Your Piano Is Deliberately Out of Tune, and It Has Been Since Bach

A perfect fifth is two notes whose frequencies sit in a 3:2 ratio, and it is the most consonant interval there is after the octave. The trouble is arithmetic: stack twelve perfect fifths and you land very slightly past seven octaves, not exactly on them. The gap is small, audible, and impossible to remove without giving something up.

Equal temperament gives up purity. It divides the octave into twelve mathematically identical steps, which leaves every interval except the octave a little narrow or a little wide — the fifth by about two cents — and in exchange every key sounds equally usable. That trade is why a keyboard can play in all twelve keys at all, and why older tunings made some keys luminous and others unusable.

Source: Journal of the Acoustical Society of America

The Post Office That Ran a Bank for Fifty Years

From 1911 to 1967 the United States Postal Savings System held deposits for ordinary Americans at a flat two percent. It was created for an unglamorous reason: immigrants who distrusted private banks were mailing cash home to European postal banks instead, and Congress decided that money should stay in the country.

It died not from failure but from success elsewhere. Federal deposit insurance arrived in 1933 and removed the safety argument, and by the 1960s commercial rates had left the statutory two percent far behind. The system was wound down quietly, and the idea has resurfaced roughly once a decade ever since.

Source: Smithsonian National Postal Museum

Tardigrades Survive Drying Out by Turning Into Glass

The mechanism behind tardigrade desiccation tolerance appears to be vitrification. As water leaves the cell, a family of intrinsically disordered proteins unique to the phylum forms an amorphous, glass-like matrix that physically immobilises everything inside. Nothing moves, so nothing degrades.

The applied interest is obvious. If the same proteins can be made to work in mammalian cells, room-temperature storage of blood products and vaccines becomes conceivable — and cold-chain logistics currently consume an enormous share of what it costs to deliver a vaccine anywhere difficult.

Source: Nature Communications

Why Bread Made With Four Ingredients Keeps Better Than Bread Made With Twenty

Sourdough’s keeping quality is not nostalgia. A long fermentation drops the dough’s pH far enough to slow the moulds that spoil bread, and the lactic acid bacteria doing the work produce compounds that inhibit them directly. The loaf stales more slowly too, because the acid interferes with how starch recrystallises.

Industrial bread solves the same problem from the other end, with preservatives and emulsifiers, because a two-hour process cannot produce what a twelve-hour one does. Neither approach is a trick. They are two different answers to the question of what stops a loaf going off.

Source: Journal of Cereal Science