Adam Roberts

Sky’s Not the Limit

The Future of Humanity: Terraforming Mars, Interstellar Travel, Immortality and Our Destiny Beyond Earth


Allen Lane 339pp £20 order from our bookshop

The old Whig historians saw history as an inevitable and glorious march towards modern-day constitutional monarchy and parliamentary democracy. Contemporary Whig physicists have rather bigger timescales to play with. Michio Kaku, a respected superstring theorist and a familiar face from popular-science television documentaries, has written a future history of humanity, from now to the end of the universe. Things will, it seems, go as follows: we’ll return to the Moon, colonise Mars, move out to the stars, transfer our consciousnesses into computers to become immortal, harness the energy of the whole cosmos and, finally, survive the end of the universe as dimensionally transcendent superbeings indistinguishable from gods. Macaulay’s histories look positively piddling in comparison.

Kaku spells out in detail how each of these stages can be achieved. Although he gets a bit hand-wavy in the later sections, he is scrupulous about sticking either to known science or else to plausibly extrapolated possible science. He throws a great many facts onto the page and a lot of them stick. I didn’t realise, for instance, that the Oort Cloud (the millions of comets orbiting the Sun out beyond the furthest planet) could actually extend a full three light years into space – which, since Alpha Centauri is only slightly more than four light years away, means it might be possible to hop from comet to comet, utilising their water-ice to fuel a mission to that star system. Physics says that we could create wormholes in space to short-cut the journey but for that we’d have to convert the entire mass of Jupiter into the energy required to propel a starship through one.

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