- General similarity solutions are obtained for spherical, cooling blast waves in an Omega(b) much less than Omega = 1 universe, given an energy input that is some power of time. The distortion of the microwave background is calculated in terms of the present-day peculiar velocities and the present-day voids in velocity space caused by the explosions under the assumption of sustained energy input. The predicted distortion is found to be marginally consistent with the present-day observations and could provide a test of the model in the near future. It is briefly noted that high peculiar velocities of galaxies at the epoch of their formation make dark matter capture by them questionable and also that explosions in a shadow sector would trivially overcome some of the potential problems of the model. 26 references.