- Direct measurements of the brightness and distance of objects in the Universe such as stars, galaxies and supernovae, which allowed us to build a ruler of cosmic distances.
- Measurements of large-scale structure, galaxy clustering and baryonic acoustic oscillations.
- Oscillations in the microwave cosmic background, a kind of “snapshot” of the Universe when it was only 380,000 years old.
There is a unique relationship between the age of the Universe and its expansion during the creation of its history.
In other words, if we could measure the expansion of the Universe today and how it has expanded throughout its history, we would know exactly what the different components make it up. We learned this from a number of observations, including:
You put it all together and you get a Universe that today is 68% dark energy, 27% dark matter, 4.9% ordinary matter, 0.1% neutrinos, 0.01% radiation , and all sorts of little things.
Then you look at the expansion of the Universe today and extrapolate it back in time, piecing together the history of the expansion of the Universe, and therefore its age.
We get a figure - most accurately from Planck, but supplemented by other sources like supernova measurements, the key HST project and the Sloan Digital Sky Survey - the age of the Universe, 13.81 billion years, give or take 120 million years. We are 99.1 percent sure of the age of the universe, which is pretty cool.
We have a number of different data sets that point to this conclusion, but they are, in fact, obtained using a single method. We're just lucky that there's a consistent picture with all the points pointing in the same direction, but in reality it's impossible to accurately tell the age of the Universe. All these points offer different probabilities, and somewhere at the intersection our opinion about the age of our world is born. 
If the Universe had the same properties, but consisted of 100% ordinary matter (that is, without dark matter or dark energy), our Universe would be only 10 billion years old. If the Universe consisted of 5% ordinary matter (without dark matter and dark energy), and the Hubble constant was 50 km/s/Mpc rather than 70 km/s/Mpc, our Universe would be 16 billion years old. With the combination of all this, we can almost certainly say that the age of the Universe is 13.81 billion years. Finding out this figure is a huge feat for science.
This method of finding out is rightfully the best. He is the main one, the most confident, the most complete and has been verified by many different pieces of evidence pointing to him. But there is another method, and it is very useful for checking our results.
It comes down to the fact that we know how stars live, how they burn their fuel and die. In particular, we know that all stars, while they live and burn through the main fuel (synthesizing helium from hydrogen), have a certain brightness and color, and remain at these specific indicators for a specific period of time: until the fuel runs out in the cores.
At this point, bright, blue, and massive stars begin to evolve into giants or supergiants. 
By looking at these points in a cluster of stars that formed at the same time, we can find out - if, of course, we know how stars work - the age of the stars in the cluster. Looking at old globular clusters, we find that these stars most often came to life about 13.2 billion years ago. (However, there are small deviations of a billion years).
An age of 12 billion years is quite common, but an age of 14 billion years or more is something strange, although there was a period in the 90s when an age of 14-16 billion years was mentioned quite often. (Improved understanding of stars and their evolution has significantly lowered these numbers.)
So, we have two methods - cosmic history and measurements of local stars - which indicate that the age of our Universe is 13-14 billion years. It will not surprise anyone if the age is clarified to 13.6 or even 14 billion years, but it is unlikely to be 13 or 15. If you are asked, say that the age of the Universe is 13.8 billion years, there will be no complaints against you.
People have been interested in the age of the Universe since ancient times. And although you cannot ask her for a passport to see her date of birth, modern science has been able to answer this question. True, only quite recently.
Passport to the Universe Astronomers have studied in detail the early biography of the Universe. But they had doubts about her exact age, which were only dispelled in the last couple of decades.
The sages of Babylon and Greece considered the universe eternal and unchanging, and Hindu chroniclers in 150 BC. determined that he was exactly 1,972,949,091 years old (by the way, in terms of the order of magnitude, they were not much mistaken!). In 1642, the English theologian John Lightfoot, through a scrupulous analysis of biblical texts, calculated that the creation of the world occurred in 3929 BC; a few years later, Irish Bishop James Ussher moved it to 4004. The founders of modern science, Johannes Kepler and Isaac Newton, also did not ignore this topic. Although they appealed not only to the Bible, but also to astronomy, their results turned out to be similar to the calculations of theologians - 3993 and 3988 BC. In our enlightened times, the age of the Universe is determined in other ways. To see them in a historical perspective, let’s first take a look at our own planet and its cosmic environment.
Astronomers have studied in detail the early biography of the Universe. But they had doubts about her exact age, which were only dispelled in the last couple of decades.
Fortune telling by stones
Since the second half of the 18th century, scientists began to estimate the age of the Earth and the Sun based on physical models. Thus, in 1787, the French naturalist Georges-Louis Leclerc came to the conclusion that if our planet was a ball of molten iron at birth, it would need from 75 to 168 thousand years to cool to its current temperature. After 108 years, the Irish mathematician and engineer John Perry re-calculated the thermal history of the Earth and determined its age at 2-3 billion years. At the very beginning of the 20th century, Lord Kelvin came to the conclusion that if the Sun gradually contracts and shines solely due to the release of gravitational energy, then its age (and, consequently, the maximum age of the Earth and other planets) could be several hundred million years. But at that time, geologists could neither confirm nor refute these estimates due to the lack of reliable geochronological methods.
In the middle of the first decade of the twentieth century, Ernest Rutherford and the American chemist Bertram Boltwood developed the basis of radiometric dating of earth rocks, which showed that Perry was much closer to the truth. In the 1920s, mineral samples were found whose radiometric age was close to 2 billion years. Later, geologists increased this value more than once, and by now it has more than doubled - to 4.4 billion. Additional data is provided by the study of “heavenly stones” - meteorites. Almost all radiometric estimates of their age fall within the range of 4.4−4.6 billion years.
Modern helioseismology makes it possible to directly determine the age of the Sun, which, according to the latest data, is 4.56 - 4.58 billion years. Since the duration of the gravitational condensation of the protosolar cloud was measured in only millions of years, we can confidently say that no more than 4.6 billion years have passed from the beginning of this process to the present day. At the same time, solar matter contains many elements heavier than helium, which were formed in the thermonuclear furnaces of massive stars of previous generations that burned out and exploded in supernovae. This means that the existence of the Universe greatly exceeds the age of the Solar System. To determine the extent of this excess, you need to go first into our Galaxy, and then beyond its limits.
