Опасная зона

Опасная зона

Sunday, February 17, 2013

The World Did Not End

.. but it was very close!

Meteor trace from 15.Feb.2013, Chelyabinsk. (chelyabinsk.ru)

No, I am not referring to the potential damage a >1 km diameter meteor would have caused.

Instead I thought of the unrelated coincidence that the recent meteor impact near Chelyabinsk happened almost simultaneously when a vagabonding asteroid 2012 DA14 reached Earth closer than the geosynchronous orbit distance.

2012 DA14 passing earth on the 16th February 2013. (nasa.gov)

And indeed these two events are unrelated, which was pointed out by numerous experts in the field.

Now, human minds are put together in such a way, if two very unlikely events happen at the same time, they tend to give it some special meaning, possibly some unphysical, supernatural cause.

This is related to selection bias.

Imagine you have a dream, and a day later it actually comes true. Is this premonition?
No, you just have rejected all the cases where your dream did not come true. Sooner or later you just might get it right.

Think of sampling from a normal distribution, and you have a very small probability to achieve something which is more than 3 sigmas beyond the mean.
Then imagine two normal distributions, the likelihood that you will sample in the extreme tails in both functions the same time, whoho... must be magic when that happens.Yet, these events DO happen, and there is nothing magic about that!

My end of the world scenario looks rather different. Just imagine, the aforementioned events had happened app. 55 days earlier: 21st December 2012.

I imagine mass-hysteria in public, mountains crowed with UFO fanatics, people with tin foil hats roaming the streets, and a surge in people claiming they are Christ the Savior or Buddha themselves.

Some random dude from Wikipedia wearing a tin foil hat. (wikipedia.org)
Now, as a scientist try to explain to a general public that there is no relation between a nearby asteroid, a pretty violent meteor hit, and the end of the Maya calendar.

It would have been the end of the civilization as we know it! A simple series of random cosmic and spritual events happening within a few days, resulting in disintegration of scientific methods and bringing us back to the middle ages. The pope just decided to quit his job, now God is angry (or other way round, whatever). New age fruitcakes, conspiracy freaks and tea party maniacs will go viral and define a new world agenda. Gibberish and nonsense will form new paradigms taught at schools and universities. Creationism, intelligent design, you name it...

What is more likely: a hit by a >1 km diameter meteor, or a hit by a 10 meter meteor, which by chance "collides" with, say, 2 other rare events - inducing a permanent mass hysteria?

Superposition of very unlikely events happen all the time, but by nature they are rare. People work with this professionally in risk management, the trick is here not to make a single rare event be fatal for a critical system. This is what makes flying airplanes safe, today an entire chain of unlikely events have to happen in order to provoke a fatal plane crash.Think of the famous SAS MD-87 crash in Linate:
  • fog, i.e. no visibility
  • missing ground radar
  • missing / ambiguous numbering of taxi ways
  • pilot of Cessna was not certified for landing in visibility below 550 m, i.e. he should not have landed there a few hours ago
if just one of these conditions were not fulfilled, the accident would not have happened. There are heaps of such cases. Another very interesting story which just comes to my mind is how a faulty radiation therapy machine Therac-25 lethally injured several patients due to software errors and other unfortunate circumstances.

Therac-25 radiotherapy unit.
Some recommended scary bed-time reading:

In the end, it's science! Make no mistake.