The accelerated expansion of the universe has been confirmed. Expansion of the universe The universe is expanding faster than light evidence

So where is the universe actually expanding? Yes, to nowhere. There is no space closet filled with things. But to understand this, let's look at what general relativity says about space-time.

In general relativity (as professionals say), the most important property of space (and time) is the distance (and time interval) between two points. In fact, distance completely determines space. The evolution of the distance scale is determined by the amount of matter and energy in space, and as time goes on, the scale increases and so does the distance between galaxies. However - and this is the strange thing - this happens without the actual movement of the galaxies.

Perhaps at this point your intuition failed. But that won't stop us from figuring out the oddities.

We have already said that galaxies are moving away from us. Not really. It’s just easier for scientists to explain what’s really happening. They are deceiving you.

“But wait!”, the most scientifically savvy of you will say. - “We measure the Doppler shift of distant galaxies.” This so-called “red shift”, which you know about, is recorded on the Earth, and like the siren of a passing ambulance, it lets us know that there is movement. But this is not what happens on cosmological scales. It’s just that since distant galaxies emitted light and it reached us, the scale of space has seriously changed and grown. As space has expanded, the wavelength of photons has also increased, which is why light appears red.

This approach leads to another question: “Is the Universe really expanding faster than the speed of light?” It is absolutely true that most distant galaxies increase their distance from us faster than the speed of light, but so what? They do not move faster than light (they generally stand still). Moreover, knowing this will not help you in any way: the information is not transmitted. If you send a package of food to another galaxy faster than the speed of light, this cannot be done (and even here, in principle). The speed of light remains the universal speed limiter.

We have presented the most widespread (or well-established in the field of relativists) opinion regarding cosmological expansion, but it would be logical to end with the fact that we do not understand at all. All of the above works great if you have room to step forward and stretch. But what happened at the very beginning that caused space to form literally out of nothing? Physics has no answer to this question. And we will have to wait until someone appears and sheds light on this issue.

Created: 10/25/2013, 11224 46

"He created the earth by His power, established the world by His wisdom, and spread out the heavens with His understanding"

Jeremiah 10:12

In the process of the development of science, many scientists began to look for the possibility of excluding God from their views as the First Cause of the appearance of the universe. As a result, many different theories of the origin of the universe, as well as the appearance and development of living organisms, appeared. The most popular of them are the Big Bang theory and the Evolution theory. In the process of substantiating the Big Bang theory, one of the fundamental theories of evolutionists was created - the “Expanding Universe”. This theory suggests that there is an expansion of outer space on the scale of the universe, which is observed due to the gradual separation of galaxies from one another.

Let's look at the arguments that some scientists use to prove this theory. Evolutionary scientists, in particular Stephen Hawking, believe that the expanding universe is the result of the Big Bang and that after the explosion there was a rapid expansion of the universe, and then it slowed down and now this expansion is slow, but this process continues. They argue for this by measuring the speed of other galaxies moving away from our galaxy using the Doppler effect, and also by the fact that they know the speed in percentage terms, which Stephen Hawking says: “So all we know is that the expansion rate of the Universe is from 5 to 10 % per billion years." (S. Hawking “The Shortest History of Time” trans. L. Mlodinow, p. 38). However, questions arise here: how was this percentage obtained, and who and how conducted this study? Stephen Hawking doesn't explain this, but he talks about it as a fact. Having studied this issue, we received information that today, to measure the speed of receding galaxies, they use Hubble’s law, which uses the theory of “Red Shift,” which in turn is based on the Doppler Effect. Let's see what these concepts are:

Hubble's Law is a law that relatesredshift of galaxiesand the distance to them in a linear manner. This law has the form: cz = H 0 D, where z is the redshift of the galaxy; H 0 - proportionality coefficient, called the “Hubble constant”; D is the distance to the galaxy. One of the most important elements for Hubble's law is the speed of light.

Redshift -shift of spectral lines of chemical elements to the red side. It is believed that this phenomenon may be an expression of the Doppler effect or gravitational redshift, or a combination of both, but most often the Doppler effect is taken into account. This is expressed more simply by the fact that the further away a galaxy is, the more its light is redshifted.

Doppler effect -a change in the frequency and length of sound waves recorded by a receiver, caused by the movement of their source as a result of the movement of the receiver. Simply put, the closer the object, the higher the frequency of sound waves, and vice versa, the further away the object, the lower the frequency of sound waves.

However, there are a number of problems with these principles for measuring the receding velocity of galaxies. For Hubble's law, it is a problem to estimate the “Hubble constant”, since in addition to the receding speed of galaxies, they also have their own speed, which leads to the fact that Hubble’s law is poorly satisfied, or not at all, for objects located at a distance closer than 10-15 million .light years. Hubble's law is also poorly fulfilled for galaxies at very large distances (billions of light years), which correspond to a redshift greater than 1. Distances to objects with such a large redshift lose their uniqueness, since they depend on the accepted model of the Universe and on what they are assigned to a moment in time. In this case, only redshift is usually used as a measure of distance. Thus, it turns out that determining the speed at which distant galaxies are receding is practically impossible and is determined only by the model of the universe that the researcher accepts. This suggests that everyone believes in their own subjective speed of receding galaxies.

It must also be said that it is impossible to measure the distance to distant galaxies relative to their brightness or redshift. This is hampered by some facts, namely, that the speed of light is not constant and changes, and these changes are slowing down. IN1987 year In a report from the Stanford Research Institute, Australian mathematicians Trevor Norman and Barry Setterfield postulated that there had been a large reduction in the speed of light in the past (B. Setterfield, The Velocity of Light and the Age of the Universe.). IN 1987 year Nizhny Novgorod theoretical physicist V.S. Troitsky postulated that over time there was a huge decrease in the speed of light. Doctor Troitsky spoke about decreasespeedSvetaV10 millionsonce compared to its current value (V.S. Troitskii, Physical Constants and Evolution of the Universe, Astrophysics and Space Science 139(1987): 389-411.). IN1998 year Theoretical physicists at Imperial College London, Albrecht and Joao Mageijo, also postulated a decrease in the speed of light. On November 15, 1998, the London Times published the article “The speed of light, the fastest in the universe, is decreasing” ( The speed of light - the fastest thing in the universe - is getting slower, The London Times, Nov. 15, 1998).Regarding this, it must be said that the speed of light is influenced by many factors, for example, the chemical elements through which light passes, as well as the temperature they have, because light passes through some elements more slowly, and through others much faster, which has been proven experimentally . So18 February1999 of the yearThe highly respected (and 100% evolutionary) scientific journal Nature published a scientific article detailing an experiment in whichspeedSvetamanageddecreasebefore17 metersVgive me a sec,ThatThere isbeforesome60 kilometersVhour.This means that he could be watched like a car driving down the street. This experiment was carried out by Danish physicist Lene Hau and an international team of scientists from Harvard and Stanford universities. They passed light through sodium vapor cooled to incredibly low temperatures, measured in nanokelvins (that is, billionths of a kelvin; practically absolute zero, which is defined as -273.160C). Depending on the exact temperature of the vapors, the speed of light was reduced to values ​​​​in the range of 117 km/h - 61 km/h; that is, essentiallybefore1/20,000,000thfromordinaryspeedSveta(L.V. Hau, S.E. Harris, Science News, March 27, p. 207, 1999).

