The law of universal recession of galaxies. Dark energy and Hubble's law Distances to galaxies Hubble's law

In the article dated 05/23/2013 “A new look at the nature of dark energy (DE) in the consequences of general relativity” a version was proposed about the global influence of cosmic gravity on the Hubble law, in the form of a correction for the additional blue gravitational shift of the radiation spectrum of distant galaxies (interpretation under TE ). This is a new direction in TE research, which unexpectedly found theoretical confirmation, so the version has a continuation.

Let us turn to the work of Ya. Zeldovich and I. Novikov “Structure and evolution of the Universe”, in chapter 3.5. – equation (10) considers the formula of the complete Hubble law, taking into account the blue gravitational shift, and comments on it in Chapter 3.12. pp. 123-124, we present it in a more convenient form:

1+ Z hubble (R) -2/3 πρ mGR 2 /C 2 =ν(R)/ν o, (1)

Where: ρ m- critical density of matter in the Universe, Z hubble– cosmological redshift, ν(R)– observed frequency, ν o– true frequency.

Equation (1) is interesting for its content; it includes the constant 2/3 πρ mG, let's call it the gravitational displacement constant Λ grav, which is written in a form similar to Einstein’s cosmological constant Λ einsh =4/3πρ m G in the original version. In cosmology Λ einsh associated with TE, this is what makes formula (1) unique, it initially theoretically contained an effect under the interpretation of TE, but this was 1975.

Let us analyze equation (1), the constant Λ grav follows from Poisson solutions for a spherically symmetric homogeneous Universe,

ƒ(R) - ƒ(0) =∆ƒ =2/3 πρ mGR 2 , (2)

where: ƒ – Newtonian gravitational potential (GP).

And it shows how the MS of the Universe is formed; from equation (2) it follows that the main contribution to the formation of the MS is made by distant masses, for the gravitationally bound (visible) part of the Universe with a radius R all (t)=C∆t(Where ∆ t– age of the Universe). In Friedmann's equations the product ρ eR 2 all is a constant throughout the entire arrow of time, which means that the GP at all points of the Universe and throughout the entire arrow of time is a constant, substituting the modern values of the parameters of the Universe into equation (2) we get,

∆ƒ = 2/3 πρ mGR 2 =0.75*3.14*9.6*10 -26 *6.7*10 -11 *1.7*10 52 =3*10 16 ≈С 2

approximately equal to the speed of light squared. Then the parameter R in equation (2) acquires a specific value as the radius of the visible part of the Universe, and it is unacceptable to use arbitrary distances to calculate the GP, it is the same everywhere.

The question arises, what kind of blue gravitational shift of the radiation spectrum are we talking about in equation (1), if the gravitational field of the Universe is globally homogeneous, it is for this reason that the correction for the blue gravitational shift - 2/3 πρ mGR 2 /C 2 is not considered in cosmology. On the other hand, the simplicity and, most importantly, naturalness of the explanation of the nature of TE is quite logical and extremely attractive; perhaps the Zeldovich-Novikov amendment is related to the question: does gravity (as a form of energy) obey Hubble's law of cosmological redshift, let us turn to the theory of inflation.

One of the key and indispensable conditions of the theory of inflation is the zero energy conditions for the origin and further development of the Universe, the negative energy of cosmic gravity is strictly equal to the positive energy of all matter and radiation. And this energy balance must be maintained throughout the arrow of time; GTR does not contradict these conditions; moreover, they to some extent follow from GTR, specifically.

1. Equality of gravitational and inertial mass

This axiom allows us to formally write the zero conditions in the form

M all C 2 + M all ∆ƒ=0

Where: M all C 2- total energy of all matter and radiation; M all ∆ƒ– gravitational energy of the entire Universe.

From the equation it follows that ∆ƒ= -С 2, the question is how is it formed ∆ƒ , is discussed below.

2. Gravity has no screens and is cumulative in nature.

The GP for a specific point is formed due to the imposition (accumulation) of GP from gravitational sources throughout the entire volume of the Universe and, in principle, allows one to achieve GP= -C 2.

3. The speed of gravity is equal to the speed of light

This condition makes it possible to limit the region of formation of the MS to the region of the visible part of the Universe, otherwise the MS tends to infinity.

4. Energy in general relativity gravitates

This corollary from general relativity allows us to answer the question: whether gravity (as a form of energy) obeys Hubble's law of cosmological redshift.

Energy in general relativity gravitates, therefore all calculations in modern cosmology are carried out through energy density, it is more convenient and simpler. So we will simplify the task and, as an observer, analyze the parameters of the early Universe, when radiation dominated, radiation clearly becomes the source of gravity (matter and dark matter can be neglected). The Universe is expanding with a slowdown, then the energy of quanta coming to the observer, according to Hubble's law, falls in proportion to the distance and for the boundaries of the visible part of the Universe tends to zero. Since the energy of gravitational sources tends to zero, then the gravitational energy from these sources should decrease in the same order; if we do not see matter beyond the horizon of particles, then we definitely do not see gravity, for example: if the GP of the observer is equal to –С 2, then along the arrow of time back the GP, like the energy of the quanta, should tend to zero. Only in this way are zero energy conditions observed.

