What makes our galaxy fly with a huge speed? The Hubble Law appreciating the rate of removal of the galaxy from us is directly proportional to the distance to the galaxies fly away.

The law of Hubble seemingly the rate of removal of the galaxy from us is directly proportional to the distance to it. Returning from the First World War, Edwin Hubble got a job in the Alpine Astronomical Observatory Mount Wilson in Southern California, which in those years was the best in the world at the perception. Using its newest telescope reflector with a diameter of the main mirror of 2.5 m, he conducted a series of curious measurements, forever overwhelmed our ideas about the universe. In fact, Hubble intended to investigate one formerly astronomical problem - the nature of the nebulae. These mysterious objects, starting from the XVIII century, worried scientists with the mysteriousness of their origin. By the XX century, some of these nebulae were given by the stars and resolved, but most of the clouds remained foggy - and by their nature, in particular. There are scientists and wondered: and where, in fact, these foggy formations are in our galaxy? Or some of them are other "islands of the Universe", if they are expressed by the sophisticated language of that era? Before entering the telescope on Mount Wilson in 1917, this question was purely theoretically, since for measuring distances to these nebulae technical means was not available. He began his research Hubble with the most, perhaps, from the time immemorial times of Andromeda nebula. By 1923 he managed to consider that the outskirts of this nebula are accumulated by individual stars, some of which belong to the class of Cefeide variables (according to the astronomical classification). Watching the Cefeide variable for sufficiently long time, astronomers measure the period of changing its luminosity, and then depending on the period of the period, the amount of light emitted by it is determined. To better understand what the next step is to give such an analogy. Imagine that you are standing in extremely dark night, and here someone includes an electric lamp. Since nothing but this distant light bulb, you do not see around yourself, it is almost impossible to determine the distance to it. Maybe it is very bright and glows far away, and maybe dim and glowing nearby. How to determine? And now imagine that you somehow managed to learn the lamp power - say, 60, 100 or 150 watts. The task is immediately simplified, because according to the visible luminosity you can easily estimate the geometrical distance to it. So: Measuring the period of changing the luminosity of Cefeid, an astronomer is about in the same situation as you, calculating the distance to the remote lamp, knowing it with a light (radiation power). The first thing that Hubble did, - calculated the distance to Cefeid on the outbreaks of Andromeda nebula, and therefore to the most nebula: 900,000 light years (more precisely designed to date before the Galaxy Andromeda, as it is now called, is 2.3 million Light years. - approx. the author) - that is, the nebula is far beyond the Milky Way - our galaxy. Jumping this and other nebula, Hubble came to the basic conclusion about the structure of the Universe: it consists of a set of huge star clusters - galaxies. It is they who seem to us in the sky of distant misty "clouds", since we cannot consider individual stars on such a huge removal. This opening, actually, would have enough Hubble for worldwide recognition of his merit in front of science. The scientist, however, was not limited to this and noticed another important aspect in the data obtained, which astronomers were observed before, but it was difficult to interpret. Namely: the observed length of spectral light waves emitted by atoms of remote galaxies is slightly lower than the length of the spectral waves emitted by the same atoms in the conditions of earth laboratories. That is, in the emission spectrum of the neighboring galaxies, the quantum of light emitted by the atom with an electron jump from orbit into orbit is shifted in frequency in the direction of the red part of the spectrum compared to a similar quantum emitted by the same atom on Earth. Hubble took over the courage to interpret this observation as a manifestation of the Doppler effect, which means that all observed neighboring galaxies are removed from the ground, since almost all galactic objects outside the Milky Way, there is a red spectral displacement, proportional to the speed of their removal. The most important thing, Hubble managed to compare the results of its distances measurements to neighboring galaxies (according to the observations of Cefeide variables) with measurements of the speeds of their removal (on red displacement). And Hubble found out that the farther from us is the galaxy, the more speed it is removed. This is the most phenomenon of the centripetal "running" of the visible universe with an increasing rate as removal from the local point of observation and the name of the Hubble law is called. It is very simple mathematically: v \u003d hr where V is the rate of removal of the galaxy from us, R is the distance to it, and H is the so-called permanent Hubble. The latter is determined experimentally, and today is estimated as equal to about 70 km / (from · MPK) (kilometers per second for megaparsec; 1 MPK is approximately 3.3 million light years). And this means that the galaxy removed from us for a distance of 10 megaparsek runs away from us with a speed of 700 km / s, a galaxy removed by 100 IPCs - at a rate of 7000 km / s, etc. and, although initial Hubble It came to this law based on the observation of just a few nearest galaxies, none of the many of those discovered since then new, more and more remote from the Milky Way of Galaxies of the visible universe from under the actions of this law does not fall. So, the main thing - it would seem - an incredible consequence of the Hubble law: the Universe expands! This image is clear to me: the galaxies are raisins in a rapidly external yeast dough. Imagine yourself a microscopic creature on one of the rayminum, the dough for which it seems transparent: and what will you see? Since the dough rises, all other raisins are deleted from you, and the further the raymina, the faster it is removed from you (since there is more expanding test between you and distant raisins than between you and the closest raisins). At the same time, you will seem to be that this is exactly you are in the very center of an expanding universal test, and there is nothing strange in this - if you were on another raisin, you would see everything in accuracy as well. So the galaxies are running out for one simple reason: the fabric of world space is expanding. All observers (and we are not an exception) consider themselves in the center of the universe. It is best that this formulated the thinker of the XV century Nikolai Kuzansky: "Any point is the center of the limitless universe."

