Six Famous Thought Experiments, Animated in 60 Seconds Each

We need intellectual challenges to reduce our chances of getting dementia. So your doctor should be prescribing stuff like this. Does your doctor know the answer to an infinite bus of passengers arriving at an infinite hotel? What else has your doctor given you to stimulate your intellect? Nothing!
How stupid is your doctor?
http://www.brainpickings.org/index.php/2011/10/19/open-university-thought-experiments/