scientific questions, such as whether humans will become extinct, whether the Earth survives when the Sun expands to become a red giant and whether proton decay will be the eventual end of all matter in the universe.

Earth, the Solar System, and the universe

All projections of the future of Earth, the Solar System and the universe must account for the second law of thermodynamics, which states that entropy, or a loss of the energy available to do work, must rise over time. Stars will eventually exhaust their supply of hydrogen fuel via fusion and burn out. The Sun will likely expand sufficiently to overwhelm most of the inner planets but not the giant planets, including Jupiter and Saturn. Afterwards, the Sun will be reduced to the size of a white dwarf, and the outer planets and their moons will continue to orbit this diminutive solar remnant. This future situation may be similar to the white dwarf star MOA-2010-BLG-477L and the Jupiter-sized exoplanet orbiting it.
Long after the death of the Solar System, physicists expect that matter itself will eventually disintegrate under the influence of radioactive decay, as even the most stable materials break apart into subatomic particles. Current data suggest that the universe has a flat geometry and will therefore not collapse in on itself after a finite time. This infinite future could allow for the occurrence of massively improbable events, such as the formation of Boltzmann brains or spontaneous inflation triggering a new Big Bang.
Keys

	Astronomy and astrophysics
	Geology and planetary science
	Biology
	Particle physics
	Technology and culture

		Event
	1,000	Due to the lunar tides decelerating the Earth's rotation, the average length of a solar day will be of an SI second longer than it is today. To compensate, either a leap second will have to be added to the end of a day multiple times during each month, or one or more consecutive leap seconds will have to be added at the end of some or all months.
	2,000	As Earth's poles precess, Gamma Cephei replaces Polaris as the northern pole star.
	1,000 – 10,000	As one of the long-term effects of global warming, the Greenland ice sheet will have completely melted. The melt rate will depend on the amount of carbon emissions in the air.
	10,000	If a failure of the Wilkes Subglacial Basin "ice plug" in the next few centuries were to endanger the East Antarctic Ice Sheet, it would take up to this long to melt completely. Sea levels would rise 3 to 4 metres. One of the potential long-term effects of global warming, this is separate from the shorter-term threat to the West Antarctic Ice Sheet.
	10,000	If humans were extinct, Earth would be midway through a stable warm period with the next glacial period of the Quaternary glaciation due in 10,000 years, but if humans survived and did impact their planet, the greenhouse gas emissions would disrupt this natural cycle. According to research, the carbon dioxide released from burning fossil fuels could cause the planet to skip glacial periods repeatedly for at least the next 500,000 years.
	10,000 – 1 million	The red supergiant stars Betelgeuse and Antares will likely have exploded as supernovae. For a few months, the explosions should be easily visible on Earth in daylight.
	11,700	As Earth's poles precess, Vega, the fifth-brightest star in the sky, becomes the northern pole star. Although Earth cycles through many different naked-eye northern pole stars, Vega is the brightest.
	11,000–15,000	By this point, halfway through Earth's precessional cycle, Earth's axial tilt will be mirrored, causing summer and winter to occur on opposite sides of Earth's orbit. This means that the seasons in the Southern Hemisphere will be less extreme than they are today, as it will face away from the Sun at Earth's perihelion and towards the Sun at aphelion; the seasons in the Northern Hemisphere will be more extreme, as it experiences more pronounced seasonal variation because of a higher percentage of land.
	15,000	The oscillating tilt of Earth's poles will have moved the North African Monsoon far enough north to change the climate of the Sahara back into a tropical one such as it had 5,000–10,000 years ago.
	17,000	The best-guess recurrence rate for a "civilization-threatening" supervolcanic eruption large enough to eject one teratonne of pyroclastic material.
	25,000	The northern polar ice cap of Mars could recede as the planet reaches a warming peak of its northern hemisphere during the c. 50,000-year perihelion precession aspect of its Milankovitch cycle.