Following white dwarfs
The lifetime of our Galaxy can be determined in different ways, but we will limit ourselves to the two most reliable ones. The first method is based on monitoring the glow of white dwarfs. These compact (about Earth-sized) and initially very hot celestial bodies represent the final stage of life for all but the most massive stars. To transform into a white dwarf, a star must completely burn all its thermonuclear fuel and undergo several cataclysms - for example, become a red giant for some time.
Natural clock
According to radiometric dating, the oldest rocks on Earth are now considered to be the gray gneisses of the Great Slave Lake coast in northwestern Canada - their age is determined to be 4.03 billion years. Even earlier (4.4 billion years ago), tiny grains of the mineral zircon, a natural zirconium silicate found in gneisses in western Australia, crystallized. And since the earth’s crust already existed in those days, our planet should be somewhat older.
As for meteorites, the most accurate information is provided by the dating of calcium-aluminum inclusions in the material of Carboniferous chondritic meteorites, which remained virtually unchanged after its formation from the gas-dust cloud that surrounded the newborn Sun. The radiometric age of similar structures in the Efremovka meteorite, found in 1962 in the Pavlodar region of Kazakhstan, is 4 billion 567 million years.
A typical white dwarf is composed almost entirely of carbon and oxygen ions embedded in degenerate electron gas, and has a thin atmosphere dominated by hydrogen or helium. Its surface temperature ranges from 8,000 to 40,000 K, while the central zone is heated to millions and even tens of millions of degrees. According to theoretical models, dwarfs consisting predominantly of oxygen, neon and magnesium (which, under certain conditions, transform into stars with a mass of 8 to 10.5 or even up to 12 solar masses) may also be born, but their existence has not yet been proven. The theory also states that stars with at least half the mass of the Sun end up as helium white dwarfs. Such stars are very numerous, but they burn hydrogen extremely slowly and therefore live for many tens and hundreds of millions of years. So far, they simply haven’t had enough time to exhaust their hydrogen fuel (the very few helium dwarfs discovered to date live in binary systems and arose in a completely different way).
Since a white dwarf cannot support thermonuclear fusion reactions, it shines due to the accumulated energy and therefore slowly cools. The rate of this cooling can be calculated and, on this basis, determine the time required to reduce the surface temperature from the initial one (for a typical dwarf this is about 150,000 K) to the observed one. Since we are interested in the age of the Galaxy, we should look for the longest-lived, and therefore the coldest, white dwarfs. Modern telescopes make it possible to detect intragalactic dwarfs with a surface temperature of less than 4000 K, the luminosity of which is 30,000 times lower than that of the Sun. So far they have not been found - either they are not there at all, or there are very few of them. It follows that our Galaxy cannot be older than 15 billion years, otherwise they would be present in noticeable quantities.
To date rocks, an analysis of the content of decay products of various radioactive isotopes in them is used. Depending on the type of rock and dating time, different pairs of isotopes are used.
This is the upper age limit. What can we say about the bottom? The coolest white dwarfs currently known were detected by the Hubble Space Telescope in 2002 and 2007. Calculations showed that their age is 11.5 - 12 billion years. To this we must also add the age of the predecessor stars (from half a billion to a billion years). It follows that the Milky Way is no younger than 13 billion years old. So the final estimate of its age, obtained from observations of white dwarfs, is approximately 13 - 15 billion years.
Ball certificates
The second method is based on the study of spherical star clusters located in the peripheral zone of the Milky Way and orbiting its core. They contain from hundreds of thousands to more than a million stars bound by mutual attraction.
Globular clusters are found in almost all large galaxies, and their number sometimes reaches many thousands. Almost no new stars are born there, but older stars are present in abundance. About 160 such globular clusters have been registered in our Galaxy, and perhaps two to three dozen more will be discovered. The mechanisms of their formation are not entirely clear, however, most likely, many of them arose soon after the birth of the Galaxy itself. Therefore, dating the formation of the oldest globular clusters makes it possible to establish a lower limit on the galactic age.
This dating is very technically complex, but it is based on a very simple idea. All stars in the cluster (from supermassive to the lightest) are formed from the same gas cloud and therefore are born almost simultaneously. Over time, they burn out the main reserves of hydrogen - some earlier, others later. At this stage, the star leaves the main sequence and undergoes a series of transformations that culminate in either complete gravitational collapse (followed by the formation of a neutron star or black hole) or the emergence of a white dwarf. Therefore, studying the composition of a globular cluster makes it possible to determine its age quite accurately. For reliable statistics, the number of clusters studied should be at least several dozen.
This work was carried out three years ago by a team of astronomers using the ACS (Advanced Camera for Survey) camera of the Hubble Space Telescope. Monitoring of 41 globular clusters in our Galaxy showed that their average age is 12.8 billion years. The record holders were the clusters NGC 6937 and NGC 6752, located 7,200 and 13,000 light years from the Sun. They are almost certainly no younger than 13 billion years, with the most probable lifetime of the second cluster being 13.4 billion years (although with an error of plus or minus a billion).
Stars with a mass on the order of the Sun, as their hydrogen reserves are depleted, swell and become red dwarfs, after which their helium core heats up during compression and helium combustion begins. After some time, the star sheds its shell, forming a planetary nebula, and then becomes a white dwarf and then cools down.
However, our Galaxy must be older than its clusters. Its first supermassive stars exploded as supernovae and ejected the nuclei of many elements into space, in particular the nuclei of the stable isotope beryllium-beryllium-9. When globular clusters began to form, their newborn stars already contained beryllium, and more so the later they arose. Based on the beryllium content in their atmospheres, one can determine how much younger the clusters are than the Galaxy. As evidenced by data on the NGC 6937 cluster, this difference is 200 - 300 million years. So, without much of a stretch, we can say that the age of the Milky Way exceeds 13 billion years and perhaps reaches 13.3 - 13.4 billion. This is almost the same estimate as that made on the basis of observations of white dwarfs, but it was obtained in a completely different way way.
