[Academy] Magic of the Universe: why it is transparent, how atoms, matter and antimatter were formed

 Hello dear steemians !
I continue to watch the Greatest Unsolved Mysteries of the Universe course and take part in the Academy. The second week was, like the first one, quite large and complex in terms of information perception. Since childhood I have not been very friendly with chemistry, so now I start from the very beginning to understand the basics, in order to better understand astrophysics. In this post I want to tell you about 4 unsolved mysteries that predetermined the development of our universe in the initial stages, which allowed the formation of life. 

 I will be very grateful if there are people who know more about this topic and will be able, if something, to correct some inaccuracies or reveal it more. 

 In the last post I mentioned such things about the early Universe: 

• High density
• High energy
• High particle velocity

 All the phenomena that I will describe further became possible only thanks to these properties. 

Relic radiation or cosmic microwave background radiation

 Our universe is now transparent, we can see many heavenly bodies and phenomena. But it was not always so. The first few hundred thousand years the entire universe was filled with a glowing fog and light, where nothing but light could be seen. 

 Relicative radiation - this uniform thermal radiation, which fills our universe, is considered one of the proofs of the The Big Bang Theory. 

 How did it happen that now it is transparent?

Originally our universe was very hot, had a high density. Electrons, baryons and photons were constantly present in it, which were emitted and absorbed.
Gradually, space expanded, the speed of all particles slowed and electrons were able to connect with protons (hydrogen nuclei) and alpha particles (helium nuclei), forming atoms. This process is called recombination. 

 Recombination occurred at the approximate age of the universe - 400,000 years. 

 Consequences of recombination: 

• Free charged particles became less
• Space has become more
• Photons could move almost without interacting with particles

 As a result, those photons that were radiated by the plasma, but did not have time to dissipate due to recombination, now reach our Earth. 

Primal nucleosynthesis

 We already know that our universe originally existed from electrons, neutrons and protons. Now it contains hydrogen atoms, helium and many others. 

 There was a hypothesis that all the chemical elements that now exist were formed together with the Big Bang, but it turned out not to be so.
What should have happened is nuclear synthesis, the combination of subatomic particles to form more complex elements, for example, carbon.

The difficulty is that the nuclear reaction is a very complex reaction due to the fact that the nuclei have a positive charge, so they constantly repulse and avoid each other. In order for nuclear fusion to occur it is necessary that the following conditions exist: 

• Rapid movement
• The presence of highly charged particles
• High density

 How did this all happen in the universe?
When the universe was only 10 seconds, its density was one ton per cubic centimeter. It's quite a high density. At first, the photon energy was very high, and it was enough to break the connection between the proton and the neutron (deuterium), but then, gradually, with the expansion of space, this energy began to weaken, which allowed the formation of deuterium and more complex elements. 

 So the initial nucleosynthesis of the first atoms occurred, which then allowed to form more complex particles and molecules. 

 

Acquisition of the form of the universe

 Looking now in the sky, we see a lot of Galaxies, stars, asteroids and stuff. There are places in the universe where there is a large accumulation of celestial bodies, and there are almost empty places. Why did it happen? How was this form chosen? 

magine a completely homogeneous universe with the same density as it was originally. But then a small piece with a slightly higher density appears, correspondingly, it also has more attraction forces. Matter begins to move towards him more and more. Simultaneously, in other places, emptiness is formed. This process is called gravitational instability

 But the main question is, how did these heterogeneities initially originate? 

 Some scientists explain this by the fact that when there was a lot of energy in the particles, they could, in the literal sense of the word, form particles inside and out. We call this a virtual particle. Agree, it sounds like a fantasy - energy and particles formed out of nowhere. But this is something that can be observed in the laboratory, but it is still difficult to explain (it is assumed that the development of quantum sciences will answer these questions). So far we know that vacuum is not a vacuum, as we thought, there are fluctuations. What forms these fluctuations is not yet known. 

 Matter and antimatter

 Matter prevails in our Universe. However, matter has its own antimatter. 

 Antimatter is a form of matter in which most of its attributes have negative signs. 

 If antimatter prevailed, nothing living could come about, how did it happen that in a completely symmetrical and homogeneous universe, matter began to predominate over antimatter?

In the early universe, photons were constantly turning into particles and antiparticles, which then merged and formed photons again. With time, when the density and velocity of the particles decreased, the photons formed did not have enough energy to turn into particles and antiparticles. The whole universe, logically, would have to consist only of photons, however, we are made up of atoms. Why?

 If we imagine that the Universe has a certain balance between matter and antimatter, then it is easy to assume that there are places where matter prevails, and where antimatter. For example, near the Earth - matter, and next to the galaxy is made entirely of antimatter. However, this theory has some difficulties and inconsistencies in the real world. If we imagine that at the boundary of matter and antimatter, these two particles accidentally strike each other, then the energy allocated in this case should be simply incredible (for example, if 100 kg particles accidentally come into contact, the explosion will be 100,000 times stronger than from Atomic bomb). On the scale of the universe, it should have been so strong flashes that, one way or another, they should have already reached Earth, but this did not happen.
Therefore now it is explained by, 

 

What was most memorable

 

What was most memorable

Much of what exists now is a chain of random and random events. Much remains unclear. Much remains to be discovered and learned, but everything has become possible precisely because of the expansion of space and some dark energy that affects it. In the next post I'll tell you about her.

source: 1 , 2 , 3 , 4 , 5

Thanks for reading this post .

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