Black holes, Planckian granularity, and the changing cosmological ‘constant’
Résumé
In a recent work we have argued that noisy energy momentum diffusion due to space-time discreteness at the Planck scale (naturally expected to arise from quantum gravity) can be responsible for the generation of a cosmological constant at the electro-weak phase transition era of the cosmic evolution. Simple dimensional analysis and an effectively Brownian description of the propagation of fundamental particles on a granular background yields a cosmological constant of the order of magnitude of the observed value, without fine tuning. While the energy diffusion is negligible for matter in standard astrophysical configurations (from ordinary stars to neutron stars), here we argue that a similar diffusion mechanism could, nonetheless, be important for black holes. If such effects are taken into account, two observational puzzles might be solved by a single mechanism: the ‘$H_0$ tension’ and the relatively low rotational spin of the black holes detected via gravitational wave astronomy.
Mots clés
Dark energy
Unimodular gravity
Quantum gravity
black hole: spin
analysis: dimensional
space-time: discrete
spin: rotation
scale: Planck
diffusion
cosmological constant
gravitational radiation
electroweak interaction: critical phenomena
scale: electroweak interaction
energy-momentum
quantum gravity
neutron star
particle: propagation
Hubble constant
tension
star
cosmological model
gravitation: unimodular
dark energy
Black holes