For Santa to visit three billion children and deliver his gifts to all the world's children in just one 24 hour period, his sleigh and reindeer would need to fly, obviously, quite quickly. He needs to visit at least 8000 homes per second.

Putting aside the problem of the heat of friction could he do it? Up until recently he was limited to the speed of light - 299,800,000 meters per second, but scientists have recently discovered neutrinos actually travel faster than light, so this opens up all sorts of possibilities for Santa. If he can travel as fast as neutrinos then he might be able to time travel - perhaps he could slow his delivery to 4000 homes per second, but do it twice in the same second.

Or if he's pressed for time perhaps he could become more of a stickler for the rules - he needs to check his naughty and nice list more carefully and avoid wasting time at the wrong chimneys - no toys for naughty children. I think he's too forgiving sometimes.

The Earth is slowing down – by nearly 2 seconds a century. This means that 140 million years ago dinosaurs had only 23 hours in each day, and whoever (or whatever) will be around in 140 million years will have 25 hours in each day.

From the last pages of In The Footsteps of Stamford Raffles by Nigel Barley:

In the 1800s there was two measurements of dates. The maritime day ran from noon till noon (think 'noon sightings') and the terrestrial day from midnight to midnight.

Stamford Raffles was born at sea - on July 4th 1781, which was July 5th 1781 on land. He had two birth dates and he died at age 44 or 45 depending on which one you use.

By the way, this is a very interesting book about the founder of Singapore and "the Honourable, the Lieutenant Governor of Java", during the brief respite the Dutch colony had during the Napoleonic wars.