The authors contend that just as life on Earth today was preceded by a long period of microbial dominance, complex life will eventually disappear, ecosystem by ecosystem, leaving only microbial life. “The last life may look much like the first life–a single-celled bacterium, survivor and descendant of all that came before,” the authors write. Finally, even the surviving microbes “will be seared out of existence.” The authors also contend that the prospects of humans surviving by moving to some other habitable planet or moon aren’t good, because even if such a place were found, getting there would be a huge obstacle. Probes could be sent into space containing a DNA sample from every human, they say, but it’s not likely the human species itself will survive.
Still, one could argue that this is a decidedly pessimistic view. In Arthur C. Clarke’s classic novel “The Songs of Distant Earth,” the ill-fated Earth sends probes containing billions of DNA sequences encoded digitally, along with a genetic resequencer to create the human babies once a suitable planet has been found. Then in Earth’s last days, a new technology is discovered that allows colonists themselves to flee. Perhaps such a new technology could be anti-gravity drives or warp-drives based on the principal of stretching and contracting space-time so as to effectively achieve faster-than-light speeds without violating the principals of general relativity, as described in the now-famous Alcubierre paper (which, admittedly, has its problems).
Perhaps we’ll destroy ourselves long, long before we ever need worry about being scorched by the sun. Or perhaps new discoveries will see us colonizing new worlds within the next several hundred years. The latter is certainly more pleasant to consider.