Based on the above, let's make calculations, we have Hubble's law

V(R)=HR,

Where: V(R)– the speed of the Hubble expansion is proportional to the distance R.

Let's square both sides of it,

V 2 (R)=H 2R 2, (3)

from WIKI we take the modern value of the critical density of matter

ρ m =3H 2 /8πG,

from which it follows

H 2 =8/3 πρ mG,

let's substitute it into equation (3)

V 2 (R)=8/3 πρ mGR 2.

We have the right to believe that the change in the expansion rate is associated with the gravity of space, the observer’s GP is always and everywhere equal to –С 2, and changes according to the Hubble expansion law as –С 2 +V 2 (R).

then the difference GP will be,

∆ƒ = –С 2 – (-С 2 +V 2 (R)) = -V 2 (R) =8/3 πρ mGR 2, (4)

compare it with Poisson's equation

∆ƒ = 2/3 πρ mGR 2. (2)

We see that, in terms of the form of the physical content, equations (2) and (4) are identical, Hubble’s law (squared) is unambiguous, follows from observations and shows how the GP is formed along the entire arrow of time, while remaining the same at every point in the Universe. And we have reason to believe that equation (4) is Hubble’s law for the gravitational field of the Universe. Then radiation propagating in the gravitating Universe should be subject, according to general relativity, to additional gravitational displacement, because braking acceleration is always directed towards the observer, then the displacement should be blue, then Hubble's law (1) takes the form

1+ Z hubble (R) -V 2 (R)/C 2 =ν(R)/ν o(5)

Look carefully at how completely equation (5) describes, and as a consequence, explains the Hubble diagrams in Fig.1, on the basis of which TE was discovered.

Where the red line is the dependence of distances on the redshift of the spectrum of galaxies, constructed from observations of type Ia supernovae, which corresponds to the accelerated expansion of the Universe ( Z obs.). The blue (dashed) line corresponds to theoretical calculations for the linear expansion of the Universe ( Z theor), then the difference between,

Returning from the First World War, Edwin Hubble took a job at the Mount Wilson High-Altitude Astronomical Observatory in Southern California, which at that time was the best equipped in the world. Using its newest reflecting telescope with a primary mirror diameter of 2.5 m, he made a series of curious measurements that forever changed our understanding of the Universe.

In fact, Hubble intended to investigate one long-standing astronomical problem - the nature of nebulae. These mysterious objects, starting from the 18th century, worried scientists with the mystery of their origin. By the 20th century, some of these nebulae gave birth to stars and dissolved, but most of the clouds remained nebulous - and by their nature, in particular. Here scientists asked themselves the question: where exactly are these nebulous formations located - in our Galaxy? or do some of them represent other “islands of the Universe”, to use the sophisticated language of that era? Before the commissioning of the telescope on Mount Wilson in 1917, this question was purely theoretical, since there were no technical means to measure the distances to these nebulae.

Hubble began his research with perhaps the most popular nebula since time immemorial.
Andromeda. By 1923, he was able to see that the outskirts of this nebula were clusters of individual stars, some of which belonged to the class of Cepheid variables (according to the astronomical classification). By observing a Cepheid variable for quite a long time, astronomers measure the period of change in its luminosity, and then, using the period-luminosity relationship, determine the amount of light emitted by it. To better understand what the next step is, let's give this analogy. Imagine that you are standing in a pitch-dark night, and then in the distance someone turns on an electric lamp. Since you see nothing around you except this distant light bulb, it is almost impossible for you to determine the distance to it. Maybe it is very bright and glows far away, or maybe it is dim and glows nearby. How to determine this? Now imagine that you somehow managed to find out the power of the lamp - say, 60, 100 or 150 watts. The task is immediately simplified, since from the visible luminosity you can already approximately estimate the geometric distance to it. So: when measuring the period of change in the luminosity of a Cepheid, the astronomer is in approximately the same situation as you, calculating the distance to a distant lamp, knowing its luminosity (radiation power).

The first thing Hubble did was calculate the distance to the Cepheids on the outskirts of the Andromeda nebula, and therefore to the nebula itself: 900,000 light years (the more accurately calculated distance to the Andromeda galaxy, as it is now called, is 2.3 million light years.) - that is, the nebula is located far beyond the Milky Way - our galaxy. After observing this and other nebulae, Hubble came to a basic conclusion about the structure of the Universe: it consists of a collection of huge star clusters - galaxies. It is they who appear to us as distant foggy “clouds” in the sky, since we simply cannot see individual stars at such a huge distance. This discovery alone, in fact, would have been enough for Hubble to gain worldwide recognition of his services to science.

The scientist, however, did not stop there and noticed another important aspect in the data obtained, which astronomers had observed before, but found it difficult to interpret. Namely: the observed length of spectral light waves emitted by atoms of distant galaxies is somewhat lower than the length of spectral waves emitted by the same atoms in terrestrial laboratories. That is, in the radiation spectrum of neighboring galaxies, the quantum of light emitted by an atom when an electron jumps from orbit to orbit is shifted in frequency towards the red part of the spectrum compared to a similar quantum emitted by the same atom on Earth. Hubble took the liberty of interpreting this observation as a manifestation of the Doppler effect, which means that all observed neighboring galaxies are moving away from the Earth, since almost all galactic objects outside the Milky Way exhibit a spectral red shift proportional to the speed of their removal.

