The recent discovery of gravitational waves from the Big Bang that gave birth to our universe has triggered waves in astrophysicist and cosmological circles. Some enthusiastically welcomed the new discovery, claiming that it finally proved the reality of inflation (the so-called rapid expansion of the universe postulated by the theory after the Big Bang).
Others called for caution, pointing out that the waves detected could have been due in part to factors other than inflation alone. Some announced that these results finally buried almost all alternative theories put forward to explain the observed properties of the universe, others warned against excessive haste, calling first to "reliably prove" the inconsistency of possible alternatives. Against this general agitated background, the speech of one of the leading modern cosmologists, Andrei Linde from Stanford University, was especially interesting.
Welcoming the new discovery, he said that it not only “removes 90 percent of all other inflation models from discussion,” but also “fits perfectly with the theory of chaotic inflation,” that is, the theory that Linde himself developed about 30 years ago. It was not by chance that Linde's words aroused the special interest of all his colleagues. The fact is that if further tests really confirm the reality of chaotic inflation, this will mean that cosmology has finally managed to solve a painful and fundamental question, to which it has not been able to give a satisfactory answer for many decades.
This question, as you will now see, is also fundamental for us, ordinary curious people, because in its most primitive form it sounds like this: why do we exist at all?
Let me explain now. Already in the middle of the last century, it was noticed that the basic physical constants (for example, the electron charge, the gravitational constant in the law of universal gravitation and a number of other fundamental quantities) are extremely accurately adjusted to ensure that life in the universe could exist in the form in which we we know.
There are numerous other examples of such a fine adjustment of the laws of nature to the needs of an anthropos, that is, a person. Let's say that our life is based on carbon, and carbon, as the study of the processes of formation of chemical elements has shown, could not appear in the universe if the energy levels in atoms lighter than carbon, elements differed even by billionths of what is on really.
Another example, already from the geometry of space: for the emergence and development of life, planets are needed that revolve around their stars according to the law of gravity. And the general theory of relativity shows that in the space of two dimensions, gravity would be too weak to keep the planets near the stars, and in the space of four or more dimensions, there can be no gravity at all.
For the anthropos, only that space of three dimensions remains, which we see around us. And there are a great many such examples. Those who are interested I will refer to the wonderful book by Barrow and Tippler, "The Cosmological Anthropic Principle."
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How do you explain such a subtle fit? Back in 1973, the famous astrophysicist Brandon Carter, speaking at the Krakow conference in honor of the 500th anniversary of the birth of Copernicus, formulated a possible answer to this question. This answer is called the "anthropic principle". He argues that contrary to the old (Copernican) belief that the Earth's location in space is no different from all other possible locations in the universe, in fact, Carter says, “its position, while not necessarily central, is still somewhat special. ".
What is this feature? The fact that in the entire surrounding part of the universe visible to us, the laws and constants of nature are exactly what are needed for the emergence of life and anthropos as its "crown".
In other words, we appeared in such a special (from our point of view) place in the universe, where only we could appear. If we assume that there are many other corners in the universe that we do not see, then it is quite possible that the laws and constants of nature are different there, life and man could not appear there, and therefore no one can wonder why the laws of nature are around him are such that they exclude its occurrence.
Thus, the answer to our fundamental question boils down to the fact that we exist, because by some incredibly happy coincidence in our part of the universe, exactly such laws and constants of nature have formed, which turned out to be ideally adjusted to the possibility of our appearance.
This formulation of the anthropic principle was later called weak, because it is possible to make a stronger statement, which is called the strong anthropic principle. According to this principle, there are no other parts or places in the universe - it all and immediately arose such that its laws and constants are the same everywhere and are everywhere exactly adjusted to the possibility of the appearance of life and reason. This sounds more logical than the statement about “different places” of the universe with “different laws” (why would it suddenly ?!). But in this form, the anthropic principle strongly resembles stories about the deliberate (divine?) Creation of the entire universe for the sake of man, and therefore most scientists resolutely refused to accept it. Nevertheless, the fact of the fine fit was evident and demanded to be explained. Linde was one of the few who tried in earnest,that is, with the help of rigorous theoretical calculations, check: could there really be such scenarios for the birth of the universe that would explain this fit?