	36,000	The small red dwarf Ross 248 will pass within 3.024 light-years of Earth, becoming the closest star to the Sun. It will recede after about 8,000 years, making first Alpha Centauri and then Gliese 445 the nearest stars.
	50,000	According to Berger and Loutre, the current interglacial period will end, sending the Earth back into a glacial period of the Quaternary glaciation, regardless of the effects of anthropogenic global warming. However, according to more recent studies in 2016, anthropogenic climate change, if left unchecked, may delay this otherwise expected glacial period by as much as an additional 50,000 years, potentially skipping it entirely. Niagara Falls will have eroded the remaining 32 km to Lake Erie and will therefore cease to exist. The many glacial lakes of the Canadian Shield will have been erased by post-glacial rebound and erosion.
	50,000	Due to lunar tides decelerating the Earth's rotation, a day on Earth is expected to be one SI second longer than it is today. To compensate, either a leap second will have to be added to the end of every day, or the length of the day will have to be officially lengthened by one SI second.
	60,000	It is possible that the current cooling trend might be interrupted by an interstadial phase, with the next glacial maximum of the Quaternary glaciation reached only in about 100 kyr AP.
	100,000	The proper motion of stars across the celestial sphere, which results from their movement through the Milky Way, renders many of the constellations unrecognizable.
	100,000	The red hypergiant star VY Canis Majoris will likely have exploded in a supernova.
	100,000	Native North American earthworms, such as Megascolecidae, will have naturally spread north through the United States Upper Midwest to the Canada–United States border, recovering from the Laurentide ice sheet glaciation, assuming a migration rate of 10 metres per year, and that a possible renewed glaciation by this time has not prevented this.
	100,000 – 10 million	Cupid and Belinda, moons of Uranus, will likely have collided.
	100,000	Earth will likely have undergone a supervolcanic eruption large enough to erupt of magma.
	100,000	According to Berger and Loutre, the next glacial maximum of the Quaternary glaciation is expected to be the most intense, regardless of the effects of anthropogenic global warming.
	> 100,000	As one of the long-term effects of global warming, ten percent of anthropogenic carbon dioxide will still remain in a stabilized atmosphere.
	250,000	Kamaʻehuakanaloa, the youngest volcano in the Hawaiian–Emperor seamount chain, will rise above the surface of the ocean and become a new volcanic island.
	300,000	At some point in the next few hundred thousand years, the Wolf–Rayet star WR 104 may explode in a supernova. There is a small chance that WR 104 is spinning fast enough to produce a gamma-ray burst, and an even smaller chance that such a GRB could pose a threat to life on Earth.
	500,000	Earth will likely have been hit by an asteroid of roughly 1 km in diameter, assuming that it is not averted.
	500,000	The rugged terrain of Badlands National Park in South Dakota will have eroded completely.
	600,000	The estimated time for the third super-eruption of the Toba supervolcano by this date. The first super-eruption occurred around 840,000 years ago, after 1.4 million years of magma input, whereas magma fed the second super-eruption at 75,000 years.
	1 million	Meteor Crater, a large impact crater in Arizona considered the "freshest" of its kind, will have worn away.
	1 million	Desdemona and Cressida, moons of Uranus, will likely have collided. The stellar system Eta Carinae will likely have exploded in a supernova.
	1 million	Earth will likely have undergone a supervolcanic eruption large enough to erupt of magma, an event comparable to the Toba supereruption 75,000 years ago.
	1.29 ± 0.04 million	The star Gliese 710 will pass as close as 0.051 parsecs to the Sun before moving away. This will gravitationally perturb members of the Oort cloud, a halo of icy bodies orbiting at the edge of the Solar System, thereafter raising the likelihood of a cometary impact in the inner Solar System.
	2 million	The estimated time for the full recovery of coral reef ecosystems from human-caused ocean acidification if such acidification goes unchecked; the recovery of marine ecosystems after the acidification event that occurred about 65 million years ago took a similar length of time.
	2 million+	The Grand Canyon will erode further, deepening slightly, but principally widening into a broad valley surrounding the Colorado River.
