The FQXi community closed its essay contest that started in spring. The topic is "Which of Our Basic Physical Assumptions Are Wrong?".
Actually, there are a lot of these essays, and I read only one, written by Sabine Hossenfelder. She assumes in this essay that what we observe as a Planck constant is just a vacuum expectation value (VEV) of a scalar field. Thus, we see here a kind of spontaneous symmetry breaking.
Increasing temperature restores this symmetry and she assumes that the Planck constant goes top zero at high energies. That provides gravity decoupling from matter since newtons constant is proportional to Planck constant
\begin{equation}
G=\frac{\hbar c}{m_{Pl}^2}.
\end{equation}
This solves one of the problem — singularity of the initial state of the Universe. Since we have no interaction between matter and gravity at high temperatures then high densities do not form space-time singularities. Something similar happens inside black holes: as the process of a black hole formation is adiabatic (nothing escapes from it), then entropy is conserved and temperature grows while BH is collapsing.
The other problem arises when we are going to quantize gravity. It is known that gravity can be quantized perturbatively, but it is a non-renormalized theory. Setting $\hbar$ to go to zero as temperature increases solves this problem at high energies: gravity is just classical.
An interesting fact is that there disappears the notion of quantumness in this consideration. It appears as some kind of interaction of fields with VEV of a field of special type.
Actually, there are a lot of these essays, and I read only one, written by Sabine Hossenfelder. She assumes in this essay that what we observe as a Planck constant is just a vacuum expectation value (VEV) of a scalar field. Thus, we see here a kind of spontaneous symmetry breaking.
Increasing temperature restores this symmetry and she assumes that the Planck constant goes top zero at high energies. That provides gravity decoupling from matter since newtons constant is proportional to Planck constant
\begin{equation}
G=\frac{\hbar c}{m_{Pl}^2}.
\end{equation}
This solves one of the problem — singularity of the initial state of the Universe. Since we have no interaction between matter and gravity at high temperatures then high densities do not form space-time singularities. Something similar happens inside black holes: as the process of a black hole formation is adiabatic (nothing escapes from it), then entropy is conserved and temperature grows while BH is collapsing.
The other problem arises when we are going to quantize gravity. It is known that gravity can be quantized perturbatively, but it is a non-renormalized theory. Setting $\hbar$ to go to zero as temperature increases solves this problem at high energies: gravity is just classical.
An interesting fact is that there disappears the notion of quantumness in this consideration. It appears as some kind of interaction of fields with VEV of a field of special type.