In July 2000, scientists from the NEC Research Institute in Pringston reported accelerationthemSvetabeforespeed,exceedingspeedSveta! Their experiment was published in the British journal Nature. They directed a laser beam at a glass chamber containing cesium vapor. As a result of the energy exchange between photons of the laser beam and cesium atoms, a beam appeared, the speed of which at the exit from the chamber was higher than the speed of the input beam. Light is believed to travel at its fastest speed in a vacuum, where there is no resistance, and slower in any other medium due to the additional resistance. For example, everyone knows that light travels slower in water than in air. In the experiment described above, the obtained Raycame outfromcamerasWithin pairscesiummorebeforeTogo,Howfullyhas enteredVher. This difference was very interesting. LaserRayjumped overon18 metersforwardfromTogoplaces,Wheremustwasbe. In theory, this could be regarded as a consequence preceding the cause, but this is not entirely true. There is also a scientific field that studies superluminal pulse propagation. The correct interpretation of this study is: speedSvetafickleAndlightCanspeed uplikeanyoneto anotherphysicalobjectinuniverse subject to the right conditions and a suitable energy source. Scientists obtained matter from energy without loss; accelerated light to speeds exceeding the currently accepted speed of light.

Regarding redRegarding the shift, it must be said that no one can say with certainty the reason for the appearance of the red shift and how many times the light is refracted when reaching the ground, and this in turn makes the basis for measuring distances using the red shift absurd. Also, the change in the speed of light refutes all existing assumptions about the distance to distant galaxies and neutralizes the method of measuring this distance by redshift. It must also be said that the application of the Doppler effect to light is purely theoretical, and given that the speed of light changes, this makes it doubly difficult to apply this effect to light. All this says that the method of determining the distance to distant galaxies by redshift, and even more so argumentation that the universe is expanding is simply unscientific and a hoax. Let's think, even if we know the speed at which galaxies are moving away, it is impossible to say that the space of the universe is expanding. No one can say whether such an expansion is happening at all. The movement of planets and galaxies in the universe does not indicate a change in space itself, but according to the Big Bang theory, space appeared as a result of the Big Bang and is expanding. This statement is not scientific, since no one has found the edge of the universe, much less measured the distance to it.

Exploring the theory of the “Big Bang” we come across another unexplored and unproven phenomenon, but which is spoken of as a fact, namely “black matter”. Let's see what Stephen Hawking says about this: “Our and other galaxies must contain large amounts of some kind of “dark matter” that we cannot observe directly, but the existence of which we know due to its gravitational effect on the orbits of stars in the galaxies. Perhaps the best evidence for the existence of dark matter comes from the orbits of stars on the periphery of spiral galaxies like the Milky Way. These stars orbit their galaxies too quickly to be held in orbit by the gravitational pull of the galaxy's visible stars alone."(S. Hawking “The Shortest History of Time” trans. L. Mlodinow, p. 38).We want to emphasize that “black matter” is spoken of as follows: “which we cannot observe directly,” this indicates that there are no facts of the existence of this matter, but the behavior of galaxies in the universe, incomprehensible to evolutionists, forces them to believe in the existence of something , but they themselves don’t know what.Also interesting is the statement: “actually the amount of dark matterin the Universe significantly exceeds the amount of ordinary matter". This statement speaks about the amount of “dark matter”, but the question arises: how and by what method was this amount determined in conditions where it is impossible to observe and study this “matter”? We can say that it was unknown what was taken and a quantity of it was obtained, it is not clear how. The fact that scientists do not understand how the stars of spiral galaxies stay in their orbit at high speeds does not mean the existence of ghostly “matter” that no one has seen or could directly observe.

Modern science is at a disadvantage relative to its big bang fantasies. Thus, in concluding his thoughts on the existence of various matters, Stephen Hawking says: “We cannot, however, exclude the existence of other forms of matter not yet known to us, distributed almost evenly throughout the Universe, which could increase its average density. For example, there are elementary particles called neutrinos that interact very weakly with matter and are extremely difficult to detect."(S. Hawking “The Shortest History of Time” trans. L. Mlodinow, p. 38). This shows how helpless modern science is in trying to prove that the universe arose on its own without a Creator. If particles are not found, then scientific arguments cannot be built on this, since the probability that other forms of matter do not exist is greater than the probability of their existence.

Be that as it may, the movement of galaxies, planets and other cosmic bodies does not indicate the expansion of the space of the universe, since such movement has nothing to do with the definition of the expansion of space. For example, if there are two people in the same room and one moves away from the other, then this does not mean that the room is expanding, but that there is space in which it is possible to move. Similarly, in this situation, galaxies move in outer space, but this does not indicate a change in outer space. It is also absolutely impossible to prove that the most distant galaxies are at the edge of the universe and there are no other galaxies behind them, and this in turn means that the edge of the universe has not been found.

Thus, we have all the facts to assert that today there is no evidence of the expansion of the universe, and this in turn confirms the inconsistency of the Big Bang theory.

It is somewhat of an irony of nature that the most abundant form of energy in the Universe is also the most mysterious. After the stunning discovery of the accelerating expansion of the Universe, a consistent picture quickly emerged indicating that 2/3 of the cosmos is “made” of “dark energy” - some kind of gravitationally repulsive material. But is the evidence convincing enough to support these exotic new laws of nature? Maybe there are simpler astrophysical explanations for these results?

The prototype of this note was recently published in the popular science section of Habr, although under lock and key, so perhaps not everyone interested got it. In this version, quite significant additions have been made, which should be of interest to everyone.

The history of dark energy began in 1998, when two independent teams explored distant supernovae. in order to detect the rate at which the expansion of the Universe is slowing down. One of them, Supernova Cosmology Project, began work in 1988, and was led by Saul Perlmutter. Another, led by Brian Schmidt High-z Supernova Search Team, joined the research in 1994. The result shocked them: the Universe has been in an accelerated expansion mode for quite a long time.

Like detectives, cosmologists around the world were compiling a dossier on the accused responsible for the acceleration. Its special features: gravitationally repulsive, prevents the formation of galaxies (clustering of matter into galaxies), manifests itself in the stretching of space-time. The nickname of the accused is “dark energy.” Many theorists have suggested that the accused is a cosmological constant. It certainly corresponded to the scenario of accelerated expansion. But was there enough evidence to fully identify dark energy with the cosmological constant?

The existence of gravitational-repulsive dark energy would have dramatic consequences for fundamental physics. The most conservative assumption was that the Universe is filled with a homogeneous sea of ​​zero-point quantum energy, or a condensate of new particles whose mass is $((10)^(39))$ times less than an electron. Some researchers also suggested the need for changes to general relativity, in particular new long-range forces that weaken the effect of gravity. But even the most conservative proposals had serious shortcomings. For example, the zero-point energy density turned out to be 120 implausible orders of magnitude less than theoretical predictions. From the point of view of these extreme assumptions, it seemed more natural to look for a solution within the framework of traditional astrophysical concepts: intergalactic dust (the scattering of photons on it and the associated weakening of the photon flux) or the difference between new and old supernovae. This possibility has been supported by many cosmologists keeping watch in the night.

Observations of supernovae and their analysis carried out by S. Perlmutter, B. Schmidt and A. Riess made it clear that the decrease in their brightness with distance occurs noticeably faster than would be expected according to the cosmological models accepted at that time. More recently, this discovery was noted. This additional dimming means that a given redshift corresponds to some effective distance addition. But this, in turn, is possible only when the cosmological expansion occurs with acceleration, i.e. The speed at which the light source moves away from us does not decrease, but increases with time. The most important feature of the new experiments was that they made it possible not only to determine the very fact of accelerated expansion, but also to draw an important conclusion about the contribution of various components to the density of matter in the Universe.

Until recently, supernovae were the only direct evidence of accelerated expansion and the only convincing support for dark energy. Accurate measurements of the cosmic microwave background, including WMAP (Wilkinson Microwave Anisotropy Probe) data, have provided independent confirmation of the reality of dark energy. The same was confirmed by data from two more powerful projects: the large-scale distribution of galaxies in the Universe and the Sloan Digital Sky Survey (SDSS).

A combination of data from WMAP, SDSS and other sources found that the gravitational repulsion generated by dark energy is slowing the collapse of super-dense regions of matter in the Universe. The reality of dark energy immediately became significantly more acceptable.