	2.7 million	The average orbital half-life of current centaurs, which are unstable because of gravitational interactions with the several outer planets. See predictions for notable centaurs.
	3 million	Due to tidal deceleration gradually slowing Earth's rotation, a day on Earth is expected to be one minute longer than it is today. To compensate, either a "leap minute" will have to be added to the end of every day, or the length of the day will have to be officially lengthened by one SI minute.
	6 million	Estimated time for comet C/1999 F1, one of the longest-period comets known to return to the inner Solar System, after having travelled in its orbit out to its aphelion from the Sun and back.
	10 million	The Red Sea will flood the widening East African Rift valley, causing a new ocean basin to divide the continent of Africa and the African plate into the newly formed Nubian plate and the Somali plate. The Indian plate will advance into Tibet by. Nepali territory, whose boundaries are defined by the Himalayan peaks and the plains of India, will cease to exist.
	10 million	The estimated time for the full recovery of biodiversity after a potential Holocene extinction, if it were on the scale of the five previous major extinction events. Even without a mass extinction, by this time most current species will have disappeared through the background extinction rate, with many clades gradually evolving into new forms.
	15 million	An estimated 694 stars will have approached the Solar System to less than 5 parsecs. Of these, 26 have a good probability to come within and 7 within.
	20 million	The Strait of Gibraltar will have closed due to subduction and a Ring of Fire will form in the Atlantic, similar to that in the Pacific.
	30 million	Earth will likely have been hit by an asteroid of roughly 5 km in diameter, assuming that it is not averted.
	50 million	The maximum estimated time before the moon Phobos collides with Mars.
	50 million	According to Christopher Scotese, the movement of the San Andreas Fault will cause the Gulf of California to flood into the California Central Valley. This will form a new inland sea on the West Coast of North America, causing the current locations of Los Angeles and San Francisco in California to merge. The Californian coast will begin to be subducted into the Aleutian Trench. Africa's collision with Eurasia will close the Mediterranean basin and create a mountain range similar to the Himalayas. The Appalachian Mountains peaks will have largely worn away, weathering at 5.7 Bubnoff units, although topography will actually rise as regional valleys deepen at twice this rate.
	50–60 million	The Canadian Rockies will have worn away to a plain, assuming a rate of 60 Bubnoff units. The Southern Rockies in the United States are eroding at a somewhat slower rate.
	50–400 million	The estimated time for Earth to naturally replenish its fossil fuel reserves.
	80 million	The Big Island will have become the last of the current Hawaiian Islands to sink beneath the surface of the ocean, while a more recently formed chain of "new Hawaiian Islands" will then have emerged in their place.
	100 million	Earth will likely have been hit by an asteroid comparable in size to the one that triggered the K–Pg extinction 66 million years ago, assuming this is not averted.
	100 million	According to the Pangaea Proxima model created by Christopher R. Scotese, a new subduction zone will open in the Atlantic Ocean, and the Americas will begin to converge back toward Africa. Upper estimate for the lifespan of Saturn's rings in their current state.
	110 million	The Sun's luminosity will have increased by one percent.
	125 million	According to the Pangaea Proxima model created by Christopher R. Scotese, the Atlantic Ocean is predicted to stop widening and begin to shrink as the Mid-Atlantic Ridge seafloor spreading gives way to subduction. In this scenario, the mid-ocean ridge between South America and Africa will probably be subducted first; the Atlantic Ocean is predicted to narrow as a result of subduction beneath the Americas. The Indian Ocean is also predicted to be smaller due to northward subduction of oceanic crust into the Central Indian trench. Antarctica is expected to split in two and shift northwards, colliding with Madagascar and Australia, enclosing a remnant of the Indian Ocean, which Scotese calls the "Medi-Pangaean Sea".
	180 million	Due to the gradual slowing of Earth's rotation, a day on Earth will be one hour longer than it is today. To compensate, either a "leap hour" will have to be added to the end of every day, or the length of the day will have to be officially lengthened by one SI hour.
