This would be a really hard key to keep track of.
A group of scientists out of Israel have announced the creation of a keypad lock the size of a molecule. That’s not a million molecules or even a thousand or a hundred. That’s just one. Very small indeed.
So this one-molecule sized lock is of the plain old-fashioned keypad variety, which you can program to accept just one combination. The combination is, of course, a chemical one, but the lock still won’t open if you don’t do all the right things.
The lock itself is a combination of three things: our little acidic molecule, an alkaline compound, and ultraviolet light. Expose the molecule to the compound and the light and it will glow blue. Do it again, in the exact same order with the exact same measurements, no more than three minutes later and the thing glows green. Any deviation from those instructions will produce nothing and the lock will remain closed. If you do everything right, however, you’ll “unlock” the molecule, creating a chemical reaction.
Sound a little far-fetched? Well, in principle, it’s the same idea as an ATM, which won’t do a thing unless you input the correct code in the correct order. And, as anyone who has gotten the first three numbers of an ATM code but somehow forgotten that last number can attest, you have a time limit as well.
This kind of ATM is on the molecular level, so it’s tiny, tiny, tiny. But put a whole bunch of those molecules together and you have a big version of this underlying principle. The use of chemicals and light wasn’t an accident: The scientists hope to use the same sort of molecular lock to help determine when the body is exposed to certain chemicals, like nerve gas.