The next stage of the organization of matter in the Universe - Galaxy. A typical example is our galaxy - the Milky Way. It contains about 10 11 stars and has a shape of a thin disc with thickening in the center.
In fig. 39 schematically shows the structure of our galaxy Milky Way and the position of the Sun in one of the spiral sleeves of the galaxy is indicated.

Fig. 39. The structure of the Galaxy Milky Way.

In fig. 40 shows the projection on the plane of the 16 Nearest neighbors of our Galaxy.

Fig. 40. The 16 Nearest neighbors of our galaxy designed to the plane. BMO and MMO - Big and Small Magellanovo Cloud

Stars in galaxies are unevenly distributed.
Dimensions of galaxies vary from 15 to 800 thousand light years. The mass of galaxies varies from 10 7 to 10 12 of the mass of the sun. The main number of stars and cold gas is concentrated in galaxies. Stars in galaxies are held by the total gravitational field of the Galaxy and Dark Matter.
Our galaxy Milky Way is a typical spiral system. Stars in the Galaxy Along with the overall rotation of galaxies also have their own speeds regarding the galaxy. The orbital speed of the Sun in our galaxy is 230 km / s. Own speed of the sun regarding the galaxy is
20 km / s.

The opening of the world of galaxies belongs to E. Hubble. In 1923-1924, observing changes in the luminosity of Cefeide, which are in separate nebulae, he showed that the nebulae detected by them are galaxies located outside our galaxy - the Milky Way. In particular, he found that the nebula of Andromeda is another star system - a galaxy that is not part of our Galaxy Milky Way. Andromeda nebula is a spiral galaxy located at a distance of 520 PDAs. The transverse size of Andromeda nebula is 50 PDAs.
Studying the rays speed of individual galaxies, Hubble made an outstanding discovery:

H \u003d 73.8 ± 2.4 km · s -1 · megaparsek -1 - the Hubble parameter.

Fig. 41. Original schedule of Hubble from the work of 1929

Fig. 42. The removal rate of galaxies depending on the distance to the Earth.

In fig. 42 At the beginning of the coordinate, the square of the velocities of the galaxies and distances to them, on the basis of which E. Hubble derived the relation (9).
The opening of Hubble had a prehistory. In 1914, astronomer V. Slofer showed that Andromeda nebula and several more nebulae move relative to the solar system with speeds of about 1000 km / h. E. Hubble, who worked on the world's largest telescope with the main mirror with a diameter of 2.5 M of the Observatory Mount Wilson in California (USA), managed for the first time to resolve individual stars in Andromeda nebula. Among these stars were star cefete, for which the relationship between the period of changes in luminosity and the luminosity is known.
Knowing the luminosity of the star and the speed of the star, E. Hubble received the dependence of the speed of removal of stars from the solar system depending on the distance. In fig. 41 shows a schedule from the original work of E. Hubble.

Fig. 43. Hubble Space Telescope

Doppler effect Doppler effect - change in frequency recorded by the receiver when the source or receiver moves. If a moving source emits a light having a frequency ω 0, then the frequency of light recorded by the receiver is determined by the relation c is the speed of light in vacuo, V is the speed of movement of the radiation source relative to the radiation receiver, θ is the angle between the direction on the source and the speed vector in the receiver reference system. θ \u003d 0 corresponds to the radial removal of the source from the receiver, θ \u003d π corresponds to the radial approximation of the source to the receiver.

The radiation speed of the celestial objects - stars, galaxies - determine, measuring the change in the frequency of spectral lines. When the radiation source is removed from the observer, the wavelengths in the direction of longer wavelengths (red displacement) occurs. When the radiation source approaches the observer, the wavelengths in the direction of shorter wavelengths (blue offset) occurs. By increasing the width of the distribution of the spectral line, you can determine the temperature of the emitting object.
Hubble divided galaxies by their appearance for three large classes:

elliptical (E),

spiral (s),

irregular (IR).

Fig. 44. Types of galaxies (spiral, elliptical, irregular).

