Parallel, intersecting, branching and re-converging worlds. Is this an invention of science fiction writers or a reality that has not yet been realized?
The theme of many-worlds, developed by philosophers since ancient times, in the middle of the 20th century became the subject of discussion of physicists. On the basis of the principle of interaction of the observer with quantum reality, a new interpretation of quantum mechanics has appeared, which is called "Oxford". Its author, the young physicist Hugh Everett, met with Niels Bohr, the founder of the then generally accepted "Copenhagen" interpretation of quantum mechanics. But they did not find a common language. Their worlds diverged …
The idea of a plurality of worlds originated in vast areas from the mountains and plains of Hellas to Tibet and the Ganges valley in India about 2500 years ago. Discussions about the many-worlds can be found in the teachings of the Buddha, talks between Leucippus and Democritus. The famous philosopher and historian of science Viktor Pavlovich Vizgin traced the evolution of this idea among ancient philosophers - Aurelius Augustine, Nicholas of Cusansky, Giordano Bruno, Bernard Le Beauvier de Fontenelle. At the end of the 19th - beginning of the 20th centuries, Russian thinkers also appeared in this series - Nikolai Fedorov with his "Philosophy of a Common Cause", Daniil Andreev with "The Rose of the World", Velimir Khlebnikov in "Boards of Fate" and Konstantin Tsiolkovsky, whose ideas are still very little studied …
The 20th century in science is, admittedly, the “age of physics”. And physics could not pass over in silence the fundamental ideological question: do we live in a single Universe or there are many universes - worlds similar to ours or different from it?
In 1957, among the many philosophical varieties of the idea of many-worlds, the first strictly physical appeared. The journal "Reviews of Modern Physics" (1957, v. 29, No. 3, p. 454 - 462) published an article by Hugh Everett III "Relative State" Formulation of Quantum Mechanics "(" Formulation of quantum mechanics through "related states"), and a new direction in science arose: everettika, the doctrine of the physicality of many-worlds. In Russian, the term was formed on behalf of the author of the main physical idea; in the West they speak more often of the “many-worlds interpretation” of quantum mechanics.
Why today these ideas are discussed not only by physicists, and why does the whole range of assessments and emotions sound to Everett's address - from “genius physicist” to “abstract dreamer”?
Everett suggested that the Copernican Universe is only one of the universes, and the basis of the universe is the physical many-worlds.
From the point of view of the most general cosmological theory of chaotic inflation, developed by many famous physicists, the universe is represented as a multiverse, a “tree of branches”, each of which has its own “rules of the game” - physical laws. And each branch of the multiverse has its own "players" - elements of nature, very different from our particles, atoms, planets and stars. They interact to create "spaces and times" specific to each branch. Therefore, most of the branches of the multiverse are absolute terra incognita for our perception and understanding. But there are also those among them, the conditions in which are favorable for the emergence of Reason of our type. We live in one of these universes.
Promotional video:
Until recently, physicists studying the "rules of the game" in our branch of the multiverse paid attention to everything - from strong interaction in the smallest particles of matter to gravity that controls metagalaxies - with the exception of consciousness - that reality phenomenon that determines the specifics of our Universe.
In fact, taboo in theoretical physics, consciousness is studied by sciences “bordering” with the humanities - psychology, psychiatry, sociology, etc. At the same time, consciousness is not clearly distinguished from the complex mental complex - the triad of consciousness, reason, intellect.
And in the pioneering article by Everett, the consciousness of the observer first received the status of a "physical parameter". And this is the second basis on which the everettika developed.
From an everetic point of view, "perceived reality" is a set of classical realizations of physical worlds (CFM) and intelligently realized worlds built on their basis, reflecting the interaction of the Observer with the only quantum reality of our universe. This set, at the suggestion of the leading researcher of the Lebedev Physical Institute, Doctor of Physical and Mathematical Sciences, Professor Mikhail Borisovich Mensky, was named "alterverse".
The essence of the everettical interpretation of events in our branch of the multiverse boils down to the fact that none of the possible outcomes of the quantum interaction of the Observer and the Object remains unrealized, but each of them is realized in its own QPM ("parallel universe", as it is often called in popular literature).
