By 2100 courageous pioneers may have established “bases” independent from the Earth but do not ever expect mass emigration from Earth. It is a dangerous delusion to think that space offers an escape from Earth’s problems. There is no “Planet B” and space is an inherently hostile environment for humans. For that reason, even though we may wish to regulate genetic and cyborg technology on Earth, we should surely wish the space pioneers good luck in using all such techniques to adapt to different atmospheres, different g-forces, and so on. This might be the first step toward divergence into a new species: the beginning of the post-human era.

But are we unique, or is there intelligent life out there already? There may be simple organisms on Mars or in the ice-covered oceans of Jupiter’s moon Europa but few would bet on it; and certainly nobody expects a complex biosphere in such locations. For that, we must look to the distant stars and here the prospects are far brighter: we have recognized that there are, within our Milky Way Galaxy, millions of planets resembling the young Earth. But do we expect alien life on these extra-solar planets? Conjectures about advanced or intelligent life are, of course, far shakier than those about simple life.

Perhaps the Galaxy already teems with advanced life, and our descendants will “plug in” to a galactic community —as rather “junior members.” On the other hand, our Earth may be unique and the searches may fail. This would disappoint the searchers. But it would have an upside. Humans could then be less cosmically modest. Our tiny planet could be the most important place in the entire cosmos. Moreover, we would be living at a unique time in our planet’s history: our species would have cosmic significance, for being the transient precursor to a culture dominated by machines, extending deep into the future and spreading far beyond Earth.

Interstellar travel is inherently of long duration, and is, therefore, an enterprise for post-humans, evolved from our species not via natural selection but by design. The first voyagers to the stars will not be human, and maybe not even organic. Evolution is just beginning. Intelligent entities—descended from Earthly life—could spread through the entire Galaxy, evolving into a teeming complexity far beyond what we can even conceive.

And that is not all: there is a final disconcerting twist. Post-human intelligence will develop hyper-computers with the processing power to simulate living things —even entire worlds as complex as the one we perceive ourselves to be in. Maybe these kinds of superintelligences already exist elsewhere in the multiverse. What would these superintelligences do with their hyper-computers? They could create virtual universes vastly outnumbering the “real” ones. So perhaps we are “artificial life” in a virtual universe. This concept opens up the possibility of a new kind of “virtual time travel,” because the advanced beings creating the simulation can, in effect, rerun the past.

Possibilities once in the realms of science fiction have shifted into serious scientific debate. From the very first moments of the big bang to the mind-blowing possibilities for alien life, parallel universes, and beyond, scientists are led to worlds even weirder than most fiction writers envisage. It is remarkable that our brains, which have changed little since our ancestors roamed the African savannah, have allowed us to understand the counter-intuitive worlds of the quantum and the cosmos. But there is no reason to think that our comprehension is matched to an understanding of all key features of reality. If our remote descendants reach the stars, they will surely far surpass us not only in lifespan, but in insight as well as technology.

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