On Exclusion of Positive Cosmological Constant

Understand

Some time ago we have suggested that positive vacuum energy exhibits a finite quantum break time, which can be a signal that a positive cosmological constant is inconsistent.

• From the requirement that Universe never undergoes through quantum breaking, we have derived an absolute lower bound on the speed of variation of positive vacuum energy.
• The same suggestion about exclusion of positive cosmological constant was made recently.
• We show that the new bound represents a particular string theoretic version of the old bound, which is more general.