A Conjecture on the Origin of Dark Energy

Abstract

A conjecture on the origin of the dark energy in our universe isproposed. The analysis indicates that the dark energy may originatefrom the quantum fluctuations of space–time limited in our universe.Applying both the uncertainty principle and the holographic principle,the author finds that the density of such quantum fluctuation energy isρ V = 3c 4/32GL H 2 , where L H is the size ofthe event horizon of our universe and G is the gravitational constant.Using this dark energy model which contains no adjustable parameters,we obtain the current fraction ΩΛ≡ρ V /ρ c ≈π/4and the corresponding equation of state w(z)≈−1+(1−π/4)z with ρ c being the critical energy density. These theoreticalresults are perfectly consistent with the recent cosmologicalobservations. The striking coincidence implies that the quantumfluctuation energy of space–time may be the only source of dark energy.In addition, the analysis shows that the vacuum fluctuation energy doesexist, but it comes from space–time rather than matter. This may havesome deep implications for discrete space–time and quantum gravity.