Most importantly, Hubble was able to compare the results of its measurements of distances to neighboring galaxies (based on observations of Cepheid variables) with measurements of their recession rates (based on redshift). And Hubble found that the farther a galaxy is from us, the faster it is moving away. This very phenomenon of centripetal “scattering” of the visible Universe with increasing speed as it moves away from the local observation point is called Hubble’s law. Mathematically, it is formulated very simply:

v = Hr

Where v is the speed at which the galaxy is moving away from us, r is the distance to it, and H is the so-called Hubble constant.

The latter is determined experimentally, and is currently estimated to be approximately 70 km/(s Mpc) (kilometers per second per megaparsec; 1 Mpc is approximately equal to 3.3 million light years). This means that a galaxy at a distance of 10 megaparsecs from us escapes from us at a speed of 700 km/s, a galaxy at a distance of 100 Mpc at a speed of 7000 km/s, etc. And, although initially Hubble came to this law as a result of observing only a few galaxies closest to us; not one of the many new galaxies of the visible Universe that have been discovered since then, increasingly distant from the Milky Way, falls out of the scope of this law.

So, the main and seemingly incredible consequence of Hubble's law: the Universe is expanding! This image seems most clearly to me like this: galaxies are raisins in a quickly rising yeast dough. Imagine yourself as a microscopic creature on one of the raisins, for which the dough appears transparent: what will you see? As the dough rises, all other raisins move away from you, and the further away a raisin is, the faster it moves away from you (since there is more expanding dough between you and distant raisins than between you and nearby raisins). At the same time, it will seem to you that it is you who are at the very center of the expanding universal test, and there is nothing strange in this - if you were on another raisin, everything would seem exactly the same to you. So galaxies are scattering for one simple reason: the very fabric of world space is expanding. All observers (and you and I are no exception) consider themselves to be at the center of the Universe. This was best formulated by the 15th century thinker Nicholas of Cusa: “Any point is the center of the limitless Universe.”

However, Hubble's law also tells us something else about the nature of the Universe - and this “something” is simply extraordinary. The universe had a beginning in time. And this is a very simple conclusion: it is enough to take and mentally “rewind” the conventional motion picture of the expansion of the Universe we are observing - and we will reach the point when all the matter of the universe was compressed into a dense lump of proto-matter, enclosed in a very small volume compared to the current scale of the Universe. The idea of the Universe, born from a super-dense clump of super-hot matter and since then expanding and cooling, is called the Big Bang theory, and today there is no more successful cosmological model of the origin and evolution of the Universe. Hubble's law, by the way, also helps to estimate the age of the Universe (of course, very simplified and approximately). Let's assume that all the galaxies from the very beginning were moving away from us with the same speed v that we observe today.

Let t be the time elapsed since the beginning of their flight. This will be the age of the Universe, and it is determined by the relations:

v x t = r, or t = r/V

But from Hubble's law it follows that

r/v = 1/H

Where H is the Hubble constant. This means that by measuring the speed of retreat of external galaxies and experimentally determining H, we thereby obtain an estimate of the time during which the galaxies disperse. This is the estimated lifetime of the Universe. Try to remember: the most recent estimates put the age of our Universe at about 15 billion years, give or take a few billion years. (For comparison, the Earth is estimated to be 4.5 billion years old, and life began on it about 4 billion years ago.)

“In 1744, the Swiss astronomer de Chezo and independently in 1826 Olbers formulated the following paradox,” T. Regge writes in his book, “which led to a crisis in the then naive cosmological models. Let us imagine that the space around the Earth is infinite, eternal and unchanging and that it is evenly filled with stars, and their density is on average constant. Using simple calculations, Schezot and Olbers showed that the total amount of light sent to Earth by the stars should be infinite, which is why the night sky will not be black, but, to put it mildly, flooded with light. To get rid of their paradox, they proposed the existence of vast wandering opaque nebulae in space, obscuring the most distant stars. In fact, there is no way out of the situation: having absorbed light from the stars, the nebulae would inevitably heat up and emit light themselves in the same way as the stars.

So, if the cosmological principle is true, then we cannot accept Aristotle’s idea of an eternal and unchanging Universe. Here, as in the case of relativity, nature seems to prefer symmetry in its development rather than the imaginary Aristotelian perfection.

However, the most serious blow to the inviolability of the Universe was dealt not by the theory of stellar evolution, but by the results of measurements of the removal rates of galaxies obtained by the great American astronomer Edwin Hubble.

Hubble (1889–1953) was born in the small town of Marshfield, Missouri, to insurance agent John Powell Hubble and his wife Virginia Lee James. Edwin became interested in astronomy early, probably under the influence of his maternal grandfather, who built himself a small telescope.

In 1906, Edwin graduated from school. At the age of sixteen, Hubble entered the University of Chicago, which was then one of the top ten best educational institutions in the United States. Astronomer F.R. worked there. Multon, author of the famous theory of the origin of the solar system. He had a great influence on the subsequent choice of Hubble.

After graduating from university, Hubble managed to receive a Rhodes Scholarship and go to England for three years to continue his education. However, instead of natural sciences, he had to study jurisprudence at Cambridge.

