Thursday, August 23, 2007

Our Days Are Numbered

There will come a time when every human on Earth is dead.

The only questions are when and how.

Nuclear holocaust. If a global thermonuclear war happens, then the resulting clouds of fallout could kill most of those who lived through the blasts. Anyone who manages to avoid that might starve trying to find uncontaminated food supplies. Even if that problem is solved, they might find themselves with no healthy mate, thus preventing the next generation. And if they pass all those hurdles, then their reproductive organs might be damaged enough to prevent viable offspring.

That could happen tomorrow. On the other hand, it could have happened yesterday, or thirty years ago, and it hasn’t yet. There is at least some hope that it won’t happen at all. In any event, there may yet be time for other options.

Global Warming. A few degrees one way or the other won’t kill off humanity, but there’s no real reason it has to stop there. It is at least vaguely possible that the greenhouse effect could feed on itself and become a runaway. For the end result of that, take a look at Venus – surface temperatures averaging over 860° F. It’s going to be hard for anyone to stay alive in temperatures too hot for baking.

This one isn’t real likely – the theory of global warming is fairly well-established, and there’s not much room in it for a runaway greenhouse effect. On the other hand, theory is not a substitute for testing – and this test could have a very high learning curve.

Ice Age Maximus. Current theories in physics indicate that nuclear fusion produces neutrinos. These faster-than-light particles are hard to spot – they’ve got a 50% chance of getting through a light-year thickness of lead. Nonetheless, there are theoretical means of capturing them, and sites constructed to do just that – capture the neutrino’s produced by the Sun’s fusion. Unfortunately, they haven’t found any. This leads to a few possible conclusions, but one is that the nuclear furnace of our nearest star has gone out.

That would mean that all that light and heat we currently enjoy is just the remnants of earlier fusion percolating up through those thousands of miles of compressed gas – and that at any time now, it could stop. If that happens, it’s gonna get chilly. Not just the ice caps expanding and glaciers forming. Not just the oceans freezing over. I’m talking about the atmosphere freezing out, one gas at a time – a layer of dry ice, buried under a blanket of frozen nitrogen, with drifts of oxygen settling out on top. I’m talking about trying to choose between breathing frozen air or breathing vacuum – not that your choice will make a lot of difference.

This is another one that could happen at any time. But again, it hasn’t happened yet.

Various other methods – a massive comet strike could crack the Earth like a coconut. The Sun’s fusion might restart, igniting a massive solar flare that would blast our atmosphere off the surface, frying half the planet instantly while the other half struggled – briefly – with storms that would make a hurricane look like a summer breeze. A bioweapon gone wrong that wipes out such a high percentage of humanity that the few survivors die of other diseases, infrastructure collapses, or simply can’t find each other to reproduce and keep us going. If nothing else, the Sun will eventually expand to a red giant, turning the Earth to a charred cinder similar to Mercury.

There will come a time when every human on Earth is dead.

It would be nice if my descendents lived somewhere else when that happens.

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