From Planck Density ρ_pl to Vacuum Energy Density ρ_Λ and Cosmological Critical Density ρ_c

Abstract: Within the framework of general relativity, this paper takes the redefined Planck density ρ_pl as its starting point and investigates the dynamical process by which the vacuum energy density and the cosmological critical density evolve from the Planck-scale m^4_pl in the extremely early universe to today's astronomical observational results. By introducing dimensionless evolution factors, this paper establishes a quantitative relationship between microscopic physical quantities at the Planck scale and macroscopic cosmological parameters. It is thereby conjectured that the cosmological constant and the Hubble constant may not be fixed constants, but may instead be physical parameters that evolve with the dynamical evolution of the universe. An attempt is made, on this basis, to explain the cosmological constant problem from an evolutionary perspective, i.e., the enormous discrepancy in orders of magnitude between the theoretically calculated value of the vacuum energy density given by quantum field theory and astronomical observations.