Limits of physics and physical experiment

A hundred years ago, the situation in physics was exactly the opposite of today. In the hands of scientists were the results of proven experiments that were repeated many times, which, however, often could not be explained using existing physical theories. Experience clearly preceded theory. Theorists had to get to work.

Currently, the balance is tilting towards theorists whose models are very different from what is seen from possible experiments such as string theory. And it seems that there are more and more unsolved problems in physics (1).

1. The most important modern trends and problems in physics - visualization

The famous Polish physicist, prof. Andrzej Staruszkiewicz during the "Limits of Knowledge in Physics" debate in June 2010 at the Ignatianum Academy in Krakow said: “The field of knowledge has grown enormously over the last century, but the field of ignorance has grown even more. (…) The discovery of general relativity and quantum mechanics are monumental achievements of human thought, comparable to those of Newton, but they lead to the question of the relationship between the two structures, a question whose scale of complexity is simply shocking. In this situation, questions naturally arise: can we do it? Will our determination and will to get to the bottom of the truth be commensurate with the difficulties we face?”

Experimental stalemate

For several months now, the world of physics has been busier than usual with more controversy. In the journal Nature, George Ellis and Joseph Silk published an article in defense of the integrity of physics, criticizing those who are increasingly ready to postpone experiments to test the latest cosmological theories until an indefinite "tomorrow". They should be characterized by "sufficient elegance" and explanatory value. “This breaks the centuries-old scientific tradition that scientific knowledge is empirically proven knowledge,” scientists thunder. The facts clearly show the "experimental impasse" in modern physics.

The latest theories about the nature and structure of the world and the Universe, as a rule, cannot be verified by experiments available to mankind.

By discovering the Higgs boson, scientists have "completed" the Standard Model. However, the world of physics is far from satisfied. We know about all the quarks and leptons, but we have no idea how to reconcile this with Einstein's theory of gravity. We don't know how to combine quantum mechanics with gravity to create a hypothetical theory of quantum gravity. We also don't know what the Big Bang is (or if it actually happened!) (2)

At present, let's call it classical physicists, the next step after the Standard Model is supersymmetry, which predicts that every elementary particle known to us has a "partner".

This doubles the total number of building blocks of matter, but the theory fits perfectly into the mathematical equations and, importantly, offers a chance to unravel the mystery of cosmic dark matter. It remains only to wait for the results of experiments at the Large Hadron Collider, which will confirm the existence of supersymmetric particles.

However, no such discoveries have yet been heard from Geneva. Of course, this is only the beginning of a new version of the LHC, with twice the impact energy (after a recent repair and upgrade). In a few months, they may be shooting champagne corks in celebration of supersymmetry. However, if this did not happen, many physicists believe that supersymmetric theories would have to be gradually withdrawn, as well as the superstring, which is based on supersymmetry. Because if the Large Collider doesn't confirm these theories, then what?

However, there are some scientists who do not think so. Because the theory of supersymmetry is too "beautiful to be wrong."

Therefore, they intend to reevaluate their equations in order to prove that the masses of supersymmetric particles are simply outside the range of the LHC. The theorists are very right. Their models are good at explaining phenomena that can be measured and verified experimentally. One may therefore ask why we should exclude the development of those theories that we (yet) cannot know empirically. Is this a reasonable and scientific approach?

universe from nothing

The natural sciences, especially physics, are based on naturalism, that is, on the belief that we can explain everything using the forces of nature. The task of science is reduced to considering the relationship between various quantities that describe phenomena or some structures that exist in nature. Physics does not deal with problems that cannot be described mathematically, that cannot be repeated. This is, among other things, the reason for its success. The mathematical description used to model natural phenomena has proven to be extremely effective. Achievements of natural science resulted in their philosophical generalizations. Directions such as mechanistic philosophy or scientific materialism were created, which transferred the results of the natural sciences, obtained before the end of the XNUMXth century, into the field of philosophy.