	230 million	Prediction of the orbits of the Solar System's planets is impossible over timespans greater than this, due to the limitations of Lyapunov time.
	240 million	From its present position, the Solar System completes one full orbit of the Galactic Center.
	250 million	According to Christopher R. Scotese, due to the northward movement of the West Coast of North America, the coast of California will collide with Alaska.
	250–350 million	All the continents on Earth may fuse into a supercontinent. Four potential arrangements of this configuration have been dubbed Amasia, Novopangaea, Pangaea Proxima and Aurica. This will likely result in a glacial period, lowering sea levels and increasing oxygen levels, further lowering global temperatures.
	> 250 million	The supercontinent's formation, thanks to a combination of continentality increasing distance from the ocean, an increase in volcanic activity resulting in atmospheric CO₂ at double current levels, increased interspecific competition, and a 2.5 percent increase in solar flux, is likely to trigger an extinction event comparable to the Great Dying 250 million years ago. Mammals in particular are unlikely to survive, assuming they still exist in their current forms by this point.
	300 million	Due to a shift in the equatorial Hadley cells to roughly 40° north and south, the amount of arid land will increase by 25%.
	300–600 million	The estimated time for Venus's mantle temperature to reach its maximum. Then, over a period of about 100 million years, major subduction occurs and the crust is recycled.
	350 million	According to the extroversion model first developed by Paul F. Hoffman, subduction ceases in the Pacific Ocean basin.
	400–500 million	The supercontinent will likely have rifted apart. This will likely result in higher global temperatures, similar to the Cretaceous period.
	500 million	The estimated time until a gamma-ray burst, or massive, hyperenergetic supernova, occurs within 6,500 light-years of Earth; close enough for its rays to affect Earth's ozone layer and potentially trigger a mass extinction, assuming the hypothesis is correct that a previous such explosion triggered the Ordovician–Silurian extinction event. However, the supernova would have to be precisely oriented relative to Earth to have such effect.
	600 million	Tidal acceleration moves the Moon far enough from Earth that total solar eclipses are no longer possible.
	500–600 million	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 will die. The extinction of plant life is likely to be a long-term decline rather than a sharp drop. It is likely that plant groups will die one by one well before the critical carbon dioxide level is reached. The first plants to disappear will be herbaceous plants, followed by deciduous forests, evergreen broad-leaf forests, and finally evergreen conifers. However, a 2024 paper by RJ Graham et al. argues that silicate weathering is far less temperature-dependent than initially thought, and that falling carbon dioxide levels are unlikely to lead to the death of life on Earth.
	500–800 million	As Earth begins to warm and carbon dioxide levels fall, plants—and, by extension, animals—could survive longer by evolving other strategies such as requiring less carbon dioxide for photosynthetic processes, becoming carnivorous, adapting to desiccation, or associating with fungi. These adaptations are likely to appear near the beginning of the moist greenhouse. The decrease in plant life will result in less oxygen in the atmosphere, allowing for more DNA-damaging ultraviolet radiation to reach the surface. The rising temperatures will increase chemical reactions in the atmosphere, further lowering oxygen levels. Plant and animal communities become increasingly sparse and isolated as the Earth becomes more barren. Flying animals would be better off because of their ability to travel large distances looking for cooler temperatures. Many animals may be driven to the poles or possibly underground. These creatures would become active during the polar night and aestivate during the polar day due to the intense heat and radiation. Much of the land would become a barren desert, and plants and animals would primarily be found in the oceans.
	500–800 million	As pointed out by Peter Ward and Donald Brownlee in their book The Life and Death of Planet Earth, according to NASA Ames scientist Kevin Zahnle, this is the earliest time for plate tectonics to eventually stop, due to the gradual cooling of the Earth's core, which could potentially turn the Earth back into a water world. This would, in turn, likely cause the extinction of Earth's remaining land life.
