We didn’t know how many of those stars had planets that could potentially harbor life, how often life might evolve and lead to intelligent beings, and how long any civilizations might last before becoming extinct.” “Thanks to NASA's Kepler satellite and other searches, we now know that roughly one-fifth of stars have planets in “habitable zones,” where temperatures could support life as we know it.So one of the three big uncertainties has now been constrained.” Frank said that the third big question--how long civilizations might survive--is still completely unknown.The Fermi paradox or Fermi's paradox, named after physicist Enrico Fermi, is the apparent contradiction between the lack of evidence and high probability estimates, e.g., those given by the Drake equation, for the existence of extraterrestrial civilizations.According to this line of reasoning, the Earth should have already been visited by extraterrestrial aliens. There comes a point in our whole worldview on Mars in which we have to prepare ourselves for the prospect of having Martian children living on a colony for the first time.Children born on Mars will be one of the biggest highlights of the history of the human race.Also known as the “Goldilocks zone,” this is the range of orbital distances from a particular star in which water could exist in a liquid form, neither boiled away nor frozen solid.It seems there are plenty of habitable planets out there — Kepler has even found two such worlds orbiting a single star.
" The Fermi paradox is a conflict between arguments of scale and probability that seem to favor intelligent life being common in the universe, and a total lack of evidence of intelligent life having ever arisen anywhere other than on the Earth.
The second aspect of the Fermi paradox is the argument of probability: given intelligent life's ability to overcome scarcity, and its tendency to colonize new habitats, it seems possible that at least some civilizations would be technologically advanced, seek out new resources in space, and colonize their own star system and, subsequently, surrounding star systems.
Since there is no significant evidence on Earth or elsewhere in the known universe of other intelligent life after 13.8 billion years of the universe's history, then there is a conflict requiring a resolution.
Some examples of possible resolutions are that intelligent life is rarer than we think, that our assumptions about the general development or behavior of intelligent species are flawed, or, more radically, that our current scientific understanding of the nature of the universe itself is quite incomplete. The first is, "Why are no aliens or their artifacts found here on Earth, or in the Solar System?
" If interstellar travel is possible, even the "slow" kind nearly within the reach of Earth technology, then it would only take from 5 million to 50 million years to colonize the galaxy.