  We propose a (physical)-geometrical method to measure the present rates of
the density cosmological parameters for a Friedmann-Lemaitre universe. The
distribution of linear separations between two interacting galaxies,when both
of them undergo a first massive starburst, is used as a standard of length.
Statistical properties of the linear separations of such pairs of
``interactivated'' galaxies are estimated from the data in the Two Degree Field
Galaxy Redshift Survey. Synthetic samples of interactivated pairs are generated
with random orientations and a likely distribution of redshifts. The resolution
of the inverse problem provides the probability densities of the retrieved
cosmological parameters. The accuracies that can be achieved by that method on
matter and cosmological constant densities parameters are computed depending on
the size of ongoing real samples. Observational prospects are investigated as
the foreseeable surface densities on the sky and magnitudes of those objects.