Space expansion

Cosmic expansion was discovered by Edwin Hubble in the late 1920s and may be the most important feature of our Universe. Not only do astronomical bodies move under the influence of the gravitational interaction of their neighbors, but large-scale structures are even more stretched by cosmic expansion. A popular analogy is the movement of raisins in a very large cake in the oven. As the pie rises, the distance between any pair of raisins embedded in the pie increases. If we imagine that one particular highlight represents our galaxy, then we will find that all other highlights (galaxies) are moving away from us in all directions. Our Universe expanded from the hot, dense cosmic soup created by the Big Bang into the much cooler, thinner collection of galaxies and galaxy clusters we see today.

Light emitted by stars and gas in distant galaxies is similarly stretched, lengthening its wavelength as it travels to Earth. This shift in wavelength is given by the redshift $z=\left(\lambda_(obs)-\lambda_0\right)/\lambda_0$, where $\lambda_(obs)$ is the length of light on Earth and $\lambda_(0) $ is the wavelength of the emitted light. For example, the Lyman alpha transition in the hydrogen atom is characterized by a wavelength of $\lambda_0=121.6$ nanometers (when returning to the ground state). This transition can be detected in the radiation of distant galaxies. In particular, it was used to detect a record high redshift: a stunning z=10 with the Lyman alpha line at $\lambda_(obs)=1337.6$ nanometers. But redshift describes only the change in cosmic scale as light is emitted and absorbed, and does not provide direct information about the distance to the emitter or the age of the universe when the light was emitted. If we know both the distance to the object and the redshift, we can try to obtain important information about the dynamics of the expansion of the Universe.

Observations of supernovae have revealed some gravitational-repulsive substance that controls the acceleration of the Universe. This is not the first time that astronomers have encountered the problem of missing matter. The luminous masses of galaxies turned out to be significantly smaller than the gravitating masses. This difference was made up by dark matter - cold, non-relativistic matter, probably mostly composed of particles that interact weakly with atoms and light.

However, observations indicated that the total amount of matter in the Universe, including dark matter, is only 1/3 of the total energy. This has been confirmed by the study of millions of galaxies within the 2DF and SDSS projects. But general relativity predicts that there is a precise relationship between expansion and the energy content of the universe. We therefore know that the total energy density of all photons, atoms and dark matter must be added to some critical value, determined by the Hubble constant $H_(0)$: $((\rho)_(crit))=3H_(0 )^(2)/8\pi\cdot(G)$. The catch is that it doesn't, but that's a completely different story.

Mass, energy and space-time curvature are directly related in general relativity. One explanation, therefore, may be that the gap between the critical density and the observed matter density is filled by some energy density associated with the deformation of space at large scales and observable only at scales on the order of $c/((H)_(0)) \sim 4000\ Mpc$. Fortunately, the curvature of the Universe can be determined using precision ICF measurements. A relic, with an origin 400,000 after the Big Bang, the ICF is black body radiation, the source of which is the primordial plasma. When the Universe cooled below $3000\K$, the plasma became transparent to photons and they were able to freely propagate in space. Today, almost 15 billion years later, we observe a thermal reservoir of photons at a temperature of $2.726\K$, which represents the result of a redshift due to cosmic expansion.

A remarkable image of the ICF was obtained using the WMAP satellite, showing the slightest changes in the photon temperature of the “sky”. These variations, known as ICF anisotropy, reflect small variations in the density and motion of the early Universe. These variations, which arise at the $((10)^(-5))$ level, are the seeds of the large-scale structure (galaxies, clusters) that we observe today.

The coldest/hottest spots in the cosmic microwave background are due to photons that escaped from areas of the highest/least density gravitational potential. The dimensions of these regions are well determined by plasma physics. When we consider the full Universe, the apparent angular size of these anisotropies should be about $((0.5)^(0))$ if the Universe has enough curvature to fill the energy gap and twice the angular size in the absence of any curvature of space. The easiest way to visualize this geometric effect is to imagine a triangle with a fixed base and sides (just sides?), drawn on surfaces of varying curvature. For a saddle surface/sphere, the interior angles will be smaller/larger than the same triangle drawn on a flat surface (with Euclidean geometry).

Since 1999, a number of experiments have been carried out (TOCO, MAXIMA, BOOMERANG, WMAP), which have shown that the MCF spots have dimensions of the order of $((1)^(0))$. This means that the geometry of the Universe is flat. From the perspective of the missing energy problem, this means that something other than curvature must be responsible for filling the gap. To some cosmologists, this result looked like déjà vu. Inflation, the ICF's best theory for the origin of primordial fluctuations, suggests that the very early Universe experienced a period of accelerated expansion that was driven by a particle called an inflaton. The inflaton would stretch out any large-scale curvature, making the geometry of the universe flat or Euclidean. The evidence suggests the existence of a form of energy that prevents galaxy clustering, which is gravitationally repulsive, and which may be due to a particle other than the inflaton.

Cosmic harmony

CMB and supernova data have consistently confirmed that the source of cosmic acceleration is dark energy. But that was only the beginning. By combining precision ICF measurements from WMAP with radio, optical and X-ray sensing of large-scale matter distributions, astrophysicists have obtained further evidence of an accelerating rate of expansion of the Universe. It turned out that the gravitational potential holes of density and compaction in the Universe were stretched and smoothed over time, as if under the influence of repulsive gravity. This effect is known as the integral effect (Sachs-Wolfe (ISW)). It leads to a correlation between temperature anisotropy in the CMB and the large-scale structure of the Universe. Although the primordial plasma became transparent to photons as the Universe cooled, photons do not travel unimpeded. Space is riddled with irregularities that are strong at short distances (where matter clusters into stars, galaxies and nebulae) and gradually weaken over large length scales... During their flight, photons fall into and out of gravitational holes.

After cosmic rays were first detected (about 40 years ago), Sachs and Wolff showed that a time-varying potential should result in an energy shift in the ICF of photons passing through it. A photon gains energy when it falls into a gravitational hole and spends it when it gets out of it. If the potential became deeper during this process, then the photon as a whole would therefore lose energy. If the potential becomes shallower, the photon will gain energy.

In a Universe where the full critical density is formed only by atoms and dark matter, weak gravitational potentials at very large spatial scales (which correspond to gentle waves of matter density) evolve too slowly to leave noticeable traces in ICF photons. Denser regions simply absorb surrounding matter at the same rate at which cosmic expansion lengthens the waves, leaving the potential unchanged. However, with the faster expansion of the Universe due to dark energy, matter accretion cannot compete with stretching. Effectively, the gravitational collapse is slowed down by repulsive dark matter. Consequently, the gravitational potential tends to flatten and photons gain energy when passing through these areas. Likewise, photons lose energy when passing through regions of low density. (Not trivial!)

Negative pressure

The greatest mystery of cosmic acceleration is not that it implies that 2/3 of the substance filling the Universe is not visible to us, but that it imposes the existence of matter with gravitational repulsion. To consider this strange property of dark energy, it is useful to introduce the quantity $w=((p)_(dark))/((\rho )_(dark))$. This expression resembles the equation of state of a gas. In general relativity, the rate of change of cosmic expansion is proportional to $-\left(((\rho )_(total))+3((p)_(total)) \right)$. For accelerated expansion this value must be positive. Since $((\rho )_(total))$ is positive, and the average pressure of ordinary and dark matter is negligible (because it is cold and non-relativistic), we arrive at the requirement $3w\times ((\rho )_(dark ))+((\rho )_(total))

Why does pressure affect the expansion of the Universe? Einstein showed that matter and energy bend space-time. Therefore, for a hot gas, the kinetic energy of its atoms contributes to their gravitational forces, as measured by measuring the acceleration of distant bodies. However, the forces required to contain or isolate the gas work against this excess pressure. The universe on the other hand is neither isolated nor limited. The expansion of space filled with hot gas will effectively occur more slowly (due to self-gravity) than the expansion of a universe filled with cold gas. By the same logic, a medium with such negative pressure that $((\rho )_(total))+3p

Negative pressure is not such a rare occurrence. The water pressure in some tall trees becomes negative as nutrition rises through their vascular system. In a uniform electric or magnetic field, configurations with negative pressure can also be found. In these cases, the pressure is something like a stretched spring under tension caused by internal forces. At the microscopic level, the reservoir of Higgs bosons (the hypothetical particles that generate particle mass in the Standard Model) creates negative pressure when its thermal or kinetic excitations are small. Indeed, the inflaton can be considered as a heavy version of the Higgs boson. One proposed version of dark energy—quintessence—may even be a lighter version of the Higgs.