	800–900 million	Carbon dioxide levels will fall to the point at which photosynthesis is no longer possible. 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 disappear shortly afterward. At most, animal life could survive about 3 to 100 million years after plant life dies out. Just like plants, the extinction of animals will likely coincide with the loss of plants. It will start with large animals, then smaller animals and flying creatures, then amphibians, followed by reptiles and, finally, invertebrates. In the book The Life and Death of Planet Earth, authors Peter D. Ward and Donald Brownlee state that some animal life may be able to survive in the oceans. Eventually, however, all multicellular life will die out. The first sea animals to go extinct will be large fish, followed by small fish and then, finally, invertebrates. The last animals to go extinct will be animals that do not depend on living plants, such as termites, or those near hydrothermal vents, such as worms of the genus Riftia. The only life left on the Earth after this will be single-celled organisms.
	1 billion	27% of the ocean's mass will have been subducted into the mantle. If this were to continue uninterrupted, it would reach an equilibrium where 65% of present-day surface water would be subducted.
	1 billion	By this point, the Sagittarius Dwarf Spheroidal Galaxy will have been completely consumed by the Milky Way.
	1.1 billion	The Sun's luminosity will have increased by 10%, causing Earth's surface temperatures to reach an average of around. The atmosphere will become a "moist greenhouse", resulting in a runaway evaporation of the oceans. This would cause plate tectonics to stop completely, if not already stopped before this time. Pockets of water may still be present at the poles, allowing abodes for simple life.
	1.2 billion	High estimate until all plant life dies out, assuming some form of photosynthesis is possible despite extremely low carbon dioxide levels. If this is possible, rising temperatures will make any animal life unsustainable from this point on.
	1.3 billion	Eukaryotic life dies out on Earth due to carbon dioxide starvation. Only prokaryotes remain.
	1.5 billion	Callisto is captured into the mean-motion resonance of the other Galilean moons of Jupiter, completing the 1:2:4:8 chain.
	1.5–1.6 billion	The Sun's rising luminosity causes its circumstellar habitable zone to move outwards; as carbon dioxide rises in Mars's atmosphere, its surface temperature increases to levels akin to Earth during the ice age.
	1.5–4.5 billion	Tidal acceleration moves the Moon far enough from the Earth to the point where it can no longer stabilize Earth's axial tilt. As a consequence, Earth's true polar wander becomes chaotic and extreme, leading to dramatic shifts in the planet's climate due to the changing axial tilt.
	1.6 billion	Lower estimate until all remaining life, which by now had been reduced to colonies of unicellular organisms in isolated microenvironments such as high-altitude lakes and caves, goes extinct.
	1.66–1.86 billion	Estimated time until plant life goes extinct if silicate weathering does not increase fast enough to deplete atmospheric carbon dioxide below the minimum for photosynthesis, and biosphere decline is instead driven by overheating past the upper limit of documented for a symbiont of Dichanthelium lanuginosum. If this happens, then the disappearance of other multicellular life on land will happen around the same time.
	< 2 billion	The first close passage of the Andromeda Galaxy and the Milky Way.
	2 billion	High estimate until the Earth's oceans evaporate if the atmospheric pressure were to decrease via the nitrogen cycle.
	2.55 billion	The Sun will have reached a maximum surface temperature of. From then on, it will become gradually cooler while its luminosity will continue to increase.
	2.8 billion	Earth's surface temperature will reach around, even at the poles.
	2.8 billion	High estimate until all remaining Earth life goes extinct.
	3–4 billion	The Earth's core freezes if the inner core continues to grow in size, based on its current growth rate of in diameter per year. Without its liquid outer core, Earth's magnetosphere shuts down, and solar winds gradually deplete the atmosphere.
	3 billion	There is a roughly 1-in-100,000 chance that the Earth will be ejected into interstellar space by a stellar encounter before this point, and a 1-in-300-billion chance that it will be both ejected into space and captured by another star around this point. If this were to happen, any remaining life on Earth could potentially survive for far longer if it survived the interstellar journey.