In the summer of 1913, Edwin returned to his homeland, but did not become a lawyer. Hubble aspired to science and returned to the University of Chicago, where he prepared his dissertation for the degree of Doctor of Philosophy at the Yerke Observatory under the direction of Professor Frost. His work was a statistical study of faint spiral nebulae in several areas of the sky and was not particularly original. But even then, Hubble shared the opinion that “spirals are star systems at distances often measured in millions of light years.”

At this time, a great event was approaching in astronomy - the Mount Wilson Observatory, which was headed by the remarkable science organizer D.E. Hale, was preparing to commission the largest telescope - a hundred-inch reflector (250-centimeter - Author's note). Hubble, among others, received an invitation to work at the observatory. However, in the spring of 1917, as he was finishing his dissertation, the United States entered World War I. The young scientist declined the invitation and volunteered for the army. As part of the American Expeditionary Force, Major Hubble arrived in Europe in the fall of 1918, shortly before the end of the war, and did not have time to take part in hostilities. In the summer of 1919, Hubble was discharged and hurried to Pasadena to accept Hale's invitation.

At the observatory, Hubble began studying nebulae, focusing first on objects visible in the band of the Milky Way.

The anthology “The Book of Primary Sources on Astronomy and Astrophysics, 1900–1975” by K. Lang and O. Gingerich (USA), which reproduces the most outstanding research for three quarters of the twentieth century, contains three works by Hubble, and the first of them is a work on the classification of extragalactic nebulae. The other two relate to the establishment of the nature of these nebulae and the discovery of the law of red shift.

In 1923, Hubble began observing the nebula in the constellation Andromeda using sixty and one hundred inch reflectors. The scientist concluded that the large Andromeda Nebula is indeed another star system. Hubble obtained the same results for the MOS 6822 nebula and the Triangulum nebula.

Although a number of astronomers soon became aware of Hubble's discovery, the official announcement came only on January 1, 1925, when G. Russell read out Hubble's report at the meeting of the American Astronomical Society. The famous astronomer D. Stebbins wrote that Hubble's report “expanded the volume of the material world a hundredfold and definitely resolved the long dispute about the nature of spirals, proving that they are gigantic collections of stars, almost comparable in size to our own Galaxy.” Now the Universe appears to astronomers as a space filled with star islands - galaxies.

Just establishing the true nature of nebulae determined Hubble's place in the history of astronomy. But he also had an even more outstanding achievement - the discovery of the law of red shift.

Spectral studies of spiral and elliptical “nebulae” were started in 1912 on the basis of such considerations1 if they are really located outside our Galaxy, then they do not participate in its rotation and therefore their radial velocities will indicate the movement of the Sun. It was expected that these speeds would be on the order of 200–300 kilometers per second, i.e., they would correspond to the speed of the Sun around the center of the Galaxy.

Meanwhile, with a few exceptions, the radial velocities of galaxies turned out to be much greater: they were measured in thousands and tens of thousands of kilometers per second.

In mid-January 1929, in the Proceedings of the National Academy of Sciences of the United States, Hubble presented a short note entitled “On the relation between the distance and radial velocity of extragalactic nebulae.” At that time, Hubble was already able to compare the speed of a galaxy with its distance for 36 objects. It turned out that these two quantities are related by the condition of direct proportionality: the speed is equal to the distance multiplied by the Hubble constant.

This expression is called Hubble's law. The scientist determined the numerical value of the Hubble constant in 1929 to be 500 km/(c x Mpc). However, he made a mistake in establishing the distances to the galaxies. After multiple corrections and refinements of these distances, the numerical value of the Hubble constant is now accepted as equal to 50 km/(c x Mpc).

The Mount Wilson Observatory began determining the radial velocities of increasingly distant galaxies. By 1936, M. Humason published data for one hundred nebulae. A record speed of 42,000 kilometers per second was recorded from a member of the distant Ursa Major cluster of galaxies. But this was already the limit of the capabilities of a hundred-inch telescope. More powerful tools were needed.

“We can approach the issue of the Hubble expansion of space using more familiar, intuitive images,” says T. Rege. - For example, imagine soldiers lined up on some square with an interval of 1 meter. Let the command then be given to move the rows apart in one minute so that this interval increases to 2 meters. No matter how the command is executed, the relative speed of two soldiers standing next to each other will be equal to 1 m/min, and the relative speed of two soldiers standing at a distance of 100 meters from each other will be 100 m/min, given that the distance between them increases from 100 to 200 meters. Thus, the speed of mutual removal is proportional to the distance. Note that after expanding the series, the cosmological principle remains valid: the “soldier galaxies” are still distributed evenly, and the same proportions between different mutual distances remain.

The only drawback of our comparison is that in practice one of the soldiers always stands motionless in the center of the square, while the rest scatter at speeds that increase the greater the distance from them to the center. In space, there are no milestones against which absolute measurements of speed could be made; We are deprived of such a possibility by the theory of relativity: everyone can compare his movement only with the movement of those walking next to him, and at the same time it will seem to him that they are running away from him.

We see, therefore, that Hubble's law ensures the immutability of the cosmological principle at all times, and this confirms our opinion that both the law and the principle itself are truly valid.