The branching of the CFMM generates Everett's "related state" - the interacting unity of the Observer and the Object. According to Everett's concept, the quantum-mechanical interaction of the Object and the Observer leads to the formation of a set of different worlds, and the number of branches is equal to the number of physically possible outcomes of this interaction. And all these worlds are real.
Based on such a physical foundation, called today the Oxford Interpretation of Quantum Mechanics, Everettica generalizes Everett's postulate to the general case of any interaction. This statement is equivalent to what is recognized as real physical many-dimensionality, which includes consciousness as an integral element.
The Oxford interpretation of quantum mechanics is today promoted by physicists, whose authority in the world of modern physics is indisputable, but unconditional authorities (for example, Roger Penrose) also oppose it. Their counterarguments do not refute the physical correctness of Everett's constructions (its mathematical perfection has been repeatedly verified by top-class specialists), but relate to the very area from the recognition of the physicality of which quantum mechanics has so far evaded - the role of the psychic in the Universe. The main reason for refusing to accept Everett's ideas is the assertion that these ideas are "experimentally unprovable." Indeed: one cannot seriously discuss a theory that is fundamentally impossible to prove or disprove in experiment or by observation. The persuasive force of everettism is not sufficient for the general acceptance of everettics.
This, however, does not discredit everettics, since it is impossible to prove anything "to everyone and forever", if only because before a proof is required, there must be a feeling of doubt about the validity of the statement under discussion. And doubt arises in the process of assimilating the meaning of the subject of proof, which requires the expenditure of spiritual forces, and not everyone and not always are ready for this.
Here is how Hermann von Helmholtz (1821-1894), one of the last universal scientists in the history of science, who was engaged in research linking medicine, physics and chemistry, defined this situation: “The author of a new concept, as a rule, is convinced that it is easier to discover a new truth, than to find out why others do not understand him. This was the case in the 19th century, and it remained the same in the 21st century.
Everettica expanded the range of basic ideas for describing the physical many-world. Let's note two of them. The first is that the observer's consciousness is recognized as a factor dividing different physical worlds, according to Mensky. The second idea proposed by the author of this article is the presence of the interaction of the branches of the alterverse in the processes of the so-called everetic gluing.
Glues are the processes of interaction between the branches of the alterverse and the manifestation of their results in our reality. They can be both material of various forms - from the seemingly strange result of interaction of two photons during interference to “suddenly found” glasses, and mental - from “prophetic dreams”, for example, to the reification of “mysterious artifacts”.
The range of gluing scales covers all the "kingdoms of physics" - microworld, macroworld and megaworld. And the realization that gluing of various scales serves as a mechanism to counteract the "monstrous growth of the number of branches of the alterverse" also removes those objections to everettics, which are based on emotional rejection of the enormous number of branches.
According to the science of science, any scientific statement, firstly, must be proven (verification criterion) and, secondly, any scientific statement can be refuted (falsification criterion).
"The decisive experiment" in science is considered to be an experiment, according to the results of which one can unambiguously choose between competing theories that explain a certain set of facts in different ways.
At the same time, one should not think that such a choice leads to the truth. True - even in the understanding of the truth that the scientific paradigm adheres to today - may turn out to be a certain "third theory" for which this experiment has no meaning.
From this we can conclude that the concept of a "decisive experiment", like the concept of truth in general, does not mean that its conduct will exclude disputes, doubts, hesitations and even a decisive proof of truth by this experiment.
Everettics is essentially a worldview complex. Its experimental field is just being formed (but it is being actively formed, and the everettics already have proposals for setting up verification experiments), but now it is difficult to predict the point where the efforts of researchers will lead to "decisive success." Only one thing is clear - a "conscious element" must be present in the decisive experiment of everettics.
Another thing is the concrete physical side of everettics. Opponents of the “many-worlds concept” believe that Everett's theory does not meet the verification criterion and, therefore, cannot be recognized as a real natural science theory. The maximum that the opponents of everettism agree on is the assignment of the status of a "philosophical concept" to it.
But despite the sharp rejection of the very idea of many-worlds by many physicists of the middle and older generations, it attracted the interest of young, but experienced and qualified experimenters who wanted to test it.
In 1994, an international group of physicists led by P. Kvyat carried out an experiment that is proposed to be considered as a verification experiment for physical everettism *.
The very idea of the experiment, based on the assumption of the physical reality of "parallel worlds", was proposed by Israeli physicists A. Elitzur and L. Weidman in 1993 **.
