Our Universe originated 13.7 billion years ago, generated by the Big Bang, and for several generations, scientists have been trying to understand this phenomenon.
At the end of the 20s of the XX century, Edwin Hubble discovered that all the galaxies we see scatter - like fragments of a grenade after an explosion, at the same time the Belgian astronomer and theologian Georges Lemaitre put forward his hypothesis (in 1931 it was published on the pages of "Nature"). He believes that the history of the universe began with the explosion of the "primary atom", and this gave rise to time, space and matter (earlier, in the early 1920s, the Soviet scientist Alexander Fridman, analyzing Einstein's equations, also came to the conclusion that "The universe was created from a point" and it took "tens of billions of our usual years").
At first, astronomers vehemently rejected the Belgian theologian's reasoning. Because the Big Bang theory was perfectly combined with the Christian belief in God the Creator. For two centuries, scientists have suppressed the penetration into science of any kind of religious speculation about the "beginning of all beginnings." And now God, expelled from nature under the measured swaying of the wheels of Newtonian mechanics, unexpectedly returns. He is coming in the flames of the Big Bang, and it is difficult to think of a more triumphant picture of his appearance.
However, the problem was not only in theology - the Big Bang did not obey the laws of the exact sciences. The most important moment in the history of the Universe was beyond comprehension. At this singular (singular) point, located on the axis of space-time, the general theory of relativity ceased to operate, because pressure, temperature, energy density and curvature of space rushed to infinity, that is, they lost all physical meaning. At this point, all these seconds, meters and astronomical units disappeared, turned not into zero, not into negative values, but into their complete absence, into absolute meaninglessness. This point is a gap that cannot be overcome on the stilts of logic or mathematics, a hole through time and space.
It was not until the late 1960s that Roger Penrose and Stephen Hawking showed convincingly that, within the framework of Einstein's theory, the Big Bang singularity is inevitable. However, this could not facilitate the work of theorists. How to describe the Big Bang? What was, for example, the cause of this event? After all, if before him there was no time at all, then there seemed to be no reason that gave birth to him.
As we now understand, in order to create a complete theory of the Big Bang, it is necessary to link together Einstein's doctrine, which describes space and time, with quantum theory, which deals with elementary particles and their interactions. Probably, it may take more than one decade before it will be possible to do this and to derive a single "formula of the universe."
And where, for example, could the enormous amount of energy appear that gave rise to this explosion of incredible power? Perhaps it was inherited by our Universe from its predecessor, which collapsed into a singular point? However, then where did she get it? Or was the energy poured into the primordial vacuum, from which our Universe slipped out like a "bubble of foam"? Or do the universes of the older generation transfer energy to the universes of the younger generation through black holes - those singular points - in the depths of which, perhaps, new worlds are born that we will never see? Be that as it may, the Universe in such models appears as an "open system", which does not fully correspond to the "classical" picture of the Big Bang: "There was nothing, and suddenly the universe was born."
The universe at the time of formation was in an extremely dense and hot state.
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Or perhaps, according to some of the researchers, our Universe is generally … devoid of energy, or rather, its total energy is zero? The positive energy of radiation emitted by matter is superimposed on the negative energy of gravity. Plus and minus gives zero. This notorious “0” seems to be the key to understanding the nature of the Big Bang. From him - from "zero", from "nothing" - everything was instantly born. By chance. Spontaneously. Just. A negligible deviation from 0 gave rise to a universal avalanche of events. One can also make such a comparison: a stone ball, balancing on a top of some Chomolungma as thin as a spire, suddenly swung and rolled down, creating an "avalanche of events."
1973 - physicist Edward Trion from America, tried to describe the process of the birth of our universe, using the Heisenberg uncertainty principle, one of the foundations of quantum theory. According to this principle, the more accurately we, for example, measure energy, the more uncertain time becomes. So, if the energy is strictly zero, then the time can be arbitrarily long. So large that sooner or later a fluctuation will arise in the quantum vacuum from which the Universe is to be born. This will lead to the rapid growth of space, seemingly out of nothing. “It's just that Universes are sometimes born, that's all,” so simply Trion explained the background of the Big Bang. It was a big Random Explosion. That's all.