In principle, there is no lower limit to pressure in the Universe. Although strange things happen if $w$ drops to a value less than $-1.$ Isolated pieces of such material can have negative mass. …..But one thing is obvious. Such a strong negative pressure does not occur for normal particles and fields in general relativity. Numerous observations lead to a narrower range of dark energy parameters than those that follow from the above general reasoning.

A combination of predictions from various theoretical models and the best observations of the CMB, large-scale structures and supernovae leads to $$\Omega_(dark)= 0.728^(+0.015)_(-0.016)$$ $$w= -0.980\pm0.053 $ $

A Brief History of Dark Energy

Dark energy, or something similar to it, has appeared many times in the history of cosmology. Pandora's box was opened by Einstein, who introduced the gravitational field into his equations. Cosmic expansion had not yet been discovered and the equations correctly “suggested” that the Universe containing matter could not be static without the mathematical addition of the cosmological constant, which is usually denoted by $\Lambda$. The effect is equivalent to filling the Universe with a sea of ​​negative energy, in which stars and nebulae drift. The discovery of the extension eliminated the need for this ad hoc addition to the theory.

In subsequent decades, desperate theorists periodically introduced $\Lambda$ in an attempt to explain new astronomical phenomena. These returns were always short-lived and usually resulted in more plausible explanations for the data obtained. However, since the 60s, the idea began to emerge that the vacuum (zero) energy of all particles and fields should inevitably generate a term similar to $\Lambda$. In addition, there is reason to believe that the cosmological constant could naturally arise in the early stages of the evolution of the Universe.

In 1980, the theory of inflation was developed. In this theory, the early Universe experienced a period of accelerated exponential expansion. The expansion was due to negative pressure due to the new particle - . Inflaton proved to be very successful. He allowed a lot. These paradoxes include the problems of the horizon and the flatness of the Universe. The theory's predictions were in good agreement with various cosmological observations.

Dark energy and the future of the Universe

With the discovery of dark energy, ideas about what the distant future of our Universe might be like have changed dramatically. Before this discovery, the question of the future was clearly associated with the question of the curvature of three-dimensional space. If, as many previously believed, the curvature of space by 2/3 determined the current rate of expansion of the Universe, and there was no dark energy, then the Universe would expand without limit, gradually slowing down. Now it is clear that the future is determined by the properties of dark energy.

Since we know these properties poorly now, we cannot yet predict the future. You can only consider different options. It is difficult to say what is happening in theories with new gravity, but other scenarios can be discussed now. If dark energy is constant over time, as is the case with vacuum energy, then the Universe will always experience accelerated expansion. Most galaxies will eventually move away from ours to an enormous distance, and our Galaxy, along with its few neighbors, will turn out to be an island in the void. If dark energy is quintessential, then in the distant future the accelerated expansion may stop and even be replaced by compression. In the latter case, the Universe will return to a state with hot and dense matter, a “Big Bang in reverse” will occur, back in time.

Energy budget of our Universe. It is worth paying attention to the fact that the share of familiar matter (planets, stars, the entire world around us) accounts for only 4 percent, the rest is made up of “dark” forms of energy.

An even more dramatic fate awaits the Universe if dark energy is a phantom, and such that its energy density increases without limit. The expansion of the Universe will become more and more rapid, it will accelerate so much that galaxies will be torn out of clusters, stars from galaxies, planets from the solar system. It will come to the point that electrons will break away from atoms, and atomic nuclei will split into protons and neutrons. There will be, as they say, a big break.

Such a scenario, however, does not seem very likely. Most likely, the phantom's energy density will remain limited. But even then, the Universe may face an unusual future. The fact is that in many theories, phantom behavior - an increase in energy density over time - is accompanied by instabilities. In this case, the phantom field in the Universe will become highly inhomogeneous, its energy density in different parts of the Universe will be different, some parts will rapidly expand, and some may experience collapse. The fate of our Galaxy will depend on which region it falls into.

All this, however, relates to the future, distant even by cosmological standards. In the next 20 billion years, the Universe will remain almost the same as it is now. We have time to understand the properties of dark energy and thereby more definitely predict the future - and perhaps influence it.

If, out of curiosity, we pick up a reference book or some popular science guide, we will certainly come across one of the versions of the theory of the origin of the Universe - the so-called “big bang” theory. Briefly, this theory can be stated as follows: initially, all matter was compressed into one “point” that had an unusually high temperature, and then this “point” exploded with enormous force. As a result of the explosion, atoms, substances, planets, stars, galaxies and, finally, life were gradually formed from a superhot cloud of subatomic particles gradually expanding in all directions.

At the same time, the expansion of the Universe continues, and it is unknown how long it will continue: perhaps someday it will reach its limits.

The conclusions of cosmology are based both on the laws of physics and on the data of observational astronomy. Like any science, cosmology in its structure, in addition to the empirical and theoretical levels, also has the level of philosophical prerequisites, philosophical foundations.

Thus, the basis of modern cosmology is the assumption that the laws of nature, established on the basis of the study of a very limited part of the Universe, most often based on experiments on planet Earth, can be extrapolated to much larger areas, ultimately to the entire Universe.

This assumption about the stability of the laws of nature in space and time belongs to the level of the philosophical foundations of modern cosmology.

The emergence of modern cosmology is associated with the creation of a relativistic theory of gravity - the general theory of relativity by Einstein (1916).

From Einstein's equations of general relativity follows the curvature of space-time and the connection between curvature and mass (energy) density.

Applying the general theory of relativity to the Universe as a whole, Einshein discovered that there was no such solution to the equations that would correspond to a Universe that did not change over time.

However, Einstein imagined the Universe as stationary. Therefore, he introduced an additional term into the resulting equations, ensuring the stationarity of the Universe.

In the early 20s, the Soviet mathematician A.A. Friedman was the first to solve the equations of the general theory of relativity in relation to the entire Universe, without imposing stationarity conditions.

He showed that the Universe, filled with gravitating matter, should expand or contract.

The equations obtained by Friedman form the basis of modern cosmology.

In 1929, the American astronomer E. Hubble published an article “The relationship between the distance and radial velocity of extragalactic nebulae,” in which he came to the conclusion: “Distant galaxies are moving away from us with a speed proportional to their distance from us.

Hubble obtained this conclusion based on the empirical establishment of a certain physical effect - red shift, i.e.

an increase in the wavelengths of lines in the spectrum of the source (shift of lines towards the red part of the spectrum) compared to the lines of the standard spectra, due to the Doppler effect in the spectra of galaxies.

Hubble's discovery of the redshift effect, the recession of galaxies, underlies the concept of an expanding Universe.

According to modern cosmological concepts, the Universe is expanding, but there is no center of expansion: from any point in the Universe, the expansion pattern will appear the same, namely, all galaxies will have a redshift proportional to their distance.

The space itself seems to be inflated.

If you draw galaxies on a balloon and start inflating it, the distances between them will increase, and the faster the further they are located from each other. The only difference is that the galaxies drawn on the ball themselves increase in size, while real star systems throughout the Universe maintain their volume due to the forces of gravity.

One of the biggest problems facing proponents of the Big Bang theory is precisely that none of the scenarios they propose for the origin of the Universe can be described mathematically or physically.

According to basic Big Bang theories, the original state of the Universe was an infinitely small point with an infinitely high density and an infinitely high temperature. However, such a state goes beyond the limits of mathematical logic and cannot be formally described. So, in reality, nothing definite can be said about the initial state of the Universe, and calculations fail here. Therefore, this condition was called a “phenomenon” among scientists.

