Molecular low energy collisions: past, present and future

A number of early molecular beam scattering experiments at subthermal collision energies carried out since about the time of the first Molecular Low Energy Collisions (MOLEC) meeting in 1976 are reviewed. Then, present day efforts to develop universally applicable molecular beam sources which go down to even lower energies are briefly surveyed. In the final section, the prospects of studying chemically reactive collisions at temperatures of 0.37 K inside superfluid helium droplets are assessed and some ideas for extending these experiments are proposed