The Universe is a global object that includes time, space and all its contents: galaxies, stars, planets, their moons, all other bodies, all matter, all energy. This huge and wonderful object was once born. Like all good things, the universe also has its end. With the past and the birth of the universe, scientists seem to have decided. But the predictions about the end of the universe remain a set of theories that give a different result depending on the accepted values ​​of several constants.

Birth and life

The dominant theory of the birth of the universe in modern science is the Big Bang . If we extrapolate the visible expansion of the Universe, 13.799 ± 0.021 billion years ago, all matter was at one point of zero size with infinite density and temperature. Then the expansion began. Few of the subsequent processes are within the full understanding of modern physics.

For picoseconds, elementary particles originated from quark-gluon plasma . Later, protons and neutrons were formed from them, which in turn produced nuclei of light isotopes. So far, only the nucleus is far from atoms to atoms.

After 70 thousand years from the starting point, matter begins to dominate radiation. From about 380 thousand years after the Big Bang, electrons and nuclei form neutral atoms for the first time. The stars don't exist yet. The very first are formed from 550 million years after the Big Bang. Stars gather in galaxies. The last gravitational interaction forms in clusters.
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According to the nebular hypothesis , after ≈9 billion years after the Big Bang (or ≈4.6 billion years ago), what would later become the Solar System began to form from a single gas-dust cloud. The fragment of the cloud shrank into a ball in the center, the surrounding parts also shrank and rotated faster, forming a characteristic disk. From the ball lit our star, in the cold edges in the condensation of matter planets formed.

In this brief description we are interested in the ability to predict how much the sun can still exist. 13.799 billion years after everything started, we have a blue earth from the oceans, life and free pornography over data networks. A convenient order of life will exist for a long time, but only by human standards.

In 2.4 billion years from now, the Milky Way and the Andromeda Galaxy will collide . From Earth it will be no one to watch. Life on our planet will die out in about a billion years - the sun will produce too much heat, and the oceans will simply evaporate. The star itself will exist for a long time.


The life cycle of the sun.

After billions of years, the Sun will already be a red giant, which has long consumed its hydrogen fuel reserves. It will expand about 250 times. Some studies show that before collapsing into a white dwarf, the Sun will still capture the Earth, since the orbit of the planet will fall below. However, it does not matter - after 7.6 billion years, when this happens, there will be nothing alive on our planet. The sun will shine for billions more years, but much duller. In the end, it will turn into a black dwarf . After another billions of years, the gravity of other stars will select the remaining planets. The solar system will cease to exist.

In the next hundreds of millions of years, there is no need to worry about the destruction of the Earth - during this period the Solar System is stable . Burning out the fuel of the nearest star after billions of years cannot be called even problems. Modern humanity has real challenges that threaten a significant deterioration in the quality of life. There are many of them: from antibiotics that stop working due to the emergence of superbugs to global climate change due to greenhouse gas emissions. Finally, there is a banal danger of unleashing a thermonuclear war or destroying ourselves in some other way.

Perhaps our descendants will move the Earth's orbit or even move from it. Perhaps the Earth will survive this process without much help. But what problems will face posthumanity, which will leave the "cradle of civilization"? What expects other, extraterrestrial life forms? The question of the ultimate fate of the universe is on the border of modern cosmological science.

Compression

The universe is expanding, galaxies scatter from each other. Perhaps the expansion speed will slow down, reach zero, and then go in the opposite direction. The universe may begin to shrink, gradually collapsing into black holes. And these black holes merge into one. This hypothesis is called " Great Compression ."

In the Hubble law, the state of expansion of the Universe is determined by its density. If the density is below critical , then the Universe will continue to grow in size and cool down. If the density of the universe is higher, then the gravitational force will gradually stop the scattering and direct it backwards. The universe will shrink.



Collapse will be different from the original expansion. Huge clusters of galaxies will come together , then whole galaxies will begin to merge. At some point, the stars approach each other so closely that it comes to frequent collisions. Stars will not be able to dissipate the heat generated and begin to explode, leaving a hot heterogeneous gas. Due to the increasing temperature, its atoms will disintegrate into elementary particles, which will be absorbed by accreting black holes. The hypothesis does not indicate what the final will be.

