The discovery of primordial black holes (PBHs) would not directly solve the problem of quantum gravity. However, their existence could provide valuable insights into the nature of gravity and potentially offer constraints on various theories, including those related to quantum gravity. Let me explain further:
Primordial black holes are hypothetical black holes that could have formed in the early universe, shortly after the Big Bang. Unlike black holes formed from the collapse of massive stars, PBHs would originate from the extreme conditions of the early universe. Their formation would be influenced by quantum mechanical processes and the properties of the early universe.
If PBHs were detected, it would imply that the conditions in the early universe were favorable for their formation. The study of PBHs can provide valuable information about the primordial density fluctuations, which are important for understanding the early universe and the evolution of cosmic structures. These density fluctuations are directly connected to the quantum nature of the universe.
Furthermore, PBHs could be used to probe the behavior of gravity in extreme regimes. Since PBHs are expected to be much smaller than stellar black holes, they are subject to stronger gravitational effects, including quantum effects. Observations of PBHs, particularly their formation, growth, and evaporation, could help test and constrain various theories of gravity, including those related to quantum gravity.
For example, some theories of quantum gravity, such as certain modifications of general relativity or certain approaches within string theory, predict the formation of PBHs. Observing the properties of PBHs and comparing them with theoretical predictions could provide clues about the underlying theory of quantum gravity.
In summary, the detection and study of primordial black holes would not solve quantum gravity directly. However, they could offer valuable information about the early universe, the nature of cosmic density fluctuations, and potential constraints on theories of gravity, including those related to quantum gravity.