Since this barrier has not yet been overcome, in popular science publications for the general public the topic of the “phenomenon” is usually omitted altogether, but in specialized scientific publications and editions, the authors of which are trying to somehow cope with this mathematical problem, about the “phenomenon” " is said to be a scientifically unacceptable thing, Stephen Hawking, Professor of Mathematics at the University of Cambridge, and J. F. R. Ellis, Professor of Mathematics at the University of Cape Town, in their book "The Long Scale of Space-Time Structure" point out: " Our results support the concept that the Universe began a finite number of years ago.

However, the starting point of the theory of the origin of the Universe – the so-called “phenomenon” – is beyond the known laws of physics.”

How the expansion of the Universe was discovered

Then we have to admit that in order to justify the “phenomenon”, this cornerstone of the “big bang” theory, it is necessary to allow the possibility of using research methods that go beyond the scope of modern physics.

“Phenomenon,” like any other starting point of the “beginning of the Universe,” which includes something that cannot be described by scientific categories, remains an open question.

However, the following question arises: where did the “phenomenon” itself come from, how was it formed? After all, the problem of the “phenomenon” is only part of a much larger problem, the problem of the very source of the initial state of the Universe. In other words, if the Universe was originally compressed into a point, then what brought it to this state? And even if we abandon the “phenomenon” that causes theoretical difficulties, the question will still remain: how did the Universe form?

In an attempt to get around this difficulty, some scientists propose the so-called “pulsating universe” theory.

In their opinion, the Universe endlessly, over and over again, either shrinks to a point, or expands to some boundaries. Such a Universe has neither beginning nor end, there is only a cycle of expansion and a cycle of contraction. At the same time, the authors of the hypothesis claim that the Universe has always existed, thereby seemingly completely eliminating the question of the “beginning of the world.”

But the fact is that no one has yet provided a satisfactory explanation for the pulsation mechanism.

Why does the Universe pulsate? What are the reasons for it? Physicist Steven Weinberg, in his book “The First Three Minutes,” points out that with each successive pulsation in the Universe, the ratio of the number of photons to the number of nucleons must inevitably increase, which leads to the extinction of new pulsations.

Weinberg concludes that thus the number of pulsation cycles of the Universe is finite, which means that at some point they must stop. Consequently, the “pulsating Universe” has an end, which means it also has a beginning.

In 2011, the Nobel Prize in Physics was awarded to Saul Perlmutter of the Lawrence Berkeley National Laboratory, a member of the Supernova Cosmology project, and Brian P., a member of the High-z Supernova research team.

Schmidt of the Australian National University and Adam G. Riess of Johns Hopkins University.

Three scientists shared the prize for discovering the acceleration of the expansion of the Universe by observing distant supernovae. They studied a special type of supernova, Type Ia.

These are exploding old compact stars that are heavier than the Sun but the size of Earth. One such supernova can emit as much light as an entire galaxy of stars. Two teams of researchers have discovered more than 50 distant supernovae Ia whose light was fainter than expected.

This was proof that the expansion of the Universe is accelerating. The research repeatedly encountered puzzles and complex problems, but in the end, both teams of scientists came to the same conclusions about the accelerating expansion of the Universe.

This discovery is actually surprising.

We already know that after the Big Bang about 14 billion years ago, the Universe began to expand. However, the discovery that this expansion was accelerating surprised the discoverers themselves.

The reason for the mysterious acceleration is attributed to hypothetical dark energy, which is estimated to make up about three-quarters of the Universe, but still remains the biggest mystery of modern physics.

Astronomy

Astronomy->Expanding Universe->

Testing online

material from the book “A Brief History of Time” by Stephen Hawking and Leonard Mlodinow

Doppler effect

In the 1920s, when astronomers began studying the spectra of stars in other galaxies, something very interesting was discovered: they turned out to have the same characteristic patterns of missing colors as stars in our own galaxy, but they were all shifted to the red end of the spectrum , and in the same proportion.

Physicists know a shift in color or frequency as the Doppler effect.

We are all familiar with how this phenomenon affects sound. Listen to the sound of a car passing by.

Expanding Universe

When it approaches, the sound of its engine or horn seems higher, and when the car has already passed by and began to move away, the sound decreases. A police car driving towards us at a speed of one hundred kilometers per hour develops about a tenth of the speed of sound. The sound of his siren is a wave, alternating crests and troughs. Recall that the distance between the nearest crests (or troughs) is called the wavelength. The shorter the wavelength, the more vibrations reach our ear every second and the higher the tone, or frequency, of the sound.

The Doppler effect is caused by the fact that an approaching car, emitting each successive sound wave crest, will be closer to us, and as a result, the distances between the crests will be less than if the car were standing still.

This means that the wavelengths coming to us become shorter and their frequency higher. Conversely, if the car moves away, the wavelengths we pick up become longer and their frequency lower. And the faster the car moves, the stronger the Doppler effect appears, which makes it possible to use it to measure speed.

When the source emitting waves moves towards the observer, the wavelength decreases.

As the source moves away, on the contrary, it increases. This is called the Doppler effect.

Light and radio waves behave in a similar way. Police use the Doppler effect to determine the speed of cars by measuring the wavelength of the radio signal reflected from them.

Light is vibrations, or waves, of an electromagnetic field. The wavelength of visible light is extremely small - from forty to eighty millionths of a meter. The human eye perceives different wavelengths of light as different colors, with the longest wavelengths at the red end of the spectrum and the shortest at the blue end.

Now imagine a light source located at a constant distance from us, such as a star, emitting light waves of a certain wavelength. The length of the recorded waves will be the same as those emitted. But suppose now that the light source begins to move away from us. As with sound, this will cause the wavelength of light to increase, meaning the spectrum will shift towards the red end.

Expansion of the Universe

Having proved the existence of other galaxies, Hubble in subsequent years worked on determining the distances to them and observing their spectra.

At the time, many assumed that galaxies moved randomly and expected that the number of blue-shifted spectra would be about the same as the number of red-shifted ones. Therefore, it was a complete surprise to discover that the spectra of most galaxies show a red shift - almost all star systems are moving away from us!

Even more surprising was the fact discovered by Hubble and made public in 1929: the redshift of galaxies is not random, but is directly proportional to their distance from us. In other words, the farther a galaxy is from us, the faster it is moving away! It followed from this that the Universe cannot be static, unchanged in size, as previously thought.

In reality, it is expanding: the distance between galaxies is constantly growing.

The realization that the Universe is expanding produced a real revolution in the mind, one of the greatest in the twentieth century. In retrospect, it may seem surprising that no one thought of this before. Newton and other great minds must have realized that a static universe would be unstable. Even if at some moment it were motionless, the mutual attraction of stars and galaxies would quickly lead to its compression.

Even if the Universe were to expand relatively slowly, gravity would eventually put an end to its expansion and cause it to contract. However, if the expansion rate of the Universe is greater than a certain critical point, gravity will never be able to stop it and the Universe will continue to expand forever.

Here there is a vague resemblance to a rocket rising from the surface of the Earth.

At a relatively low speed, gravity will eventually stop the rocket and it will begin to fall toward Earth. On the other hand, if the rocket's speed is higher than critical (more than 11.2 kilometers per second), gravity cannot hold it and it leaves the Earth forever.

In 1965, two American physicists, Arno Penzias and Robert Wilson of Bell Telephone Laboratories in New Jersey, were debugging a very sensitive microwave receiver.

(Microwaves are radiation with a wavelength of about a centimeter.) Penzias and Wilson were concerned that the receiver was detecting more noise than expected. They found bird droppings on the antenna and eliminated other potential causes of failure, but soon exhausted all possible sources of interference. The noise was different in that it was recorded around the clock throughout the year, regardless of the Earth’s rotation around its axis and its revolution around the Sun. Since the movement of the Earth directed the receiver into different sectors of space, Penzias and Wilson concluded that the noise was coming from outside the Solar System and even from outside the Galaxy.