A characteristic feature of spiral galaxies are spiral branches extending from the center around the stellar disk.
Elliptic galaxies are the structureless systems of the elliptical form.
Irregagular galaxies are allocated to the externally chaotic, knocked structure and do not have some specific form.
Such a classification of galaxies reflects not only their external forms, but also the properties of the stars included in them.
Elliptical galaxies consist mainly of old stars. In irregular galaxies, the main contribution to the radiation gives the stars younger than the sun. Stars of all ages are found in the spiral galaxies. Thus, the difference in the appearance of galaxies is determined by the nature of their evolution. In elliptic galaxies, star formation almost ceased billions of years ago. In spiral galaxies, the formation of stars continues. In irregular galaxies, star formation occurs as intensively as billions years ago. Almost all stars are concentrated in a wide disk, the bulk of which is the interstellar gas.
Table 19 shows the relative comparison of these three types of galaxies and comparing their properties based on E.Habble analysis.

Table 19.

The main types of galaxies and their properties (by E. Hubble)
Spiral	Elliptical	Irregigular
Percentage in the Universe
Form and structural properties
Flat stars and gas with spiral sleeves thickening to the center. The core of older stars and approximately spherical halo (interstellar gas, some stars and magnetic fields)

Currently, according to astronomical observations, it has been established that Universe on a large scale homogeneous. All its areas in size from 300 million light years and look more likely. In a smaller scale, the universe has areas where the accumulations of galaxies are found and, on the contrary, emptiness, where there are few them.

The galaxy is called the system of stars with a general origin and attraction related to the forces. Galaxy in which our Sun is located - Milky Way

The distances to celestial bodies in astronomy are determined differently depending on that close or far from our planet these objects are located. In outer space, it is customary to use the following units for measuring distances:

1 A.E. ( astronomical unit) \u003d (149597870 2) km;

1 PC ( parsec) \u003d 206265 A.E. \u003d 3,086 · 10 m;

1 s.g. ( light year) \u003d 0.307 PC \u003d 9.5 · 10 m. Light year is the path that light passes for the year.

In this paper, a method for determining distances to distant galaxies on "red displacement" is proposed, i.e. By increasing wavelengths in the spectrum of the observed remote radiation source compared with the corresponding wavelengths of lines in the reference spectra.

Under the source of light, they understand the radiation of distant galaxies (the most bright stars or gas-penetrating nebulaes in them). Under " red displacement"- shift of spectral lines in the spectra of chemical elements from which these objects consist in a long-wave (red) side, compared with wavelengths in the spectra of reference elements on Earth. "Red shift" is due to the effect of Doppler.

Doppler effect It is that the radiation sent by the source removing from the fixed receiver will be accepted as a longer-wave, compared to radiation from the same fixed source. If the source is approaching the receiver, then the wavelength of the registered signal, on the contrary, will decrease.

In 1924, the Soviet physicist Alexander Friedman predicted that the Universe was expanding. Currently available data show that the evolution of the Universe began from Big explosion.About 15 billion years ago the universe was a point (it is called point of singularity), To which, due to the strongest gravity in it, very high temperature and density, the well-known laws of physics are not applicable. In accordance with the model adopted now, the universe began to swell out of the point of singularity with increasing acceleration.

In 1926, experimental evidence of the expansion of the Universe was obtained. American astronomer E.Habble, when studying with a telescope spectra of distant galaxies, opened the red shift of spectral lines. This meant that galaxies are removed from each other, and at a rate increasing with distance. Hubble built a linear relationship between the distance and speed associated with the Doppler effect ( hubble Law):

(1) where

r. - distance between galaxies;

v -the removal rate of galaxies;

N.- Permanent Hubble. Value N. It depends on the time passed since the beginning of the expansion of the Universe to the present moment, and changes in the range from 50 to 100 km / s · MPK. In astrophysics, as a rule, use H \u003d 75 km / s · MPK. The accuracy of determining constant Hubble is

0.5 km / s · MPK;

from- the speed of light in vacuum;

Z.- Red shift wavelength, so-called. Cosmological factor.

(2) where

- wavelength taken by the radiation receiver;

- The wavelength of the radiation emitted by the object.

Thus, measuring the magnitude of the displacement of the lines, for example, ionized hydrogen (H +) in the visible part of the spectrum, can be determined by the formula (2) of its red displacement Z.and, using the Hubble law (1), calculate the distance to it or the speed of its removal:

Procedure for performing work

1. Call the "Definition of Distance to Galaktik" program on the computer desktop. The area of \u200b\u200bthe universe with nine different galaxies observed from the surface of the Earth will appear on the monitor screen. A spectrum of visible light appears at the top of the screen and the wavelength marker of ionized hydrogen H +.

