Suppose you’re standing on top of a volcano. Suppose the volcano is erupting. You’re stood there on a hillside and there’s a couple of cubic kilometres of magma underneath you waiting to come out. What happens next depends on what kind of magma it is. Really runny magma? That stuff just kind of oozes out, like pus from a weeping sore. If you’re choosing a volcano to stand on, this would be the one. I’m thinking Mauna Loa here, or Kilauea. Toasty but undramatic. Down from that would be the magma that has some silica in it. This makes it thicker and stickier so it comes out in splattery lumps like jam bubbling on the stove. Jam made of liquid glass glowing orange at twelve hundred degrees mind you, but as long as you don’t actually get any on you, you should be okay. But what’s really bad is the magma with silica and dissolved gas in it. Because as that magma shoots up the volcano vent, the pressure drops by about 1.2 million atmospheres and all that gas comes out of solution. This makes it expand and accelerate still further until, just before it reaches the surface, the force of this fiery froth overwhelms the tensile strength of the rock around it and the entire top of the mountain gets blown off. When Krakatoa did this in 1883, two-thirds of the island was vaporised and the bang was the loudest sound ever in recorded history.
When you’re standing on top of this kind of volcano, the hypersonic pressure wave will kill you before the magma even reaches you. It will take just 170 nanoseconds to reach you and another 25 to tear you to atoms. Or something. It’s not very long, is my point. Fortunately, your mind works a lot faster under stress and as long as you are prepared to skip over the boring bits, there should still be just time to see your life flash before your eyes.
In my case I had a running start because, apart from the time when the dustmen threw out my papier-mâché train set landscape by mistake when I was four, and the time I fell twenty-eight feet out of a tree on to my brother, asleep in his pram, and nearly killed us both, my life had been pretty dull. Oh there were other odd moments here and there; having sex, driving my first car, having sex while driving my first car, that kind of thing. There weren’t nearly enough of them though and if it wasn’t for the stuff that had happened in the last three days, those 195 nanoseconds would really have dragged.