It seemed to come equally from all directions of space. We now know that, no matter where the receiver is pointed, this noise remains constant, apart from negligible variations. So Penzias and Wilson accidentally stumbled upon a striking example that the Universe is the same in all directions.

What is the origin of this cosmic background noise? Around the same time that Penzias and Wilson were investigating the mysterious noise in the receiver, two American physicists at Princeton University, Bob Dick and Jim Peebles, also became interested in microwaves.

They studied George Gamow's proposal that in the early stages of its development the Universe was very dense and white-hot. Dick and Peebles believed that if this was true, then we should be able to observe the glow of the early Universe, since light from very distant regions of our world is only now arriving at us. However, due to the expansion of the Universe, this light should be shifted so much to the red end of the spectrum that it will turn from visible radiation into microwave radiation.

Dick and Peebles were just preparing to search for this radiation when Penzias and Wilson, hearing about their work, realized that they had already found it.

For this discovery, Penzias and Wilson were awarded the Nobel Prize in 1978 (which seems somewhat unfair to Dick and Peebles, not to mention Gamow).

At first glance, the fact that the Universe looks the same in any direction suggests that we occupy some special place in it. In particular, it may seem that since all the galaxies are moving away from us, then we must be at the center of the Universe.

There is, however, another explanation for this phenomenon: the Universe may look the same in all directions also when viewed from any other galaxy.

All galaxies are moving away from each other.

This is reminiscent of the spreading of colored spots on the surface of an inflated balloon. As the size of the ball increases, the distances between any two spots increase, but none of the spots can be considered the center of expansion.

Moreover, if the radius of the balloon is constantly growing, then the further apart the spots on its surface are, the faster they will move away as they expand. Let's say that the radius of the balloon doubles every second.

Then two spots, initially separated by a distance of one centimeter, after a second will already be two centimeters apart (measured along the surface of the balloon), so that their relative speed will be one centimeter per second.

On the other hand, a pair of spots that were separated by ten centimeters will, a second after the expansion begins, move apart by twenty centimeters, so that their relative speed will be ten centimeters per second. The speed at which any two galaxies move away from each other is proportional to the distance between them.

Thus, the redshift of a galaxy should be directly proportional to its distance from us - this is the same dependence that Hubble later discovered. Russian physicist and mathematician Alexander Friedman in 1922 managed to propose a successful model and anticipate the results of Hubble's observations; his work remained almost unknown in the West until in 1935 a similar model was proposed by the American physicist Howard Robertson and the British mathematician Arthur Walker, following in the footsteps of Hubble's discovery expansion of the Universe.

Due to the expansion of the Universe, galaxies are moving away from each other.

Over time, the distance between distant stellar islands increases more than between nearby galaxies, just as the spots on an inflating balloon do.

Therefore, to an observer from any galaxy, the speed at which another galaxy is moving away seems to be greater, the further away it is located.

Three types of expansion of the Universe

The first class of solutions (the one Friedman found) assumes that the expansion of the universe is slow enough that the attraction between galaxies gradually slows down and eventually stops it.

After this, the galaxies begin to move closer together, and the Universe begins to shrink. According to the second class of solutions, the Universe is expanding so quickly that gravity will only slightly slow down the retreat of galaxies, but will never be able to stop it. Finally, there is a third solution, according to which the Universe is expanding at just the right speed to avoid collapse. Over time, the speed of galaxy expansion becomes less and less, but never reaches zero.

An amazing feature of Friedman's first model is that in it the Universe is not infinite in space, but at the same time there are no boundaries anywhere in space.

Gravity is so strong that space collapses and closes in on itself. This is to some extent similar to the surface of the Earth, which is also finite, but has no boundaries. If you move along the surface of the Earth in a certain direction, you will never come across an insurmountable barrier or the end of the world, but in the end you will return to where you started.

In Friedman's first model, space is arranged in exactly the same way, but in three dimensions, rather than two, as in the case of the Earth's surface. The idea that one can go around the Universe and return to the starting point is good for science fiction, but has no practical significance, since, as can be proven, the Universe will shrink to a point before the traveler returns to the beginning of his journey.

The universe is so large that you need to move faster than light in order to finish your journey where you started, and such speeds are prohibited (by the theory of relativity). In Friedman's second model, space is also curved, but in a different way.

And only in the third model is the large-scale geometry of the Universe flat (although space is curved in the vicinity of massive bodies).

Which Friedman model describes our Universe? Will the expansion of the Universe ever stop and be replaced by compression, or will the Universe expand forever?

It turned out that answering this question is more difficult than scientists initially thought. Its solution depends mainly on two things - the currently observed rate of expansion of the Universe and its current average density (the amount of matter per unit volume of space).

The higher the current rate of expansion, the greater the gravity, and therefore the density of matter, required to stop the expansion. If the average density is above a certain critical value (determined by the rate of expansion), then the gravitational attraction of matter can stop the expansion of the Universe and cause it to contract. This behavior of the Universe corresponds to Friedman's first model.

If the average density is less than a critical value, then gravitational attraction will not stop the expansion and the Universe will expand forever - as in the second Friedmann model. Finally, if the average density of the Universe is exactly equal to the critical value, the expansion of the Universe will slow down forever, getting closer and closer to a static state, but never reaching it.

This scenario corresponds to Friedman's third model.

So which model is correct? We can determine the current rate of expansion of the Universe if we measure the speed at which other galaxies are moving away from us using the Doppler effect.

This can be done very accurately. However, the distances to galaxies are not very well known, since we can only measure them indirectly. Therefore, we only know that the expansion rate of the Universe is from 5 to 10% per billion years. Our knowledge of the current average density of the Universe is even more vague. So, if we add up the masses of all the visible stars in our and other galaxies, the sum will be less than a hundredth of what is required to stop the expansion of the Universe, even at the lowest estimate of the expansion rate.

But that's not all.

Our galaxy and others must contain large amounts of some kind of “dark matter” that we cannot observe directly, but whose existence we know due to its gravitational effect on the orbits of stars in the galaxies. Perhaps the best evidence for the existence of dark matter comes from the orbits of stars on the periphery of spiral galaxies like the Milky Way.

These stars orbit their galaxies too quickly to be held in orbit by the gravitational pull of the galaxy's visible stars alone. Additionally, most galaxies are part of clusters, and we can similarly infer the presence of dark matter between galaxies in these clusters from its effect on the motion of galaxies.

In fact, the amount of dark matter in the Universe greatly exceeds the amount of ordinary matter. If we include all the dark matter, we get about a tenth of the mass needed to stop the expansion.

However, we cannot exclude the existence of other forms of matter, not yet known to us, distributed almost evenly throughout the Universe, which could increase its average density.

For example, there are elementary particles called neutrinos that interact very weakly with matter and are extremely difficult to detect.

Over the past few years, different groups of researchers have been studying the tiny ripples in the microwave background that Penzias and Wilson discovered. The size of these ripples can serve as an indicator of the large-scale structure of the Universe. Its character seems to indicate that the Universe is flat after all (as in Friedmann's third model)!

But since the total amount of ordinary and dark matter is not enough for this, physicists postulated the existence of another, not yet discovered, substance - dark energy.

And as if to complicate the problem further, recent observations have shown that The expansion of the Universe is not slowing down, but accelerating.

Contrary to all Friedman's models! This is very strange, since the presence of matter in space - high or low density - can only slow down the expansion. After all, gravity always acts as an attractive force. Accelerating cosmological expansion is like a bomb that collects rather than dissipates energy after it explodes.

What force is responsible for the accelerating expansion of space? No one has a reliable answer to this question. However, Einstein may have been right after all when he introduced the cosmological constant (and its corresponding antigravity effect) into his equations.

Einstein's mistake

The expansion of the universe could have been predicted at any time in the nineteenth or eighteenth century and even at the end of the seventeenth century.