2. Install the cursor on the galaxy specified by the teacher and click the key.

3. Record the wavelength in the measurement table and λ Emitted by this galaxy when it is removed.

In the relative proximity to our galaxy, the Milky Way of Astronomers discovered several small galaxies that made them think about the laws known for them. These galaxies form a whole ring with a diameter of 10 million light years and fly away from us with such a high speed that scientists cannot find a clear explanation of such a fast reversal.

Finding the analogies between the founded structure and a large explosion, scientists are confident that she was formed and received speed by rapprochement of the Milky Way and the Galaxy Andromeda in the distant past.

The problem is in one: scientists cannot understand why, with such a split, these small galaxies received such a high speed.

"If Einstein's gravity theory is true, our galaxy never could approach Andromeda to throw something at a similar speed," explained Zhao Hongsheng from St. Andrews University (Scotland), the author of the study published in the journal Mnras. .

Zhao with colleagues study the movements of this ring of small galaxies, which, together with the Milky, and the Andromeda Galaxy, are part of the so-called local group, which includes a minimum of 54 galaxies. Our spiral galaxy Milky Way and the neighboring Galaxy Andromeda share 2.5 million light years, however, unlike most famous galaxies, our neighbor is not removed from us, and takes advantage at a speed of more than 400 km / c.

Using the standard cosmological model in the calculations (the so-called λCDM model), scientists suggest that after 3.75 billion years, two galaxies must encounter, and another a few billion years of age, this collision will lead to strong destruction of both galaxies and the formation of a new one. But if these galaxies come closer now, could they get closer in the past?

In 2013, the team Zhao suggested that 7-11 billion years ago the Milky Way and Andromeda have already flown by each other for a very close distance.

This gave rise to "tsunami-like" waves in them, thanks to which smaller galaxies were thrown out, which are observed today flying away from us.

Similar rapprochement of two galaxies are known to astronomers (on the illustration of the note - the approach of the NGC 5426 and NGC 5427 galaxies). However, they scatter too quickly. "The high galactic center radial speeds of some galaxies of the local group were caused by the forces acting on them, which our model does not take into account," they concluded in the article. Moreover, in the total past of the Milky Way, Andromeda and these flying galaxies do not doubt if they are because they are about the same plane, they argue scientists.

"Ring-shaped distribution is very specific. These small galaxies look like raindrops flying away from a rotating umbrella - explained the co-author of the study of the Indonon Banike.

- According to my estimates, the chance that accidentally distributed galaxies are lined up in a similar way amounts to 1/640.

I traced their origin before the dynamic event that happened when the universe was two times younger. "

ΛCDM model - which takes into account the presence in the universe of the usual (baryon matter, dark energy described in Einstein equations in the form of constant λ) and cold dark matter.

The problem of the described scenario of the separation of small galaxies is not only in the hypothetical violation of the λCDM model. Calculations show that such close rapprochement of the Milky Way and Andromeda in the past was to lead to their merger, which is known, did not happen.

"So high speed (galaxies) requires 60 times greater mass of stars than we see today in the Milky Way and Andromeda. However, friction that would arise between massive halo from dark matter in the center of Galaktik and these stars would lead to their merger, and not to $ 2.5 million, which occurred, "the banner explained.

"Science is developing through challenges," says Marseil Pavlovski, Astrophysicist from California University in Irway. - This is a gigantic ring creates a serious challenge to the standard paradigm. "

Even astronomers do not always correctly understand the expansion of the universe. Inflatable balloon - old, but good analogy of the expansion of the universe. The galaxies located on the surface of the ball are still, but since the universe expands, the distance between them increases, and the dimensions of the galaxies themselves do not increase.

In July 1965, scientists announced the opening of obvious signs of expanding the universe from a hotter and dense initial state. They found a cooled afterglow of a large explosion - relic radiation. From this point on, the expansion and cooling of the universe formed the basis of cosmology. Cosmological expansion makes it possible to understand how simple structures were formed and how they gradually developed into complex. 75 years after the opening of the expansion of the Universe, many scientists cannot penetrate his true meaning. James Peebles Peebles, a cosmologist from Princeton University, who studies relict radiation, wrote in 1993: "It seems to me that even specialists do not know what the importance and possibility of a hot large explosion model."

Famous physicists, authors of astronomy textbooks and popularizers of science sometimes give an incorrect or distorted interpretation of the expansion of the universe, which formed the basis of the large explosion model. What do we mean when we say that the universe expands? Undoubtedly, confusing the fact that they are now talking about accelerating the expansion, and it puts us in a dead end.

Overview: Space misunderstanding

* Expansion of the Universe is one of the fundamental concepts of modern science - still receives various interpretation.

* Do not perceive the term "big explosion" literally. He was not a bomb exploded in the center of the Universe. It was the explosion of the very space that occurred everywhere, just as the surface of an inflated balloon expands.

