Like a pebble tossed in a pond, the cultural and political ripples from the pioneering WBCN continue. Launched in March 1968 with Cream’s “I Feel Free,” it became a national phenomenon. With the release of the long anticipated documentary “WBCN and The American Revolution,” award winning filmmaker Bill Lichtenstein (who was a volunteer there at age 14) says the station “moved the zeitgeist.” At a groundbreaking antiwar rally on Boston Common a skywriter placed a peace symbol with the call letters in the sky above. Not just great rock and roll, WBCN figured largely in the women’s rights and gay rights movements, as Lichtenstein so colorfully describes. It was the start of something big: media and social and political change. If you like rock and roll and politics, you won’t want to miss this show!