Moscow, July 3 - RIA Novosti, Vladislav Strekopytov. The term "our universe" is often encountered in scientific articles about cosmology. It turns out that scientists are seriously considering the possibility that others existed - before us, or in parallel, made of antimatter , or those that traveled backwards in time. All of this is supported by rigorous physical and mathematical calculations. Various models about the universe and recently obtained new data - in the materials of RIA Novosti.
Our Universe
Modern physics does not rule out the possibility that the universe we live in is not the only one. So, just in case, scientists have agreed to write the word "universe" in uppercase letters when referring to our space-time, and in lowercase letters otherwise.
According to calculations by cosmologists, the universe was formed 13.77 billion years ago by the Big Bang of a very small volume of highly concentrated matter. Since then, it has been expanding at a rate equal to the Hubble constant, one of the fundamental physical parameters.
Based on the volume of all visible and invisible matter that can be detected in any way, the length of the universe today from edge to edge is about 93 billion light years. Beyond this limit, some scientists call it "infinite nothingness," while others believe that space-time will close in on itself, forming a hypersphere.
In particular, this is shown by deviations in the cosmic microwave background - residual electromagnetic radiation produced about 375,000 years after the Big Bang when the first atoms were formed.
Researchers, meanwhile, agree that the universe was much smaller in the past, and purely theoretically, tracking its evolution in the opposite direction could lead to the Big Bang, when everything was created from nothing.
to our universe
According to generally accepted cosmological theory, the universe was formed from a singularity - when matter and energy were compressed to a single point. During the first fraction of a second of the Big Bang, known as inflation, the universe expanded to gigantic proportions. What happened before Singularity is not explained by theory, and there is no physical or mathematical description of this state itself.
Scientists who adhere to the cyclic model believe that there were other universes before ours. Maybe similar to ours, but going in the opposite direction. Over time, she shrank to a point. A big bang happened. The
conformal cycle model shows that our universe is just one stage in the life of the multiverse that goes through countless cycles. During each of them, it cools and expands until the mass of all its material particles is reduced to zero. The duration of the cycle is trillions of years.
Since the 1980s, American scientists at Pennsylvania State University have been developing an alternative Big Bounce model, according to which the expanding universe is the result of the collapse of a previous phase of a supercompressed universe. Using a mathematical device that combines quantum mechanics and relativity, theorists have shown that inhomogeneities in the cosmic microwave background radiation are the result of inevitable quantum fluctuations in this transition.
There are many more bizarre assumptions. For example, our universe is a white hole , the hypothetical rear of a black hole in another universe. From the other side it sucks in matter, from this side it throws it out. Most physicists believe that white holes cannot exist because they would violate the second law of thermodynamics. However, the general relativity equations allow them to exist under conditions where time flows backwards. There is mathematical evidence that the Big Bang may have originated at the site of a supermassive white hole.
The universe never began
Almost all concepts, whether they view the universe as a self-contained system or as an element of a complex cyclic process, start from the fact that there was a singularity at the beginning. In rebuttal, some scientists argue that such a state is impossible even in theory. The matter of the world cannot be reduced to an infinitesimal point, and at this point, time does not exist.In modern physics, space and time are continuous, smooth structures that make up reality. In such a space-time continuum, two points can be infinitely close, but they will never coincide.
British scientists Bruno Valeisho Bentou and Stav Zalel propose using causal set theory to describe the universe—a quantum approach in which space-time is not a continuum but a collection of discrete fragments.
As an analogy, they reference a monitor screen, which appears smooth and continuous but is actually made up of individual pixels. In this case, it is not possible to achieve such an increase in merging or splitting a pixel with neighboring pixels.
Causal set theory understands singularities as single quanta or atoms in the universe from which all others are formed. At the same time, it turns out that the universe did not have a unique beginning moment, and that the physical world in one form or another has always existed.
Mirror Universe
Science fiction writers often use the image of a mirror universe, which means a parallel world where you can meet your double or change your personal destiny. The concept of a mirror universe also exists in theoretical cosmology.
In physics experiments, all particles appear together with the antiparticle . So scientists have long been puzzled by the fact that the universe is mostly composed of matter and actually has no antimatter. To explain this asymmetry, in the 1990s cosmologists proposed the hypothesis that, along with our "matter" universe, mirror pairs were formed filled with antimatter.
Later, scientists showed that each of these universes had its own time, coinciding with the increase in entropy, but that its general direction was preserved. Therefore, the hypothesis of the mirror universe is quite consistent with physical theory and does not violate the second law of thermodynamics.
In a recent article, Canadian and British scientists proposed this concept, suggesting that time flows symmetrically in two directions and that the universe before the Big Bang was an "inverse version" of our own. Such models explain many unresolved physics problems related to neutrino oscillations, dark energy, dark matter, and the absence of strong gravitational waves in space.
The authors say dark matter is sterile neutrinos formed during the Big Bang, similar to the Hawking radiation of black holes. The energy of gravitational waves is supposed to shake our world, but instead it separates the two universes.
American physicists from the University of New Mexico and the University of California, Davis believe that the concept of a mirror universe could also solve the problem of discrepancies between different measurements of the Hubble constant. They found that when the expansion rate of the universe changes in a cosmological model, other constants, such as gravity free fall or the photon-electron scattering rate, remain unchanged. According to the researchers, this invariance means there is an expanding mirror universe balancing our universe with a weak gravitational pull.
The multiverse
Inflation model, proposed by American scientist Alan Guth in 1981 and developed by Soviet astrophysicists Alexei Starobinsky, Andrei Linde, and Vyacheslav Mukhanov, suggests that the physical expansion in the early stages of the Big Bang formed a soap bubble cosmic network. Together. We lived in one of them and couldn't see what was going on elsewhere.
The multiverse theory can neither be proven nor falsified by . But it opens up vast vistas for new theory building, which is why scientists love it. For example, within the framework of this hypothesis, physicists from France and Switzerland explained why the mass of the Higgs boson obtained in experiments is three times smaller than the mass predicted by the standard model.
Scientists believe that initially bosons were not evenly distributed among different parts of the multiverse. Due to internal forces, regions containing heavy particles are destroyed within a fraction of a second. Our universe with the light Higgs boson still exists.
