Within the laws of physics, how could one man and his sleigh pulled by reindeer deliver presents to the whole world on one night? “Actually, he has more than one night,” says Dr George. “The Orthodox calendar puts Christmas on a different day, in January, so he has two shots at this.” Then she drops a bombshell: “Not everybody believes in Santa!! Not everybody is good.” This comes from experience, having just given a public lecture on “The Science of Santa”. They like to engage people of all ages with science and technology at Keele, and themes like this help with that. “I don’t say: ‘This is exactly how it happens.’ I do say: ‘This theory exists. This offers a possibility.’” So.. let’s hear it… There are 2.2 billion children in the world according to Unicef; Dr George divides that in half (roughly two per household). Then she divides it again to reflect the proportion of families with value systems based on Christianity, which has been crucial to the evolution of the pagan figure of midwinter into Saint Nicholas, then into the fat, jolly chap in his red Coca-Cola outfit. “About one third of children believe and are good,” says Dr George with a dollop of parental generosity. That leaves Santa with 366 millionish visits to make. His journey around the world has been calculated at 7.5 million kilometres. “That’s to the Moon and back 10 times.” She divides the distance by 48 hours to calculate that he needs to move at 156,579 kilometres per hour. Scientists disagree about this – they really do, passionately; it’s one of their favourite things to do at Christmas – because some want to take into account the extra hours he can get by flying west across time zones. Still, he’s fast. America’s fastest fighter jet, unveiled earlier this year, will fly at Mach 5.1. By most calculations Santa’s sleigh has to reach at least Mach 100. The top speed of the average reindeer is just 15 miles per hour. Fortunately, these are not be the average reindeer. They can fly, for a start. If that seems impossible, consider this: according to a study in the journal PLOS Biology, there are 8.7 million species in the world and humans have yet to discover, categorise or name 86 per cent of them. So in theory, Rudolph could be out there. The heat generated by all that friction would vaporise him (although Dr George believes Rudolph is actually a female reindeer, because the males have all lost their antlers by this time of year) but the Norwegian astrophysicist Knut Jorgen Roed Odegaard provides the definitive word: “Santa obviously has an ion-shield of charged particles, held together by a magnetic field, surrounding his entire sleigh.” There should, however, be a continuous series of sonic booms as Santa breaks the sound barrier many times on Christmas Eve. “That would be deafening,” says Dr George. “It would wake all the children up.” Her solution has to do with a phenomenon observed in quantum physics, in which some particles appear to pass through energy barriers that should stop them. “Instead of burning up in the sky or having a magic key to get into everyone’s houses, he could be using quantum tunnelling.” The theory is related to Schrödinger’s cat, which is a hypothetical animal inside a box, with a poison that will be released if an unpredictable source starts generating radiation. Scientists like to say the cat is both alive and dead until you open the box and see what has happened. Dr George applies this to mean that, in theory, Santa could actually be all over the world on Christmas Eve – as long as nobody sees him. “If you observe him then the wave form collapses, your Santa is fine and he’s there, but all the other Santas in the world disappear, you spoil Christmas for everybody else.” So keep your eyes shut for all our sakes!!