○ According to Durkovich and colleagues, primordial black holes can serve as a channel for exchanging energy between our world and mirror world.
○ According to them, blackholes (BH) will be born in the particle collisions, and in a world with a higher temperature, their birth is more efficient.
○ During the quantum evaporation and decay of the BH, particles of both our and the mirror universe are equally likely to be born. Thus, there is a transfer of energy from our to the mirror world. The reverse flow of energy will be less, because the temperature of the mirror world is lower. Due to the energy exchange, the temperatures of our and the mirror world can be equalized.”, told Durkovich.
○ They found that the multidimensional Planck mass M must be larger than the reheating temperature ∼ 10¹³ GeV — the maximum temperature in the hot universe. In order to avoid primordial nucleosynthesis violation.
Dubrovich and colleagues in their recent paper, considered the energy exchange between our and the mirror world by the birth and evaporation of microscopic BHs.
Durkovich is not the first, but previously, several works also considered the possibility that our and mirror world interact not only gravitationally, but also through some exchange of energy and matter. The matter can be transferred by the oscillations of charged leptons, neutrons or neutrinos into the corresponding particles of mirror world and vice verse due to the high-order operators in the Lagrangian. Also, the formation of microscopic black holes (BH) in particle collisions in the early universe was discussed earlier in various studies.
Now, Durkovich and colleagues proposed the energy exchange between our and the mirror world by the birth and evaporation of microscopic BHs.
In the presence of additional dimensions, multidimensional Planck mass M can be many orders of magnitude smaller than the usual 4-dimensional Planck mass, which reduces the energy necessary for the BH production.
If a BH borns when two particles of our world collide, the BH evaporates both in our and in mirror particles. Thus, there is a transfer of energy from our to the mirror world. The reverse flow of energy will be less, because the temperature of the mirror world is lower. Due to the energy exchange, the temperatures of our and the mirror world can be equalized.— said Durkovich, lead author of the study
They considered the cosmological model where their dark matter is a mirror substance (mirror barion, mirror leptons etc), and the temperature of our world is different (higher) from the temperature of the mirror world. At temperatures, T ≥ M, blackholes (BH) will be born in the particle collisions, and in a world with a higher temperature, their birth is more efficient. During the quantum evaporation and decay of the BH, particles of both our and the mirror universe are equally likely to be born. Thus, there will be a flow of energy from our hotter universe to the colder mirror universe. They further evaluated how effective this process is, and whether the temperatures of our world and the mirror world will equalize.
They found that the multidimensional Planck mass M must be larger than the reheating temperature ∼ 10¹³ GeV — the maximum temperature in the hot universe. Otherwise, the temperatures of our world and the mirror world equalise, and the universe becomes symmetrical, violating the primordial nucleosynthesis constraints.
We also saw that the temperature equalization occurs at all masses M during one Hubble time. The only way to avoid it, is to suppose that M (which is also called Planck mass) is larger than the maximum temperature in the history of the hot universe, i.e. the reheating temperature. Therefore the effect of the microscopic BH production exclude the masses M < Tr ∼ 10¹³ GeV in the mirror matter models.— said Dubrovich, lead author of the study
The equalisation of temperatures between our and mirror world occurs during one Hubble time near T ∼ M (even if it has not occurred early). Therefore, the physics of the multidimensional universe at T ≪ M is not very important. We can use ordinary 4D physics near T ∼ M for estimates.
They also made a few comments which I explained below:
- Entropy transfer: From Foots paper, they noted that although there is a balance of energy, the total entropy increases, because δQ2 = – δQ1, but at the different temperatures δQ1/T1 ≠ – δQ2/T2. The increase of entropy occurs in the same way as the entropy increases when the temperatures of two bodies initially having different temperatures are equalized. Foot in his other paper considered the mixing of our photons and mirror worlds photon. With this mixing, the entropy in the intermediate states is not delayed. However, Dubrovich and colleagues variant with BHs is more interesting in this respect, since it is known, that BHs themselves carry entropy, and the BH entropy is expressed through its horizon area by known formulas. Therefore, it is interesting to consider the two questions: how much entropy a BH transfers between worlds in comparison with own BH’s entropy and how much entropy is enclosed in BHs at every cosmological instant of time. The last question has sense because the BHs evaporate not instantaneously, but have a certain lifetimes. One should take into account that black holes can born with relativistic velocities, therefore their energy Mc² / (√1 – v²/c²) can exceed the rest energy Mc². However, the BH motion does not affect its entropy as in the case of the moving medium.
- Planckeons. The remnants of primordial BHs were considered in many works in different aspects. In particular, the remnants can help solving the information loss paradox. The remnants of the micro BHs can form at the particles collisions (not primordial) in the early universe. In the case the black holes leave stable remnants (Planckeon) the fate of the multi-dimensional universe would be dramatic not only in the mirror matter models but even for single particle sector because the universe goes into the dust-like stage very early.
- Primordial BHs. The evaporation of primordial BHs can also be considered as a canal between our and mirror worlds (especially the region of their masses < 10^9 g). Equalization of the temperatures in this case provides new constraints on the primordial black holes at small mass region. One can assume that in the early epoch the primordial BHs begin to dominate in density, then evaporate, and all was thermalized. In ordinary cosmology, this would have consequences for entropy generation. In models with mirror matter, due to the evaporation of primordial BHs, the temperature asymmetry between our and the mirror world will be destroyed. Thus, it is possible to obtain new constraints on the primordial BHs in models with mirror matter in comparison with the known entropy bounds on primordial BHs. Microscopic primordial BHs may from the preheating instability, subsequently dominate the content of the Universe, and their evaporation may be the source of reheating.
Reference: V. K. Dubrovich, Yu. N. Eroshenko, M. Yu. Khlopov, “Production and evaporation of micro black holes as a link between mirror universes”, Astrophysical Journal, pp. 1-7, 2021. https://arxiv.org/abs/2102.03028
Copyright of this article totally belongs to our author S. Aman. One is allowed to reuse it only by giving proper credit either to him or to us