A NEW COSMOLOGICAL CONSTANT MODEL

We propose a new cosmological model with a time-dependent cosmological constant (Λ∝1/t²), which starting at the Planck time as , evolves to the present-day allowed value of . This scenario is supported by noncritical string theory considerations. We compute the age of the Universe and the time dependence of the scale factor in this model, and find general agreement with recent determinations of the Hubble parameter for substantial values of Ω_Λ. This effectively low-density open Universe model differs from the traditional cosmological constant model, and has observable implications for particle physics and cosmology.