Another example of an intuitive image would be a bomb exploding; in this case, the faster the fragment flies, the farther it will fly. A moment after the explosion itself, we see that the fragments are distributed in accordance with Hubble's law, that is, their speeds are proportional to the distances to them. Here, however, the cosmological principle is violated, since if we move far enough from the explosion site, we will not see any fragments. This image suggests the most famous term in modern cosmology, “big bang.” According to these ideas, about 20 billion years ago, all the matter of the Universe was collected at one point, from which the rapid expansion of the Universe to its present size began.”

Hubble's law was almost immediately recognized in science. The significance of Hubble's discovery was highly appreciated by Einstein. In January 1931 he wrote: "The new observations of Hubble and Humason regarding the red shift... make it probable that the general structure of the Universe is not stationary."

Hubble's discovery finally destroyed the idea of a static, unshakable Universe that had existed since the time of Aristotle. Currently, Hubble's law is used to determine distances to distant galaxies and quasars.

CLASSIFICATION OF GALAXIES

The history of the “discovery” of the world of galaxies is very instructive. More than two hundred years ago, Herschel built the first model of the Galaxy, reducing its size by fifteen times. Studying numerous nebulae, the diversity of whose forms he was the first to discover, Herschel came to the conclusion that some of them were distant star systems “like our star system.” He wrote: “I do not consider it necessary to repeat that the heavens consist of areas in which the suns are collected in systems.” And one more thing: “... these nebulae can also be called the milky ways - with a small letter, in contrast to our system.”

However, in the end, Herschel himself took a different position regarding the nature of nebulae. And this was no accident. After all, he managed to prove that most of the nebulae discovered and observed by him consist not of stars, but of gas. He came to a very pessimistic conclusion: “Everything outside our own system is covered in the darkness of the unknown.”

The English astronomer Agnes Clarke wrote in her book The Star System in 1890: “It is safe to say that no competent scientist, in possession of all available evidence, would be of the opinion that even one nebula is a stellar system comparable in size to Milky Way. It has been practically established that all objects observed in the sky (both stars and nebulae) belong to one huge unit”...

The reason for this point of view was that for a long time astronomers were not able to determine the distances to these star systems. Thus, from measurements taken in 1907 it seemed to follow that the distance to the Andromeda Nebula did not exceed 19 light years. Four years later, astronomers concluded that the distance was about 1,600 light years. In both cases, the impression was created that the mentioned nebula was actually located in our Galaxy.

In the twenties of the last century, a fierce dispute broke out between astronomers Shapley and Curtis about the nature of the Galaxy and other objects visible with telescopes. Among these objects is the famous Andromeda Nebula (M31), which is visible to the naked eye as only a fourth magnitude star, but unfolds into a majestic spiral when viewed through a large telescope. By this time, outbursts of novae had been detected in some of these nebulae. Curtis suggested that at maximum brightness, the mentioned stars emit the same amount of energy as the new stars of our Galaxy. Thus, he established that the distance to the Andromeda Nebula is 500,000 light years. This gave Curtis the basis to argue that spiral nebulae are distant stellar universes like the Milky Way. Shapley did not agree with this conclusion, and his reasoning was also quite logical.

According to Shapley, the entire Universe consists of one of our Galaxy, and spiral nebulae like M31 are smaller objects scattered inside this Galaxy, like raisins in a cake.

Suppose, he said, that the Andromeda Nebula is the same size as our Galaxy (300,000 light years by his estimate). Then, knowing its angular dimensions, we find that the distance to this nebula is 10 million light years! But then it is not clear why the new stars observed in the Andromeda Nebula are brighter than in our Galaxy. If the brightness of novae in this “nebula” and in our Galaxy is the same, then it follows that the Andromeda Nebula is 20 times smaller than our Galaxy.

Curtis, on the contrary, believed that M31 is an independent island galaxy, not inferior in dignity to our Galaxy and distant from it by several hundred thousand light years. The creation of large telescopes and the progress of astrophysics led to the recognition that Curtis was right. The measurements made by Shapley turned out to be erroneous. He greatly underestimated the distance to M31. Curtis, however, was also wrong: it is now known that the distance to M31 is more than two million light years.

The nature of spiral nebulae was finally established by Edwin Hubble, who at the end of 1923 discovered the first and soon several more Cepheids in the Andromeda Nebula. Having estimated their apparent magnitudes and periods, Hubble found that the distance to this “nebula” is 900,000 light years. Thus, the belonging of spiral “nebulae” to the world of stellar systems such as our Galaxy was finally established.

If we talk about the distances to these objects, then they still had to be clarified and revised. So, in fact, the distance to the M 31 galaxy in Andromeda is 2.3 million light years.

The world of galaxies turned out to be surprisingly huge. But even more surprising is the variety of its forms.

The first and quite successful classification of galaxies by their appearance was undertaken by Hubble in 1925. He proposed that galaxies be classified into one of the following three types: 1) elliptical (denoted by the letter E), 2) spiral (S), and 3) irregular (1 g).

Elliptical galaxies are those that look like regular circles or ellipses and whose brightness gradually decreases from the center to the periphery. This group is divided into eight subtypes from EO to E7 as the apparent compression of the galaxy increases. SO lenticular galaxies resemble highly oblate elliptical systems, but have a clearly defined central star-shaped core.

