How did the universe begin?

 How did the universe begin?

The universe was born about 15 billion years ago. The structure of the universe, changes, geometry, movements, measurements of light tell us its history. This data has long been and continues to be carefully obtained. It has been analyzed with great diligence and it is our great achievement to know this whole history. Although some things are not complete, the cosmology model of cosmic history is based on good empirical and theoretical evidence. And that leads us to the next question. How much do we know about how the universe began?

We know that the universe is expanding and as it is expanding, the matter and energy found in it are diluting. About fourteen billion years ago, when it was young, matter and energy were more dense. And because they were dense, the temperature was high. And higher temperatures meant that particles would collide with more energy. And what happens when particles collide with more energy? The most energy collisions we've tested experimentally are in the Large Hadron Collider. These energies are in the teraelectron volt range. If it is converted to temperature, it emits 10 ^ 16 K. In words That's 10 billion degrees Celsius. (Since this is such a large number, we do not use this scale for it).

At this temperature we know the physics of the early universe. And we can express it with good confidence. That is, not only do we have good theories, but we also have empirical evidence. This is the Big Bang cosmological model of the large-scale evolution of the universe from the earliest known scale of time. When we go beyond that, then we can only speculate.

The simplest way to speculate about the early universe is to take the known theory further back in time and extrapolate it at higher temperatures. The implication is that at higher temperatures the theory will not change.

If we keep going backwards in this way, we reach such a high energy density that the quantum fluctuations of space and time begin to gain importance. In order to make any calculations for this condition, we must have the theory of quantum gravity. But there is a problem. We do not have any such theory in any form.

In short, at the moment we have no idea how the universe began. The story is over. We hope you find the answer to your question. This may not be satisfactory, but it is the right answer.

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But it's not interesting to read (and if you're a cosmologist you can't publish this answer). There are hundreds of views on this question. So, let's take a look at some of the popular theories about the origin of the universe.

Most popular theories assume that the electromagnetic force combines with the strong and weak nuclear force at high energy. (This is called Grand Unified Theory). At the same time, another assumption is made about the presence of an additional field. This is called an inflaton field. Due to the presence of the inflaton field, the expansion of the early universe was very fast. This was the age of cosmic inflation. The inflation field created the substance of the universe. It doesn't exist anymore because we don't see it anymore.

The birth of the universe in this family of theories was the result of quantum fluctuations in the inflaton field. This birth event was the Big Bang.

If this idea is correct, then such quantum fluctuations would be "out" of our universe. And new universes are constantly being created.

There are two major problems with this family of theories. One problem is that we have no evidence that the forces of the universe ever came together, and the other is that there is just as good evidence (ie zero) that the inflaton field existed.

The early universe went through a phase in which expansion was very fast. This idea is somewhat consistent with the data. But the evidence is not yet strong. As for the reason for this rapid spread, whether it was an inflaton field or something else. This data does not indicate that.

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There is another family of theories according to which the universe was not created once but has been repeated. These are cosmological cyclical models. It replaces one-time Big Bang with one-time or unlimited Big Bounce. There are many types of bicycle models.

One type is the ekpyrotic universe. This idea was taken from string theory. This led to the collision of high dimension members and the beginning of our universe. One of the big assumptions made here is string theory and then a special version of it and then a special scene of it.

Another idea is conformal cyclical cosmology. According to him, if the end of the universe is heat death, then not only the sense of time but also the sense of space disappears. This means that there is no difference between big and small. The beginning and the end of the universe are in fact the same state. There is a hypothetical heat death. The second is his condition. The third is about the state of time and space itself.

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According to another theory, new universes are born inside a black hole. This includes a few hypotheses about black holes.

According to another very different theory, four dimensions in space are born from a black hole. It contains assumptions about black holes and the dimensions of space.

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Another idea is that the universe did not have a "beginning." There was no time before a certain time. There was only space. This is a new boundary proposal. Another similar proposal for the disappearance of time comes from loop quantum cosmology, which researchers call asymptotic silence.

Another idea is string gas cosmology. In it, the early universe remained almost the same for an indefinite period of time and then began to expand.

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Among many other ideas, we have the cosmology of space turtles. According to which space began to expand when a large space turtle laid an egg from which the universe was discovered. The assumption is that ... Or no, nothing like that happened. I just made this idea myself. (But did you find out?).

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In short, the physicist has many, many different ideas about the origin of the universe. The problem is that there is no evidence behind these ideas. And it is possible that this evidence will never be found. Because as we go back in time, the data available becomes less and less.

There are some speculations about the early state of the universe that can be predicted. But even if they are confirmed, this particular idea will not be confirmed. Because the same prediction can be made from many different theories. This is a fundamental problem with our scientific endeavors. Physicists have created a variety of mathematical stories about how it all began. But that's it, we're here right now.

Our knowledge of the fourteen billion years from the earliest known time of the universe to the present is based on good evidence. And this is a great achievement in the field of cosmology. We all expect that even if we don't get to the beginning, there is still a lot more to learn about the early universe.

We do not currently have the empirical evidence or any theoretical model to go beyond that. To go back, we have to go ahead in physics. And the next big step is to find the theory of quantum gravity. The initial state of the universe cannot be explained by ignoring quantum gravity.

One of the long-standing problems of physics is what quantum gravity is. The search has not been successful for the last 90 years. But there are good reasons to be reasonably optimistic about progress