Could the Big Bang happen again?
Oddly enough, yes. We live in a universe that can still bear fruit and give birth to new worlds. Several models have been created that describe the "Big Bangs" of the future.
Why, for example, in the same vacuum that gave birth to our Universe, do not new fluctuations appear? Perhaps, over these 13.7 billion years, an innumerable set of worlds appeared next to our universe, which did not touch each other in any way. They have different laws of nature, there are different physical constants. In most of these worlds, life could never arise. Many of them die immediately, collapse. But in some Universes - by pure chance! - there are conditions under which life is capable of originating.
But the point is not only in the vacuum that remains before the beginning of "all times and peoples." Fluctuations fraught with future worlds can also arise in a vacuum that is diffused in our Universe - more precisely, in the dark energy that fills it. This kind of model of the "renewing Universe" was developed by the American cosmologist, a native of the Soviet Union, Alexander Vilenkin. These new "big bangs" do not threaten us. They will not destroy the structure of the Universe, they will not burn it to ashes, but only create a new space beyond the limits of our observation and understanding. Perhaps, such "explosions", marking the birth of new worlds, occur in the depths of numerous black holes dotting space, believes the American astrophysicist Lee Smolin.
Another native of the USSR, living in the West, cosmologist Andrei Linde believes that we ourselves are capable of creating a new Big Bang, having collected at some point in space a huge amount of energy exceeding a certain critical limit. According to his calculations, space engineers of the future could take an invisible pinch of matter - only a few hundredths of a milligram - and condense it to such an extent that the energy of this clot will be 1015 gigalectronvolts. A tiny black hole will form, which will begin to expand exponentially. This will create a “daughter universe” with its own space-time, rapidly separating from our universe.
… There are many fantastic things in the nature of the Big Bang. But the validity of this theory is proved by a number of natural phenomena. These include the observed expansion of the Universe, the picture of the distribution of chemical elements, as well as the cosmic background radiation, which is called the "relic of the Big Bang".
Before the Big Bang?
The world does not exist forever. It originated in the flames of the Big Bang. However, was this a unique phenomenon in the history of space? Or a recurring event like the birth of stars and planets? What if the Big Bang is just a phase of transition from one state of Eternity to another?
Many physicists say that initially there was Something and not Nothing. Perhaps our universe - like others - was born from an elementary quantum vacuum. But no matter how “minimal simple” such a state is - and the laws of physics do not allow to exist less than a quantum vacuum - it cannot be called “Nothing”.
Perhaps the Universe we see is just another aggregate state of Eternity? And the bizarre arrangement of galaxies and galaxy clusters - something like a crystal lattice, which in the n-dimensional world that existed before the birth of our Universe, had a completely different structure and which was possibly predicted by the "formula for everything" that Einstein was looking for? And will it be found in the coming decades? Scientists are intensely peering through the wall of the Unknown, which has fenced off our universe, trying to understand what happened in a moment before, according to our usual ideas, there was absolutely nothing. What forms of the Eternal cosmos can be imagined by endowing time and space with those qualities that are inconceivable in our universe?
Some of the most promising theories that physicists are trying to squeeze a whole Eternity into are perhaps the theory of quantum geometry, quantum spin dynamics, or quantum gravity. The greatest contributions to their development were made by Abei Ashtekar, Ted Jacobson, Jerzy Lewandowski, Carlo Rovelli, Lee Smolin and Thomas Thiemann. All these are the most complex physical constructions, whole palaces, erected from formulas and hypotheses, just to hide the gap hidden in their depth and darkness, the singularity of time and space.
The era of the singularity
The roundabout paths of new theories force us to step over the seemingly obvious truths. So, in quantum geometry, space and time, previously infinitely split, suddenly break into separate islands - portions, quanta, less than which there is nothing. All singular points can be embedded in these "boulders". Space-time itself turns into an interweaving of one-dimensional structures - a "network of spins", that is, it becomes a discrete structure, a kind of chain woven from separate links.
