  In addressing the cosmological constant problem, we propose that the
discrepancy between the theoretical and observed values can be ascribed to the
inherent uncertainty in the spacetime metric. Mach's principle, which posits
that mass shapes spacetime, intersects with quantum mechanics' description of a
particle as a quantum cloud, rendering the precise location of a particle's
mass unknowable. Consequently, understanding spacetime structure at the quantum
level becomes elusive. This connection between quantum and spacetime
uncertainty could hold the key to resolving the cosmological constant problem.
Intriguingly, the length scale of spacetime uncertainty, aligns with the
macroscopic quantum weirdness observed in recent experiments. The spacetime
uncertainty can be quantified by the scale factor in the
Friedmann-Lemaitre-Robertson-Walker (FLRW) universe.
