In celebration of the centenary this year of Albert Einstein's annus mirabilis (for which he should, by rights, have won not one, but three Nobel Prizes), I think it's about time I told you my Einstein joke. It's a fairly significant anniversary for the joke as well: I thought of it 25 years ago this year. I was still at school studying physics, and there had been a lot of programmes on the telly about the 75th anniversary that year of Einstein's annus mirabilis.
So, without further ado, here it is:
The Einstein Joke
Albert Einstein had a brother named Fred, who also dabbled in physics. Being a close relative of Albert's, he had more than a passing interest in Albert's ideas on relativity.
Fred read up on the subject and learnt that, as objects move towards you at close to the speed of light, they appear to be more blue in colour (a phenonmenon known as blue shift), whereas objects moving away from you at close to the speed of light appear more red in colour (a phenomenon known as red shift).
This got Fred thinking: what would objects look like if they moved across your field of vision at close to the speed of light? Would they be red-shifted or blue-shifted?
So Fred took out his slide-rule and his protractor and set to work trying to answer this fascinating question. After many months of calculations, he came to the remarkable conclusion that objects moving across your field of vision at close to the speed of light would appear to have red and blue diagonal stripes running across them. Because this phenomenon was half red shift and half blue shift, Fred decided to name it half shift.
Full of excitement, Fred showed his calculations to his brother. But Albert took one look at them and sadly shook his head:
"Nein, Friedrich," he said (because he was still German in those days), "I am afraid zat you are inkorrect: as any dummkopf knows, light can't half shift."
I thank you.