Ronald Gurney and Edward Condon, at Princeton University's Palmer Physical Laboratory, independently and almost simultaneously with Gamow solve the same problem: why alpha decay, which classically would require energies far greater than observed, occurs with half-lives varying by more than twenty orders of magnitude for relatively small energy variations. Invoking the just-discovered phenomenon of quantum barrier penetration (tunneling), they propose that the alpha particle "leaks out almost unnoticed" instead of being violently ejected, as had been assumed until then. Their Nature paper was published approximately a month before Gamow's, though without the same quantitative development that allowed deriving the Geiger-Nuttall law.