Spiral galaxies, depending on the degree of development of the spirals, are divided into subclasses Sa, Sb and Sc. In Sa type galaxies, the main component is the core, while the spirals are still weakly expressed. The transition to the next subclass is a statement of the fact of an increasing development of spirals and a decrease in the apparent size of the nucleus.

Parallel to normal spiral galaxies, there are also so-called crossed spiral systems (SB). In galaxies of this type, a very bright central core is intersected along the diameter by a transverse stripe. The spiral branches begin from the ends of this bridge, and depending on the degree of development of the spirals, these galaxies are divided into subtypes SBa, SBb and SBc.

Irregular galaxies (Ir) are objects that do not have a clearly defined nucleus and do not exhibit rotational symmetry. Their typical representatives are the Magellanic Clouds.

“I used it for 30 years,” the famous astronomer Walter Baade later wrote, “and although I persistently looked for objects that could not really be included in the Hubble system, their number turned out to be so insignificant that I can count them on my fingers.” The Hubble classification continues to serve science, and all subsequent modifications of the creature have not affected it.

For some time it was believed that this classification has an evolutionary meaning, that is, that galaxies “move” along the Hubble “tuning fork diagram”, successively changing their shape. This view is now considered erroneous.

Among the several thousand brightest galaxies, 17 percent are elliptical, 80 percent are spiral, and about 3 percent are irregular.

In 1957, Soviet astronomer B.A. Vorontsov-Velyaminov discovered the existence of “interacting galaxies” - galaxies connected by “bridges”, “tails”, as well as “gamma-forms”, i.e. galaxies in which one spiral “twists”, while the other “unwinds”. Later, compact galaxies with dimensions of only about 3,000 light-years and isolated star systems with a diameter of only 200 light-years were discovered. In appearance, they are practically no different from the stars of our Galaxy.

The new general catalog (NCC) contains a list of about ten thousand galaxies along with their most important characteristics (luminosity, shape, distance, etc.) - and this is only a small fraction of the ten billion galaxies that are in principle visible from Earth. A fairytale giant, capable of covering a hundred or two million light years with his gaze, looking at the Universe, would see that it is filled with cosmic fog, the droplets of which are galaxies. From time to time there are clusters consisting of thousands of galaxies gathered together. One such giant cluster is located in the constellation Virgo.

He got a job at the Mount Wilson High-Altitude Astronomical Observatory in Southern California, which at that time was the best equipped in the world. Using its newest reflecting telescope with a primary mirror diameter of 2.5 m, he made a series of curious measurements that forever changed our understanding of the Universe.

Hubble began his research with the Andromeda nebula, perhaps the most popular since time immemorial. By 1923, he was able to see that the outskirts of this nebula were clusters of individual stars, some of which belonged to the class of Cepheid variables (according to the astronomical classification). By observing a Cepheid variable for quite a long time, astronomers measure the period of change in its luminosity, and then, using the period-luminosity relationship, determine the amount of light emitted by it.

To better understand what the next step is, let's give this analogy. Imagine that you are standing in a pitch-dark night, and then in the distance someone turns on an electric lamp. Since you see nothing around you except this distant light bulb, it is almost impossible for you to determine the distance to it. Maybe it is very bright and glows far away, or maybe it is dim and glows nearby. How to determine this? Now imagine that you somehow managed to find out the power of the lamp - say, 60, 100 or 150 watts. The task is immediately simplified, since from the visible luminosity you can already approximately estimate the geometric distance to it. So: when measuring the period of change in the luminosity of a Cepheid, the astronomer is in approximately the same situation as you, calculating the distance to a distant lamp, knowing its luminosity (radiation power).

The first thing Hubble did was calculate the distance to the Cepheids on the outskirts of the Andromeda nebula, and therefore to the nebula itself: 900,000 light years (the more accurately calculated distance to the Andromeda galaxy, as it is now called, is 2.3 million light years - author's note) - that is, the nebula is located far beyond the Milky Way - our galaxy. After observing this and other nebulae, Hubble came to a basic conclusion about the structure of the Universe: it consists of a collection of huge star clusters - galaxies. It is they who appear to us as distant foggy “clouds” in the sky, since we simply cannot see individual stars at such a huge distance. This discovery alone, in fact, would have been enough for Hubble to gain worldwide recognition of his services to science.

v = Hr

Where v is the speed at which the galaxy is moving away from us, r is the distance to it, and H is the so-called Hubble constant. The latter is determined experimentally, and is currently estimated to be approximately 70 km/(s Mpc) (kilometers per second per megaparsec; 1 Mpc is approximately equal to 3.3 million light years). This means that a galaxy at a distance of 10 megaparsecs from us escapes from us at a speed of 700 km/s, a galaxy at a distance of 100 Mpc at a speed of 7000 km/s, etc. And, although initially Hubble came to this law as a result of observing only a few galaxies closest to us; not one of the many new galaxies of the visible Universe that have been discovered since then, increasingly distant from the Milky Way, falls out of the scope of this law.

v x t = r, or t = r/V

But from Hubble's law it follows that

r/v = 1/H

Comments: 0

Dmitry Vibe

The sight of the night sky strewn with stars has long instilled awe and delight in the human soul. Therefore, even with a slight decline in general interest in science, astronomical news sometimes leaks into the media to shake up the imagination of the reader (or listener) with a message about a mysterious quasar on the very outskirts of the Universe, about an exploded star, or about a black hole hidden in the depths of a distant galaxy. It is quite natural that sooner or later an interested person will have a legitimate question: “Come on, aren’t they leading me by the nose?” Indeed, many books have been written on astronomy, popular science films are being made, conferences are being held, the circulation and volume of professional astronomical magazines are constantly growing, and all this is a product of simply looking at the sky?

