At first … well, maybe it didn’t start. Perhaps our universe has always existed — and a new theory of quantum gravity reveals how it works.
Bruno Bent, a physicist studying the nature of time at the University of Liverpool in the United Kingdom, said:
In his work, he adopted a new theory of quantum gravity called the causal set theory. In this theory, space and time are decomposed into individual chunks of space-time. At some level Space-time, According to this theory.
Bento and his collaborators used this causal set approach to explore the beginnings of the universe.They discovered that the universe may have never started — it has always existed in an infinite past and has just evolved into what we call it. big Bang..
connection:Big Bang to Civilization: Events of 10 Amazing Origins
Quantum of gravity
Quantum gravity is probably the most frustrating problem facing modern physics. There are two very effective theories in the universe: quantum physics and quantum physics. General theory of relativity..Quantum physics has produced three successful descriptions four The basic power of nature (((Electromagnetic, Weak and strong) down to a microscopic scale. On the other hand, the general theory of relativity is gravity Invented so far.
But despite all its strengths, the general theory of relativity is incomplete. In at least two specific places in the universe, arithmetic The general theory of relativity simply collapses and cannot produce reliable results: the center of a black hole and the beginning of the universe. These areas, called “singularities,” are space-time spots where the current laws of physics collapse, and are mathematical warning signs that the general theory of relativity overturns itself. In both of these singularities, gravity becomes incredibly strong on a very small length scale.
Related: Eight ways to see Einstein’s theory of relativity in real life
Thus, to solve the mystery of the singularity, physicists need a microscopic description of strong gravity, also known as the quantum theory of gravity. There are many candidates there. String theory And loop Quantum gravity..
And there is another approach that completely rewrites our understanding of space and time.
Causal set theory
In all current physics theories, space and time are continuous. They form the smooth fabric that underlies all reality. In such a continuous space-time, two points can be as close to each other as possible in space, and two events can be as close in time to each other as possible.
“There are so many things in reality that most people are even involved in science fiction and fantasy.”
Bruno Bent
However, another approach, called causal set theory, reconsiders space-time as a series of individual chunks, or “atoms” of space-time. This theory imposes strict limits on how close an event can be in space and time, as an event cannot be closer than the size of an “atom”.
Related: Can I stop the time?
For example, if you’re looking at the screen reading this, everything looks smooth and continuous. However, if you look at the same screen through a magnifying glass, you may see pixels that divide the space, and you can see that it is impossible to bring two images on the screen closer than one pixel.
This theory of physics excited Bento. “It’s an approach to quantum gravity, not only trying to be as basic as possible, actually rethinking the concept of space-time itself, but also playing a central role in time and what it is physically. I was excited to find this theory of giving, which means over time, how physical your past really is, and whether the future already exists, “Bent told Live Science. rice field.
The beginning of time
Causal sets theory has important implications for the nature of time.
“Most of the philosophy of causal sets is that the passage of time is physical and results from some emergent illusion or something that happens in the brain that makes us think that time has passed. It’s not. This process is itself a manifestation of physical theory. ” “Therefore, in the theory of causal sets, a causal set grows one” atom “at a time and grows larger and larger. “
The causal set approach removes the big bang singularity problem neatly, as singularities cannot theoretically exist. Matter cannot be compressed into infinitely small points — they cannot be smaller than the size of space-time atoms.
So what would the beginning of our universe look like without the Big Bang singularity? There, Bento and his collaborator, Imperial College London graduate student Stav Zalel, took up the thread and explored what causal sets theory says about the first moments of the universe. Their work appears in a treatise published in the preprint database on September 24th. arXiv.. (This treatise has not yet been published in a peer-reviewed scientific journal.)
The treatise examined “whether there must be a beginning in the causal set approach,” Bento said. “In the formulation and dynamics of the original causal sets, classically speaking, the causal sets grow from nothing to the universe we see today. Instead, in our work, the causal sets are infinite. So there is no big bang as a starting point. It’s the past, so something is always in front. “
Their work implies that the universe may not have had its beginnings — it simply always existed. What we perceive as the Big Bang is a particular moment in the evolution of this ever-present causal set, which may not have been the true beginning.
However, there is still a lot to do. It is not yet clear whether this endless causal approach will enable a physical theory that can be used to explain the complex evolution of the universe during the Big Bang.
“You can ask if this is still [causal set approach] We can interpret what such dynamics mean physically in a broader sense, in a “reasonable” way, but we have shown that the framework is actually possible. You can do this, at least mathematically. “
In other words, it’s … the beginning.
Originally published in Live Science.
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