re: If the world were going to end and you knew the day...
Well there are two ends to the Earth that we care about.
1) The day the last humans perish.
2) The day the Earth actually perishes.
There will be a vast period of time between the two.
There is another end of the world for those who colonize it after humanity is gone. They get their own end of the world as well.
So that makes 3 end of the worlds.
And to be honest, no one will get to enjoy the last day of humanity on Earth. No normal activities will be able to occur. It will be a pretty lousy day and there won't be too many humans left on that day to enjoy it.