	3.3 billion	There is a roughly one percent chance that Jupiter's gravity may make Mercury's orbit so eccentric as to cross Venus's orbit by this time, sending the inner Solar System into chaos. Other possible scenarios include Mercury colliding with the Sun, being ejected from the Solar System, or colliding with Venus or Earth.
	3.5–4.5 billion	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. The greenhouse effect caused by the massive, water-rich atmosphere will result in Earth's surface temperature rising to, which is hot enough to melt some surface rock.
	3.6 billion	Neptune's moon Triton falls through the planet's Roche limit, potentially disintegrating into a planetary ring system similar to Saturn's.
	4.32 billion	Due to the gradual slowing of Earth's rotation, a day on Earth will be twice as long as it is today. To compensate, either a "leap day" will have to be added to the end of every day, or the length of the day will have to be officially lengthened by one day.
	4.5 billion	Mars reaches the same solar flux as that of the Earth when it first formed 4.5 billion years ago from today.
	< 5 billion	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. The planets of the Solar System will almost certainly not be disturbed by these events.
	5.4 billion	The Sun, having now exhausted its hydrogen supply, leaves the main sequence and begins evolving into a red giant.
	6.5 billion	Mars reaches the same solar radiation flux as Earth today, after which it will suffer a similar fate to the Earth as described above.
	6.6 billion	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.
	7.5 billion	Earth and Mars may become tidally locked with the expanding red giant Sun.
	7.59 billion	The Earth and Moon are very likely destroyed by falling into the Sun, just before the Sun reaches the top of its red giant phase. Before the final collision, the Moon possibly spirals below Earth's Roche limit, breaking into a ring of debris, most of which falls to the Earth's surface. During this era, Saturn's moon Titan, if not already ejected from the Saturnian system, may reach surface temperatures necessary to support life and would orbit further out from Saturn.
	7.9 billion	The Sun reaches the top of the red-giant branch of the Hertzsprung–Russell diagram, achieving its maximum radius of 256 times the present-day value. In the process, Mercury, Venus and Earth are likely destroyed.
	8 billion	The Sun becomes a carbon–oxygen white dwarf with about 54.05% of its present mass. At this point, if the Earth survives, temperatures on the surface of the planet, as well as the other planets in the Solar System, will begin dropping rapidly, due to the white dwarf Sun emitting much less energy than it does today.
	>22.3 billion	22.3 billion years is the estimated time until the end of the universe in a Big Rip, assuming a model of dark energy with = −1.5. If the density of dark energy is less than −1, then the universe's expansion will continue to accelerate and the observable universe will grow ever sparser. Around 200 million years before the Big Rip, galaxy clusters like the Local Group or the Sculptor Group will be destroyed; 60 million years before the Big Rip, all galaxies will begin to lose stars around their edges and will completely disintegrate in another 40 million years; three months before the Big Rip, star systems will become gravitationally unbound, and planets will fly off into the rapidly expanding universe; 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. The universe would enter into a "rip singularity" when all non-zero distances become infinitely large. Whereas a "crunch singularity" involves all matter being infinitely concentrated, in a "rip singularity", all matter is infinitely spread out. Observations of galaxy cluster speeds by the Chandra X-ray Observatory suggest that the value of is c. −0.991, meaning the Big Rip is unlikely to occur. Meanwhile, more recent data from the Planck mission indicates the value of to be c. −1.028, pushing the earliest possible time of the Big Rip to approximately 200 billion years into the future.
	50 billion	If the Earth and Moon are not engulfed by the Sun, by this time they will become tidally locked, with each showing only one face to the other. Thereafter, the tidal action of the white dwarf Sun will extract angular momentum from the system, causing the lunar orbit to decay and the Earth's spin to accelerate.
	65 billion	The Moon may collide with the Earth or be torn apart to form an orbital ring due to the decay of its orbit, assuming the Earth and Moon have not already been destroyed.
	100 billion – 1 trillion	All the ≈47 galaxies of the Local Group will coalesce into a single large galaxy—an expanded "Milkomeda"/"Milkdromeda"; the last galaxies of the Local Group coalescing will mark the effective completion of its evolution.