* Understanding the differences between expansion of space and expansion in space is extremely important in order to understand what the size of the universe, the speed of the galaxies of galaxies, as well as the possibility of astronomical observations and the nature of the expansion acceleration, which is likely to experience the universe.

* The big explosion model describes only what happened after it.

What is the extension?

When something familiar is expanding, for example, a wet spot or the Roman Empire, they become more, their borders are moving away, and they begin to occupy a larger volume in space. But the universe seems to have no physical restrictions, and it has nowhere to move. The expansion of our universe is very similar to the influx of the balloon. Distance to distant galaxies increase. Typically, astronomers say that the galaxies are removed or run away from us, but do not move in space as the fragments of the Big Explosion bomb. In fact, the space between us and galaxies is expanding, chaotic moving inside almost fixed clusters. Relic radiation fills the universe and serves as a reference system similar to the rubber surface of the balloon, with respect to which movement and can be measured.

Being outside the ball, we see that the expansion of its twisted two-dimensional surface is possible only because it is in three-dimensional space. In the third dimension, the center of the ball is located, and its surface is expanding into the surrounding volume. Based on this, it would be possible to conclude that the expansion of our three-dimensional world requires the presence of the fourth dimension in the space. But according to the general theory of Einstein's relativity, the space is dynamic: it can expand, shrink and bend.

Traffic jam

The universe is self-sufficient. Neither the center is not required to expand from it, nor free space from the outside (wherever it is) to expand there. True, some of the latest theories, such as string theory, postulate the presence of additional measurements, but when expanding our three-dimensional universe, they are not required.

In our universe, like on the surface of the balloon, each object is distinguished from all others. Thus, the big explosion was not an explosion in space, but rather it was an explosion of the very space that did not occur in a certain place and then did not expand into the surrounding emptiness. It happened everywhere at the same time.

What was the big explosion like?

WRONG: The universe was born then when the substance, like a bomb, exploded in a certain place. The pressure was high in the center and low in the surrounding emptiness, which caused a revelation of a substance.

RIGHT: It was the explosion of the very space that brought the substance in motion. Our space and time arose in the Big Bang and began to expand. Nowhere was the center, because The conditions were everywhere the same, no pressure difference characteristic of a regular explosion was not.

If you imagine that we scroll through the film in the reverse order, we will see how all the areas of the universe are compressed, and the galaxies come closer until everyone together in a large explosion like cars in the road traffic jam. But the comparison is not complete here. If it were about the incident, then you could drive around the jam, having heard the messages about it on the radio. But the big explosion was a disaster that could be avoided. It looks like the way if the surface of the earth and all the roads were laughed at it, but cars would remain for the same size. In the end, the car would face, and no message on the radio would help prevent it. Also a big explosion: he occurred everywhere, unlike a bomb explosion, which occurs at a certain point, and fragments are flying out in all directions.

The theory of the Big Explosion does not give us information about the size of the Universe and even that it is finite or infinite. The theory of relativity describes how each space area expands, but nothing is said about the size or form. Sometimes cosmologists say that the universe was once no more grapefruit, but they mean only that part of it, which we can now watch.

In the inhabitants of the nebulae Andromeda or other galaxies their observed universes. Observers located in Andromeda can see the galaxies that are not available to us, simply because they are a little closer to them; But they cannot contemplate those that we consider. Their observed universe was also the size of grapefruit. You can imagine that the early universe was similar to a bunch of these fruits, and endlessly stretching in all directions. So, the idea that the big explosion was "small", erroneously. The space of the universe is infinite. And as it is neither squeezing, it will remain.

Faster light

Error performances are associated with a quantitative expansion description. The speed with which the distance between the galaxies increases, is subject to the simple patterns identified by the American astronomer Edwin Hubble (Edwin Hubble) in 1929: the removal rate of the galaxy v is directly proportional to its distance from us d, or V \u003d HD. The ratio of the proportionality H is called the Hubble constant and determines the rate of expansion of space both around us and around any observer in the universe.

Some confuses the fact that not all galaxies are subject to the law of Hubble. The closest to us a large galaxy (Andromeda) is generally moving towards us, and not from us. Such exceptions are, since the Hubble Law describes only the average behavior of galaxies. But each of them can have a small one's own movement, since the galaxies gravitational affect each other, as, for example, our Galaxy and Andromeda. Remote galaxies also have small chaotic speeds, but with a large distance from us (with a large value d), these random speeds are negligible against the background of high removal velocities (V). Therefore, for distant galaxies, the Hubble law is performed with high accuracy.