These experiments are called "interaction-free measurements." They demonstrated the physical reality of solving a paradoxical problem, which the authors deliberately sharpened, formulating it in the form of a scientific-detective problem of "testing especially sensitive bombs."
Suppose that terrorists seized a warehouse where "superbombs" are stored, the detonator of which is sensitive enough to be triggered by interaction with a single photon. Some of the fuses were damaged during the capture. The task is to assess the possibility of finding, using optical methods with absolute guarantee, at least a few serviceable bombs among the entire set of bombs. The question, the answer to which is vitally important for the terrorists, and for the special forces that surrounded them, and for the population of nearby cities …
This conditional problem should show the possibility of quantum interactions, in which the interaction event itself is not observed in our branch of the alterverse, but other observed "here and now" events occur.
If this problem is successfully solved, the worldview dilemma boils down to the fact that from the point of view of the Copenhagen interpretation of quantum mechanics, the “objective possibility of explosion” has not materialized into reality, and from the point of view of the Oxford one, the bomb will still explode, but in a “parallel world”.
Later, the field of experimental physics, which developed from the solution of this problem, was named with the Russian-language abbreviation BIEV (Non-contact measurements of Elitsur-Weidmann). It corresponds to the English EVIFM (Elitzur-Vaidman Interaction-Free Measurement).
The paradox of the problem of A. Elitzur and L. Weidmann lies in the fact that the choice must be made optically, and the detonator of a serviceable bomb is so sensitive that it is triggered by interaction with a single photon that hits its sensory element. Of course, in a real experiment, instead of a "supersensitive bomb", a simple sensor was used, the signal from which went not to the bomb detonator, but to a recording physical device. The problem conditions are illustrated in Fig. 1a.
And its solution, proposed by Elitzur and Weidman, can be obtained using the installation, the diagram of which is shown in Fig. 1b.
The essence of the decisive experiment is that a "test bomb" is placed in a Mach-Zehnder interferometer as one of the mirrors (Fig. 1b). According to the predictions of Elitzur and Weidmann, in 25% of the cases when the bomb is “operational”, detector B is triggered and no “explosion” occurs.
The very fact that detector B was triggered without an explosion serves as a sufficient basis to assert that the bomb is operational.
To verify this, consider the many-worlds interpretation of the operation of an interferometer without a bomb and in solving the Elitzur-Weidmann problem.
In fig. 2 shows a diagram of the alterverse branches when a single quantum passes through the interferometer without a bomb.
As a result of the passage of a quantum through an equal-arm interferometer, detector A is always triggered. From the many-worlds point of view, this is explained as follows.
With an equal probability of 50%, after the quantum is admitted into the interferometer, alterverses 1 and 2 are formed. They differ in the direction of the quantum motion after its interaction with the first semitransparent mirror. In alterverse 1, the quantum goes to the right, and in alterverse 2 - up.
Further, the reflection occurs on opaque mirrors, and alterverse 1 is transformed into alterverse 3, and alterverse 2 - into alterverse 4.
Alterverse 3 with a probability of 50% generates alterverse 5 and 6, which differ in which detector (B or A, respectively) captures the quantum at the output of the interferometer.
Alterverse 4 (also with a 50% probability) generates alterverse 7 and 8, which differ in which detector (B or A, respectively) fixes the quantum at the output of the interferometer.
Of particular interest are the 6 and 7 alters. They form a gluing in which the physical configurations of both alterverses are absolutely identical. The difference between them consists in the history of their origin, that is, in the difference in the paths along which the quantum came.
The traditional quantum mechanical formalism describes in this case a quantum as a wave and predicts the emergence of “destructive interference” of the split wave functions of a quantum with zero probability of detecting it in this state.
The meaning of the description is as follows. A photon (single!) In the form of a wave is split on the first mirror and then passes through the interferometer in the form of two half-waves ("split wave functions"), while remaining the only particle! How he succeeds and what a "photon half-wave" is, the Copenhagen interpretation is silent. At the exit, the half-waves interfere and combine again into a “full-fledged photon,” and it turns out that it can only move to the right.
