Atom's 100th birthday celebrated with liquid nitrogen

The atom as we know it was first described in 1913, when Niels Bohr published the trilogy of articles that gave birth to Quantum Mechanics. In 1922, Bohr was awarded the Nobel prize for his work. In the next century, his idea transformed society: Everything from your car, to your phone is stuffed with electronics, that owe their existence to Bohr’s 1913 papers.

On October 5, one century after its discovery, Bohr’s atomic model was celebrated with a birthday party at the Black Diamond, in Copenhagen. See the photos here.

Highlights of the event were the talks by William D. Phillips and Steven Chu, who shared the Physics Nobel prize in 1997. Professor Phillips surprised the audience with liquid nitrogen-based magic tricks. Professor Chu, former Secretary of Energy under Barack Obama, closed the afternoon of talks, screenings and experiments talking of Quantum Mechanics and climate change.

See our previous feature on the birthday of the atomic model, which includes a video here.

Don’t try this at home

Phillips’ research is focused on atomic clocks, the most accurate clocks in the world (earlier this year an American team reached an accuracy of a part in a billion billions, equivalent to knowing the age of the universe with a precision of less than one second).

To tick, atomic clocks use the fact that, for a certain element, all excited atoms relax in the same way, as first described by Bohr. More technical details here.

Atomic clocks are installed on GPS satellites and are crucial to return your position when driving, biking or playing golf. To achieve the highest possible precision, atoms in atomic clocks are cooled down to less than -270 degrees Celsius using lasers. That’s almost as cold as it can get!

To give a feeling of a winter at that temperature, Phillips turned into a magician and showed the wonders of liquid nitrogen, which in contact with warmer objects boils at -196 degrees Celsius. A flower bouquet was petrified and broken into pieces, and frozen balloons thrown at the audience. Only a cabbage survived the glaciation on stage.

It’s getting hot in here

In the final talk Chu, now at Stanford University, remembered the importance of Bohr’s contribution to the development of Quantum Mechanics, the theory that makes computer and lasers work. His presentation included several animated cartoons.

“Quantum Mechanics is horrible and we hate it. But it works, no matter how hard you try to reject it,” said Prof. Chu.

As Secretary of Energy, he worked to raise the awareness on global warming, another issue that many tried to reject despite its solid scientific foundations. He thinks it’s not too late to act and quoted the first Law of Holes:

if you find yourself in a hole, you should probably stop digging.

universitypost@adm.ku.dk

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