Einstein’s Theory of Relativity, which was initially published in 1905, said that space and time were interwoven in a single continuum known as space time, but that events could occur at different times depending on the position of the observer.
Dr Sheen will tell children at the University of Exeter Christmas and Science Festival that relativity also explains why Father Christmas appears not to grow older, because relativity can slow down clocks.
When Dr Sheen was seven years old she wrote a letter to Santa asking why he never aged. She received a response telling her it was “all magic”.
Not convinced she decided to become a scientist to one day find a rational explanation, and 26 years later has come up with a solution.
She found that the time dilation – which is part of Einstein’s theory of relativity – occurs as time speeds up relative to the observer. So if Santa was travelling at such high speeds, he would age more slowly than somebody moving at a normal speed.
Elsewhere, scientists warned that holly and mistletoe may not looks so festive in future years because of a decline in bees.
Both holly and mistletoe are completely dependent on insect pollination due to a quirk of their biology which sees both species grow as separate male and female plants.
It is only the female plants which tend to have berries, and scientists have noticed that in years of poor pollination there are fewer female plants.
Dr Tom Breeze from the University of Reading, who specialises in pollinator research, said: “While bees might be the last thing on our minds as we put up our Christmas decorations in December, in reality here’s be a lot less colour in our festive cheer without them.
“We know that a decline in pollinators would be costly to agriculture, but this study shows it could also damage two of our great British seasonal icons.”