Another principle that I believe can be justified by scientific evidence so far is that nobody is going to emigrate from this planet not ever....It will be far cheaper, and entail no risk to human life, to explore space with robots. The technology is already well along....the real thrill will be in learning in detail what is out there...It is an especially dangerous delusion if we see emigration into space as a solution to be taken when we have used up this planet....Earth, by the twenty-second century, can be turned, if we so wish, into a permanent paradise for human beings...