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If life on Earth had to achieve n 'hard steps' to reach humanity's level,then the chance of this event rose as time to the n-th power. Integrating thisover habitable star formation and planet lifetime distributions predicts >99%of advanced life appears after today, unless n<3 and max planet duration<50Gyr. That is, we seem early. We offer this explanation: a deadline is set by'loud' aliens who are born according to a hard steps power law, expand at acommon rate, change their volumes' appearances, and prevent advanced life likeus from appearing in their volumes. 'Quiet' aliens, in contrast, are muchharder to see. We fit this three-parameter model of loud aliens to data: 1)birth power from the number of hard steps seen in Earth history, 2) birthconstant by assuming a inform distribution over our rank among loud alien birthdates, and 3) expansion speed from our not seeing alien volumes in our sky. Weestimate that loud alien civilizations now control 40-50% of universe volume,each will later control ~10^5 - 3x10^7 galaxies, and we could meet them in~200Myr - 2Gyr. If loud aliens arise from quiet ones, a depressingly lowtransition chance (~10^-4) is required to expect that even one other quietalien civilization has ever been active in our galaxy. Which seems bad news forSETI. But perhaps alien volume appearances are subtle, and their expansionspeed lower, in which case we predict many long circular arcs to find in oursky.

If Loud Aliens Explain Human Earliness, Quiet Aliens Are Also Rare