BEIJING, May 6 (Xinhua) — For decades, physicists have told us that the universe was at an infinitely high density and temperature, imagining it as an infinitely dense sphere, and then exploded, producing atoms, molecules, stars and galaxies that we see today, according tomedia reports.
But recently, new theoretical physics studies have found a possible window into the early universe, noting that this period may not be really “very early”. Instead, this may be just part of the latest “explosion-rebound” cycle. Such a cycle has occurred at least once and may last forever.
Of course, these theoretical predictions will need to be tested a lot before physicists decide to abandon the Big Bang in favor of the “Big Bang-Bounce” cycle.
The Big Bang Theory
Scientists have a good understanding of the early universe, and this is the Big Bang theory that we know and widely accept. In this model, the universe was much smaller, much hotter and much denser from the present. In the early universe 13.8 billion years ago, the elements that make up everything today were formed in about 12 minutes.
The Big Bang theory suggests that even earlier, at some point, the entire universe (containing all the stars, all the galaxies, all things) was only the size of a peach, and the temperature was more than a trillion degrees.
Surprisingly, all the observations so far confirm this fantastic story. Astronomers have done everything from observing the electromagnetic radiation left over from the young universe to measuring the abundance of the lightest elements, and they are found to fit the Predictions of the Big Bang theory. As far as we know, this is the most accurate picture of the early universe available.
Still, we know that the framework of the Big Bang Theory is incomplete – there’s a piece of jigsaw puzzle that’s missing, and that piece of the puzzle is the earliest moment of the universe itself.
This is one of the biggest puzzles in the universe.
The problem is that the physics we used to understand the early universe (the wonderful and complex mix of general relativity and the physics of high-energy particles) only brought us to the moment of the Big Bang. As we try to push the first moments of the universe forward, mathematics becomes more and more difficult to understand until it can’t be applied.
An important problem that physicists have yet to explore is the “oddity” of the big bang, or a point of infinite density. On the face of it, this tells us that at some point the universe is crammed into a point of infinite size and density. This is clearly absurd, and what it really means is that we need new physics to solve this problem – the theoretical tools at the moment are not good enough.
To solve this problem, we need new physics tools, something that can handle gravity and other forces at ultra-high energy. This is what string theory claims, and it can be used as a physical model capable of handling gravity and other forces at ultra-high energy. In other words, string theory claims to explain the first moments of the universe.
One of the earliest string theory concepts was the “ekpyrotic universe”, a word derived from The Greek language, meaning “fire”. Under this concept, what we know about the Big Bang is caused by other events that occurred before it — the Big Bang is not the beginning, but part of a larger process.
After the expansion of the concept of the “fire universe”, a theory inspired by string theory, the cyclic cosmology, was developed. Technically, the concept of the universe’s constant cycle-after has been around for thousands of years, earlier than physics, but string theory has laid a solid mathematical foundation for the idea. As is generally expected, this “circular universe” continues to bounce between the Big Bang and the Big Crunch, either an eternity of the past or the eternity of the future.
According to the great bounce theory, each cycle begins with a smooth little universe, but is unlikely to be as small as a wonder;
Before the initial
The “circular universe” theory sounds cool, but early mathematical models had difficulty matching observations. This is a very important issue when we really try to do scientific research.
The main obstacle is how to match the observations of the cosmic microwave background. Cosmic microwave background is the 380,000-year-old thermal radiation left over from the birth of the universe, known as “the oldest light in the universe.” Although we cannot directly observe everything before the cosmic microwave background, if we want to begin to repair the physics of the early universe in theory, we will affect these “residual light” patterns.
Therefore, the circular universe seems to be a simple but incorrect concept. For years, however, scientists have been carrying the seeds of the “fire universe” theory. In a paper published in the arXiv database in January 2020, researchers such as Robert Brandenberger, a physicist at McGill University in Canada, explored the theory’s mathematical conundrums and found factors that had previously gone unnoticed. They found that at the time of the “bounce”, when the universe shrinks to a tiny point and returns to the Big Bang state, theoretical predictions can be agreed with the results of observational tests.
In other words, although the physics of this critical period is very complex (and has limited understanding), it does give us a fundamental correction of the time and position of the universe. Of course, to fully test this model, we must also wait for a new generation of cosmological experiments. Until then, “what the universe was before” will be a question of mystery. (Any day)