According to the Hubble law, the universe is expanding not at constant speed. Some galaxies are removed from us at a speed of 1 thousand km / s, others that are twice as much as the speed of 2 thousand km / s, etc. Thus, the Hubble Law indicates that, starting from a certain distance, called Hubblovsky, the galaxies are removed with superluminal velocity. For the measured value of the Hubble constant, this distance is about 14 billion light years.

But is the private theory of Einstein's relativity does not claim that no object can have a speed above the speed of light? Such a question put in a dead end, many generations of students. And the answer is that the private theory of relativity is applicable only to "normal" speeds - to movement in space. In the law of Hubble, we are talking about the removal rate caused by the expansion of the space itself, and not by the movement in space. This effect of the general theory of relativity does not obey the private theory of relativity. The presence of a removal rate above the speed does not violate the private theory of relativity. It is still true that no one can catch up with a ray of light.

Can galaxies remove with speed above the speed of light?

WRONG: The private theory of Einstein's relativity prohibits it. Consider the area containing several galaxies. Because of its expansion, the galaxy is removed from us. The further galaxy, the greater its speed (red arrows). If the speed of light is a limit, then the removal rate should eventually become constant.

RIGHT: Of course, maybe. Private theory of relativity does not consider the removal rate. The removal rate is infinitely increasing with distances. Further of a certain distance called Hubblovsky, it exceeds the speed of light. This is not a violation of the theory of relativity, the removal is not caused by the removal in space, but the expansion of the space itself.

Can I see galaxies that are removed faster than light?

WRONG: Of course not. Light from such galaxies flies with them. Let the galaxy be for the limit of the Hubble distance (sphere), i.e. It is removed from us faster than the speed of light. She emits a photon (marked yellow). While the photon flies through the space, it is expanding itself. The distance to the Earth increases faster than the photon moves. He will never reach us.

RIGHT: Of course it is possible, since the rate of expansion changes with time. First, the photon is really demolished. However, the Hubble distance is not constantly: it increases, and in the end, the photon can get into the sphere of Hubble. As soon as it happens, the photon will move faster than the earth is removed, and he will be able to achieve us.

Stretching photons

The first observations showing that the Universe expands was made between the 1910 and 1930 in the laboratory atoms emit and absorb light always on certain wavelengths. The same is observed in the spectra of distant galaxies, but with a displacement to the long-wavelength region. Astronomers say that the radiation of the Galaxy is experiencing a red displacement. Explanation Simple: When expanding the space, the light wave is stretched and therefore weakens. If during that time until the light wave reached us, the universe was twice as well, then the wavelength doubled, and its energy weakened twice.

Hypothesis fatigue

Every time Scientific American publishes an article on cosmology, many readers write to us that, in their opinion, the galaxies are not actually removed from us and that the expansion of space is an illusion. They believe that the red shift in the galaxies spectra is caused by something like "fatigue" from a long trip. A certain unknown process forces light, spreading through the space, lose energy and therefore blush.

This hypothesis has been more than half a century, and at first glance it looks reasonable. But it is completely inconsistent with observations. For example, when the star explodes as a supernova, it flashes, and then fades. The whole process lasts about two weeks in a supernova type, which astronomers are used to determine the distances to galaxies. During this period of time, the stream of photons radiates. The hypothesis of light fatigue says that during the path of the photons will lose energy, but the observer will still receive the flow of photons in a duration of two weeks.

However, in an expanding space, not only the photons themselves are stretched (and therefore lose energy), but their stream is also stretched. Therefore, it takes more than two weeks so that all photons get to the ground. Observations confirm such an effect. The outbreak of supernova in the galaxy with a red displacement of 0.5 is observed for three weeks, and in the galaxy with a red displacement of 1 month.

The hypothesis of light fatigue contradicts the observations of the spectrum of relict radiation and measurements of the surface brightness of distant galaxies. It's time to send the "tired light" (Charles Lineviver and Tamara Davis).

Supernovae, like this in the accumulation of galaxies in the Virgo, help measure the cosmic extension. Their observed properties exclude alternative cosmological theories in which the space does not expand.

The process can be described in terms of temperature. Photons emitted by the body have an energy distribution, which is generally characterized by a temperature indicating how much the body is hot. When photons are moving in an expanding space, they lose energy and their temperature is reduced. Thus, the universe is cooled at the expansion, as a compressed air escaping from the scablast cylinder. For example, the relic radiation now has a temperature of about 3 k, whereas it was born at a temperature of about 3000 K. But since that time the universe increased in the amount of 1000 times, and the photon temperature dropped at the same time. Watching gas in distant galaxies, astronomers directly measure the temperature of this radiation in the distant past. Measurements confirm that the universe is cooled over time.

In connection between red displacement and speed, there are also some contradictions. The red displacement caused by extension is often confused with a more familiar red displacement caused by the Doppler effect, which usually makes sound waves longer if the sound source is deleted. The same is true for light waves that become longer if the light source is given in space.