Phil Plate

The universe is a little older than we thought. Moreover, the composition of its components is slightly different from what we expected. And moreover, how they are mixed is also slightly different from our understanding. And even more than that, there are hints, rumors and whispers that there is something else there that we knew nothing about before.

National Geographic

Three theoretical physicists from Ontario published an article in Scientific American explaining that our world may well be the surface of a four-dimensional black hole. We considered it necessary to publish appropriate clarifications.

Since the 30s of the 20th century, astrophysicists already knew that, according to Hubble's law, The universe is expanding, which means it had its beginning at a certain point in the past. The task of astrophysicists, thus, outwardly looked simple: to trace all stages of the Hubble expansion in reverse chronology, applying the corresponding physical laws at each stage, and, having gone this way to the end - or rather, to the very beginning - to understand exactly how everything happened .

In the late 1970s, however, several fundamental problems associated with the early Universe remained unresolved, namely:

· Antimatter problem. According to the laws of physics, matter and antimatter have an equal right to exist in the Universe ( cm. Antiparticles), but the Universe consists almost entirely of matter. Why did it happen?
· Horizon problem. Based on background cosmic radiation ( cm. Big Bang) we can determine that the temperature of the Universe is approximately the same everywhere, but its individual parts (clusters of galaxies) could not be in contact (as is commonly said, they were outside horizon each other). How did it happen that thermal equilibrium was established between them?
· The problem of straightening space. The universe appears to have just the right amount of mass and energy to slow down and stop the Hubble expansion. Of all the possible masses, why does the Universe have just this one?

The key to solving these problems was the idea that immediately after its birth the Universe was very dense and very hot. All the matter in it was a hot mass of quarks and leptons ( cm. Standard model), which had no way to unite into atoms. The various forces acting in the modern Universe (such as electromagnetic and gravitational forces) then corresponded to a single field of force interaction ( cm. Universal theories). But as the Universe expanded and cooled, the hypothetical unified field split into several forces ( cm. Early Universe).

In 1981, American physicist Alan Guth realized that the separation of strong interactions from a unified field, which occurred approximately 10-35 seconds after the birth of the Universe (just think - that's 34 zeros and a one after the decimal point!), was a turning point in its development. Happened phase transition substances from one state to another on the scale of the Universe is a phenomenon similar to the transformation of water into ice. And just as when water freezes, its randomly moving molecules suddenly “grab” and form a strict crystalline structure, so under the influence of the released strong interactions, an instant restructuring took place, a kind of “crystallization” of matter in the Universe.

Anyone who has seen how water pipes or car radiator tubes burst in severe frost, as soon as the water in them turns into ice, knows from personal experience that water expands when it freezes. Alan Guth was able to show that when strong and weak interactions separated, something similar happened in the Universe - a jump-like expansion. This is an extension called inflationary, many times faster than the usual Hubble expansion. In about 10-32 seconds, the Universe expanded by 50 orders of magnitude - it was smaller than a proton, and became the size of a grapefruit (for comparison, water expands by only 10% when it freezes). And this rapid inflationary expansion of the Universe removes two of the three above-mentioned problems, directly explaining them.

Solution space straightening problems The following example demonstrates this most clearly: imagine a coordinate grid drawn on a thin elastic map, which is then crumpled haphazardly. If we now take and strongly shake this elastic map, crumpled into a ball, it will again take a flat appearance, and the coordinate lines on it will be restored, no matter how much we deformed it when we crumpled it. Likewise, it does not matter how curved the space of the Universe was when its inflationary expansion began, the main thing is that at the end of this expansion, space turned out to be completely straightened. And since from theory of relativity We know that the curvature of space depends on the amount of matter and energy in it, it becomes clear why there is exactly as much matter in the Universe as is necessary to balance the Hubble expansion.

Explains the inflation model and horizon problem, although not so directly. From theory black body radiation we know that the radiation emitted by a body depends on its temperature. Thus, from the radiation spectra of distant parts of the Universe, we can determine their temperature. Such measurements yielded stunning results: it turned out that at any observable point in the Universe the temperature (with a measurement error of up to four decimal places) is the same. Based on the normal Hubble expansion model, the matter immediately after the Big Bang would have spread too far apart for temperatures to equalize. According to the inflationary model, the matter of the Universe until the moment t = 10-35 seconds remained much more compact than during the Hubble expansion. This extremely short period was quite enough to establish a thermal equilibrium, which was not disturbed at the stage of inflationary expansion and has been preserved to this day.

