Doomsday - the end of the world

Quote of the post: "The human development will be the most likely reason of humanity destruction in the near future and may lead to doomsday" - Quote about Doomsday - Sachin Kumar Gupta

There is a major prediction that a comet is hitting the earth on 21, December 2012. The image is taken from 2012-comet.com site. Whatever It is true prophecy or just some vivid theories. I browsed the youtube and found a nice documentary with some reasoning and effects about doomsday. They have presented it in the order of least likely to most likely to happen and the effects ranked.

7b. Gamma Ray Bursts
7a. Black Hole
6. Intelligent Machines
5. Supervolcano
4. Asteroid; Comet
3. Nuclear War; Atomic Bomb; Third World War
2. Plague; Bioweapon
1. Climate Change; Global Warming

The below is a very nice 100 mins video (summed-up approx) documentary about doomsday.

Doomsday: Last Days on Earth Part 1: Is it possible?

Doomsday: Last Days on Earth Part 2: Gamma Ray Bursts
This is the least likely disaster to happen on Earth. Ozone layer will diminish, and rest you can imagine.

Doomsday: Last Days on Earth Part 3: Black Hole
If black hole start sucking earth, you don't have even time to blink a bit.

Doomsday: Last Days on Earth Part 4: Intelligent Machines
"Computers are likely to overtake humans in intelligence at some point in the next hundred years." - Stephen Hawking

Doomsday: Last Days on Earth Part 5: Supervolcano
The world will be like toxic ash tray.

Doomsday: Last Days on Earth Part 6: Supervolcano continues...
Everything will be out of supply and panic all aound.(Ice age)

Doomsday: Last Days on Earth Part 7: Asteroid
April 13, 2029, 2036 Alert!!! "may happen the worst damage to earth in recorded history"

Doomsday: Last Days on Earth Part 8: Asteroid continues...
Firestorm

Doomsday: Last Days on Earth Part 9: Nuclear War
Are we our own enemy?

Doomsday: Last Days on Earth Part 10: Plague
Bioweapon War or Unknown Deadly Disease

Doomsday: Last Days on Earth Part 11: Climate Change
Global warming.

Doomsday: Last Days on Earth Part 12: Climate Change continues...
A Wake-up call; Follow our 4G Rule and Spread Earth Hour in your daily life.

What will you do, if you know the Doomsday - the last day of living on earth?