However, the belief in a static Universe was so strong that the delusion retained its power over minds until the beginning of the twentieth century. Even Einstein was so confident in the static nature of the Universe that in 1915 he made a special amendment to the general theory of relativity by artificially adding a special term to the equations, called the cosmological constant, which ensured the static nature of the Universe.

The cosmological constant manifested itself as the action of a certain new force - “antigravity”, which, unlike other forces, did not have any specific source, but was simply an integral property inherent in the fabric of space-time itself.

Under the influence of this force, space-time exhibited an innate tendency to expand. By choosing the value of the cosmological constant, Einstein could vary the strength of this tendency. With its help, he was able to precisely balance the mutual attraction of all existing matter and, as a result, obtain a static Universe.

Einstein later rejected the idea of ​​a cosmological constant, admitting it to be his “biggest mistake.”

As we will soon see, there are reasons today to believe that Einstein may have been right after all in introducing the cosmological constant. But what must have saddened Einstein most was that he allowed his belief in a stationary universe to overshadow the conclusion that the universe must expand, predicted by his own theory. Only one person seems to have seen this consequence of general relativity and taken it seriously. While Einstein and other physicists were looking for how to avoid the non-static nature of the Universe, Russian physicist and mathematician Alexander Friedman, on the contrary, insisted that it was expanding.

Friedman made two very simple assumptions about the Universe: that it looks the same no matter which direction we look, and that this assumption is true no matter where in the Universe we look from.

Based on these two ideas and solving the equations of general relativity, he proved that the Universe cannot be static. Thus, in 1922, several years before Edwin Hubble's discovery, Friedman accurately predicted the expansion of the Universe!

Centuries ago, the Christian Church would have considered it heretical, since church doctrine postulated that we occupy a special place at the center of the universe.

But today we accept Friedman's assumption for almost the opposite reason, out of a kind of modesty: it would seem absolutely amazing to us if the Universe looked the same in all directions only to us, but not to other observers in the Universe!

UNIVERSE(from the Greek “oikoumene” - populated, inhabited earth) - “everything that exists”, “a comprehensive world whole”, “the totality of all things”; the meaning of these terms is ambiguous and determined by the conceptual context.

We can distinguish at least three levels of the concept “Universe”.

1. The universe as a philosophical idea has a meaning close to the concept of “universe”, or “world”: “material world”, “created being”, etc. It plays an important role in European philosophy. Images of the Universe in philosophical ontologies were included in the philosophical foundations of scientific research of the Universe.

2. The Universe in physical cosmology, or the Universe as a whole, is an object of cosmological extrapolations.

In the traditional sense - a comprehensive, unlimited and fundamentally unique physical system (“The Universe is published in one copy” - A. Poincaré); the material world, considered from a physical and astronomical point of view (A.L. Zelmanov). Different theories and models of the Universe are considered from this point of view as not equivalent to each other of the same original.

This understanding of the Universe as a whole was justified in different ways: 1) with reference to the “presumption of extrapolability”: cosmology claims to represent the comprehensive world whole in the system of knowledge with its conceptual means, and until the contrary is proven, these claims must be accepted in full ; 2) logically - the Universe is defined as a comprehensive global whole, and other Universes cannot exist by definition, etc. Classical, Newtonian cosmology created an image of the Universe, infinite in space and time, and infinity was considered an attributive property of the Universe.

It is generally accepted that Newton's infinite homogeneous Universe “destroyed” the ancient cosmos. However, scientific and philosophical images of the Universe continue to coexist in culture, mutually enriching each other.

The Newtonian Universe destroyed the image of the ancient cosmos only in the sense that it separated man from the Universe and even contrasted them.

In non-classical, relativistic cosmology, the theory of the Universe was first constructed.

Its properties turned out to be completely different from Newton's. According to the theory of the expanding Universe, developed by Friedman, the Universe as a whole can be both finite and infinite in space, and in time it is in any case finite, i.e.

had a beginning. A.A. Friedman believed that the world, or the Universe as an object of cosmology, is “infinitely narrower and smaller than the world-universe of the philosopher.” On the contrary, the overwhelming majority of cosmologists, based on the principle of uniformity, identified the models of the expanding Universe with our Metagalaxy. The initial moment of the expansion of the Metagalaxy was considered as the absolute “beginning of everything”, from a creationist point of view - as the “creation of the world”. Some relativist cosmologists, considering the principle of uniformity to be an insufficiently justified simplification, considered the Universe as a comprehensive physical system on a larger scale than the Metagalaxy, and the Metagalaxy as only a limited part of the Universe.

Relativistic cosmology radically changed the image of the Universe in the scientific picture of the world.

In ideological terms, it returned to the image of the ancient cosmos in the sense that it again connected man and the (evolving) Universe. A further step in this direction was anthropic principle in cosmology.

The modern approach to the interpretation of the Universe as a whole is based, firstly, on the distinction between the philosophical idea of ​​the world and the Universe as an object of cosmology; secondly, this concept is relativized, i.e. its volume correlates with a certain level of knowledge, cosmological theory or model - in a purely linguistic (irrespective of their objective status) or in an objective sense.

The Universe was interpreted, for example, as “the largest set of events to which our physical laws, extrapolated in one way or another, can be applied” or “could be considered physically connected with us” (G. Bondi).

The development of this approach was the concept according to which the Universe in cosmology is “everything that exists” not in some absolute sense, but only from the point of view of a given cosmological theory, i.e. a physical system of the greatest scale and order, the existence of which follows from a certain system of physical knowledge.

This is a relative and transitory boundary of the known mega-world, determined by the possibilities of extrapolation of the system of physical knowledge. The Universe as a whole does not in all cases mean the same “original.” On the contrary, different theories may have unequal originals as their object, i.e. physical systems of different order and scale of structural hierarchy. But all claims to represent a comprehensive world whole in an absolute sense remain unsubstantiated.

When interpreting the Universe in cosmology, a distinction must be made between potentially existing and actually existing. What is considered non-existent today may tomorrow enter the realm of scientific research, turn out to exist (from the point of view of physics) and be included in our understanding of the Universe. Thus, if the theory of the expanding Universe essentially described our Metagalaxy, then the theory of the inflationary (“inflating”) Universe, most popular in modern cosmology, introduces the concept of many “other universes” (or, in terms of empirical language, extra-metagalactic objects) with qualitatively different properties.

Inflationary theory recognizes, therefore, a megascopic violation of the principle of uniformity of the Universe and introduces, in its meaning, the principle of infinite diversity of the Universe.

I.S. Shklovsky proposed to call the totality of these universes the “Metaverse”. Inflationary cosmology in a specific form revives, therefore, the idea of ​​the infinity of the Universe (Metaverse) as its infinite diversity. Objects like the Metagalaxy are often called “miniuniverses” in inflationary cosmology.

Miniverses arise through spontaneous fluctuations of the physical vacuum. From this point of view it follows that the initial moment of expansion of our Universe, the Metagalaxy should not necessarily be considered the absolute beginning of everything.

This is only the initial moment of the evolution and self-organization of one of the cosmic systems. In some versions of quantum cosmology, the concept of the Universe is closely linked to the existence of the observer (“the principle of participation”). “Having generated observer-participants at some limited stage of its existence, does not the Universe, in turn, acquire through their observations that tangibility that we call reality? Isn’t this a mechanism of existence?” (A.J. Wheeler).

The meaning of the concept of the Universe in this case is determined by a theory based on the distinction between the potential and actual existence of the Universe as a whole in the light of the quantum principle.

3. The Universe in astronomy (observable, or astronomical Universe) is an area of ​​the world covered by observations, and now partly by space experiments, i.e.

“everything that exists” from the point of view of observational means and research methods available in astronomy. The astronomical Universe is a hierarchy of cosmic systems of increasing scale and order of complexity that have been successively discovered and studied by science. This is the Solar System, our star system, the Galaxy (the existence of which was proven by V. Herschel in the 18th century), the Metagalaxy discovered by E. Hubble in the 1920s.