Hubble's Law
The scientific formulation of the question about the age of the Universe became possible only at the beginning of the second quarter of the last century. In the late 1920s, Edwin Hubble and his assistant Milton Humason began to clarify the distances to dozens of nebulae outside the Milky Way, which only a few years earlier had become independent galaxies.
These galaxies are moving away from the Sun at radial velocities that were measured by the redshift of their spectra. Although the distances to most of these galaxies could be determined with a large error, Hubble still found that they were approximately proportional to the radial velocities, as he wrote about in an article published in early 1929. Two years later, Hubble and Humason confirmed this conclusion based on observations of other galaxies - some of them more than 100 million light years away.
These data formed the basis of the famous formula v=H0d, known as Hubble's law. Here v is the radial velocity of the galaxy relative to the Earth, d is the distance, H0 is the proportionality coefficient, whose dimension, as is easy to see, is the inverse of the dimension of time (previously it was called the Hubble constant, which is incorrect, since in previous epochs the value of H0 was different than Nowadays). Hubble himself and many other astronomers for a long time rejected assumptions about the physical meaning of this parameter. However, Georges Lemaitre showed back in 1927 that the general theory of relativity allows us to interpret the expansion of galaxies as evidence of the expansion of the Universe. Four years later, he had the courage to take this conclusion to its logical conclusion, putting forward the hypothesis that the Universe arose from an almost point-like embryo, which he, for lack of a better term, called an atom. This primordial atom could remain in a static state for any time up to infinity, but its “explosion” gave birth to an expanding space filled with matter and radiation, which in a finite time gave rise to the present Universe. Already in his first article, Lemaitre derived a complete analogue of the Hubble formula and, having the data known by that time on the velocities and distances of a number of galaxies, he obtained approximately the same value of the coefficient of proportionality between distances and velocities as Hubble. However, his article was published in French in a little-known Belgian magazine and initially went unnoticed. It became known to most astronomers only in 1931 after the publication of its English translation.
The evolution of the Universe is determined by the initial rate of its expansion, as well as the effects of gravity (including dark matter) and antigravity (dark energy). Depending on the relationship between these factors, the graph of the size of the Universe has a different shape both in the future and in the past, which affects the estimate of its age. Current observations show that the Universe is expanding exponentially (red graph).
Hubble time
From this work by Lemaître and the later works of both Hubble himself and other cosmologists it directly followed that the age of the Universe (naturally, measured from the initial moment of its expansion) depends on the value 1/H0, which is now called Hubble time. The nature of this dependence is determined by the specific model of the universe. If we assume that we live in a flat Universe filled with gravitating matter and radiation, then to calculate its age 1/H0 must be multiplied by 2/3.
This is where the snag arose. From the measurements of Hubble and Humason it follows that the numerical value of 1/H0 is approximately equal to 1.8 billion years. It followed that the Universe was born 1.2 billion years ago, which clearly contradicted even the greatly underestimated estimates of the age of the Earth at that time. One could get out of this difficulty by assuming that galaxies are moving away more slowly than Hubble thought. Over time, this assumption was confirmed, but it did not solve the problem. According to data obtained by the end of the last century using optical astronomy, 1/H0 ranges from 13 to 15 billion years. So the discrepancy still remained, since the space of the Universe was and is considered flat, and two-thirds of Hubble time is much less than even the most modest estimates of the age of the Galaxy.
Empty world
According to the latest measurements of the Hubble parameter, the lower limit of Hubble time is 13.5 billion years, and the upper limit is 14 billion. It turns out that the current age of the Universe is approximately equal to the current Hubble time. Such equality must be strictly and invariably observed for an absolutely empty Universe, where there is neither gravitating matter nor anti-gravitating fields. But in our world there is enough of both. The fact is that space first expanded slowly, then the speed of its expansion began to increase, and in the current era these opposing trends almost compensated for each other.
In general, this contradiction was eliminated in 1998 - 1999, when two teams of astronomers proved that over the last 5 - 6 billion years, outer space has been expanding not at a decreasing, but an increasing rate. This acceleration is usually explained by the fact that in our Universe the influence of the anti-gravity factor, the so-called dark energy, the density of which does not change over time, is growing. Since the density of gravitating matter decreases as the Cosmos expands, dark energy competes more and more successfully with gravity. The duration of the existence of a Universe with an antigravitational component does not have to be equal to two-thirds of Hubble time. Therefore, the discovery of the accelerating expansion of the Universe (noted in 2011 by the Nobel Prize) made it possible to eliminate the discrepancy between cosmological and astronomical estimates of its lifetime. It was also a prelude to the development of a new method for dating her birth.
Cosmic rhythms
On June 30, 2001, NASA sent Explorer 80 into space, two years later renamed WMAP, the Wilkinson Microwave Anisotropy Probe. His equipment made it possible to record temperature fluctuations of the microwave cosmic microwave background radiation with an angular resolution of less than three tenths of a degree. It was already known then that the spectrum of this radiation almost completely coincides with the spectrum of an ideal black body heated to 2.725 K, and its temperature fluctuations in “coarse-grained” measurements with an angular resolution of 10 degrees do not exceed 0.000036 K. However, in “fine-grained” measurements on the scale of the WMAP probe, the amplitudes of such fluctuations were six times larger (about 0.0002 K). The cosmic microwave background radiation turned out to be spotty, closely dotted with slightly more and slightly less heated areas.
Fluctuations in the cosmic microwave background radiation are generated by fluctuations in the density of the electron-photon gas that once filled outer space. It dropped to almost zero about 380,000 years after the Big Bang, when virtually all the free electrons combined with the nuclei of hydrogen, helium and lithium, thereby giving rise to neutral atoms. Until this happened, sound waves propagated in the electron-photon gas, influenced by the gravitational fields of dark matter particles. These waves, or, as astrophysicists say, acoustic oscillations, left their mark on the spectrum of the cosmic microwave background radiation. This spectrum can be deciphered using the theoretical apparatus of cosmology and magnetic hydrodynamics, which makes it possible to re-evaluate the age of the Universe. As the latest calculations show, its most probable extent is 13.72 billion years. It is now considered the standard estimate of the lifetime of the Universe. If we take into account all possible inaccuracies, tolerances and approximations, we can conclude that, according to the results of the WMAP probe, the Universe has existed for between 13.5 and 14 billion years.