Let me remind you that the original scenario of the Big Bang was born almost immediately after Einstein created the general theory of relativity, which connected gravity with the properties of space and time. Einstein believed that the universe is always in a stationary state, and the gravity of all its bodies to each other is balanced by a kind of bursting field (today it is called the field of dark energy).
But a few years later, Hubble discovered that the universe is actually expanding (all galaxies are moving away from each other) with a certain small but noticeable speed, as if all these galaxies had once received some initial impulse and continue to move by inertia (today it is known that the field of dark energy even accelerates this movement). This initial impulse was named the Big Bang (astrophysicist Hoyle derisively christened it Big Bang - "Big Clapperboard").
The Big Bang theory described the birth and development of the universe very well. She argued that the universe arose as a lump of extremely hot and dense plasma, which gradually expanded (along with its space) and gradually cooled down.
Initially, its matter could not be divided into matter and energy, but as it cooled down, force (energy) fields began to appear (separate from each other) - nuclear, weak, electromagnetic, and along with them particles corresponding to them began to appear - quarks, electrons, neutrinos, etc. And then finally (the theory indicated that about 380 thousand years after the explosion) the universe cooled down so much that the quanta of energy did not break the newborn atoms, and then the substance fell out of the general plasma.
A void (vacuum) remained between the atoms, which was filled with electromagnetic radiation of enormous intensity. Atoms began to stick together into clumps of matter (eventually forming the first stars and galaxies), and the residual radiation continued to cool, that is, from very short-wavelengths to become increasingly long-wavelengths (both due to energy loss in collisions with matter, and as a result of stretching of waves from for the continued expansion of space), and by now it has cooled down to 3 degrees Kelvin (its wavelength is already several millimeters). It was called residual, or relict cosmic radiation.
This slender and impressive picture was brilliantly confirmed when Penzias and Wilson discovered just such radiation with a temperature of 2.7 Kelvin and reaching the Earth from all sides of the sky, that is, filling the entire universe. But along with the confirmation came another question, because it turned out that this radiation is uniform, that is, it has the same temperature in all directions, that is, in the entire universe. How can it be? The theory says that the Big Bang happened 13.7 billion years ago. This means that the relic radiation was formed about 13.3 billion years ago.
The farthest points from which this light can come to Earth today may be 13.3 light years away, which means that the distance between two such points on opposite sides of the sky is 26.6 billion light years. No energy could move from one such point to another, because for this it would need to move at twice the speed of light, which is impossible. Meanwhile, measurements by Penzias and Wilson showed that these two points emit residual radiation of the same temperature, which means they are in a state of thermal equilibrium.
This oddity has been called the horizon problem (because both of the above points are on the edge, or on the horizon, of today's universe). In an attempt to solve this problem, Alan Guth in 1981 put forward the idea of inflation (inflation is also translated as "inflation", "swelling"), according to which the initial plasma clot resulting from the Big Bang was small, and therefore all its parts could exchanging energy, come to the same temperature.
And then, in a monstrously short time (10 to the minus 35th power of a second), there was a short but monstrously rapid inflation of the space of the universe, which increased to its present apparent size (10 to the 23rd power of km). It's not worth trying to visualize these numbers. The rate of this inflation unimaginably exceeded the speed of light (which, however, did not violate the principle of the limit of the speed of light, because there was no signal transmission through space, but the expansion of space itself).
And of course, during this time all parts of the universe could not change their state, and therefore remained everywhere in a state of thermal equilibrium with each other.
Guth's inflationary theory solved more than just the horizon problem. At the same time, she explained why the observed universe appears to us, on average (that is, at very large distances), practically homogeneous and flat (that is, one in which the laws of Euclidean geometry are fulfilled, and not, say, the laws of Riemann's spherical geometry or Lobachevsky's hyperbolic geometry).