It seemed that we could know the whole world, that there is complete determinism in nature, because we can determine how the planets will move in millions of years, or how they moved millions of years ago. These achievements gave rise to a pride that absolutized the human mind. To a decisive extent, methodological naturalism stimulates the development of natural science even today. There are, however, some cut-off points that seem to be indicative of the limitations of naturalistic methodology.

If the Universe is limited in volume and arose “out of nothing” (3), without violating the laws of conservation of energy, for example, as a fluctuation, then there should be no changes in it. In the meantime, we are watching them. Trying to solve this problem on the basis of quantum physics, we come to the conclusion that only a conscious observer actualizes the possibility of the existence of such a world. That is why we wonder why the particular one we live in was created from many different universes. So we come to the conclusion that only when a person appeared on Earth, the world - as we observe - really “became” ...

How do measurements affect events that happened a billion years ago?

4. Wheeler experiment - visualization

One of the modern physicists, John Archibald Wheeler, proposed a space version of the famous double slit experiment. In his mental design, light from a quasar, a billion light years away from us, travels along two opposite sides of the galaxy (4). If observers observe each of these paths separately, they will see photons. If both at once, they will see the wave. So the very act of observing changes the nature of the light that left the quasar a billion years ago!

For Wheeler, the above proves that the universe cannot exist in a physical sense, at least in the sense in which we are accustomed to understand "a physical state." It can't have happened in the past either, until... we've taken a measurement. Thus, our current dimension influences the past. With our observations, detections and measurements, we shape the events of the past, deep in time, up to ... the beginning of the Universe!

Neil Turk of the Perimeter Institute in Waterloo, Canada, said in the July issue of New Scientist that “we cannot understand what we find. The theory becomes more and more complex and sophisticated. We throw ourselves into a problem with successive fields, dimensions and symmetries, even with a wrench, but we cannot explain the simplest facts.” Many physicists are obviously annoyed by the fact that modern theorists' mental journeys, such as the above considerations or superstring theory, have nothing to do with experiments currently being carried out in laboratories, and there is no way to test them experimentally.

In the quantum world, you need to look wider

As Nobel laureate Richard Feynman once said, no one really understands the quantum world. Unlike the good old Newtonian world, in which the interactions of two bodies with certain masses are calculated by equations, in quantum mechanics we have equations from which they do not so much follow, but are the result of strange behavior observed in experiments. The objects of quantum physics do not have to be associated with anything "physical", and their behavior is a domain of an abstract multi-dimensional space called Hilbert space.

There are changes described by the Schrödinger equation, but why exactly is unknown. Can this be changed? Is it even possible to derive quantum laws from the principles of physics, as dozens of laws and principles, for example, concerning the movement of bodies in outer space, were derived from Newton's principles? Scientists from the University of Pavia in Italy Giacomo Mauro D'Ariano, Giulio Ciribella and Paolo Perinotti argue that even quantum phenomena that are clearly contrary to common sense can be detected in measurable experiments. All you need is the right perspective - Perhaps the misunderstanding of quantum effects is due to an insufficiently broad view of them. According to the aforementioned scientists in New Scientist, meaningful and measurable experiments in quantum mechanics must meet several conditions. This is:

• causality - future events cannot influence past events;
• distinguishability - states we must be able to separate from each other as separate;
• композиция - if we know all the stages of the process, we know the whole process;
• compression – there are ways to transfer important information about the chip without having to transfer the entire chip;
• tomography – if we have a system consisting of many parts, the statistics of measurements by parts is sufficient to reveal the state of the entire system.

The Italians want to expand their principles of purification, a broader perspective, and meaningful experimentation to also include the irreversibility of thermodynamic phenomena and the principle of entropy growth, which do not impress physicists. Perhaps here, too, observations and measurements are affected by artifacts of a perspective that is too narrow to comprehend the entire system. “The fundamental truth of quantum theory is that noisy, irreversible changes can be made reversible by adding a new layout to the description,” says Italian scientist Giulio Ciribella in an interview with New Scientist.

Unfortunately, skeptics say, the "cleansing" of experiments and a broader measurement perspective could lead to a many-worlds hypothesis in which any outcome is possible and in which scientists, thinking they are measuring the correct course of events, simply "choose" a certain continuum by measuring them.