Thus, astronomers, estimating the age of the Universe in three different ways, obtained quite compatible results. Therefore, we now know (or, to put it more cautiously, we think that we know) when our universe arose - at least to an accuracy of several hundred million years. Probably, descendants will add the solution to this age-old riddle to the list of the most remarkable achievements of astronomy and astrophysics.
According to the latest data, the Universe is approximately 13.75 billion years old. But how did scientists arrive at this number?
Cosmologists can determine the age of the Universe using two different methods: studying the oldest objects in the Universe, And measuring the rate of its expansion.
Age restrictions
The Universe cannot be “younger” than the objects within it. By determining the age of the oldest stars, scientists will be able to estimate age boundaries.
The life cycle of a star is based on its mass. More massive stars burn faster than their smaller brothers and sisters. A star 10 times more massive than the Sun can burn for 20 million years, while a star with half the mass of the Sun will live for 20 billion years. Mass also affects the brightness of stars: the more massive the star, the brighter it is.
NASA's Hubble Space Telescope has captured images of red dwarf CHXR 73 and its companion, believed to be a brown dwarf. CHXR 73 is a third lighter than the Sun.
This image from the Hubble Space Telescope shows Sirius A, the brightest star in our night sky, along with its faint and tiny companion star Sirius B. The astronomers deliberately overexposed the image of Sirius A to reveal Sirius B (the tiny dot below left). The crossed diffraction beams and concentric rings around Sirius A, as well as a small ring around Sirius B, were created by the telescope's image processing system. The two stars circle each other every 50 years. Sirius A is 8.6 light years from Earth and is the fifth closest star system known to us.
Dense clusters of stars known as globular clusters have similar characteristics. The oldest known globular clusters contain stars that are between 11 and 18 billion years old. Such a large range is associated with problems in determining the distances to clusters, which affects the estimate of brightness and, therefore, mass. If the cluster is further away than scientists think, the stars will be brighter and more massive, and therefore younger.
Uncertainty still places limits on the age of the Universe; it must be at least 11 billion years old. She may be older, but she is not younger.
Expansion of the Universe
The universe we live in is not flat or unchanging, it is constantly expanding. If the rate of expansion is known, then scientists can work backwards and determine the age of the Universe. So the expansion rate of the universe, known as the Hubble constant, is the key.
A number of factors determine the value of this constant. First of all, it is the type of matter that dominates the Universe. Scientists must determine the ratio of ordinary and dark matter to dark energy. Density also plays a role. A universe with low matter density is older than one with more matter.
This composite image from the Hubble Space Telescope shows a ghostly "ring" of dark matter in the galaxy cluster Cl 0024 +17.
The galaxy cluster Abell 1689 is famous for its ability to refract light, a phenomenon called gravitational lensing. New research on the cluster is revealing secrets about how dark energy shapes the Universe.
To determine the density and composition of the Universe, scientists turned to a number of missions, such as the Wilkinson Microwave Anisotropy Probe (WMAP) and the Planck spacecraft. By measuring the thermal radiation left over from the Big Bang, missions like these can determine the density, composition and expansion rate of the Universe. Both WMAP and Planck have detected residual radiation called the cosmic microwave background and mapped it.
In 2012, WMAP suggested the age of the universe to be 13.772 billion years, with an error of 59 million years. And in 2013, Planck calculated that the Universe is 13.82 billion years old. Both results fall under the 11 billion minimum, regardless of globular clusters, and both have relatively small margins of error.
People have been interested in the age of the Universe since ancient times. And although you cannot ask her for a passport to see her date of birth, modern science has been able to answer this question. True, only quite recently.
The sages of Babylon and Greece considered the universe eternal and unchanging, and Hindu chroniclers in 150 BC. determined that he was exactly 1,972,949,091 years old (by the way, in terms of the order of magnitude, they were not much mistaken!). In 1642, the English theologian John Lightfoot, through a scrupulous analysis of biblical texts, calculated that the creation of the world occurred in 3929 BC; a few years later, Irish Bishop James Ussher moved it to 4004. The founders of modern science, Johannes Kepler and Isaac Newton, also did not ignore this topic. Although they appealed not only to the Bible, but also to astronomy, their results turned out to be similar to the calculations of theologians - 3993 and 3988 BC. In our enlightened times, the age of the Universe is determined in other ways. To see them in a historical perspective, let’s first take a look at our own planet and its cosmic environment.
Fortune telling by stones
Since the second half of the 18th century, scientists began to estimate the age of the Earth and the Sun based on physical models. Thus, in 1787, the French naturalist Georges-Louis Leclerc came to the conclusion that if our planet was a ball of molten iron at birth, it would need from 75 to 168 thousand years to cool to its current temperature. After 108 years, Irish mathematician and engineer John Perry re-calculated the thermal history of the Earth and determined its age at 2–3 billion years. At the very beginning of the 20th century, Lord Kelvin came to the conclusion that if the Sun gradually contracts and shines solely due to the release of gravitational energy, then its age (and, consequently, the maximum age of the Earth and other planets) could be several hundred million years. But at that time, geologists could neither confirm nor refute these estimates due to the lack of reliable geochronological methods.
In the middle of the first decade of the twentieth century, Ernest Rutherford and the American chemist Bertram Boltwood developed the basis of radiometric dating of earth rocks, which showed that Perry was much closer to the truth. In the 1920s, mineral samples were found whose radiometric age was close to 2 billion years. Later, geologists increased this value more than once, and by now it has more than doubled - to 4.4 billion. Additional data is provided by the study of “heavenly stones” - meteorites. Almost all radiometric estimates of their age fall within the range of 4.4–4.6 billion years.
Modern helioseismology makes it possible to directly determine the age of the Sun, which, according to the latest data, is 4.56–4.58 billion years. Since the duration of the gravitational condensation of the protosolar cloud was measured in only millions of years, we can confidently say that no more than 4.6 billion years have passed from the beginning of this process to the present day. At the same time, solar matter contains many elements heavier than helium, which were formed in the thermonuclear furnaces of massive stars of previous generations that burned out and exploded in supernovae. This means that the existence of the Universe greatly exceeds the age of the Solar System. To determine the extent of this excess, you need to go first into our Galaxy, and then beyond its limits.
