... galaxies . ... Cosmic Adventures . ... Hubble study challenges "cosmic fireworks" as largest driver of galaxy growth . ... HUBBLE . ... A Hubble Space Telescope study of massive galaxies two to three billion years after the Big Bang has uncovered two remarkable results that challenge the common lore that major mergers play a dominant role in growing galaxies over a wide range of cosmic epochs. ... They are spectacular cosmic fireworks, but they do not necessarily drive galaxy growth at all epochs,т?...