	100–150 billion	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.
	150 billion	The universe will have expanded by a factor of 6,000, and the cosmic microwave background will have cooled by the same factor to around. The temperature of the background will continue to cool in proportion to the expansion of the universe.
	325 billion	The estimated time by which the expansion of the universe will have isolated all gravitationally bound structures within their own cosmological horizon. At this point, the universe will have expanded by a factor of more than 100 million from today, and even individual exiled stars will be isolated.
	800 billion	The expected time when the net light emission from the combined "Milkomeda" galaxy begins to decline as the red dwarf stars pass through their blue dwarf stage of peak luminosity.
	1 trillion	A low estimate for the time until star formation ends in galaxies as galaxies are depleted of the gas clouds they need to form stars. The universe's expansion, 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 undetectable. However, it may still be possible to determine the expansion of the universe through the study of hypervelocity stars.
	1.05 trillion	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.
	1.4 trillion	The estimated time by which the cosmic background radiation cools to a floor temperature of 10⁻³⁰ K and does not decline further. This residual temperature comes from horizon radiation, which does not decline over time.
	2 trillion	The estimated time by which all objects beyond our former Local Group are redshifted by a factor of more than 10⁵³. Even gamma rays that they emit are stretched so that their wavelengths are greater than the physical diameter of the horizon. The resolution time for such radiation will exceed the physical age of the universe.
	4 trillion	The estimated time until the red dwarf star Proxima Centauri, the closest star to the Sun today, at a distance of 4.25 light-years, leaves the main sequence and becomes a white dwarf.
	10 trillion	The estimated time of peak habitability in the universe, unless habitability around low-mass stars is suppressed.
	12 trillion	The estimated time until the red dwarf star VB 10—as of 2016, the least-massive main-sequence star with an estimated mass of 0.075 —runs out of hydrogen in its core and becomes a white dwarf.
	30 trillion	The estimated time for stars to undergo a close encounter with another star in local stellar neighborhoods. Whenever two stars pass close to each other, their planets' orbits can be disrupted, potentially ejecting them from the system entirely. On average, the closer a planet's orbit to its parent star the longer it takes to be ejected in this manner, because it is gravitationally more tightly bound to the star.
	100 trillion	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. By this time, the universe will have expanded by a factor of approximately 10²⁵⁵⁴.
	110–120 trillion	The time by which all stars in the universe will have exhausted their fuel. After this point, the stellar-mass objects remaining are stellar remnants and brown dwarfs. Collisions between brown dwarfs will create new red dwarfs on a marginal level: on average, about 100 stars will shine in what was once "Milkomeda". Collisions between stellar remnants will create occasional supernovae.
	10¹⁵	The estimated time until stellar close encounters detach all planets in star systems from their orbits. By this point, the black dwarf that was once the Sun will have cooled to.
	10¹⁹ to 10²⁰	The estimated time until 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 "Milkomeda"/"Milkdromeda" to eject the majority of its brown dwarfs and stellar remnants.
	10²⁰	The estimated time until the Earth collides with the black dwarf Sun due to the decay of its orbit via emission of gravitational radiation, if the Earth is not ejected from its orbit by a stellar encounter or engulfed by the Sun during its red giant phase.
	10²³	Around this timescale most stellar remnants and other objects are ejected from the remains of their galactic cluster.
	10³⁰	The estimated time until most or all of the remaining 1–10% of 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, via emission of gravitational radiation, only solitary objects will remain in the universe.
	2×10³⁶	The estimated time for all nucleons in the observable universe to decay, if the hypothesized proton half-life takes its smallest possible value.
	10³⁶–10³⁸	The estimated time for all remaining planets and stellar-mass objects, including the Sun, to disintegrate if proton decay can occur.
	3×10⁴³	The estimated time for all nucleons in the observable universe to decay, if the hypothesized proton half-life takes the largest possible value of 10⁴¹ years, 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, if protons do decay, the Black Hole Era, in which black holes are the only remaining celestial objects, begins.