The many-worlds interpretation proceeds from the corpuscular description of the quantum and shows that in this gluing, due to the law of conservation of momentum, the total momentum transmitted to the mirror by alterverses 6 and 7 should be equal to zero. In this case, the momentum of the quantum must also become zero, which is impossible in our branch of the multiverse, and therefore such a gluing cannot be realized in any branch of the QPSK. Indeed, according to the Oxford interpretation, not all are realized, but only physically possible results of interaction.
From this it follows that in this scheme, when a photon passes, it is possible to realize only alterverses 5 and 8. Whichever of them becomes “our” alterverse, we will find that detector A has triggered with a probability of 100%.
Let us now consider the many-worlds interpretation of the Elitzur-Weidmann problem.
In fig. 3 shows a diagram of the branching of alterverses in an experiment demonstrating the possibility of solving the Elitzur-Weidman problem.
The configuration of the elements that make up the alterverse in Fig. 3 differs from the configuration of the elements in Fig. 2 in that a bomb with a supersensitive fuse is connected to the opaque mirror in the lower right corner of the figure, which is triggered by a single contact with a quantum of light.
As in the classical quantum interferometer, alterverse 1 and 2 are formed with an equal probability of 50% after the quantum is admitted into the modified interferometer. They differ in the direction of the quantum motion after its interaction with the first semitransparent mirror. In alterverse 1, the quantum goes to the right, and in alterverse
2 - up.
As a result, a bomb detonates in alterverse 1. This, however, does not mean the end of the experiment in alterverse 1. The quantum moves with the speed of light, and the secondary quanta generated by the explosion (and even more so the blast wave) always lag behind it. Therefore, we can continue to follow the fate of the quantum in this alterverse even after the explosion of the bomb, regardless of the catastrophic consequences that will destroy the installation in alterverse 1 a moment after the end of our thought experiment.
Further, the reflection occurs on opaque mirrors, and alterverse 1 is transformed into alterverse 3, and alterverse 2 - into alterverse 4.
Alterverse 3 with a probability of 50% generates alterverse 5 and 6, which differ in which detector (B or A, respectively) captures the quantum at the output of the interferometer. However, the results of this fixation are completely useless - the installation in both of these alterverses is destroyed by the explosion.
Alterverse 4 (also with a 50% probability) generates alterverse 7 and 8, which also differ in which detector (B or A, respectively) captures the quantum at the output of the interferometer.
Alterverse 8 is of no interest, since the triggering of detector A in it is no different from the triggering of the detector in the previously considered case of interference without a bomb fuse and therefore cannot give information about whether the fuse is working properly.
Alterverse 7 is of particular interest. Detector B was triggered in it, which could not have happened if there was no operational bomb in the interferometer. At the same time, the quantum did not touch the fuse mirror and the bomb did not explode! Such a result became possible because gluing is impossible between altervers 6 and 7 - their physical configurations are completely different. (In a "parallel world" that could provide "destructive interference," a bomb explosion destroyed the mirror needed for gluing.)
As a result, out of four alterverses, we will get a successful result for the purposes of the experiment only in one, that is, with a probability of 25%, which is what the experiments have shown. Today, after improvements in the methods of BIEV, it was possible to increase the share of successful detection of objects by a non-contact method from 25 to 88%.
From the foregoing, it is clear what role the concept of gluing, introduced in everettics, plays to explain the phenomenon of interference.
What does the new "physical technology" predicted on the basis of Everett's work give to humanity? This is how the authors of the discovery - P. Kvyat, H. Weinfurter and A. Zeilinger - see the prospects for BIEV themselves in a report about it in Scientific American:
“What good is all this quantum magic? It seems to us that this situation resembles the one that was in the early days of the laser, when scientists knew that it would be the perfect solution to many unknown problems.
For example, the new method of non-contact measurements can be used as a rather unusual tool for photography. With this method, an object is rendered without being exposed to light … Imagine being able to take an X-ray of someone without exposing that person to X-rays. Such imaging techniques will be less risky for patients than using any radiation …
An area of faster application will be the image of clouds of ultracold atoms, which have recently been obtained in several laboratories - Bose-Einstein condensates, in which many atoms act collectively as one whole. In this cloud, each atom is so cold, that is, it moves so slowly that a single photon can remove an atom from the cloud. At first, there seemed to be no way to get an image without destroying the cloud. Non-contact measurement techniques may be the only way to obtain images of such atomic collectives.