5. Time hands in the form of clock hands

No time?

The concept of the so-called Arrows of time (5) was introduced in 1927 by the British astrophysicist Arthur Eddington. This arrow indicates time, which always flows in one direction, i.e. from the past to the future, and this process cannot be reversed. Stephen Hawking, in his A Brief History of Time, wrote that disorder increases with time because we measure time in the direction in which disorder increases. This would mean that we have a choice - we can, for example, first observe pieces of broken glass scattered on the floor, then the moment when the glass falls to the floor, then the glass in the air, and finally in the hand of the person holding it. There is no scientific rule that the "psychological arrow of time" must go in the same direction as the thermodynamic arrow, and the entropy of the system increases. However, many scientists believe that this is so because energetic changes occur in the human brain, similar to those that we observe in nature. The brain has the energy to act, observe and reason, because the human "engine" burns fuel-food and, like in an internal combustion engine, this process is irreversible.

However, there are cases when, while maintaining the same direction of the psychological arrow of time, entropy both increases and decreases in different systems. For example, when saving data in computer memory. The memory modules in the machine go from unordered state to disk write order. Thus, the entropy in the computer is reduced. However, any physicist will say that from the point of view of the universe as a whole - it is growing, because it takes energy to write to a disk, and this energy is dissipated in the form of heat generated by a machine. So there is a small "psychological" resistance to the established laws of physics. It is difficult for us to consider that what comes out with the noise from the fan is more important than the recording of a work or other value in memory. What if someone writes on their PC an argument that will overturn modern physics, unified force theory, or the Theory of Everything? It would be difficult for us to accept the idea that, despite this, the general disorder in the universe has increased.

Back in 1967, the Wheeler-DeWitt equation appeared, from which it followed that time as such does not exist. It was an attempt to mathematically combine the ideas of quantum mechanics and general relativity, a step towards the theory of quantum gravity, i.e. the Theory of Everything desired by all scientists. It wasn't until 1983 that physicists Don Page and William Wutters offered an explanation that the time problem could be circumvented using the concept of quantum entanglement. According to their concept, only the properties of an already defined system can be measured. From a mathematical point of view, this proposal meant that the clock does not work in isolation from the system and starts only when it is entangled with a certain universe. However, if someone looked at us from another universe, they would see us as static objects, and only their arrival to us would cause quantum entanglement and literally make us feel the passage of time.

This hypothesis formed the basis of the work of scientists from a research institute in Turin, Italy. Physicist Marco Genovese decided to build a model that takes into account the specifics of quantum entanglement. It was possible to recreate a physical effect indicating the correctness of this reasoning. A model of the Universe has been created, consisting of two photons.

One pair was oriented - vertically polarized, and the other horizontally. Their quantum state, and therefore their polarization, is then detected by a series of detectors. It turns out that until the observation that ultimately determines the frame of reference is reached, photons are in a classical quantum superposition, i.e. they were oriented both vertically and horizontally. This means that the observer reading the clock determines the quantum entanglement that affects the universe of which he becomes a part. Such an observer is then able to perceive the polarization of successive photons based on quantum probability.

This concept is very tempting because it explains many problems, but it naturally leads to the need for a "super-observer" who would be above all determinisms and would control everything as a whole.

6. Multiverse - Visualization

What we observe and what we subjectively perceive as "time" is in fact the product of measurable global changes in the world around us. As we delve deeper into the world of atoms, protons and photons, we realize that the concept of time becomes less and less important. According to scientists, the clock that accompanies us every day, from a physical point of view, does not measure its passage, but helps us organize our lives. For those accustomed to the Newtonian concepts of universal and all-encompassing time, these concepts are shocking. But not only scientific traditionalists do not accept them. Prominent theoretical physicist Lee Smolin, previously mentioned by us as one of the possible winners of this year's Nobel Prize, believes that time exists and is quite real. Once - like many physicists - he argued that time is a subjective illusion.

Now, in his book Reborn Time, he takes a completely different view of physics and criticizes the popular string theory in the scientific community. According to him, the multiverse does not exist (6) because we live in the same universe and at the same time. He believes that time is of paramount importance and that our experience of the reality of the present moment is not an illusion, but the key to understanding the fundamental nature of reality.