Roughly speaking, inflation “rolled out” the rolled “carpet” of the universal space, removing the smallest deviations from the plane and making it Euclidean, and the universe itself - homogeneous.
(For the sake of rigor, I note that in our time, the discovery of dark matter, which in the universe is several times larger than usual, has raised the problem of flatness and uniformity for scientists anew, since it turned out that dark matter is distributed in space differently than the usual, visible one. gave rise to new, more complex inflationary theories, but they have nothing to do with the history of the anthropic principle in cosmology.)
What was the root cause of the Big Bang and subsequent inflation? According to Guth, it all started with the quantum fluctuations of the vacuum. Roughly speaking, in quantum physics, a vacuum is not a void, but a special state of a certain field in which energy fluctuations can occur. One such vibration for a short time increases the energy of the field, and then an unstable state called false vacuum arises.
Such a state disintegrates extremely quickly, that is, it returns to normal, but under certain conditions, a piece of space in which a false vacuum arose and then disintegrated can use the energy that suddenly appeared in it for its frantic expansion, in other words, for inflation. According to Guth, it was precisely such a process that gave rise to the universe we observe, and it took place in such a microscopic, and therefore homogeneous and equilibrium area, that the universe that arose from it also turned out, as we have already said, homogeneous and equilibrium.
Moreover, the original site was so small that the laws of physics in it were the same everywhere - so in the instantly inflated universe they remained the same everywhere. And the fact that at the same time they turned out to be favorable for the emergence of life and reason is already a pure coincidence. The answer, in essence, repeats a strong anthropic principle, giving it a rigorous scientific foundation.
This conclusion was unacceptable to Linde, and he tried to generalize Guth's theory. He rejected his assumption of microscopicity, and therefore the homogeneity of the initial area where the false vacuum appeared, and investigated (theoretically, of course) what would happen if we consider a sufficiently large area of space, which certainly could not be either homogeneous or energetically equilibrium.
Calculations led him to unusually interesting results. It turned out that in this case, quantum fluctuations of the false vacuum can occur in different places of this area at different times and with different intensities. Because of this, some places will swell at an inflationary rate, while others will either not expand at all or stop expanding early. There will arise not a single universe, as in Guth's theory, but a whole bunch of universes, each as large as the only one Guth.
And since this cluster of universes (similar to the universe, Linde called it multiverse, that is, something like a "multiverse") was born from a chaotic state of vacuum and in chaotic disorder, it will itself be chaotic, that is, it is impossible to indicate any single the moment of birth, in each of its compartments (in each separate universe) there will certainly be its own laws of space, time and nature in strict accordance with the weak anthropic principle.
The new theory is called chaotic inflation. Developing it, Linde, in his 1986 work, showed that in the rapidly growing compartments of the multiverse, its own quantum fluctuations of the vacuum and other fields should arise, which should lead to a continuous and endless inflation of such places in these compartments, so that the multiverse should reproduce itself indefinitely.
This process has no beginning and no end, and therefore Linde called this new grandiose scenario the theory of eternal chaotic inflation. This infinite inflation will also be chaotic in the sense that all new compartments arising in different compartments (they are also universes) (they are new and new universes), in principle, should have different geometries (including a different number of dimensions of space), different properties time and different types of particles and fields.
So it is possible that many of them have, say, six spatial dimensions or do not contain any particles of matter, and so on and so forth. (Of course, it is also quite likely that many of them - and their number is infinite - will be quite suitable for the emergence of life and mind, although each in its own time, not necessarily coinciding with the others.)
And now Linde asserts (and Guth has already expressed his agreement with him) that the new data on gravitational waves best coincide with the predictions of this theory of his.
As I said, if his words are finally confirmed, science will finally receive an answer as to why we exist at all. Because in the endless and eternal process of the chaotic appearance of more and more new universes with more and more new laws and constants, someday (and more than once) there must have appeared one where the emergence of life and reason became possible. This will be a huge scientific victory, but, of course, only within the framework of physics and cosmology. For a complete answer to the question of why we exist at all requires, of course, also a biological explanation of how life could arise from "dead" matter and develop before the appearance of reason.