Following white dwarfs
The lifetime of our Galaxy can be determined in different ways, but we will limit ourselves to the two most reliable ones. The first method is based on monitoring the glow of white dwarfs. These compact (about Earth-sized) and initially very hot celestial bodies represent the final stage of life for all but the most massive stars. To transform into a white dwarf, a star must completely burn all its thermonuclear fuel and undergo several cataclysms - for example, become a red giant for some time.
A typical white dwarf is composed almost entirely of carbon and oxygen ions embedded in degenerate electron gas, and has a thin atmosphere dominated by hydrogen or helium. Its surface temperature ranges from 8,000 to 40,000 K, while the central zone is heated to millions and even tens of millions of degrees. According to theoretical models, dwarfs consisting predominantly of oxygen, neon and magnesium (which, under certain conditions, transform into stars with a mass of 8 to 10.5 or even up to 12 solar masses) may also be born, but their existence has not yet been proven. The theory also states that stars with at least half the mass of the Sun end up as helium white dwarfs. Such stars are very numerous, but they burn hydrogen extremely slowly and therefore live for many tens and hundreds of millions of years. So far, they simply haven’t had enough time to exhaust their hydrogen fuel (the very few helium dwarfs discovered to date live in binary systems and arose in a completely different way).
Since a white dwarf cannot support thermonuclear fusion reactions, it shines due to the accumulated energy and therefore slowly cools. The rate of this cooling can be calculated and, on this basis, determine the time required to reduce the surface temperature from the initial one (for a typical dwarf this is about 150,000 K) to the observed one. Since we are interested in the age of the Galaxy, we should look for the longest-lived, and therefore the coldest, white dwarfs. Modern telescopes make it possible to detect intragalactic dwarfs with a surface temperature of less than 4000 K, the luminosity of which is 30,000 times lower than that of the Sun. Until they are found - either they are not there at all, or there are very few of them. It follows that our Galaxy cannot be older than 15 billion years, otherwise they would be present in noticeable quantities.
This is the upper age limit. What can we say about the bottom? The coolest white dwarfs currently known were detected by the Hubble Space Telescope in 2002 and 2007. Calculations showed that their age is 11.5–12 billion years. To this we must also add the age of the predecessor stars (from half a billion to a billion years). It follows that the Milky Way is no younger than 13 billion years old. So the final estimate of its age, based on observations of white dwarfs, is approximately 13–15 billion years.
Natural clock
According to radiometric dating, the oldest rocks on Earth are now considered to be the gray gneisses of the Great Slave Lake coast in northwestern Canada - their age is determined to be 4.03 billion years. Even earlier (4.4 billion years ago), tiny grains of the mineral zircon, a natural zirconium silicate found in gneisses in western Australia, crystallized. And since the earth’s crust already existed in those days, our planet should be somewhat older. As for meteorites, the most accurate information is provided by the dating of calcium-aluminum inclusions in the material of Carboniferous chondritic meteorites, which remained virtually unchanged after its formation from the gas and dust cloud that surrounded the newborn Sun. The radiometric age of similar structures in the Efremovka meteorite, found in 1962 in the Pavlodar region of Kazakhstan, is 4 billion 567 million years.
Ball certificates
The second method is based on the study of spherical star clusters located in the peripheral zone of the Milky Way and orbiting its core. They contain from hundreds of thousands to more than a million stars bound by mutual attraction.
Globular clusters are found in almost all large galaxies, and their number sometimes reaches many thousands. Almost no new stars are born there, but older stars are present in abundance. About 160 such globular clusters have been registered in our Galaxy, and perhaps two to three dozen more will be discovered. The mechanisms of their formation are not entirely clear, however, most likely, many of them arose soon after the birth of the Galaxy itself. Therefore, dating the formation of the oldest globular clusters makes it possible to establish a lower limit on the galactic age.
This dating is very technically complex, but it is based on a very simple idea. All stars in the cluster (from supermassive to the lightest) are formed from the same gas cloud and therefore are born almost simultaneously. Over time, they burn out the main reserves of hydrogen - some earlier, others later. At this stage, the star leaves the main sequence and undergoes a series of transformations that culminate in either complete gravitational collapse (followed by the formation of a neutron star or black hole) or the emergence of a white dwarf. Therefore, studying the composition of a globular cluster makes it possible to determine its age quite accurately. For reliable statistics, the number of clusters studied should be at least several dozen.
This work was carried out three years ago by a team of astronomers using the ACS camera ( Advanced Camera for Survey) Hubble Space Telescope. Monitoring of 41 globular clusters in our Galaxy showed that their average age is 12.8 billion years. The record holders were the clusters NGC 6937 and NGC 6752, located 7,200 and 13,000 light years from the Sun. They are almost certainly no younger than 13 billion years, with the most likely lifetime of the second cluster being 13.4 billion years (although with an error of plus or minus a billion).
However, our Galaxy must be older than its clusters. Its first supermassive stars exploded as supernovae and ejected the nuclei of many elements into space, in particular the nuclei of the stable isotope of beryllium, beryllium-9. When globular clusters began to form, their newborn stars already contained beryllium, and more so the later they arose. Based on the beryllium content in their atmospheres, one can determine how much younger the clusters are than the Galaxy. As evidenced by data on the NGC 6937 cluster, this difference is 200–300 million years. So, without much of a stretch, we can say that the age of the Milky Way exceeds 13 billion years and possibly reaches 13.3–13.4 billion. This is almost the same estimate as that made on the basis of observations of white dwarfs, but it was obtained in a completely different way way.
Hubble's Law
The scientific formulation of the question about the age of the Universe became possible only at the beginning of the second quarter of the last century. In the late 1920s, Edwin Hubble and his assistant Milton Humason began to clarify the distances to dozens of nebulae outside the Milky Way, which only a few years earlier had become independent galaxies.
These galaxies are moving away from the Sun at radial velocities that were measured by the redshift of their spectra. Although the distances to most of these galaxies could be determined with a large error, Hubble still found that they were approximately proportional to the radial velocities, as he wrote about in an article published in early 1929. Two years later, Hubble and Humason confirmed this conclusion based on observations of other galaxies - some of them more than 100 million light years away.
