Given the innate human tendency to explore and expand – 'to boldly go' – it seems reasonable to suppose that, over the coming millennia, our race will set up colonies elsewhere in space, first on other worlds in the solar system, and later on the planets of other stars. If there are other technological civilizations in the Galaxy, some of them are presumably older and more advanced than ourselves and will have started their interstellar colonization earlier. Even assuming that the light-speed barrier is ultimately unassailable (an unlikely scenario), it should still be possible, given the will, to settle the entire Milky Way system within 10 million years. The fact that no substantive evidence has yet been found for the activities of alien colonizers has suggested to some that such beings do not exist and that we may be alone in the Galaxy (see Fermi Paradox).