N. Musoke et al. / Physical Review Letters, 2020
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Scientists have built
numerical model of the growth of inhomogeneities from quantum fluctuations in the dark ages in the framework of the theory of inflationary expansion. It turned out that increasing the contrast
density occurs very quickly, as soon as the process goes into non-linear mode.
The results allow us to better understand the key stage of the very early existence.
The universe within the dominant theoretical concept and confirm
the potential for experimental verification of the idea of inflation, they write
authors in the journal Physical Review Letters.
Theory of the Hot Big
explosion describes in detail the evolution of the universe, starting with a high-energy hot
stage. This concept has been verified by numerous observations, and its predictions
correspond to reality with high accuracy. However, she is not able to give
answers to a number of questions, such as problems of curvature and horizon, due to which
scientists are working on a more general theory.
Currently proposed
many alternative ideas, but none of them got convincing
evidence. The most popular and developed is the hypothesis of
cosmological inflation – the preceding hot Big Bang
exponentially fast expansion of space, which leads to smoothing of all inhomogeneities and in addition to quantum fluctuations. Such a process
allows you to resolve many difficulties encountered, but some aspects of the
inflation remains without a detailed assessment.
In the framework of the theory of inflation
many different models are formulated that are similar in overall dynamics, but
differ in details. In simple scenarios, the universe is growing by now
at least 1060 times, and the inflationary phase itself accounts for 30 orders of magnitude,
then, in a trillionth fraction of a second (primary dark centuries), another 15
orders, after which we can talk about relatively familiar to physicists
interactions at energies typical of the Large Hadron Collider. Expansion
the remaining 15 orders stretched over the next 13.8 billion years before
present time.
New Zealand scientists from Auckland
University led by Richard Easther conducted the first
detailed studies of the growth of heterogeneity immediately after inflation. These heterogeneities should
were later to become embryos as differences visible in the CMB map,
and the foam-like large-scale structure of the modern Universe,
formed by clusters of galaxies.
In the framework of the theory of inflation
it is postulated that the early Universe was filled with a degenerate quantum
condensate of new particles (inflatons) – quanta of the physical field, which
and led to rapid expansion, possessing high potential energy. IN
during inflation itself, the density distribution of the inflaton condensate remains
homogeneous with high accuracy, but then quantum fluctuations grow, appear
disturbances, condensate can fragment and ultimately generate
particles known today.
Can theoretically be solved
equations of the general theory of relativity taking into account such a field, but with practical
the point of view of available computing power is not enough to achieve high
accuracy in a reasonable amount of time. In this regard, the local dynamics associated with
gravity of growing clots, previously considered in detail only in the framework of
perturbation theory, which was applied only in the linear growth mode, i.e.
density contrast of not more than one.
The authors of the new work show
that under the assumption of the leading role of one nonlinear factor –
interactions of inflatons with each other – a uniform distribution of inflatons loses
symmetry and the system goes into non-relativistic mode, because
the ongoing expansion of the universe, the wavelengths of particles are stretched, and their momenta
proportionally reduced. This stage is reminiscent of the evolution of ordinary matter in
later eras, but an important difference is the continuing degeneracy
condensate, because of which it cannot be described using classical particle physics,
but it is possible with the help of classical field theory.
This condition in
accuracy corresponds to the conditions of applicability of the Schrödinger-Poisson formalism: matter
can be described by a nonrelativistic wave function, and the gravitational potential
can be calculated from the Poisson equation. It is known that the equations in this
approximations are simple enough for an exact numerical solution in
small spatial scale.
As a result, the authors
it was possible to trace the growth of perturbations to a maximum density contrast of 600, which
goes far beyond linear mode. Researchers solve equations on small three-dimensional
grid with 512 cells along each side. Over time, the universe
manages to expand 200 times.
In the future to similar
simulations must also include the interaction of inflatons with particles
The standard model and dark matter, which will describe the process of transition to
the hot stage of life in the universe. Also, this work allows us to outline
possible way to confirm the results: it is necessary to calculate the spectrum of gravitational
perturbations generated by the growth of primary heterogeneities, and calculate its evolution
in the next steps. They should look like big gravitational waves
lengths and theoretically can fall in the sensitivity range of future gravitational
antennas, including the LISA spacecraft that is being prepared for launch in 2034.
Previously, scientists used Bose condensate for experimental modeling of the expansion of the Universe, were unable to obtain dark matter from black holes in the framework of the Higgs critical inflation theory, and proposed to check alternative inflation theories using the “standard clock” method. Cosmological inflation and the conclusions that follow from it, we wrote in the material “Space inflation
scale “.
Timur Keshelava
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