These data formed the basis of the famous formula v = H 0 d, known as Hubble's law. Here v- radial speed of the galaxy relative to Earth, d- distance, H 0 is the coefficient of proportionality, whose dimension, as is easy to see, is the inverse of the dimension of time (previously it was called the Hubble constant, which is incorrect, since in previous epochs the quantity H 0 was different than in our time). Hubble himself and many other astronomers for a long time rejected assumptions about the physical meaning of this parameter. However, Georges Lemaitre showed back in 1927 that the general theory of relativity allows us to interpret the expansion of galaxies as evidence of the expansion of the Universe. Four years later, he had the courage to take this conclusion to its logical conclusion, putting forward the hypothesis that the Universe arose from an almost point-like embryo, which he, for lack of a better term, called the atom. This primordial atom could remain in a static state for any time up to infinity, but its “explosion” gave birth to an expanding space filled with matter and radiation, which in a finite time gave rise to the present Universe. Already in his first article, Lemaitre derived a complete analogue of the Hubble formula and, having the data known by that time on the velocities and distances of a number of galaxies, he obtained approximately the same value of the coefficient of proportionality between distances and velocities as Hubble. However, his article was published in French in a little-known Belgian magazine and initially went unnoticed. It became known to most astronomers only in 1931 after the publication of its English translation.
Hubble time
From this work of Lemaître and the later works of both Hubble himself and other cosmologists it directly followed that the age of the Universe (naturally, measured from the initial moment of its expansion) depends on the value 1/ H 0, which is now called Hubble time. The nature of this dependence is determined by the specific model of the universe. If we assume that we live in a flat Universe filled with gravitating matter and radiation, then to calculate its age 1/ H 0 must be multiplied by 2/3.
This is where the snag arose. From the measurements of Hubble and Humason it followed that the numerical value 1/ H 0 is approximately 1.8 billion years. It followed that the Universe was born 1.2 billion years ago, which clearly contradicted even the greatly underestimated estimates of the age of the Earth at that time. One could get out of this difficulty by assuming that galaxies are moving away more slowly than Hubble thought. Over time, this assumption was confirmed, but it did not solve the problem. According to data obtained by the end of the last century using optical astronomy, 1/ H 0 is from 13 to 15 billion years. So the discrepancy still remained, since the space of the Universe was and is considered flat, and two-thirds of Hubble time is much less than even the most modest estimates of the age of the Galaxy.
In general, this contradiction was eliminated in 1998–1999, when two teams of astronomers proved that over the last 5–6 billion years, outer space has been expanding not at a decreasing, but an increasing rate. This acceleration is usually explained by the fact that in our Universe the influence of the anti-gravity factor, the so-called dark energy, the density of which does not change over time, is growing. Since the density of gravitating matter decreases as the Cosmos expands, dark energy competes more and more successfully with gravity. The duration of the existence of a Universe with an antigravitational component does not have to be equal to two-thirds of Hubble time. Therefore, the discovery of the accelerating expansion of the Universe (noted in 2011 by the Nobel Prize) made it possible to eliminate the discrepancy between cosmological and astronomical estimates of its lifetime. It was also a prelude to the development of a new method for dating her birth.
Cosmic rhythms
On June 30, 2001, NASA sent the Explorer 80 probe into space, two years later renamed WMAP. Wilkinson Microwave Anisotropy Probe. His equipment made it possible to record temperature fluctuations of the microwave cosmic microwave background radiation with an angular resolution of less than three tenths of a degree. It was already known then that the spectrum of this radiation almost completely coincides with the spectrum of an ideal black body heated to 2.725 K, and its temperature fluctuations in “coarse-grained” measurements with an angular resolution of 10 degrees do not exceed 0.000036 K. However, in “fine-grained” measurements on the scale of the WMAP probe, the amplitudes of such fluctuations were six times larger (about 0.0002 K). The cosmic microwave background radiation turned out to be spotty, closely dotted with slightly more and slightly less heated areas.
Fluctuations in the cosmic microwave background radiation are generated by fluctuations in the density of the electron-photon gas that once filled outer space. It dropped to almost zero about 380,000 years after the Big Bang, when virtually all the free electrons combined with the nuclei of hydrogen, helium and lithium, thereby giving rise to neutral atoms. Until this happened, sound waves propagated in the electron-photon gas, influenced by the gravitational fields of dark matter particles. These waves, or, as astrophysicists say, acoustic oscillations, left their mark on the spectrum of the cosmic microwave background radiation. This spectrum can be deciphered using the theoretical apparatus of cosmology and magnetic hydrodynamics, which makes it possible to re-evaluate the age of the Universe. As the latest calculations show, its most probable extent is 13.72 billion years. It is now considered the standard estimate of the lifetime of the Universe. If we take into account all possible inaccuracies, tolerances and approximations, we can conclude that, according to the results of the WMAP probe, the Universe has existed for between 13.5 and 14 billion years.
Thus, astronomers, estimating the age of the Universe in three different ways, obtained quite compatible results. Therefore, we now know (or, to put it more cautiously, we think that we know) when our universe arose - at least to an accuracy of several hundred million years. Probably, descendants will add the solution to this age-old riddle to the list of the most remarkable achievements of astronomy and astrophysics.
The age of the Universe is the maximum time that a clock would measure since big bang until now, if they fell into our hands now. This estimate of the age of the Universe, like other cosmological estimates, comes from cosmological models based on the determination of the Hubble constant and other observable parameters of the Metagalaxy. There is also a non-cosmological method for determining the age of the Universe (at least in three ways). It is noteworthy that all these estimates of the age of the Universe are consistent with each other. They also all require accelerated expansion Universe (that is, not zero lambda member), otherwise the cosmological age turns out to be too small. New data from the European Space Agency's (ESA) powerful Planck satellite show that The age of the universe is 13.798 billion years (“plus or minus” 0.037 billion years, all this is said in Wikipedia).
