Today we're celebrating the birthday of Hans Christian Ørsted, who as I'm sure you know is principally remembered for discovering that electric currents create a magnetic field.
What you may not know is that the 19th century Danish physicist and chemist was also the first to describe and put a name to a scientific technique that requires no special equipment, hazardous chemicals or even a laboratory. Anybody can try. It won't cost you a penny and you needn't move from your armchair. You can even do it in bed.
Ørsted called it a "gedankenexperiment", which literally means "experiment conducted in the thoughts". Of course Ørsted didn't invent the thought experiment, which had been deployed by philosophers since the Ancient Greeks and was put to good use by Galileo.
But Ørsted put the technique into words and legitimised a whole new avenue of scientific endeavour, famously explored by the 16-year-old Albert Einstein when he chased a beam of light and Erwin Schrödinger when he imprisoned a cat in a box and declared that it was simultaneously alive and dead.
In the midst of a global recession with research budgets under pressure and the likelihood of further human space exploration in our lifetime fading fast, perhaps it's time to dim the lights, close our eyes and just think: what if?
Happy Birthday Hans Christian Ørsted (1777-1851).