(ORDO NEWS) — The universe was an infinitely small point, which then exploded, and the substance rushed into space. This is how many imagine the Big Bang. But scientists would smash such a description to smithereens. Two physicists discuss the most common misconceptions about the origin of the universe.
The entire universe was reduced to an infinitely small point, which then exploded, and the substance rushed into space.
Everything is wrong in this statement, astrophysicists say.
“This is not the way to think about the Big Bang theory,” says Professor Torsten Bringmann. He is engaged in cosmology and astroparticle physics at the University of Oslo.
Professor and theoretical physicist Are Raklev at the University of Oslo notes that many of the descriptions create misconceptions about the Big Bang theory.
Raklev and Bringmann take apart the most common misconceptions for us.
Denser and hotter
First, what does the Big Bang really mean?
“The Big Bang theory is that the universe was in a much hotter and denser state about 14 billion years ago, and it was expanding. That’s all, nothing more, ”Raklev explains.
The cosmos was constantly expanding and getting colder.
Based on this theory, scientists have gained a good understanding of the history of the universe, such as when elementary particles appeared and when atoms, stars and galaxies were formed.
We know very well what happened to the universe at the age of about 10-32 seconds. This means 0.0000000000000000000000000000000001 seconds, according to astrophysicist Jostein Riiser Kristiansen.
Let’s move on to myths.
1. “It was an explosion”
The very phrase “Big Bang” sounds like something has detonated, says Are Raklev. But this is not a very good description of what happened. Why? You will soon find out.
In the early 1920s, mathematician Alexander Friedmann discovered that Einstein’s general theory of relativity implies an expansion of the universe. The Belgian priest Georges Lemaître came to the same conclusion.
Soon, Edwin Hubble demonstrated that galaxies are indeed moving away from each other.
The galaxies are moving away from us. Light from them is subject to redshift – that is, its waves have become longer and moved to the red side of the spectrum. Moreover, galaxies are disappearing faster and faster from our field of vision.
One day, almost all the galaxies that we see through telescopes today will disappear from our sky. Eventually the stars will go out, and the observer will be left with an eternally dark and desolate sky.
Fortunately, this is still very, very far away.
This story can be rewound in the opposite direction. Now the galaxies are diverging, but they were once much closer to each other.
“If you take the observable universe and rewind history, everything fits into a very small area,” says Raklev.
So we come to the moment of the Big Bang. So what happened?
It is easiest to imagine that the Big Bang was an ordinary explosion, as a result of which the substance scattered in different directions, like pieces of wood after being hit by a hand grenade.
“But during the Big Bang, it wasn’t matter at all that flew in different directions,” says Raklev. “The universe itself, the outer space itself, is expanding.”
2. “The universe is expanding in something”
Galaxies are not running away from each other – it is space itself that is expanding.
Imagine a ball of raisin dough. Dough is space, and raisins are galaxies. The dough begins to rise, and the raisins are farther apart, but they themselves do not actually move.
Thorsten Bringmann gives an example of the surface of a balloon. Draw dots on it and see how the distance between them increases as you inflate.
“However, it is also true that galaxies also move as a result of mutual gravitational attraction – this is an additional effect,” says Raklev.
Light from several galaxies is characterized by a blue shift, which means that they are moving towards us. This applies to some of the nearby galaxies. But at large distances, this effect is overridden by Hubble’s law: the speed at which galaxies move away from each other increases in proportion to the distance. It turns out that the distance increases faster than the light has time to pass between two points located very far from each other.
Okay, the ball of dough expands in the space inside the oven. What about the universe? What is there outside of it?
The universe is expanding in nothing. Scientists do not think that it has any “edge”.
What is called the observable universe is a 93 billion light-year bubble around us. The further we look, the deeper we go into the past. We cannot observe or measure anything beyond the distance that light has traveled to us since the Big Bang.
As outer space expanded, the size of the observable universe, paradoxically, exceeds 14 billion light years.
But scientists believe the universe outside of our bubble is much larger. It may be endless.
The universe can be as flat as it looks. Then the two beams of light will remain parallel and will never intersect. If you tried to go to the edge of the universe, you would never reach it. The universe goes on forever.
If the universe has a positive curvature, then in theory it can be finite. Then it will resemble a kind of ball. If you went looking for the “end,” you would return to the same place where you started, regardless of the direction you chose. As if you go around the globe and return to the starting point.
In any case, the universe is capable of expanding without resting on anything.
The infinite universe, which is getting bigger, still remains infinite. The “universe-ball” has no edge.
3. “The Big Bang had a center”
If you imagine the Big Bang as a grenade explosion, there is a great temptation to imagine some kind of epicenter. As is the case with conventional explosions.
But not with the Big Bang. Almost all galaxies are moving away from us in all directions. The feeling is created that the Earth was the center from which the universe began. But this is certainly not the case.
All other observers will see the same from their home galaxy, explains Torsten Bringmann.
The universe is expanding everywhere at the same time. The Big Bang did not take place in any particular place.
“It happened everywhere,” – Raklev.
4. “The whole universe was enclosed in a tiny point”
Indeed, at the beginning of the Big Bang, everything in our observable universe was concentrated in a very small space incredibly close to each other.
But how can the universe be both infinite and very small?
You may have read that the universe was at first smaller than an atom, and then reached the size of a soccer ball. But in this case it means that at the beginning the space still had boundaries, a certain edge.
“There is no evidence that the universe was already infinite at the time of the Big Bang,” says Raklev. “It was simply smaller in the sense that the distances that were then measured in meters increased by incomprehensible billions of light years.”
When we talk about what the universe was like at that time, we are only talking about our observable universe.
“The entire observable universe came out of a tiny area that could be called a point. But the point next to it also expanded, and the next point too. It’s just that all of this is now so far away from us that we cannot see it,” Raklev explains.
5. “The universe was infinitely small, hot and dense”
You may have heard that the universe began with a singularity? She was infinitely small, hot, and so on. It may have been, but many physicists doubt that this gives any answer.
Singularity is a concept that is used when mathematics cannot cope with a description, and it is impossible to describe a phenomenon using ordinary physics. This is how cosmologist Steen H. Hansen explains.
Thorsten Bringmann summarizes what this means in the context of the Big Bang.
“The universe is slightly larger today than it was yesterday. And even a little more than it was a million years ago. The Big Bang theory relies on extrapolating this process back in time. And this requires one more theory: the general theory of relativity.”
“If I extrapolate the process to the very end in the opposite direction, the universe will get smaller and smaller, denser and denser, hotter and hotter. Finally, you end up with something very small, very hot and dense. This is the Big Bang theory, it implies that this is how it all began. Because we just have to stop there,” says Bringmann.
If you rewind general relativity to the very end, you get a point with incredibly high density and temperature. Its dimensions tend to zero.
“This is a purely mathematical extrapolation that goes beyond what the theory actually allows,” says Bringmann.
“At the same time, at some point, it starts to talk about such density and temperature that we simply no longer have physical theories to describe them.”
Physicists need a different theory, he said. And there are people who are doing just that.
“What does it take to describe such an extreme condition? This brings us to the area where we need a theory that combines gravity and quantum theory. Nobody could formulate it. And we just expect that the theory of quantum gravity will not lead us to the conclusion that everything goes back to one specific point.”
So what happened at the very beginning of the history of the universe is still hidden from us, that – for now.
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