How Does That Work, Again?

I just read that the Chicago Bulls won the NBA draft lottery, meaning that the team with the worst record did not gain the first overall pick in the draft. Color me shocked. It was termed a “surprise” in some stories. Maybe it was a surprise that they won it, but not that the Heat — who, with the worst record had a 25% chance of winning the lottery —didn’t. Before the 1994 draft, the weighting was adjusted to give the team with the worst record a 25% of drafting first. Since that time, the team with a 25% probability has won exactly once: the Orlando Magic in the 2004 draft. (The Cavs in 2003 had a 22.5% chance, by virtue of being tied with Denver for the worst record.)

Whoever ends up in the cellar this year had better be praying for some regression to the mean.

Please Pass the Lamb Dip

Zapperz, back from vacation, notes that Willis Lamb passed away recently. The Lamb shift, the energy splitting of the 2s and 2p states of the hydrogen atom, was a huge confirmation of quantum electrodynamics and garnered him the Nobel prize, and you can read more about that here. But that’s not the only effect named after him. Another artifact is the Lamb dip.

The Lamb dip is not a sauce, nor is it related to sheep dip. It arises in a certain geometry of spectroscopy: if you pass a near-resonant laser through an atomic vapor, some of the light will be absorbed. If the laser’s frequency is scanned, you will map out an absorption profile of the atoms, but because they are moving, the absorption depends not only on the transition frequency, but also on the motion of the atoms, which causes a Doppler shift. So your absorption profile is really a representation of the thermal motion of the atoms. At any one frequency the light will be absorbed by those atoms whose motion places them in resonance with the light.

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