The volume of the smallest possible loop of space is only 10-99 cubic centimeters. This value is so small that there are many more quanta of space in one cubic centimeter than those same cubic centimeters in the Universe we observe (its volume is 1085 centimeters in a cube). There is nothing inside the quanta of space, no energy, no matter - just as inside a mathematical point - by definition - there is no triangle or icosahedron. But if we apply the "submicroscopic tissue of the universe" hypothesis to describe the Big Bang, we get amazing results, as Abei Ashtekar and Martin Bojovald of the University of Pennsylvania have shown.
If we replace the differential equations in the Standard theory of cosmology, which assume a continuous flow of space, with other differential equations following from the theory of quantum geometry, then the mysterious singularity disappears. Physics does not end where the Big Bang begins - this is the first encouraging conclusion of cosmologists, who refused to accept the properties of the universe that we see as the ultimate truth.
In the theory of quantum gravity, it is assumed that our Universe (like all others) was born in as a result of a random fluctuation of the quantum vacuum - a global macroscopic environment in which there was no time. Every time a fluctuation of a certain size appears in a quantum vacuum, a new Universe is born. It “branches off” from the homogeneous environment in which it was formed and begins its own life. Now she has her own history, her own space, her own time, her own arrow of time.
In modern physics, a number of theories have been created showing how from an eternally existing environment, where there is no Macro-time, but at some points of which its micro-time flows, such a huge world as ours can arise.
For example, physicists Gabriele Veneziano and Maurizio Gasperini from Italy, within the framework of string theory, suggest that the so-called "string vacuum" existed originally. Random quantum fluctuations in it led to the fact that the energy density reached a critical value, and this caused a local collapse. Which ended with the birth of our Universe from a vacuum.
Within the framework of the theory of quantum geometry, Abei Ashtekar and Martin Bojovald showed that space and time can arise from more primitive fundamental structures, namely "spin networks".
Eckhard Rebhan of the University of Düsseldorf and - independently of him - George Ellis and Roy Maartens of the University of Cape Town develop the idea of a "static universe", which was already pondered by Albert Einstein and the British astronomer Arthur Eddington. In their quest to dispense with the effects of quantum gravity, Rebhan and his colleagues came up with a spherical space that sits in the midst of an eternal void (or, if you prefer, empty eternity), where there is no time. Due to some instability, an inflationary process develops here, which leads to a hot Big Bang.
Of course, the listed models are speculative, but they fundamentally correspond to the modern level of development of physics and the results of astronomical observations of the last few decades. In any case, one thing is clear. The Big Bang was more of an ordinary, natural event, and not one of a kind.
Will this kind of theory help us understand what could have happened before the Big Bang? If the universe was born, what gave birth to it? Where does the “genetic imprint” of its parent appear in modern theories of cosmology? 2005 - Abei Ashtekar, for example, made public the results of his new calculations (Tomasz Pavlovsky and Paramprit Singh helped to do them). From them it was clear that if the initial premises are correct, then the same space-time existed before the Big Bang as after this event. The physics of our universe, as if in a mirror, was reflected in the physics of the other world. In these calculations, the Big Bang, like a mirror screen, cut through Eternity, placing next to the incompatible - nature and its reflection. And what is authenticity here, what is a ghost?
The only thing that can be seen "from the other side of the mirror glass" is that the Universe was not expanding at that time, but was contracting. The Big Bang became the point of its collapse. At this moment, space and time stopped for a moment in order to be reflected again - to continue - to rise like a phoenix in the world we know, that universe that we measure out with our formulas, codes and numbers. The universe has literally turned itself inside out, like a glove or a shirt, and has been steadily expanding ever since. The Big Bang was not, according to Ashtekar, "the creation of the whole Universe from Nothing", but was only a transition from one dynamic form of Eternity to another. Perhaps the Universe is going through an endless series of "big bangs", and these tens of billions (or whatever) of years separating its separate phases are only periods of the "cosmic sinusoid"according to the laws of which the universe lives?
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A. Volkov