There is one more hypothesis - continuation - Big rebound . A simple formulation states that the Universe is experiencing cycles of Big Bangs and Big Compresses. Perhaps this universe also arose as a result of the collapse of the previous one. This means that we live in one of the points of an infinite cycle of contractions and explosions. However, their numbering does not make sense due to the passage of the singularity point. Some theories claim that the result of the Big compression will be the same state that started it all. There will be another Big Bang. The cycle will continue indefinitely.

But recent experimental observations of long-range supernovae as objects of standard luminosity and mapping of the CMB show that expansion is not slowing down, but only accelerating .

Expansion

A large gap suggests that sometime in the future, all the matter of the Universe, stars and galaxies, subatomic particles, space itself and time will be broken by the rate of expansion. The scenario of this death says that the Milky Way will fall apart 60 million years before the final, the work of the Solar System will be upset in three months. Half an hour before the Big Break, the Earth will collapse (or a similar planet), atoms will begin to collapse in one nanosecond. According to the hypothesis, all this will happen only after 22 billion years, after the extinction of the Sun into a white dwarf.

However, the most popular theory remains the constant expansion and the Thermal Death resulting from it.

Over billions of years, stars will burn out. From their remains white dwarfs, neutron stars and black holes are born. After 150 billion years from the current moment, with the same acceleration of the scattering of galaxies, all galaxies outside the Local Group will go beyond the cosmological horizon. Events in the Local Group will not be able to influence events in distant galaxies, and vice versa. When observing a distant galaxy, time will slow down and then just stop. In other words, in 150 billion years an observer in the Local Group will never see events in distant galaxies. No more flights to them, nor any form of communication will be possible.

After 800 billion years, the luminosity of the Local Group will noticeably decrease. Aging stars will produce less and less light, red dwarfs will die out in white. After 2 trillion years from now, due to redshift, distant galaxies will not be able to be detected in any way: even the wavelength of their gamma rays will be higher than the size of the observed universe.


After 100 trillion years the formation of stars will end, their remains will dimly shine in space. After the last star is extinguished, the flashes of mergers of two white dwarfs will light up the space from time to time. After ^10-15 years, the planets will either fall on the remnants of their former stars, or go to other bodies. Similarly, after 10 ¹⁹ —10 ²⁰ years, objects will leave the galaxy. A small part of the objects will fall into a supermassive black hole.

Further development depends on whether the proton is stable or not. Some experiments claim that the minimum half-life of a proton is 10 ³⁴ years. If this is true, after 10 ⁴⁰ years, only leptons and photons will remain in the Universe. The remains of stars will disappear, only black holes will remain. Perhaps the process of the death of nucleons will take more time.

After 10 ¹⁰⁰ years from the current moment black holes evaporate Hawking radiation . Finally, the Universe will be almost completely empty. It will fly photons, neutrinos, electrons and positrons, occasionally colliding.

If the protons are stable, then after 10 ¹⁵⁰⁰ cold fusion and quantum tunneling, the light nuclei will turn into iron atoms of ⁵⁶ Fe. Elements heavier than this isotope will decay with the emission of alpha particles. After 10 ^{10 26} years, quantum tunneling will transform large objects into black holes. Iron stars may turn into neutron stars 10 ^{10 76} years from now.

It is likely that after 10 ^{10 10 56} years, quantum fluctuations will create a new Big Bang. Although even a rational creature can arise in this vacuum: an approximate estimate of the time of the birth of the Boltzmann brain is once every 10 ^{10 50} years.

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There are other, more exotic hypotheses. For example, in 2010, scientists predicted that in five billion years time will end . This event will be difficult to see or somehow predict, it is promised to be sudden. The space may end up due to the collapse of a false vacuum into a true, more energetically low state, which may entail the complete destruction of the objects of the Universe.

All these hypotheses are developed for the current realities of a simple equation of state for dark energy. As the name implies, little is known about dark energy. If the inflationary model of the Universe is correct, then in the first moments after the Big Bang there were other forms of dark energy. Perhaps the equation of state will change. The conclusions that can be drawn from it will change. It is difficult to predict that we will learn about dark energy, if it was developed only at the end of the last century.

But in all cases the destruction of the Universe is a very distant phenomenon by the standards of mankind. If we consider it from the scale of one person’s life expectancy, this is too global an event to worry about.