What are the top 10 existential risks to humanity? (HT: Instapundit)

It's a good thing someone is thinking about some of these things because frankly, the end of humanity is something I care not to contemplate much.

But on the other hand, some very smart people have been contemplating some of the weirdest, most bizarre means by which the human race will cease to exist. And that makes for some of the most fascinating science reading I've done in years.

Consider some of the scenarios.

1, Biological:

No intelligence agency, no matter how astute, and no military, no matter how powerful and dedicated, can assure that a small terrorist group using readily available equipment in a small and apparently innocuous setting cannot mount a first-order biological attack. With the rapid advancements in technology, we are rapidly moving from having to worry about state-based biological programs to smaller terrorist-based biological programs.
 
It's possible today to synthesize virulent pathogens from scratch, or to engineer and manufacture prions that, introduced undetectably over time into a nation's food supply, would after a long delay afflict millions with a terrible and often fatal disease. It's a new world.

Yes it is. And please keep your end of the world scenarios to yourself, thank you.

3. Extraterrestrial

As any alien race able to reach us is likely to be considerably more advanced than us, we would do well to develop a communications and diplomatic protocol to minimize any frictions caused by a first contact situation, be it friendly, unfriendly or neutral. In particular, we would discourage actions which could all too easily be misinterpreted as overtly hostile such as preemptively scrambling — let alone launching — nuclear weapons during a possible first contact. The rule when engaging in contact with an alien race is to do anything possible to avoid war since we are quite likely to lose.
 
This program will be devoted to developing the first contact protocol.
 
In addition to this protocol, we should be careful about any devices that we are told to construct via alien messages, as such devices could be unfriendly AI or other harmful devices. If such a danger is suspected, this warning must be immediately made public knowledge to discourage others from activating possible alien weapons.
 
Finally, we are against any efforts to on purposely provide our technological level and location to potentially hostile aliens.

In other words, don't piss off the aliens and try to keep a low galactic profile.

Finally, the most bizarre and most fascinating threat of all; the idea that we are all living in a computer similuation a la The Matrix and that we should never, under any circumstances, shut it down:

It starts with the assumption that future civilisations will have enough computing power and programming skills to be able to create what I call “ancestor simulations”. These would be detailed simulations of the simulators’ predecessors – detailed enough for the simulated minds to be conscious and have the same kinds of experiences we have. Think of an ancestor simulation as a very realistic virtual reality environment, but one where the brains inhabiting the world are themselves part of the simulation.

The simulation argument makes no assumption about how long it will take to develop this capacity. Some futurologists think it will happen within the next 50 years. But even if it takes10 million years, it makes no difference to the argument. Let me state what the conclusion of the argument is. The conclusion is that at least one of the following three propositions must be true:

1 Almost all civilisations at our level of development become extinct before becoming technologically mature.

2 The fraction of technologically mature civilisations that are interested in creating ancestor simulations is almost zero.

3 You are almost certainly living in a computer simulation.

Obviously, brilliant people with entirely too much time on their hands.

If you like science fiction turned science fact, read the whole thing. On the other hand, if you want to fall asleep tonight, perhaps not.