Described as "the most powerful idea in science", Albert Einstein's theory of general relativity was his masterpiece - the most important body of work in his highly accomplished career.
The German physicist gifted the world that theory 100 years ago this week.
Unfortunately, large parts of the population, probably bored to near death by middle-aged physics teachers, don't really know what it means.
But fear not, because as part of the centenary celebrations, actor David Tennant, of Doctor Who fame, is here to explain (along with the help of animator Eoin Duffy).
While the physicists are partying, the rest of us are left wondering what the f--k it's all about.
Watch the explanation, with some pretty nifty graphics and Tennant's Scottish burr, below: