Inflation and the Big Bang: not an explosion, but an expansion
What happened before the Big Bang? Period of inflation (if it actually was). What do we know about what happened before inflation?
Nothing.
Of course, there are many arguments, supported by a scientific approach, on the subject of what happened before. But there are many of them, they contradict each other, and for today we have no data that could help us to find out which of these arguments are true. There is not even a leading theory, the probability of which most of the scientists would rate as the greatest. Just about this is not known. It may even turn out that the inflation process continues to this day, and it goes in most of the Universe, stopping sometimes in small parts of it (large compared to the part of the Universe that we observe, but small compared to the Universe as a whole).
And after inflation there was a hot big bang. In a previous article explaining the confusion associated with the Big Bang, it was explained that the Universe is not expanding “into something” - it has no such thing as “outside”. Now let's take a closer look at the Big Bang itself, which was in fact not an “explosion”, but an expansion of space, despite all that countless books, videos, articles and statements often describe. Let's look at the differences between the explosion of something in space and the expansion of space itself.
Fig. one
In fig. Figure 1 shows the situation before and after the explosion. Initially, in this example, there is a certain space with a seed in the middle, the role of which is played by a bomb, a grenade, a star, another form of stored energy. Both space and seed exist in advance. Then something happens and the seed explodes. Seed content undergoes some transformation - for example, a chemical or nuclear reaction occurs - with the release of energy. This creates tremendous temperature and pressure inside the seed. Forces associated with compressed temperature and pressure cause the inside of the seed to expand outward in the form of a hot ball of substance. Energy escapes from it at high speed, with a temperature initially equal to that which was inside the seed, and then the pressure and temperature gradually fall until the inside of the seed expands outward into the space that already existed around it, in which it was originally located.
Notice that the cause of the explosion was a reaction that created extremely high pressure and temperature inside a tiny region. It is the imbalance between the enormous pressure and temperature inside the seed and the low pressure and temperature outside that causes the seed to explode outwards. And everything inside was removed from the original location at high speed. The speed of moving away from the starting point cannot exceed the speed of light, therefore there are restrictions on how quickly they can move away from each other.
In fig. 2 shows the process (which, in principle, could go before the moment, shown on the left) the expansion of space. Between the image on the left and the image on the right, the space has doubled, which can be seen from the grid lines. All that is inside the space, and held together by powerful forces - chairs, tables, cats and people - does not expand. Only the space in which they are all expands. In short, the space becomes larger, so there is more space for the objects inside it.
At the same time, objects in fact do not move! They are not pushed away by pressure or temperature, no one kicks them. It’s just that the space between them and around them grows, appears from nowhere, and makes the distance between them more than before. And this increase is uniform (for uniform expansion). In the right image, the distance between the cat and the table has doubled, as is the distance between the cat and the chair. This is what happens when the Universe doubles its size.
Fig. 2
Such a change in space is possible according to Einstein's theory of gravity, but not according to the older theory of Newton. With Einstein, space is not just a place where everything happens; it is a certain thing in itself that can grow, shrink, deform, fluctuate and change shape. (More precisely, space and time together do all this). The ripples of spacetime are called gravitational waves.
As space expands and objects do not move, the theory of relativity does not impose restrictions on the rate of growth of the distance between objects, that is, on the rate of appearance of a new space between them. The distance between two objects can increase faster than the speed of light. There is no contradiction with the theory of relativity.
People often speak using inaccurate and general phrases, something like “the theory of relativity states that nothing can move faster than light”. But the words "nothing" and "move" are ambiguous, and science tells us that the use of inaccurate words can lead to problems. Einstein’s words, if you read them, often also suffer from ambiguity and are easily misunderstood, even though he tried to speak for sure. But Einstein's equations are not ambiguous. The exact statement of the theory of relativity is that if two objects pass by each other in one place of space, and with one of them the observer moves, then the speed of the other object from the point of view of this observer will not be greater than the speed of light. But this does not contradict what I declare: that the distance between two objects in different places can grow faster. And this will be the case in a uniformly expanding universe, if two objects are far enough from each other.
Also note that the cause of the expansion of the universe, unlike an explosion, is not temperature or pressure. I deliberately drew ordinary objects, tables and chairs so that you could see that, compared with an explosion that damages or destroys normal objects, the expansion leaves them intact, they just move away from each other. Expansion may occur in a very hot universe - and in the early stages of the history of our Universe, this was the case during the hot Big Bang. But expansion can go in a very cold universe. There is a suspicion that this also happened during the period of cosmic inflation. And, of course, our Universe is quite cold today, but it is not just expanding, but expanding with acceleration.
The era of the hot Big Bang, in the last stages of which we live, began at some point in time in the form of a large area of space filled with hot, dense soup of particles, which initially expanded and cooled very quickly, and then did it all slower and slower, until the moment that came a few billion years ago. It did not start as a point object that exploded in empty space. How could the hot big bang start after inflation, we will look at the following articles.
Nothing.
Of course, there are many arguments, supported by a scientific approach, on the subject of what happened before. But there are many of them, they contradict each other, and for today we have no data that could help us to find out which of these arguments are true. There is not even a leading theory, the probability of which most of the scientists would rate as the greatest. Just about this is not known. It may even turn out that the inflation process continues to this day, and it goes in most of the Universe, stopping sometimes in small parts of it (large compared to the part of the Universe that we observe, but small compared to the Universe as a whole).
And after inflation there was a hot big bang. In a previous article explaining the confusion associated with the Big Bang, it was explained that the Universe is not expanding “into something” - it has no such thing as “outside”. Now let's take a closer look at the Big Bang itself, which was in fact not an “explosion”, but an expansion of space, despite all that countless books, videos, articles and statements often describe. Let's look at the differences between the explosion of something in space and the expansion of space itself.
Fig. one
In fig. Figure 1 shows the situation before and after the explosion. Initially, in this example, there is a certain space with a seed in the middle, the role of which is played by a bomb, a grenade, a star, another form of stored energy. Both space and seed exist in advance. Then something happens and the seed explodes. Seed content undergoes some transformation - for example, a chemical or nuclear reaction occurs - with the release of energy. This creates tremendous temperature and pressure inside the seed. Forces associated with compressed temperature and pressure cause the inside of the seed to expand outward in the form of a hot ball of substance. Energy escapes from it at high speed, with a temperature initially equal to that which was inside the seed, and then the pressure and temperature gradually fall until the inside of the seed expands outward into the space that already existed around it, in which it was originally located.
Notice that the cause of the explosion was a reaction that created extremely high pressure and temperature inside a tiny region. It is the imbalance between the enormous pressure and temperature inside the seed and the low pressure and temperature outside that causes the seed to explode outwards. And everything inside was removed from the original location at high speed. The speed of moving away from the starting point cannot exceed the speed of light, therefore there are restrictions on how quickly they can move away from each other.
In fig. 2 shows the process (which, in principle, could go before the moment, shown on the left) the expansion of space. Between the image on the left and the image on the right, the space has doubled, which can be seen from the grid lines. All that is inside the space, and held together by powerful forces - chairs, tables, cats and people - does not expand. Only the space in which they are all expands. In short, the space becomes larger, so there is more space for the objects inside it.
At the same time, objects in fact do not move! They are not pushed away by pressure or temperature, no one kicks them. It’s just that the space between them and around them grows, appears from nowhere, and makes the distance between them more than before. And this increase is uniform (for uniform expansion). In the right image, the distance between the cat and the table has doubled, as is the distance between the cat and the chair. This is what happens when the Universe doubles its size.
Fig. 2
Such a change in space is possible according to Einstein's theory of gravity, but not according to the older theory of Newton. With Einstein, space is not just a place where everything happens; it is a certain thing in itself that can grow, shrink, deform, fluctuate and change shape. (More precisely, space and time together do all this). The ripples of spacetime are called gravitational waves.
As space expands and objects do not move, the theory of relativity does not impose restrictions on the rate of growth of the distance between objects, that is, on the rate of appearance of a new space between them. The distance between two objects can increase faster than the speed of light. There is no contradiction with the theory of relativity.
People often speak using inaccurate and general phrases, something like “the theory of relativity states that nothing can move faster than light”. But the words "nothing" and "move" are ambiguous, and science tells us that the use of inaccurate words can lead to problems. Einstein’s words, if you read them, often also suffer from ambiguity and are easily misunderstood, even though he tried to speak for sure. But Einstein's equations are not ambiguous. The exact statement of the theory of relativity is that if two objects pass by each other in one place of space, and with one of them the observer moves, then the speed of the other object from the point of view of this observer will not be greater than the speed of light. But this does not contradict what I declare: that the distance between two objects in different places can grow faster. And this will be the case in a uniformly expanding universe, if two objects are far enough from each other.
Also note that the cause of the expansion of the universe, unlike an explosion, is not temperature or pressure. I deliberately drew ordinary objects, tables and chairs so that you could see that, compared with an explosion that damages or destroys normal objects, the expansion leaves them intact, they just move away from each other. Expansion may occur in a very hot universe - and in the early stages of the history of our Universe, this was the case during the hot Big Bang. But expansion can go in a very cold universe. There is a suspicion that this also happened during the period of cosmic inflation. And, of course, our Universe is quite cold today, but it is not just expanding, but expanding with acceleration.
The era of the hot Big Bang, in the last stages of which we live, began at some point in time in the form of a large area of space filled with hot, dense soup of particles, which initially expanded and cooled very quickly, and then did it all slower and slower, until the moment that came a few billion years ago. It did not start as a point object that exploded in empty space. How could the hot big bang start after inflation, we will look at the following articles.
Source: https://habr.com/ru/post/409717/