How Unlikely is a Doomsday Catastrophe?

In case you didn't realize it, there are serious people trying to derive reliable conclusions on this question. Al Gore aside (whom I consider to be a bloated buffoon who doesn't know or care what the heck he's talking about), there are a some possible scenarios that are worth our concern. The paper herein quoted analyzes, in fairly technical fashion, the likelihood of any of these possibilities occurring. Here are some portions of the paper. If they pique your interest, you can dowload the PDF.

As if we humans did not have enough to worry about, scientists have recently highlighted catastrophic scenarios that could destroy not only our civilization, but perhaps even our planet or our entire observable universe. For in-stance, fears that heavy ion collisions at the Brookhaven Relativistic Heavy Ion Collider (RHIC) might initiate such a catastrophic process triggered a detailed technical report on the subject, focusing on three risk categories:

• Initiation of a transition to a lower vacuum state, which would propagate outward from its source at the speed of light, possibly destroying the universe as we know it.
• Formation of a black hole or gravitational singularity that accretes ordinary matter, possibly destroying Earth.
• Formation of a stable "strangelet" that accretes ordinary matter and converts it to strange matter, possibly destroying Earth.

Other catastrophe scenarios range from uncontroversial to highly speculative:

• Massive asteroid impacts, nearby supernova explosions and/or gamma-ray bursts, potentially sterilizing Earth.
• Annihilation by a hostile space-colonizing robot race.

The paper continues...

One might think that since life here on Earth has survived for nearly 4 Gyr (Gigayears), such catastrophic events must be extremely rare. Unfortunately, such an argument is flawed, giving us a false sense of security. It fails to take into account the observation selection effect that precludes any observer from observing anything other than that their own species has survived up to the point where they make the observation. Even if the frequency of cosmic catastrophes were very high, we should still expect to find ourselves on a planet that had not yet been destroyed. The fact that we are still alive does not even seem to rule out the hypothesis that the average cosmic neighborhood is typically sterilized by vacuum decay, say, every 10000 years, and that our own planet has just been extremely lucky up until now. If this hypothesis were true, future prospects would be bleak.

Click here to get the PDF, if you dare.