Currently, objects in the Universe that are distant from us at a distance of approx. 9–12 billion light years.

Throughout the history of astronomy until the 2nd half.

Expanding Universe concept.

20th century In the astronomical Universe, the same types of celestial bodies were known: planets, stars, gas and dust matter. Modern astronomy has discovered fundamentally new, previously unknown types of celestial bodies, incl.

superdense objects in the nuclei of galaxies (possibly representing black holes). Many states of celestial bodies in the astronomical Universe turned out to be sharply non-stationary, unstable, i.e. located at bifurcation points. It is assumed that the overwhelming majority (up to 90–95%) of the matter of the astronomical Universe is concentrated in invisible, as yet unobservable forms (“hidden mass”).

Literature:

1. Fridman A.A.

Favorite works. M., 1965;

2. Infinity and the Universe. M., 1970;

3. Universe, astronomy, philosophy. M, 1988;

4. Astronomy and the modern picture of the world.

5. Bondy H. Cosmology. Cambr., 1952;

6. Munitz M. Space, Time and Creation. N.Y., 1965.

V.V.Kazyutinsky

• Translation

If the Universe is expanding, we can understand why distant galaxies are moving away from us. But why don't stars, planets and atoms expand?

One of the biggest scientific surprises of the 20th century was the discovery of the expansion of the Universe. Distant galaxies are moving away from us and from each other faster than closer ones, as if the very fabric of space is stretching. On the largest scales, the density of matter and energy in the Universe has been falling for billions of years, and continues to do so. And if we look far enough, we will see galaxies flying away so fast that nothing we could send to them today could catch them—not even the speed of light. But isn't there a paradox in this? This is exactly what the reader is asking:

If the universe is expanding faster than the speed of light, why doesn't this affect our solar system and the distances from the sun to the planets? And why is the relative distance between the stars of our galaxy not increasing... or is it increasing?

The reader’s idea is correct, and the Solar system, the distances between planets and stars do not increase with the expansion of the Universe. So what is expanding in an expanding universe? Let's figure it out.



Newton's original idea of ​​space as fixed, absolute and unchanging. It was a stage on which the masses could exist and be attracted

When Newton first thought about the universe, he imagined space as a grid. It was an absolute, fixed entity, filled with masses that were gravitationally attracted to each other. But when Einstein came along, he realized that this imaginary grid is not fixed, not absolute, and not like Newton's representation. This mesh is like fabric, and this fabric is twisted, distorted, and changes over time due to the presence of matter and energy. Moreover, matter and energy determine its curvature.

Curvature of space-time by gravitational masses according to general relativity

But if there were only a collection of different masses in your space-time, they would inevitably collapse and form a black hole. Einstein didn't like this idea, so he added a "correction" in the form of a cosmological constant. If there is that extra term in the equation—extra energy permeating empty space—it can push all that mass away and keep the universe still. It will prevent gravitational collapse. By adding it, Einstein allowed the Universe to exist in an almost motionless state forever.

But not everyone was attracted to the idea of ​​a static universe. One of the first solutions was obtained by a physicist named Alexander Friedman. He showed that if you do not add this cosmological constant, and fill the Universe with energy - matter, radiation, dust, liquids, etc. – then there are two classes of solutions: one for a contracting Universe, and the other for an expanding one.

A “raisin bread” model of the expansion of the Universe, where relative distances increase as space expands (dough)

Mathematics gives you possible solutions, but you need to look at the physical Universe to find out which one describes it. This happened in the 1920s thanks to the work of Edwin Hubble. Hubble was the first to discover that it was possible to measure the characteristics of individual stars in other galaxies and determine their distance. Combining these measurements with the work of Vesto Slifer, who showed that these objects undergo a shift in the atomic spectrum, he obtained an amazing result.

A plot of the apparent rate of expansion (y-axis) versus distance (x-axis) corresponds to a universe that expanded rapidly in the past but is still expanding today. This is a modern version of Hubble's work, extended to distances thousands of times greater than the original ones.

Either the entire theory of relativity is wrong, we are at the center of the Universe and everything is symmetrically running away from us, or the theory of relativity is correct, Friedman is right, and the farther a galaxy is from us, the faster on average it moves away from us. In one move, the theory of an expanding universe moved from a simple idea to the leading description of the universe.

The extension works a little counterintuitively. It all looks as if the fabric of space is stretching over time, and all the objects in this space are being pulled apart from each other. The further an object is from another, the greater the stretch between them, the faster they move away from each other. If we had a Universe uniformly filled with matter, then the matter would simply become less dense and each section of it would move away from all the others over time.

Cold fluctuations (blue) in the CMB are not inherently colder, but simply represent areas where there is greater gravitational pull due to higher density of matter. Hot spots (red) are hotter because the radiation in those spots lives in a shallower gravity well. Over time, denser areas are more likely to become stars, galaxies, and clusters, while less dense areas are less likely to become stars.

But the Universe is not perfectly uniform. It contains areas of increased density, such as planets, stars, galaxies, and galaxy clusters. It contains areas of low density, such as huge cosmic voids, where there are practically no massive objects to be found. This is due to the presence of other physical phenomena besides the expansion of the Universe. At small scales, animal-sized and smaller, electromagnetism and nuclear forces predominate. On large scales - planets, solar systems and galaxies - gravitational influence predominates. At the largest scales—sizes comparable to the Universe—the main struggle is between the expansion of the Universe and the gravitational attraction of all the matter and energy present in it.

At the largest scales, the Universe is expanding and galaxies are moving away from each other. On small scales, gravity overpowers expansion, which leads to the formation of stars, galaxies and their clusters

On the largest scales, expansion wins. The most distant galaxies are receding so quickly that no signals we could send to them, even at the speed of light, would ever reach them. The Universe's superclusters—long, thread-like structures along which galaxies line up, stretching across billions of light years—are stretched and pulled apart as the Universe expands. In a relatively short time they will disappear. And even the closest cluster of galaxies to the Milky Way, the Virgo cluster, located only 50 million light years away, will not attract us to it. Despite a gravitational pull more than a thousand times greater than our own, the expansion of the Universe will pull us apart.

A large collection of many thousands of galaxies makes up our immediate environment within 100,000,000 light years. The Virgo Cluster will remain gravitationally bound, but the Milky Way will continue to move away from it over time

But there are also smaller scales where expansion has been defeated - at least locally. The Virgo Cluster will remain gravitationally bound. The Milky Way and the entire local group of galaxies will remain connected, and will eventually merge under the influence of gravity. The Earth will still move in orbit around the Sun at the same distance, the Earth will remain the same size, and the atoms that make up everything will not expand. Why? Because the expansion of the Universe only works where other interactions - gravitational, electromagnetic, nuclear - have not overcome it. If some force is capable of holding an object intact, even the expansion of the Universe cannot change it.

The orbits of the planets in the TRAPPIST-1 system do not change with the expansion of the Universe due to the cohesive force of gravity, which overcomes all the consequences of expansion

There is a non-obvious reason for this, due to the fact that expansion is not about interaction, but more about speed. Space expands on all scales, but the expansion only affects all objects collectively. Between two points, space will expand at a certain speed, but if this speed is less than the escape speed between two objects - if there is a force between them - then the distance between them will not increase. No increase in distance, no effect of expansion. At any moment, the expansion is overcome with a margin, so it will never acquire the total effect observed between unrelated objects. As a result, stable, coherent objects can survive unchanged in an expanding universe forever.

The sizes of stable objects held together, whether they are bound by gravity, electromagnetism or another force, will not change as the universe expands. If you manage to overcome the cosmic expansion, you will remain connected forever.

As long as the Universe has the properties we measure, everything will continue to be so. Dark energy may exist and cause distant galaxies to accelerate away from us, but the effect of expansion at a fixed distance will not change. Only in option