	3.14×10⁵⁰	The estimated time until a micro black hole of one Earth mass today will have decayed into subatomic particles by the emission of Hawking radiation.
	10⁶⁵	Assuming that protons do not decay, the estimated time for rigid objects, from free-floating rocks in space to planets, to rearrange their atoms and molecules via quantum tunnelling. On this timescale, any discrete body of matter "behaves like a liquid" and becomes a smooth sphere due to diffusion and gravity.
	1.16×10⁶⁷	The estimated time until a black hole of one solar mass today will have decayed by the emission of Hawking radiation.
	1.54×10⁹¹–1.41×10⁹²	The estimated time until the resulting supermassive black hole of "Milkomeda"/"Milkdromeda" from the merger of Sagittarius A* and the P2 concentration during the collision of the Milky Way and Andromeda galaxies will have vanished by the emission of Hawking radiation, assuming it does not accrete any additional matter nor merge with other black holes—though it is most likely that this supermassive black hole will nonetheless merge with other supermassive black holes during the gravitational collapse towards "Milkomeda"/"Milkdromeda" of other Local Group galaxies. This supermassive black hole might be the very last entity from the former Local Group to disappear—and the last evidence of its existence.
	10¹⁰⁶ – 2.1×10¹⁰⁹	The estimated time until ultramassive black holes of 10¹⁴ solar masses, predicted to form during the gravitational collapse of galaxy superclusters, decay by Hawking radiation. 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 in the heat death of the universe.
	10¹⁶¹	A 2018 estimate of Standard Model lifetime before collapse of a false vacuum; 95% confidence interval is 10⁶⁵ to 10¹³⁸³ years due in part to uncertainty about the top quark's mass.
	10²⁰⁰	The highest estimate for the time it would take for all nucleons in the observable universe to decay, provided they do not decay via the above process but instead through any one of many different mechanisms allowed in modern particle physics on timescales of 10⁴⁶ to 10²⁰⁰ years.
	10^1100–32000	The estimated time for black dwarfs of 1.2 solar masses or more to undergo supernovae as a result of slow silicon–nickel–iron fusion, as the declining electron fraction lowers their Chandrasekhar limit, assuming protons do not decay.
	10¹⁵⁰⁰	Assuming that protons do not decay, the estimated time until all baryonic matter in stellar remnants, planets and planetary-mass objects will have either fused together via muon-catalyzed fusion to form iron-56 or decayed from a higher mass element into iron-56 to form iron stars.
		A low estimate for the time until all iron stars collapse via quantum tunnelling into black holes, assuming no proton decay or virtual black holes, and that Planck-scale black holes can exist. On this vast timescale, even ultra-stable iron stars will have been destroyed by quantum-tunnelling events. At this lower end of the timescale, iron stars decay directly to black holes, as this decay mode is much more favourable than decaying into a neutron star and later decaying into a black hole. On these timescales, the subsequent evaporation of each resulting black hole into subatomic particles and the subsequent shift to the Dark Era is instantaneous.
		The estimated time for a Boltzmann brain to appear in the vacuum via a spontaneous entropy decrease.
		Highest estimate for the time until all iron stars collapse via quantum tunnelling into neutron stars or black holes, assuming no proton decay or virtual black holes, and that black holes below the Chandrasekhar mass cannot form directly. On these timescales, neutron stars above the Chandrasekhar mass rapidly collapse into black holes, and black holes formed by these processes instantly evaporate into subatomic particles. This is also the highest estimated possible time for the Black Hole Era to commence. Beyond this point, it is almost certain that the universe will be an almost pure vacuum, gradually winding down its energy level until it reaches its final energy state, assuming it does not happen before this time.
		The highest estimate for the time it takes for the universe to reach its final energy state.
		Around this vast timeframe, quantum tunnelling in any isolated patch of the universe could generate new inflationary events, resulting in new Big Bangs giving birth to new universes.