One thing that I strongly dislike is the statement that “you should believe X even if X is false.” The famous “Yes Virginia, there is a Santa Claus” letter just reeks of that. (But there wasn’t much else they could do, so I don’t blame them.) There are a few exceptions, of course, but in the vast majority of cases it should either be “You should not believe X” or “X is true.” This is about the second one.
On Christmas Eve, Santa Claus goes to every house in the world giving presents to all the good children. This gets harder every year, since populations increase and contrary to what parents tend to think, Kids These Days probably aren’t significantly naughtier than Kids Any Other Set Of Days.
Lots of people have calculated and complained about how fast he would have to move. Here’s one saying that he would have to travel over a hundred thousand miles per hour. This is hard. That link explains some of the energy costs and also the more literal costs, but that’s not even the worst of it. Something moving that fast at around chimney-level would be ridiculously destructive. Santa is probably a superhumanly good pilot; maybe he can avoid crashing into anything. But even if he can, that would be a supremely powerful sonic boom. Just by flying past, he would flatten every neighborhood containing at least one kid on the nice list. And that would be counterproductive. He would be remembered not as jolly old Santa Claus, but as the annual “every building spontaneously falls down with massive loss of life” event. Fortunately, he has a better way.
You might have guessed that his speed is well over Earth’s escape velocity. In fact, it’s several times as fast as any human spaceship can go. If he can get that kind of speed, it would actually be easier, and safer, to go into orbit. There’d be less to crash into, and no blast of destruction from the sonic boom blowing everything away.
Rather than deliver presents by landing on every roof, Santa can deliver them from orbit. Going around the world in one night isn’t even a problem anymore; orbiting the Earth in hours or minutes isn’t unusual.
So Santa orbits the Earth however many times it takes to pass over every house, and when he’s directly over a house he beams the presents down through the chimneys. Why the chimneys? Well, some houses have wiring that acts as a Faraday cage and interferes with the signals…you’re not buying this, are you. Tradition, OK? It’s tradition.
Being in orbit takes care of the travel speed problem, but he still has to sort through all the presents and send them to the right houses. And pick up the cookies, if applicable. According to the U.S. Census, there are about 34.6 million households with children in the United States. Since the U.S. has about 4.4% of the world population, estimate 779 million households with children worldwide. He’d have maybe 31 hours to cover all of them. (Which hours depends on time zones; the 31 represents the total amount of time where it would be delivery time somewhere.) That gives him about one and a half thousandths of a second per house.
That’s not nearly enough time. A transporter beam takes up to two and a half seconds to scan the item and reconstitute it on the other end (Source: Star Trek), and while better technology might be able to do it faster, it still won’t be actually instantaneous. He could use multiple transporters at once, but he has to be more or less directly over the target house so that the beam goes through the chimney. The chimney thing is pretty important to him. So how does he do it? Time travel.
Instead of only working one night a year and taking the rest off, Santa works continuously. He uses time travel to jump between Christmas Eves and repeats each night as many times as he needs to to make sure that everything gets delivered. Technology can help do everything as efficiently as possible, (for instance, he uses a NORAD supercomputer to tell him the best series of orbits), but it’s still an almost impossible task. The delivery each year takes him years of work. And he does it anyway, because the presents have to be delivered.
(This is also his response when he’s asked about how hard he works the elves. Nothing he asks them to do compares with what he does, and humans and their standards look incredibly lazy from the North Pole’s point of view. The elves work hard, but Santa works more than is mathematically possible.)
So, if it isn’t Christmas, then Santa doesn’t exist at the moment. He skips over any time that isn’t time to deliver the gifts, and does those few hours over and over again. Like he always says, “there’s no time like the present.” (In his case it’s literally true, so I tolerate the terrible pun.) If it is Christmas, then not only does Santa Claus exist, but there are thousands of him all around the world delivering presents at the same time.
“Yes, Virginia, there is an orbital time-traveling Santa who teleports presents down through your chimney.”