participants showed great interest in the cosmology of the pulsating Universe (https://habr.com/ru/articles/396601/; https://habr.com/ru/articles/371363/; https://habr.com/ru/ articles/777028/), so I would like to please everyone interested with the news that in June of this year the publishing house “Peter” is releasing in mass circulation the second edition of the book “Pulsating Universe” with additions and improvements. A half-hour presentation of the book (and the cosmological theory that it sets out) from the editor “Peter” and from me can be viewed on YouTube: https://www.youtube.com/watch?v=QyVAPTdPC4Y
I would like to dwell on one cosmological moment in more detail – on relict gravitational waves. In the early 60s, a big battle broke out between three cosmological theories: the Bondi-Gold-Hoyle theory of constant growth of the Universe (without the Big Bang, and the Universe simply swells for unknown reasons); Zeldovich’s theory of the initially cold Universe, and Gamow’s theory of the hot early Universe, within which the Big Bang, the chemical composition of the early Universe and the presence around relict radiation with a temperature of several kelvins were predicted (the radiation of a very hot early Universe has stretched to our time so that it has cooled to a temperature liquid helium).
In the Estonian city of Tartu, on July 7-13, 1962, a seminar was held, the materials of which were published in the collection “Questions of Cosmogony” (1963). In the article “Prestellar Evolution of Matter,” Ya. B. Zeldovich examines the theory of the hot Universe of Gamow-Alpher-Herman, whose attempts to obtain the observable chemical composition of the cosmic environment, he considers “naive.” Zeldovich writes that in this model “the effective temperature of electromagnetic radiation (light) is equal to 23 K” (where YaB got this value instead of several degrees is unclear, perhaps from some very inaccurate work of Gamow’s group).
Zeldovich concludes: “It should be recognized that these values are beyond the bounds of reason and are not consistent with modern ideas about the material and energy balance of the Universe.” YaB further states: “Returning to the question of the initial stage of the world, it must be recognized that the ideas of Gamow, Alpher and Herman about the high temperature at this stage contradict modern information.” Zeldovich himself prefers a different scenario. “We come to the only possible, the only correct option,” namely: “The hypothesis according to which cold pure hydrogen is taken as the starting material for the stellar stage of evolution is completely consistent with modern astrophysical concepts.”
Academician A.D. Sakharov wrote about his work in the 60s: “I then, following Zeldovich and many other authors of that time, proceeded from the so-called “Cold Model of the Universe”, according to which the initial temperature of superdense matter was assumed to be equal to zero (it was assumed that the substance is heated then due to certain processes, including nuclear reactions).” (“Scientific works”, 1995)
It is easy to see that the cold model of the Universe is an analogue of a thermonuclear bomb, which, upon explosion, goes from a dense cold state to a rarefied and hot one. In fact, this was a development of Lemaitre’s “proto-atom” model, only in the spirit of the then military progress, with a change in the universal “warhead” from an atomic bomb to a more powerful thermonuclear charge, with which Zeldovich was well acquainted.
The debate between cosmologists ended in 1965, with the Nobel discovery of the cosmic microwave background radiation (at 3.5 Kelvin) by Arno Penzias and Robert Wilson, which fully confirmed the model of the hot Universe and the “naive” Gamow-Alpher-Herman theory.
But not only electromagnetic waves, but also gravitational waves can be relict waves (born somewhere near the Big Bang, or even earlier). Since 2015, the LIGO observatory has been discovering gravitational waves with a frequency of a hundred hertz, produced by the merger of a pair of black holes that are located relatively close to us. The frequency of these waves is determined by the maximum frequency of rotation of the holes around each other. The smaller (and lighter) the holes, the closer together they can get and the faster they spin around each other, generating higher frequency waves.