Entropy zero

Sandu Popescu, Tony Short, Noah Linden (7) and Andreas Winter described their findings in 2009 in the journal Physical Review E, which showed that objects achieve equilibrium, i.e. a state of uniform distribution of energy, by entering states of quantum entanglement with their surroundings. In 2012, Tony Short proved that entanglement causes finite time equanimity. When an object interacts with the environment, such as when particles in a cup of coffee collide with air, information about their properties "leaks" outward and becomes "blurred" throughout the environment. The loss of information causes the state of the coffee to stagnate, even as the state of cleanliness of the entire room continues to change. According to Popescu, her condition ceases to change over time.

7. Noah Linden, Sandu Popescu and Tony Short

As the cleanliness state of the room changes, the coffee may suddenly stop mixing with the air and enter its own clean state. However, there are far more states mixed with the environment than there are pure states available to coffee, and therefore almost never occurs. This statistical improbability gives the impression that the arrow of time is irreversible. The problem of the arrow of time is blurred by quantum mechanics, making it difficult to determine nature.

An elementary particle does not have exact physical properties and is determined only by the probability of being in different states. For example, at any given time, a particle may have a 50 percent chance of turning clockwise and a 50 percent chance of turning in the opposite direction. The theorem, reinforced by the experience of physicist John Bell, states that the true state of the particle does not exist and that they are left to be guided by probability.

Then quantum uncertainty leads to confusion. When two particles interact, they cannot even be defined on their own, independently developing probabilities known as a pure state. Instead, they become entangled components of a more complex probability distribution that both particles describe together. This distribution can decide, for example, whether the particles will rotate in the opposite direction. The system as a whole is in a pure state, but the state of individual particles is associated with another particle.

Thus, both can travel many light-years apart, and the rotation of each will remain correlated with the other.

The new theory of the arrow of time describes this as a loss of information due to quantum entanglement, which sends a cup of coffee into balance with the surrounding room. Eventually, the room reaches equilibrium with its environment, and it, in turn, slowly approaches equilibrium with the rest of the universe. The old scientists who studied thermodynamics viewed this process as a gradual dissipation of energy, increasing the entropy of the universe.

Today, physicists believe that information becomes more and more scattered, but never completely disappears. Although entropy increases locally, they believe that the total entropy of the universe remains constant at zero. However, one aspect of the arrow of time remains unresolved. Scientists argue that the ability of a person to remember the past, but not the future, can also be understood as the formation of relationships between interacting particles. When we read a message on a piece of paper, the brain communicates with it through photons reaching the eyes.

Only from now on can we remember what this message is telling us. Popescu believes the new theory does not explain why the initial state of the universe was far from equilibrium, adding that the nature of the Big Bang should be explained. Some researchers have expressed doubts about this new approach, but the development of this concept and a new mathematical formalism now helps to solve the theoretical problems of thermodynamics.

Reach for the grains of space-time

Black hole physics seems to indicate, as some mathematical models suggest, that our universe is not three-dimensional at all. Despite what our senses tell us, the reality around us may be a hologram—a projection of a distant plane that is actually two-dimensional. If this picture of the universe is correct, the illusion of the three-dimensional nature of space-time can be dispelled as soon as the research tools at our disposal become adequately sensitive. Craig Hogan, a professor of physics at Fermilab who has spent years studying the fundamental structure of the universe, suggests that this level has just been reached.

8. GEO600 Gravitational Wave Detector

If the universe is a hologram, then perhaps we have just reached the limits of reality resolution. Some physicists advance the intriguing hypothesis that the space-time we live in is not ultimately continuous, but, like a digital photograph, is at its most basic level made up of certain "grains" or "pixels." If so, our reality must have some sort of final "resolution". This is how some researchers interpreted the "noise" that appeared in the results of the GEO600 gravitational wave detector (8).

