Super-heavy turkeys and super-heavy elements

Perhaps because I’m immersed in physics, my brain spontaneously makes associations between physics and everyday life. When I glance at a digital clock that says 5:11 pm or at a rowing machine monitor that says I have 511 meters to go, the electron’s rest-mass energy, 511 keV, comes to mind. News stories about post-season college football inevitably mention BCS, which makes me think first of the Bardeen-Cooper-Schrieffer theory of superconductivity, not the Bowl Championship Series. If you’re a physicist, too, you might be similarly afflicted.

An odder association popped into my mind early last Wednesday evening. As usual, I was listening to American Public Media’s Marketplace while preparing dinner. This being the Thanksgiving season, the radio show included a story about the economics of raising turkeys for American dinner tables.

Americans’ preference for breast meat led in the 1950s to a selective breeding program that culminated in the Broad Breasted White, a turkey whose breasts are so heavy and whose legs are so short that it cannot mate. Turkey farmers have to artificially inseminate turkey hens with semen collected from toms, like the one shown here. The popularity of the Broad Breasted White’s flesh more than makes up for the additional cost of insemination.

So what did I think of when I heard about the economics of turkey insemination? Super-heavy elements. Twelve days before the story was broadcast, the International Union of Pure and Applied Chemistry announced the official names of elements 110, 111, and 112: darmstadtium, roentgenium, and copernicium.

Like the Broad Breasted White, the newly named elements owe their existence to human intervention. Darmstadtium, for instance, was first created on 9 November 1994 at the famous GSI lab outside Darmstadt, Germany. To make it, a team directed by GSI’s Sigurd Hofmann fired nickel-62 ions at a target made of lead-208.

But it wasn’t artificial synthesis that formed my mental bridge between super-heavy elements and super-heavy turkeys. Rather, it was their instability. Just as the Broad Breasted White is wobbly on its too-short feet, darmstadtium, roentgenium, and copernicium are unstable to nuclear fission. The most stable isotope of roentgenium, ²⁸¹Rg, has a half-life of just 26 seconds.

Turkey meat is rich in the amino acid tryptophan, although only marginally richer than other meats are. Perhaps because serotonin, an anxiety-relieving neurotransmitter, is derived from tryptophan, the amino acid’s presence in turkey meat has been identified as the source of postprandial drowsiness on Thanksgiving Day.

Whether or not turkey makes us pleasantly tired, consider this as you tuck into your Thanksgiving meal. Tryptophan is the biggest and heaviest of the 22 standard amino acids. Its chemical formula is C₁₁H₁₂N₂O₂. If a tryptophan molecule is made up of the most abundant isotopes of carbon, hydrogen, nitrogen, and oxygen, then it contains 108 protons and 96 neutrons. A single nucleus of the most stable isotope of copernicium, ²⁸⁵Cn, contains 112 protons and 173 neutrons.