Five centuries of the universe: in which we live and what does it mean?

Every living creature on our planet is born,grows up, gets older and eventually dies. All these laws also apply outside the Earth - stars, solar systems and galaxies also die over time. The difference exists only in time - that for you and me it seems like an eternity, by the standards of the Universe is complete nonsense. But what about the universe itself? As you know, she was born after the Big Bang 13.8 billion years ago, but what is happening to her now? What is the life cycle of the universe itself and why do researchers single out five stages of its development?

There are 5 epochs in the life cycle of the Universe. Right now we are in the second era.

Content

• 1 Five Centuries of the Universe
• 2 Primeval Era
• 3 star era
• 4 era of degeneration
• 5 era of black holes
• 6 dark era

Five centuries of the universe

Astronomers believe that the five stages of evolutionare a convenient way to represent the incredibly long life of the universe. Agree, at a time when we know only 5% of the visible Universe (the remaining 95% is occupied by the mysterious dark matter, the existence of which remains to be proved), it is rather difficult to judge its evolution. However, researchers are trying to understand the past and present of the Universe, combining the achievements of science and human thought of the last two centuries.

If you happen to be under clearsky in a dark place on a moonless night, then when you look up you will find a magnificent cosmic landscape. Using ordinary binoculars, you can see a breathtaking celestial canvas of stars and spots of light that overlap each other. Light from these stars reaches our planet overcoming vast cosmic distances and makes its way to our eyes through space-time. Such is the universe of the cosmological era in which we live. It's called the stellar era, but there are four others.

Image compiled by researchers at Princeton University, based on images taken by NASA space telescopes

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There are many ways to consider andto discuss the past, present and future of the Universe, but one of them attracted the attention of astronomers more than others. The first book on the five centuries of the universe was published in 1999, entitled "Five centuries of the universe: inside the physics of eternity." (the latest updates were made in 2013). The authors of the book Fred Adams and Gregory Laughlin gave a name to each of the five centuries:

• Primeval era
• Star era
• Degenerative era
• The era of black holes
• Dark era

It should be noted that not all scientistsare proponents of this theory. However, many astronomers find the five-step division a useful way of discussing such an unusually large amount of time.

Primeval era

The primitive era of the universe began latersecond after the big bang. During the first, very small period of time, space-time, and the laws of physics, the researchers believe, did not yet exist. This strange, incomprehensible interval is called the Planck era, it is believed that it lasted 1044 seconds. It is important to take into account the fact that many assumptions about the Planck era are based on a hybrid of the general theory of relativity and quantum theories, called the theory of quantum gravity.

In the image, all five eras of the universe are indicated in different colors.

The first second after the Big Bang beganinflation is an incredibly fast expansion of the universe. After a few minutes, the plasma began to cool, and subatomic particles began to form and stick together. 20 minutes after the Big Bang - in the super-hot, thermonuclear Universe - atoms began to form. Cooling was fast, until 75% of hydrogen and 25% of helium remained in the universe, which is similar to what is happening today on the Sun. About 380,000 years after the Big Bang, the Universe cooled so much that the first stable atoms began to form and cosmic background microwave radiation appeared, which astronomers call relic radiation.

See also: Scientists come closer to understanding why the universe exists

Star era

We live in a starry era - at this timemost of the matter existing in the Universe takes the form of stars and galaxies. The first stars in the Universe - we recently told you about its discovery - were huge and ended their lives in the form of supernova explosions, which led to the formation of many other, smaller stars. Driven by the force of gravity, they approached each other to form galaxies.

Stars and galaxies, like us, have their own life span.

One of the axioms of the star era is thatthe larger the star, the faster it burns its energy, and then dies, usually in just a couple of million years. Smaller stars that consume energy more slowly stay active longer. Scientists predict that our Milky Way galaxy, for example, will collide and unite with the neighboring Andromeda galaxy in about 4 billion years to form a new one. By the way, our solar system can survive this merger, but perhaps the sun will die much earlier.

Era of degeneration

Next comes the era of degeneration (degeneration), whichwill begin approximately 1 quintillion years after the Big Bang and will last up to 1 duodecillion after it. In this period, all the remnants of the stars visible today will dominate the Universe. In fact, in outer space there are a lot of dim light sources: white dwarfs, brown dwarfs and neutron stars. These stars are much colder and emit less light. Thus, in the era of degeneration, the Universe will be deprived of light in the visible spectrum.

The dim remnants of once bright stars will prevail in the universe in an era of degeneration

During this era, small brown dwarfswill retain most of the available hydrogen, and black holes will grow, grow and grow, feeding on the remnants of stars. When there is not enough hydrogen around, the Universe will become dimmer and colder over time. Then the protons that existed from the very beginning of the Universe will begin to die, dissolving matter. As a result, subatomic particles, Hawking radiation and black holes will mainly remain in the Universe.

Hawking Radiation - a hypothetical process of emitting a black hole of a variety of elementary particles, mainly photons; named after the British theoretical physicist Stephen Hawking.

Era of black holes

Over a significant period of time, black holes will dominate the universe, drawing in the remnants of mass and energy. However, in the end they will evaporate, albeit very slowly.

By the end of this period, photons, electrons, positrons and neutrinos will remain.

The authors of the book believe, as Big Think writes, thatwhen the black holes finally evaporate, there will be a small flash of light - the only remaining energy in the universe. At this point, the universe will be almost history, containing only low-energy, very weak subatomic particles and photons.

Dark era

Ultimately, electrons and positrons,drifting through space will collide with each other, sometimes forming prositronium atoms. These structures are unstable, but their composite particles will eventually be destroyed. Further destruction of other low-energy particles will continue, albeit very slowly. But tonight take a look at the night sky full of stars and don’t worry about anything - they won’t go anywhere for a very long time, and our understanding of the Universe and time in the future may change.