Molecular information ratchet

Booking photographs

The suspect, from its real atomic coordinates. Drag to turn it. Height chart in nanometers, ruled every 0.1 nm. The paper this is printed on is tens of thousands of times thicker.

Rap sheet

1. Answering to the name Maxwell's demon (the comparison is in the 2007 paper's own abstract).
2. Biasing: 67 of every 100 rings trapped on the side the catalyst picked, where chance says 50.
3. Shape-shifting: left- or right-handed, depending on where its ring is.
4. Running on fuel: the gate is a chemical reaction, and every closing uses up reagent.
5. An outstanding debt: what every demon owes, kT ln 2 for each bit it forgets.

Answers to

Maxwell’s demon. Unlike the original, needs fuel.

Height

2.2 nm, standing on its axle.

Weight

1.9 zeptograms, ring included.

Topology

A ring on an axle, not bonded to it. Stoppers keep it on.

Habits

Its ring hops between two identical stations, four hydrogen bonds at each.

Marks

Left- or right-handed, depending on where its ring is.

Method

A chiral catalyst shuts a gate behind the ring, sooner on one side. Swap its hand and the bias flips.

First seen

In Maxwell’s 1867 thought experiment. In a flask, 2008.

Last seen

In a colorless crystal at 173 kelvin, in a lab in Scotland.

M.O.

The ring hops between two identical fumaramide stations, four hydrogen bonds at each. A chiral catalyst closes a gate between them, by benzoylating a hydroxyl, faster when the ring is on one side, trapping it there. Swap the catalyst's hand and the bias flips.

Associates

its older sibling, the 2007 light-driven ratchet; a chiral catalyst, the inside man; Maxwell's demon (1867); Landauer's principle (1961)

Priors

A thought experiment in 1867; a light-driven version in 2007; this chemically driven version in 2008, crystallized at 173 K.

of every 100 get trapped on the side the catalyst picked.
Chance says 50. You’ve never seen one.

“Every bit you remember, you'll one day have to forget. That's when the Law collects.” — Keltar, on the case