Doppler red shift and cosmological red displacement - things are completely different and are described by various formulas. The first follows from the private theory of relativity, which does not take into account the expansion of space, and the second follows from the general theory of relativity. These two formulas are almost the same for nearby galaxies, but differ for remote.

According to the Doppler formula, if the speed of the object in space is approaching the speed of light, its red displacement tends to infinity, and the wavelength becomes too large and therefore inaccessible to observation. If it were true for galaxies, the most distant visible objects in the sky would be removed at a speed, noticeably lower speed of light. But the cosmological formula for red bias leads to another conclusion. In the framework of the standard cosmological model of the galaxy with a red displacement of about 1.5 (i.e., the received wavelength of their radiation by 50% more laboratory value) is removed at the speed of light. Astronomers have already found about 1000 galaxies with red displacement greater than 1.5. So, we know about 1000 objects that are removed faster than the speed of light. Relic radiation comes with even more distance and has a red shift of about 1000. When the hot plasma of the young universe emitted the radiation taking today, it was removed from us almost 50 times faster than the speed of light.

Running on the spot

It is difficult to believe that we can see galaxies moving faster than the speed of light, but this is possible due to the change in the expansion rate. Imagine a ray of light that goes to us from the distance of more than the distance of Hubble (14 billion light years). He moves to us at the speed of light relative to its location, but it itself is removed from us faster than the speed of light. Although the light rushes to us with the highest possible speed, it cannot please the expansion of space. It reminds the child trying to run in the opposite direction on the escalator. Photons in the Hubble distance are moving at the maximum speed to stay at the same place.

You might think that light from the areas remote on the distance of Hubble will never be able to reach us and we will never see it. But the distance of Hubble does not remain unchanged, since the constant Hubble, from which it depends changes over time. This magnitude is proportional to the speed of breaking two galaxies divided by the distance between them. (You can use any two galaxies to calculate.) In the models of the Universe, consistent with astronomical observations, the denominator increases the faster of the numerator, so the permanent Hubble decreases. Consequently, the distance of Hubble grows. And if so, the light that originally did not reach us can over time to be within the Hubble distance. Then the photons will be in the area that removes slower the speed of light, after which they will be able to get to us.

Is the Space Red Displacement really - is it a Doppler offset?

WRONG: Yes, because the removable galaxies move in space. In the Doppler effect, light waves are stretched (becoming more red) when their source is removed from the observer. The length of the wave of light does not change during his journey through the space. The observer takes the light, measures its red displacement and calculates the speed of the galaxy.

RIGHT: No, the red bias has nothing to do with the Doppler effect. The galaxy is almost stationary in space, so it emits the light of the same wavelength in all directions. During the way the wavelength becomes greater, since the space expands. Therefore, the light is gradually blushing. The observer takes the light, measures its red displacement and calculates the speed of the galaxy. The cosmic red displacement differs from the Doppler displacement, which confirm the observations.

However, the galaxy, who has sent light can continue to be removed with superluminal speed. Thus, we can observe the light from galaxies that, as before, always be removed faster than the speed of light. In short, the Hubble distance is not fixed and does not indicate us the boundaries of the observed universe.

And what actually marks the border of the observed space? There is also a certain confusion here. If the space did not expand, then we could observe the most distant object now at a distance of about 14 billion light years from us, i.e. At a distance that the light overcame for 14 billion years, which have passed since the greatest explosion. But since the Universe expands, the space crossed by the photon expanded during its path. Therefore, the current distance to the most remote from the observed objects is approximately three times more - about 46 billion light years.

Previously, cosmologists thought that we live in the slowing down universe and therefore we could observe more and more galaxies. However, in the accelerating universe, we are fenced off by the boundary, beyond which ever will never see the events - this is the Space Horizon of Events. If the light from galaxies that are removed faster than the speed of light will reach us, it means that the distance of Hubble will increase. But at the accelerating universe, its increase is prohibited. A remote event can send a ray of light in our direction, but this light will forever remain for the limit of the Hubble distance due to the acceleration of the expansion.

As we can see, the accelerating universe reminds a black hole, which also has the horizon of events, the outside of which we do not get signals. The current distance to our space horizon of events (16 billion light years) is entirely in the limits of our observed area. The light emitted by the galaxies that are now on the cosmic horizon of events will never be able to reach us, because The distance that 16 billion light years is consistent, will expand too quickly. We will be able to see the events that happened in the galaxies before they crossed the horizon, but we will never know about subsequent events.

In the universe everything expands?

