The Wonderful Experiments
January 28th, 2010
On Monday there was a lecture at the Indian Institute of Astrophysics, Bangalore by William D. Phillips, Nobel Laureate called “Time, Einstein and the Coolest Stuff in the Universe”. It was the Vainu Bappu Memorial Lecture, with a huge crowd, a packed auditorium. Why I’m writing about it is that it was like a good old fashioned science lecture, full of wonderful, spectacular experiments. I realised I was actually on the edge of my seat!
He was talking about atomic clocks and that the cooling down of atoms increases the accuracy of measurements and timekeeping and this can matter for systems like GPS. He said that somewhere he went to, he walked past a door that said “Director of Earth Rotation”. The rotation of the earth is one kind of ‘tick’, its regular like a pendulum or the vibration of an atom, but, apparently the rotation of the Earth isn’t always the same - fantastic news - and so every so often the clocks and the Earth have to be synced back together.
The video is from the end of the lecture when everyone was crowding round and asking more questions. He used lots of liquid nitrogen - he was chucking it down the aisles - because he was wanting us to understand cooling. He wanted us to understand that his experiment is about cooling atoms to four million times cooler than the temperature of outer space. Its something too abstract and extreme to understand, so he must have wanted us to understand the relative strangeness of nitrogen’s freezing and boiling points as a step to believing what he was telling us. He said it was about “the adventure of getting to colder temperatures”
The atoms are cooled by lasers. As the resonance of the laser approaches that of the atom, it moves towards absorbing it and in the process looses energy and slows, which is what cooling is, slowing down. The other part of the problem was having a container for the atoms in which the atoms wouldn’t touch the sides and condense. This is to do with BEC: Bose-Einstein Condensation. So he explained the magnetic bottle with this levitating magnet experiment.
He had IIA work hard to include the experiments in the talk. In his vote of thanks, Bhanu Das said how loved he is as a teacher and scientist. You could see by the generosity of his explanations this was true. He gave us the keys to understand something very complex and extraordinary. He told a great story.
