World without end

Street signs sometimes tell us  "end of the world is nigh.''  Environmentalists often warn of policies likely to  "destroy the Earth'', and some political writers think "the neocons will blow up the planet.'" But the task of actually destroying the planet, or "mundicide'', as UK Cambridge University mathematics student Sam Hughes calls it in his amusing website (http://ned.ucam.org/~sdh31/misc/destroy.html) is unimaginably difficult. Nevertheless we all like a challenge, so lets think of ways to turn this 6,000 million trillion-ton ball of iron that we live on into fragments, and to do it at reasonable cost. The most obvious and inexpensive solution is to do nothing and wait–for a very long time. In about 5,000 million years, as the Sun becomes a red giant, it will grow so huge that it will swallow up the inner planets. But not, alas, the Earth.

So we have to wait a bit longer. In about 1,000 trillion years (that's 1 followed by 15 noughts), atoms will start to decay and eventually the planet - and all other planets - will cease to exist. But for those who want immediate results this won't do at all. How about nuclear weapons? Well, if all the hydrogen bombs in the world were gathered together in one place and detonated, it would make a huge crater and destroy the world's eco-system, but the planet itself would be unscathed. To actually shatter the world one would need about 2.5 trillion tons of antimatter. But since only a few grams of antimatter have so far been created, such a project might be expensive. One could always cover the world's surface with Von Neumann machines–machines that make identical copies of themselves, like those in Arthur C. Clarke's story 2010: Odyssey Two that compressed Jupiter until it became a second Sun. The only problem with this is that we don't have any Von Neumann machines, and nobody knows how to build one. Or one could arrange for the planet to be sucked into a giant black hole. But the nearest known black hole is 1,600 light-years away in Sagittarius. Problem: how to get the Earth to the hole or the hole to the Earth. So an arch-terrorist or a crazed James Bond villain determined on mundicide is reduced to desperate options. He might perhaps travel back 4.6 billion years in a time machine and blow up the Earth before it was fully formed. But since the past cannot be altered, he would have to move into another universe to avoid a paradox. Mr Hughes's final suggestion is that the would-be destroyer should turn to religion. God could no doubt do the job at a mere whim. But  "the question arises of how we persuade Him to do this.'' Yet if Judaic mythology is correct, the world would end with the assassination of one or more of the  "Lamed Vav Tzadikim'', the 36 righteous men whose role in life is to justify mankind in the eyes of God. But the trouble is that none of these individuals know themselves who they are. In short, humanity may be in constant danger, but its homeworld never is.