The good news is, there are perfectly reasonable answers to the many questions relating to his annual mission. The bad news: The science involved is typically beyond the mental reach of the average six year old. Most graduate students can't understand the specifics of wormhole formation. Second-graders? Forget it.
Don't worry, though: I am a professional. Follow this simple* guide, and explain Santa's magical mission with science and technology.
The new movie Arthur Christmas describes a high-tech military-style global operation. In 1994's Miracle on 34th Street, Santa says he can slow time, and in Elf he's got a hot rod sleigh. But none of these techniques could truly get St. Nick into all those living rooms in one night.
Santa clearly uses wormholes, the tunnels through space and time that allow travelers to jump from one side of the cosmos to the other or—in this case, from one neighborhood to the next. But trying to give your kid a primer on relativity, gravity and negative energy would be pointless. Instead, take a piece of paper, draw a picture of your house on one half, then a friend's home on the opppsite one. Trace a line from one side of the sheet to the other to represent the standard path—the route Santa would take in an airborne sleigh. Now fold the paper down the middle so the two houses are back-to-back, one on either side.
You don't have to get into the curvature of space-time, but you can tell your kids that Santa uses deep scientific knowledge to see a different map of the universe, one that contains roads most people don't know about. The Jolly Old Elf may have found a way to jump or drop from one house to the next without having to travel along the same line you'd use. If they're still asking questions after that, pull up Time Bandits on Netflix streaming. If that doesn't satisfy, you might have a future physicist.
Obviously, his suit allows him to become invisible. Again, though, explaining exactly how this works can be tricky. We see everything around us because objects and people and plants give off light. When he wants to hide, however, Santa's suit cloaks him from view by deflecting and re-routing the light in the room. There are such materials in research labs today, but you're better off showing your kids a simpler example of this kind of cloaking technique, such as this new adaptive camouflage system.
The idea of someone watching your every move terrifies most adults, but kids can deal with it. They've happily welcomed the creepy Elf on the Shelf, a doll that supposedly watches them all day, then returns to Santa at night to report on their behavior. (And has some plans of its own.) Forget the elf, though. A more reasonable explanation would be that Santa has a fleet of robotic flying drones, each of which records HD video and audio, then relays this data, via satellite, back to the North Pole. If your kids are doubtful, show them these videos of Aerovironment Inc.'s amazing new hummingbird aerial vehicle.
Of course not. He's just very, very old. And if your little one wants to know how it is that he has lived so long, try a car analogy. When a part of the family sedan breaks down, we take it to the shop to have it replaced, and the car keeps running. The same holds for Santa. When one of his essential parts, such as his egg-nog-soaked liver, needs replacement, his robotic surgeons replace it with an artificial, newly-printed organ. If any more questions follow, bring up this TED talk. They'll either become a doctor or fall asleep. Either way you're set.
Although it's nice to picture the old guy sitting at a desk, glasses perched on the edge of his nose, reading through stacks of illegible wish lists, this would take forever. Kids get a kick out of big numbers, so it might be worth running through some hypotheticals. If Santa were to receive 10 million wish lists, and take a mere 20 seconds to read and choose an item from each one, the whole job would take him a little more than six years. And that's without a break. Instead, I'd suggest that he uses a rapid document scanner in tandem with optical character recognition software. In short, his computers read the notes for him.
Finally, if you're asked why elves have pointy ears, the answer is should be obvious. They are Vulcans.
Gregory Mone is the author of The Truth About Santa: Wormholes, Robots, and What Really Happens o... and the novel Fish.