The Exact Determination of the Cosmological Constant

With cooling of the cosmological plasma during phase transitions in the early Universe vacuum condensates of quantum fields were produced with negative energy density. Probably these condensates have compensated the initial vacuum energy. The present vacuum is the vacuum condensate of the last relativistic phase transition ($T_{cr}\sim 100$ MeV) (its information is carried by pseudo-Goldstone bosons ($\pi$-mesons)). This allows us to use Zeldovich's formula that can calculate exactly the value of the cosmological constant in the present epoch. If the most likely values $\Omega_\Lambda$ are 0.7-0.8 then $H_0$ falls in the range from 72.5 to 67.8 (km/s)/Mpc.