The indicated age of the Universe ( IN= 13.798.000.000 years) is not at all difficult to convert into seconds:
1 year = 365(days)*24(hours)*60(minutes)*60(sec) = 31,536,000 sec;
This means that the age of the Universe will be equal to
IN= 13.798.000.000 (years)*31.536.000 (sec) = 4.3513*10^17 seconds. By the way, the result obtained allows us to “feel” what it means – a number of the order of 10^17 (that is, the number 10 must be multiplied by itself 17 times). This seemingly small degree (only 17) actually hides behind it a gigantic period of time (13.798 billion years), which is almost escaping our imagination. So, if the entire age of the Universe is “compressed” to one earthly year (mentally imagine as 365 days), then on this time scale: the simplest life on Earth originated 3 months ago; exact sciences appeared no more than 1 second ago, and a person’s life (70 years) is a moment equal to 0.16 seconds.
However, a second is still a huge time for theoretical physics, mentally(using mathematics) studying space-time on extremely small scales - down to dimensions of the order of Planck length (1.616199*10^−35 m). This length is minimum possible in physics, “quantum” distances, that is, what happens on an even smaller scale, have not yet been invented by physicists (there are no generally accepted theories), perhaps a completely different physics is already “working” there, with laws unknown to us. It is also appropriate to say here that in our (super complex and very expensive) experiments physicists have so far penetrated “only” to a depth of about 10^-18 meters (this is 0.000...01 meters, where there are 17 zeros after the decimal point). The Planck length is the distance that a photon (quantum) of light travels in Planck time (5.39106*10^−44 sec) – minimum possible in physics there is a “quantum” of time. Physicists also have a second name for Planck time - elementary time interval (Evi – I will also use this convenient abbreviation below). Thus, for theoretical physicists, 1 second is a colossal number of Planck times ( Evi):
1 second = 1/(5.39106*10^−44) = 1.8549*10^43 Evi.
In this time O On a scale, the age of the Universe becomes a number that we can no longer somehow imagine:
IN= (4.3513*10^17 sec) * (1.8549*10^43 Evi) = 8,07*10^60 Evi.
Why did I say above that Theoretical physicists study spacetime ? The fact is that space-time is two sides single structures (mathematical descriptions of space and time are similar to each other), which are crucial for constructing a physical picture of the world, our Universe. In modern quantum theory it is space-time is given a central role, there are even hypotheses where the substance (including you and me, dear reader) is considered nothing more than... disturbance this basic structure. Visible 92% of the matter in the Universe consists of hydrogen atoms, and the average density of visible matter is estimated as 1 hydrogen atom per 17 cubic meters of space (this is the volume of a small room). That is, as has already been proven in physics, our Universe is an almost “empty” space-time, which is continuous expanding And discretely on Planck scales, that is, on dimensions of the order of the Planck length and in time intervals of the order Evi(on a scale accessible to humans, time flows “continuously and smoothly”, and we do not notice any expansion).
And then one day (back at the end of 1997) I thought that the discreteness and expansion of space-time is best “modeled” ... by a series of natural numbers 0, 1, 2, 3, 4, 5, 6, 7, ... The discreteness of this series is not there is no doubt, but its “extension” can be explained by the following representation: 0, 1, 1+1, 1+1+1, 1+1+1+1, … . Thus, if numbers are identified with Planck time, then the number series turns into a kind of flow of time quanta (space-time). As a result, I came up with a whole theory, which I called virtual cosmology , and which “discovered” the most important physical parameters of the Universe “inside” the world of numbers (we will consider specific examples below).
As one would expect, official cosmology and physics responded to all my (written) appeals to them with absolute silence. And the irony of the current moment, quite possibly, is that number theory(as a branch of higher mathematics that studies the natural series) has literally the only practical application - this is... cryptography. That is, numbers (and very large ones, on the order of 10^300) are used for message encryption(transmitting, for the most part, the purely mercantile interests of people). And at the same time the world of numbers itself is a kind of encrypted message about the fundamental laws of the universe- this is exactly what my virtual cosmology claims and makes attempts to “decipher the messages” of the world of numbers. However, it goes without saying that the most intriguing “decoding” would come from theoretical physicists if they once looked at the world of numbers without professional prejudices...
So, here is a key hypothesis from the latest version of virtual cosmology: Plackow time is equivalent to the number e = 2.718 ... (number “e”, the base of natural logarithms). Why exactly the number “e” and not one (as I thought before)? The fact is that it is the number “e” that equals the minimum possible positive value of the functionE = N / ln N - the main function in my theory. If in this function the exact equality sign (=) is replaced by the asymptotic equality sign (~, this wavy line is called tilde), then we get the most important law of the well-known number theory– law of distribution prime numbers(2, 3, 5, 7, 11, ... these numbers are only divisible by one and themselves). In number theory, studied by future mathematicians at universities, the parameter E(although mathematicians write a completely different symbol) - this is the approximate number of prime numbers per segment, that is, from 1 to numberNinclusive, and the larger the natural numberN, the more accurately the asymptotic formula works.
It follows from my key hypothesis that in virtual cosmology the age of the Universe is equivalent to at least the number N = 2,194*10^61 is a product of age IN(expressed in Evi, see above) by number e= 2.718. Why I write “at least” will become clear below. Thus, our Universe in the world of numbers is “reflected” by a segment of the number axis (with the beginning in the number e= 2.718...), which contains about 10^61 natural numbers. I called the segment of the numerical axis equivalent (in the indicated sense) to the age of the Universe Large segment .
Knowing the right boundary of the Large segment (N= 2.194*10^61), calculate the quantity prime numbers on this segment:E = N/ln N = 1.55*10^59 (prime numbers). And now, attention!, see also the table and figure (they are below). It is obvious that prime numbers (2, 3, 5, 7, 11, ...) have their serial numbers (1, 2, 3, 4, 5, ..., E) form their own segment of the natural series, which also contains simple numbers, that is, numbers in the form of prime numbers 1, 2, 3, 5, 7, 11, …. Here we will assume that 1 is the first prime number, because sometimes in mathematics they do this, and we may be considering just the case where this turns out to be very important. We will also apply a similar formula to the segment of all numbers (from prime and composite numbers):K = E/ln E, Where K– this is the quantity prime numbers on the segment. And we will also introduce a very important parameter:K / E = 1/ ln E is the ratio of the quantity (K) prime numbers to quantity (E) of all numbers on the segment. It's clear that parameter 1/ lnE has a sense of probability encounters with a prime number near a prime number on a segment. Let's calculate this probability: 1/ln E = 1/ ln (1.55*10^59) = 0.007337 and we find that it is only 0.54% more than the value... constant fine structure (PTS = 0.007297352569824…).