People often think that if the space expands, then everything in it is expanding too. But it is incorrect. Expansion as such (that is, inertia, without acceleration or deceleration) does not produce any power. The photon wavelength increases along with the increasing universe, since unlike atoms and photons planets are not related objects whose dimensions are determined by the equilibrium of forces. The changing rate of expansion really makes a new force in equilibrium, but it cannot force objects to expand or shrink.

For example, if the gravity became stronger, your spinal cord would have pressed until the electrons in the spine would have achieved a new equilibrium position, slightly closer to each other. Your growth would slightly decreased, but the compression would cease. In the same way, if we lived in the universe with the predominance of the forces of grave, as many years ago, most cosmologists believed, the expansion would slow down, and weaker compression would act for all bodies, forcing them to achieve a smaller equilibrium size. But, reaching him, they would no longer shrink.

How big is the observed universe?

WRONG: The universe is 14 billion years old, therefore its observed part must have a radius of 14 billion light years. We will consider the most distant of the observed galaxies - the one whose photons emitted immediately after the big explosion, only now reached us. Light year is the distance taken by the photom in the year. So, the photon overcame 14 billion light years

RIGHT: Since space expands, the observed area has a radius more than 14 billion light years. While the photon travels, the space that it crosses is expanding. By the time it reaches us, the distance to the empty galaxy becomes more than just calculated by flight time - approximately three times more

In fact, the expansion is accelerated, which is caused by a weak force, "inflating" all bodies. Therefore, the associated objects have dimensions a little more than would be in the non-splashing universe, since the equilibrium of forces is achieved in them with a slightly larger size. On the surface of the Earth, the acceleration directed outside, from the center of the planet, is a meager share ($ 10 ^ (- 30) $) of the normal gravitational acceleration to the center. If this acceleration is invariably, it will not force the land to expand. Just the planet takes a little more size than it would be without repulsion.

But everything will change if the acceleration is not constantly, as some cosmologists believe. If repulsion increases, then this may eventually cause the destruction of all the structures and lead to a "large rupture", which would not have occurred due to expansion or acceleration as such, but because the acceleration would be accelerated.

And objects in the universe are also expanding?

WRONG: Yes. Expansion causes the universe and all in it in it. As an object, consider the accumulation of galaxies. Once the universe becomes more, then the cluster is also. The boundary of the cluster (yellow line) expands.

RIGHT: Not. The universe is expanding, but the related objects do not make it in it. Neighboring galaxies are first removed, but ultimately their mutual attraction crosses the expansion. A cluster of this size is formed, which corresponds to its equilibrium state.

As the new accurate measurements help cosmologists to better understand the expansion and acceleration, they can be asked even more fundamental questions about the earliest moments and the greatest scale of the universe. What caused the expansion? Many cosmologists believe that the process called "inflation" (inflation) is to blame, the special type of accelerating expansion. But perhaps it is only a partial answer: so that it began, it seems that the Universe has already had to expand. And what about the greatest scale for the limit of our observations? Are different parts of the Universe in different ways expand, so that our universe is just a modest inflation bubble in a giant superunulated? No one knows. But we hope that over time we can come to understanding the process of expanding the universe.

About the authors:
Charles H. lineweaver (Charles H. lineWeaver) and Tamara Davis (Tamara M. Davis) - Astronomers from the Australian Observatory Mount Stromlo. In the early 1990s In California University in Berkeley, Linevive was a group of scientists who opened with the help of a Cobe satellite of relict radiation. He defended the dissertation not only on astrophysics, but also on the history and English literature. Davis is working on the creation of the Supernova / Acceleration Probe Space Observatory (supernova and acceleration researcher).

Remarks to the article "Paradoxes of the Big Explosion"
Professor Zapov Anatoly Vladimirovich, Phys. Ft. MSU: All misunderstandings with which the authors of the article argue are related to the fact that for visibility, the expansion of the limited volume of the universe in a rigid reference system is most often considered (and the expansion of a sufficiently small area in order not to take into account the difference in time of time on Earth and galaxies in the earth reference). Hence the presentation and the explosion, and the Doppler displacement, and the common confusion with the speeds of movement. The authors write, and write correctly, as it looks in non-inertocal (accompanying) coordinate system, in which cosmologists usually work, although the article does not speak directly about it (in principle, all distances and speeds depend on the selection of the reference system, and here always There is a certain arbitrary). The only thing that is written is unclear, so this is what is not determined that in the expanding universe is understood under the distance. First, the authors are the speed of light multiplied by the spread time, and then it is said that even accounting for expansion, which removed the galaxy even more while the light was on the way. Thus, the distance is already understood as the speed of light, multiplied by the time of distribution, which he would spend if the galaxy ceased to be deleted and radiated the light now. In fact, everything is more complicated. The distance is the magnitude of the model-dependent and directly from observations not received, so cosmologists are fine without it, replacing with a red displacement. But maybe a more rigorous approach here and inappropriate.