To test this extraordinary hypothesis, Craig Hogan, a gravitational wave physicist, he and his team developed the world's most accurate interferometer, called the Hogan holometer, which is designed to measure the most basic essence of space-time in the most accurate way. The experiment, codenamed Fermilab E-990, is not one of many others. This one aims to demonstrate the quantum nature of space itself and the presence of what scientists call "holographic noise".

The holometer consists of two interferometers placed side by side. They direct one kilowatt laser beams at a device that splits them into two perpendicular beams 40 meters long, which are reflected and returned to the split point, creating fluctuations in the brightness of the light beams (9). If they cause a certain movement in the division device, then this will be evidence of the vibration of space itself.

9. Graphic representation of the holographic experiment

Hogan's team's biggest challenge is to prove that the effects they have discovered are not just perturbations caused by factors outside the experimental setup, but the result of space-time vibrations. Therefore, the mirrors used in the interferometer will be synchronized with the frequencies of all the smallest noises coming from outside the device and picked up by special sensors.

Anthropic universe

In order for the world and man to exist in it, the laws of physics must have a very specific form, and physical constants must have precisely selected values ​​... and they are! Why?

Let's start with the fact that there are four types of interactions in the Universe: gravitational (falling, planets, galaxies), electromagnetic (atoms, particles, friction, elasticity, light), weak nuclear (source of stellar energy) and strong nuclear (binds protons and neutrons into atomic nuclei). Gravity is 1039 times weaker than electromagnetism. If it were a little weaker, the stars would be lighter than the Sun, supernovae would not explode, heavy elements would not form. If it were even a little stronger, creatures larger than bacteria would be crushed, and stars would often collide, destroying planets and burning themselves too quickly.

The density of the Universe is close to the critical density, that is, below which the matter would quickly dissipate without the formation of galaxies or stars, and above which the Universe would have lived too long. For the occurrence of such conditions, the accuracy of matching the parameters of the Big Bang should have been within ±10-60. The initial inhomogeneities of the young Universe were on a scale of 10-5. If they were smaller, galaxies would not form. If they were larger, huge black holes would form instead of galaxies.

The symmetry of particles and antiparticles in the Universe is broken. And for every baryon (proton, neutron) there are 109 photons. If there were more, galaxies could not form. If there were fewer of them, there would be no stars. Also, the number of dimensions we live in seems to be "correct". Complex structures cannot arise in two dimensions. With more than four (three dimensions plus time), the existence of stable planetary orbits and energy levels of electrons in atoms becomes problematic.

10. Man as the center of the universe

The concept of the anthropic principle was introduced by Brandon Carter in 1973 at a conference in Krakow dedicated to the 500th anniversary of the birth of Copernicus. In general terms, it can be formulated in such a way that the observable Universe must meet the conditions that it meets in order to be observed by us. Until now, there are different versions of it. The weak anthropic principle states that we can only exist in a universe that makes our existence possible. If the values ​​of the constants were different, we would never see this, because we would not be there. The strong anthropic principle (intentional explanation) says that the universe is such that we can exist (10)

From the point of view of quantum physics, any number of universes could have arisen for no reason. We ended up in a specific universe, which had to fulfill a number of subtle conditions for a person to live in it. Then we are talking about the anthropic world. For a believer, for example, one anthropic universe created by God is enough. The materialistic worldview does not accept this and assumes that there are many universes or that the current universe is just a stage in the infinite evolution of the multiverse.

The author of the modern version of the hypothesis of the universe as a simulation is the theorist Niklas Boström. According to him, the reality that we perceive is just a simulation that we are not aware of. The scientist suggested that if it is possible to create a reliable simulation of an entire civilization or even the entire universe using a powerful enough computer, and the simulated people can experience consciousness, then it is very likely that advanced civilizations have created just a large number of such simulations, and we live in one of them in something akin to The Matrix (11).

Here the words "God" and "Matrix" were spoken. Here we come to the limit of talking about science. Many, including scientists, believe that it is precisely because of the helplessness of experimental physics that science begins to enter areas that are contrary to realism, smelling of metaphysics and science fiction. It remains to be hoped that physics will overcome its empirical crisis and again find a way to rejoice as an experimentally verifiable science.