In addition to imaging quantum objects, contactless procedures can also create certain types of such objects. For example, it is technically possible to create a "Schrödinger's cat," this beloved theoretical entity in quantum mechanics. A quantum creature from the feline family was created so that it exists in two states at once: it is simultaneously alive and dead, being a superposition of these two states … The staff of the National Institute of Standards and Technology managed to create its preliminary appearance - a "kitten" from beryllium ion. They used a combination of lasers and electromagnetic fields to make an ion existing simultaneously in two places separated by a distance of 83 nanometers - a huge distance on a quantum scale. If such an ion is found by contactless measurements,the photon that detects it can also have a superposition …
Far beyond the boundaries of ordinary experiment, the concept of non-contact measurement looks strange, if not even meaningless. The key ideas to this art of quantum magic, the wave and corpuscular properties of light, and the nature of quantum measurements have been known since 1930. But only recently physicists have begun to apply these ideas to discover new phenomena in the quantum information process, including the ability to see in the dark."
But as a result of this startling success of physical everettism, a new paradox emerged. It consists in the fact that the authors of such a convincing experiment do not believe that their experiment proved the validity of Everett's theory!
However, such a paradox is not new in physics. Until the end of their days, both Max Planck and Albert Einstein did not believe in the truth of quantum mechanics, which also arose as a result of their labors (the introduction of quantization of radiation and the quantum explanation of the photoeffect), considering it a very useful, but temporary mathematical construction.
As for everettika as a new philosophical worldview, its recognition may be associated with the emergence of new humanities such as everett history and everett psychology, the contours of which are only indicated in the works of enthusiastic researchers and sagacious science fiction writers.
A striking example is the story of Pavel Amnuel “I remember how I killed Josh”. Which of the future achievements of "humanitarian everettika" can be seen in this story today? Let's try to isolate the seeds of scientific foresight from the artistic whole.
First of all, in this short everyday history, the course and meaning of world history is rethought. One of the favorite expressions of the famous historian Natan Yakovlevich Eidelman was: "The case is unreliable, but generous." But, I think, Eidelman himself did not suspect how generous the case, or, in the language of physics, probability, in the methodology of his beloved science, could be.
Natan Yakovlevich, both "in a narrow circle" and in overcrowded auditoriums, often spoke about his "accidental" discoveries of new historical facts. But, recalling some unexpected find in the archives of an important document among papers that were repeatedly reviewed by other researchers, he, of course, did not realize that a fundamental regularity of quantum mechanics could appear in the role of a happy accident.
Listening to his exciting stories, I did not know about it either. And only much later, considering the everetic interpretation of time, I saw that the everett branching of reality should manifest itself not only when moving into the future, but also when returning to the past. Not only the future branches, but the past as well!
This statement changes the worldview picture much more strongly than the statement about branching into the future. And not only the ideological "in general", but also the specific historical, ethical, legal and, of course, psychological …
This is well understood by Amnuel, who believes that with an everett view of reality, "the entire historical paradigm changes - from" … history does not know the subjunctive mood "to" there is nothing in history but the subjunctive mood."
But history is an abstract concept. The famous American philosopher and poet Ralph Waldo Emerson subtly noted this: “Strictly speaking, there is no history; there is only a biography. And every story begins with a story about her, with the interpretation of events through the feelings and memory of the narrator. A full-fledged perception of the meaning of this interpretation is the subject of everett psychology.
Of course, in Amnuel's story, all this "hidden architecture of reality", as it should be in a good literary work, is not visible to the reader. In the foreground are people, their feelings and experiences, connected with a fascinating plot.
But good literature is always multi-layered. And the better the literature, the more significant is the "after-healing effect" - the disclosure of the multi-layered work as a result of the reader's spiritual work.
Even in "pre-Everett times" the concept of branching was anticipated by Jorge Luis Borges, and not only to the future ("The Garden of Branching Paths"), but partly to the past ("Another Death").
Today, everettika introduces consciousness and reason into physics on an equal footing with space and time. Amnuel's story is a "classic" science fiction in which a powerful and fruitful scientific idea stands behind the twists and turns of a criminal plot.
… So, is the everetic many-worlds real? Or is it a theoretical phantom? Decide for yourself or believe Mikhail Bulgakov: “However, all theories are one another. There is one among them, according to which each will be given according to his faith. May it come true!"