PTS is a fundamental physical constant, and dimensionless, that is, PTS makes sense probabilities some extremely important event for His Majesty (all other fundamental physical constants have dimensions: seconds, meters, kg, ...). The fine structure constant has always been an object of fascination for physicists. The outstanding American theoretical physicist, one of the founders of quantum electrodynamics, Nobel Prize laureate in physics Richard Feynman (1918 – 1988) called PTS “ one of the greatest damned mysteries of physics: a magic number that comes to us without any human understanding of it" A large number of attempts have been made to express PTS in terms of purely mathematical quantities or to calculate based on some physical considerations (see Wikipedia). So in this article, in fact, I present my understanding of the nature of PTS (removing the veil of mystery from it?).
So, above, within the framework of virtual cosmology, we received almost PTS value. If you move (increase) the right border a little (N) of a large segment, then the number ( E) prime numbers on this segment, and the probability is 1/ln E will decrease to the “cherished” PTS value. So, it turns out that it is enough to increase the age of our Universe by only 2.1134808791 times (almost 2 times, which is not much, see below) to get an exact hit on the PTS value: taking the right boundary of the Greater segment equal toN= 4.63704581852313*10^61, we get the probability 1/ln E, which is less than PTS by only 0.0000000000013%. The right boundary of the Great segment indicated here is equivalent to, say, PTS age The universe is 29,161,809,170 years old (almost 29 billion years ). Of course, the figures I obtained here are not dogma (the figures themselves may change slightly), since it was important for me to explain the very course of my reasoning. Moreover, I am far from the first who came (to my unprecedented by) to the need to “double” the age of the Universe. For example, in the book of the famous Russian scientist M.V. Sazhin “Modern cosmology in a popular presentation” (M.: Editorial URSS, 2002) it says literally the following (on page 69): “...Estimates of the age of the Universe are changing. If 90% of the total density of the Universe is accounted for by a new type of matter (lambda term), and 10% is by ordinary matter, then The age of the Universe turns out to be almost twice as large! » (bold italics mine).
Thus, if you believe virtual cosmology, then in addition to purely “physical” definitions of PTS (there are also several of them), this fundamental “constant” (for me, generally speaking, it decreases with time) can also be defined this way (without false modesty, I note that more graceful I have never encountered a mathematical interpretation of the nature of PTS). Fine structure constant (PTS) is the probability that a randomly taken serial number prime number he will be on the segment prime number. And the specified probability will be:
PTS = 1/ln( N / ln N ) = 1/( ln N – lnln N ) . (1)
At the same time, we must not forget that formula (1) “works” relatively accurately for sufficiently large numbersN, say, at the end of the Big Segment it is quite suitable. But at the very beginning (at the emergence of the Universe), this formula gives underestimated results (dashed line in the figure, see also table)
Virtual cosmology (as well as theoretical physics) tells us that PTS is not a constant at all, but “simply” the most important parameter of the Universe, changing over time. So, according to my theory, the PTS at the birth of the Universe was equal to one, and then, according to formula (1), it decreased to the modern value of PTS = 0.007297... . With the inevitable demise of our Universe (in 10^150 years, which is equivalent to the right boundaryN= 10^201) PTS will decrease from the current value by almost 3 times and become equal to 0.00219.
If formula (1) (accurate “hit” in the PTS) was my only “trick” in terms of numerology(of which professional scientists are still absolutely sure), then I would not repeat with such persistence that the world of natural numbers is 0, 1, 2, 3, 4, 5, 6, 7, ... (in particular, its main lawE = N/ln N ) is a kind of “mirror” of our Universe (and even... any universe), helping us to “decipher” the most important secrets of the universe. All my articles and books are interesting not only psychologists who can thoroughly trace (in their candidate and doctoral works) the entire path of the ascent of an isolated mind (I practically did not communicate with literate people) - the ascent to the Truth or the fall into the deepest abyss of Self-Deception. My works contain a lot of new factual material (new ideas and hypotheses) on number theory, and also contain very interesting mathematical model of space-time, analogues of which certainly exist, but only in... distant exoplanets, where the mind has already discovered the natural series 0, 1, 2, 3, 4, 5, 6, 7, ... - the most obvious abstract Truth given everyone to a sophisticated mind any universe.
As another justification, I’ll tell you about another “trick” of my numerology. Square (S) under the graph of the functionE = N/ln N (I repeat, the main function of the world of numbers!), is expressed by the following formula:S = (N/2)^2 (this is the 4th part of the area of a square with a side equal to the numberN). At the same time, at the end PTS th Large segment(atN= 4.637*10^61) the reciprocal of this area (1/S), will be numerically equal... cosmological constant or (just a second name) lambda member L= 10^–53 m^–2, expressed in Planck units ( Evi): L= 10^–53 m^–2 = 2.612*10^–123 Evi^–2 and this, I emphasize, is only grade L(physicists do not know the exact value). And virtual cosmology claims that the cosmological constant (lambda term) is a key parameter of the Universe, decreasing with time approximately according to this law:
L = 1/ S = (2/ N )^2 . (2)
According to formula (2) at the end of the PTS-th Big segment we get the following:L = ^2 = 1,86*10^–123 (Evi^–2) – this is... the true value of the cosmological constant (?).
Instead of a conclusion. If anyone can point me to another formula (besidesE = N/ln N ) and another mathematical object (except for the elementary series of natural numbers 0, 1, 2, 3, 4, 5, 6, 7, ...), which lead to the same beautiful numerological “tricks” (so many and accurately “copying” the real physical world in its various aspects) - then I am ready to publicly admit that I am at the very bottom of the abyss of Self-Deception. To make his “verdict”, the reader can refer to all my articles and books posted on the portal (website) “Techno Community of Russia” under the pseudonym iav 2357 ( see the following link:
