AUTHOR=Soker Noam 

TITLE=Astrophysical Naturalness

JOURNAL=Frontiers in Astronomy and Space Sciences

VOLUME=Volume 8 - 2021

YEAR=2022

URL=https://www.frontiersin.org/journals/astronomy-and-space-sciences/articles/10.3389/fspas.2021.712544

DOI=10.3389/fspas.2021.712544

ISSN=2296-987X

ABSTRACT=I suggest that stars introduce mass and density scales that lead
to `naturalness' in the Universe. Namely, two ratios of order
unity. (1) The combination of the stellar mass scale,
$M_\ast(c,\hbar,G, m_p, m_e, e, \dots)$, with the Planck mass,
$M_{\rm Pl}$, and the Chandrasekhar mass leads to a ratio of order
unity that reads $N_{{\rm Pl \ast}} \equiv  {M_{\rm Pl}}/({M_\ast}
m^2_p )^{1/3} \simeq 0.15 - 3$, where $m_p$ is the proton mass.
(2) A system with a dynamical time equals to the nuclear life times of stars, $\tau_{\rm nuc \ast}$, has a density of $\rho_{\rm D \ast}(c,\hbar,G, m_p, m_e, e, \dots) \equiv ( G ~ \tau^2_{\rm nuc \ast} ) ^{-1}$. The ratio of this density to the density of the dark energy, $\rho_{\Lambda}$, is $N_{\lambda \ast} = {\rho_{\Lambda}}/{\rho_{\rm D \ast}}   \approx 10^{-7} - 10^{5}$.
Although the range is large, it is critically much smaller than
the 123 orders of magnitude usually referred to when
$\rho_{\Lambda}$ is compered to the Planck density. In the pure
fundamental particles domain there is no naturalness; either
naturalness does not exist or there is a need for a new physics or
new particles. The `Astrophysical Naturalness' offers a third
possibility: stars introduce the combinations of, or relations
among, known fundamental quantities that lead to naturalness.