Mad science: Like the fist of an angry god.

In general, I like my end-of-the-world scenarios to be as wacky as possible. Our presence on this globe is so improbable that it just seems dramatically appropriate that our exit should be just as improbable. But sometimes it rewards a person to consider the classics.

Over at the UK screamsheet tThe Independent, Chris Impey revisits one of the 20th century's most enduring contributions to the intellectual dark ride of our apocalyptic imaginations: death by space object strike:

Every century or so, a 10-meter meteor slams into the Earth with the force of a small nuclear device. Tunguska was the site of the last, in 1908, and it was pure luck that that meteor landed in the uninhabited wilderness of Siberia. Every few thousand years, Earth can pass through unusually thick parts of the debris trail of comets, turning the familiar light show of a meteor shower into a deadly firestorm. Roughly every 100,000 years, a projectile hundreds of meters across unleashes power equal to the world's nuclear arsenals. The result is devastation over an area the size of England, global tidal waves (if the impact is in the ocean), and enough dust flung into the atmosphere to dim the Sun and kill off vegetation. That could ruin your day.

Then there's the "Big One". About every 100 million years, a rock the size of a small asteroid slams into the Earth, causing global earthquakes, kilometre-high tidal waves, and immediately killing all large land animals. Creatures in the sea soon follow, as trillions of tons of vaporised rock cause drastic cooling and the destruction of the food chain based on photosynthesis. There's good evidence that this happened 65 million years ago and our tiny mammal ancestors were the beneficiaries as the giant lizards were extinguished.

Mr. Impey also considers such we're-screwed scenarios as "fried by the high-energy radiation of a distant hypernova," "Sun eats the Earth," and one of my new favorites: "the Big Rip." This is the term for the hypothesis that the expansion of the universe might eventually reach a crisis point and the whole darn thing could just unravel. That's right, the universe could break.

So enjoy the weekend like it may be your last! It's always later than we think!