The inflation hypothesis does not remove antimatter problems, but this problem can be explained by referring to other processes occurring at the same time. Interesting things are discovered: during the rapid formation of elementary particles in the early Universe, there were 100,000,000 antiparticles for approximately 100,000,001 ordinary particles. In the next fraction of a second, particles and antiparticles, united in pairs, annihilated each other with a gigantic release of energy - the mass turned into radiation. After such “weeding”, only a miserable scrap of ordinary matter remained in the Universe. It is from this “space debris” that the entire Universe known to us today consists.

Hubble began his research with the Andromeda nebula, perhaps the most popular since time immemorial. By 1923, he was able to see that the outskirts of this nebula were clusters of individual stars, some of which belonged to the class Cepheid variables(according to astronomical classification). By observing a Cepheid variable for quite a long time, astronomers measure the period of change in its luminosity, and then period-luminosity relationship The amount of light emitted by it is also determined.

The first thing Hubble did was calculate the distance to the Cepheids on the outskirts of the Andromeda nebula, and therefore to the nebula itself: 900,000 light years (the more accurately calculated distance to the Andromeda galaxy, as it is now called, is 2.3 million light years. -- Note author) - that is, the nebula is located far beyond the Milky Way - our galaxy. After observing this and other nebulae, Hubble came to a basic conclusion about the structure of the Universe: it consists of a collection of huge star clusters -- galaxies. It is they who appear to us as distant foggy “clouds” in the sky, since we simply cannot see individual stars at such a huge distance. This discovery alone, in fact, would have been enough for Hubble to gain worldwide recognition of his services to science.

The scientist, however, did not stop there and noticed another important aspect in the data obtained, which astronomers had observed before, but found it difficult to interpret. Namely: the observed length of spectral light waves emitted by atoms of distant galaxies is somewhat lower than the length of spectral waves emitted by the same atoms in terrestrial laboratories. That is, in the radiation spectrum of neighboring galaxies, the quantum of light emitted by an atom when an electron jumps from orbit to orbit is shifted in frequency towards the red part of the spectrum compared to a similar quantum emitted by the same atom on Earth. Hubble took the liberty of interpreting this observation as a manifestation Doppler effect, which means that all observed neighboring galaxies are deleted from the Earth, since almost all galactic objects outside the Milky Way have exactly red spectral shift proportional to the speed of their removal.

Where v-- the speed at which the galaxy is moving away from us,

r- the distance to it, and

H-- so-called Hubble constant.

The latter is determined experimentally, and is currently estimated to be approximately 70 km/(s Mpc) (kilometers per second per megaparsec; 1 Mpc is approximately equal to 3.3 million light years). And this means that a galaxy distant from us at a distance of 10 megaparsecs escapes from us at a speed of 700 km/s, a galaxy distant at 100 Mpc - at a speed of 7000 km/s, etc. And, although initially Hubble came to this law as a result of observing only a few galaxies closest to us; not one of the many new galaxies of the visible Universe that have been discovered since then, increasingly distant from the Milky Way, falls outside the scope of this law.

So, the main and - it would seem - incredible consequence of Hubble's law: the Universe is expanding! This image seems most clearly to me like this: galaxies are raisins in a quickly rising yeast dough. Imagine yourself as a microscopic creature on one of the raisins, for which the dough appears transparent: what will you see? As the dough rises, all other raisins move away from you, and the further away a raisin is, the faster it moves away from you (since there is more expanding dough between you and distant raisins than between you and nearby raisins). At the same time, it will seem to you that it is you who are at the very center of the expanding universal test, and there is nothing strange in this - if you were on another raisin, everything would seem exactly the same to you. So galaxies are scattering for one simple reason: the very fabric of world space is expanding. All observers (and you and I are no exception) consider themselves to be at the center of the Universe. This was best formulated by the 15th century thinker Nicholas of Cusa: “Any point is the center of the limitless Universe.”

However, Hubble's law also tells us something else about the nature of the Universe - and this “something” is simply extraordinary. The universe had a beginning in time. And this is a very simple conclusion: it is enough to take and mentally “scroll back” the conventional film picture of the expansion of the Universe we are observing - and we will reach the point when all the matter of the universe was compressed into a dense lump of proto-matter, enclosed in a very small volume compared to the current scale of the Universe . The idea of the Universe, born from a super-dense clump of super-hot matter and since then expanding and cooling, is called the theory big bang, and there is no more successful cosmological model of the origin and evolution of the Universe today. Hubble's law, by the way, also helps to estimate the age of the Universe (of course, very simplified and approximately). Let's assume that all the galaxies were moving away from us at the same speed from the very beginning v that we see today. Let t- time elapsed since the beginning of their flight. This will be the age of the Universe, and it is determined by the relations:

v x t = r, or t = r/V

But from Hubble's law it follows that

r/v = 1/H

Where N-- Hubble constant. This means that by measuring the recession velocities of external galaxies and experimentally determining N, we thereby obtain an estimate of the time during which the galaxies disperse. This is the estimated lifetime of the Universe. Try to remember: the most recent estimates put the age of our Universe at about 15 billion years, give or take a few billion years. (For comparison, the Earth is estimated to be 4.5 billion years old, and life began on it about 4 billion years ago.) The apparent speed at which a galaxy is moving away from us is directly proportional to its distance.