In the article by Gorkavy and Tyulbashev (2021) in the Astrophysical Bulletin, it was shown that at the moment of maximum compression of the Universe (to a size of ten light years), a massive merger of black holes of stellar masses occurs, which generates a powerful flash of gravitational radiation with a frequency of a hundred hertz ( at the time of the outbreak). Since after this the Universe expanded 10 billion times, the frequencies of these waves dropped to 10^-8 hertz, that is, to the nanohertz range. In the state of maximum compression of the Universe, the temperature of the cosmic microwave background radiation was 30 billion degrees (it is at this temperature that all heavy nuclei of chemical elements decay into baryons). Accordingly, an increase in the size of the universe by 10^10 times led to a cooling of the cosmic microwave background radiation to 3 kelvins. The evolution diagram of electromagnetic and gravitational relict radiation is shown in this figure:
The NANOGrav team (a North American consortium of five large radio telescopes) is accumulating and studying a multi-year dataset of millisecond pulsars. They recently found background nanohertz gravitational waves with oscillation periods ranging from 2 to 10 years. The discovery was confirmed by independent data from the Australian radio telescope (PPTA) at the Parkes Observatory, and in the summer of 2023 the quadrupole nature of the waves found was proven – that is, they are precisely gravitational.
Thus, the discovery of CMB in the nanohertz range is a direct confirmation of the cyclic model of the Universe, because its prediction inevitably follows from the very (literally!) center of our model. But we can go further and make additional predictions that can be tested by the LIGO and NANOGrav groups in the coming years.
Prediction 1: Since there are practically no black holes smaller than 3-4 solar masses for astrophysical reasons, the frequency of their mutual rotation (and the generated gravitational waves) cannot increase more than a hundred hertz (neutron stars are lighter, but larger, so the frequency of their mutual rotation drops) . That is, in the spectrum of gravitational radiation (which is certainly not thermal, unlike the relict spectrum of em radiation) there will be a strong dip in frequencies of less than a year. None of the other alternative theories expect such a failure.
Prediction 2: As LIGO data shows, stellar-mass black holes, the most numerous in the hole population, are still merging. Modern black hole mergers occur much less frequently than during the Big Bang, but the gravitational waves formed during current mergers have a small red shift and retain their initial frequency of a hundred hertz. In a cyclical Universe, background gravitational waves, like black holes, accumulate over many cycles. A gravitational wave born at some epoch corresponding to a specific radius of the Universe will increase its frequency during the subsequent compression of the Universe, and during expansion in the next cycle it will decrease again, passing through its initial frequency value precisely at the radius of the Universe when the wave was born. Therefore, around us we should observe both waves born at the moment of the Big Bang of our cycle, and waves that arose during the era of the maximum expansion of the Universe in past cycles. If gravitational waves from the Big Bang have reduced their frequency to the nanohertz range by our time, then waves from the era of the maximum size of the Universe, on the contrary, come to us with a frequency increased several times, because the observable part of the Universe of our cycle has not yet reached its maximum size, when these waves were formed.
Therefore, although the energy of background gravitational waves has a noticeable peak at the nanohertz frequency, the main energy of such waves (estimated to be millions of times greater!) will be contained in the main peak of kilohertz gravitational waves formed by the merger of stellar-mass black holes at the moment of maximum expansion of the Universe.
In conclusion, a small remark. A recent habr article about cosmology and particle physics https://habr.com/ru/articles/812639/ states: “An abundance of new evidence suggests that physics may be on the verge of something grandiose.”
Sorry, but physics has been on this threshold for five decades, so it has already taken root there and is overgrown with pensioners. The thesis of quantum cosmologists: “Observing the movement of stars and galaxies can reveal the influence of as yet undiscovered particles, and studying fundamental particles in the laboratory can tell us about the birth and evolution of the cosmos,” which has been de facto promoted by Alan Goose since 1981 (43 years ago! ), has not yet received a single experimental or convincing theoretical confirmation. The idea that the universe is governed by quantum laws – from the moment of birth to the present – is impressive, inspiring and sells well. But how long can you swim in a dry pool? Astronomers do NOT use any quantum laws to calculate the motions of asteroids, planets and stars, and there is no compelling reason to introduce quantum hypotheses into the description of the dynamics of galaxies, their clusters and the entire Universe where general relativity operates. Yes, there are problems and inconsistencies, as in all sciences – but how does it follow that they are at least to some extent quantum in nature? (We do not touch the spectra of em radiation and cosmic rays, which, despite their importance, have practically no effect on the dynamics of galaxies and the Universe). You need to look soberly – there are problems (and their revolutions) in elementary particles and quantum fields, and there are separate astronomy and cosmology with their own problems. And there is no proven and convincing connection (at the level that is proclaimed in quantum cosmology) between the micro- and macro-worlds, no matter how often and convincingly numerous prophets proclaim the opposite.
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