Biology cannot yet explain the emergence of life unambiguously. She immediately runs into the "chicken and egg" problem here. Proteins are needed to reproduce the first DNA, and DNA is needed to produce the first proteins.
They are trying to get around this difficulty by postulating that special molecules, RNA, were the first to emerge, which were able to catalyze their own reproduction. This catalysis led to the emergence of a whole world of different RNAs, from which natural selection began to select material for further complication. But the existence of such autocatalysis has not yet been fully proven, and most importantly, it is not clear why the selection of all the best RNAs should have led to the appearance of proteins (or DNA). Modern biology is also experiencing difficulties in explaining the further development of life.
She explains this process by Darwin's theory, in which evolution is presented as a slow, gradual and continuous process of accumulation and selection of random small changes (mutations) in genes, which then finds expression in equally small changes in organisms as a whole. In this manner, the theory claims, from the first living cell, various types of cells began to develop, growing like branches of a tree, then divided into even more numerous types of organisms, and so on up to the person who crowned this "tree of life."
However, in recent decades, many new facts have accumulated, indicating that in reality this process was not continuous. Rather, it was an intermittent evolution, in which short periods of the rapid appearance of new organisms in an almost finished form were replaced by long periods of their further fine tuning and finer fragmentation into subspecies (Eldridge and Gould called this process dotted evolution).
Many authors have already tried to make these adjustments to the Darwinian theory, but very recently the first generalizing and very radical hypothesis has appeared, which "corrects" Darwin with the help of Linde!
This hypothesis belongs to the outstanding modern biologist Evgeny Kunin from the National Institutes of Health in Bethesda (USA). It was fully described by him in his recent book "The Logic of Randomness", and before that - in two articles with very remarkable, as you will now see, titles: "The Cosmological Model of Eternal Inflation and the Transition from Randomness to Evolution in the History of Life" and "The Model of the Biological Big explosion for the main transitional moments of evolution”. In the first article, Kunin says something like this: “The model of eternal inflation, in contrast to the traditional cosmological model of a single, unique universe, assumes that all possible sets of initial physical conditions can randomly arise and repeat countless times in different compartments of the multiverse.
This model, therefore, also points to the possibility of an infinite number of the most complex systems appearing randomly in different such compartments, even if the probability of each single occurrence of such complexity in each separate compartment is extremely small. Life on Earth is no exception to this rule. We exist because in our compartment of the multiverse, by chance, the entire set of molecules that provided both the reproduction of DNA and the construction of proteins with its help appeared at once. The theory of eternal inflation says that in an eternal and endlessly self-multiplying multiverse, the appearance of such an accident (like any other) was necessary, so that Darwinian evolution does not require any RNA world and is, in essence, an inevitable consequence of the anthropic principle.
In the introduction to the second article, Kunin writes: “At all the main stages of biological evolution, the same scenario of the sudden appearance of various living forms of a new level of complexity is repeated. This was the case with the appearance of the first living molecules (RNA and proteins), the most important groups of viruses, two classes of protozoa (archaea and bacteria), the founders of the super-family of eukarites (cells with a nucleus) and all animal families. One might think that all these points are places of transition from one, explosive, phase of evolutionary development to another, gradual. The first, inflationary, phase very quickly generates a huge variety of new opportunities for the exchange of genetic information (horizontal gene transfer, recombination, fusion, division, etc.), while in the second phase, new life forms that have arisen in this way begin to develop and branch. This process resembles the birth of a new universe in the theory of eternal chaotic inflation, where as a result of the rapid expansion (usually called the Big Bang), a new compartment of the multiverse is born, which further begins to develop according to its internal laws. Therefore, I called the phase transitions outlined above in life history "Biological Big Bangs."
Both articles continue with a detailed analysis and proof of the hypotheses put forward in them, but their retelling requires a separate story, and we can only hope that fate will allow us to return to this. For now, I will only say: the dizzying ideas of modern science open up bottomless depths, and nature, apparently, not in vain tried so much, creating this instrument of its self-knowledge.
Raphael Nudelman