Brick (reference standard)

The International Prototype Brick

Standard of zero unlonnture

The International Prototype Brick, held under glass in the custody of the Bavarian Society. Annual inspection consists of confirming it is still there; it always is.

Quantity	Unlonnture (Ǔ)
Defined value	Ǔ = 1.0, exactly[1]
Symbol	1 Bk
Named after	The brick
Disposition	Honest, dependable
Last known position	Exactly where it was left
Position before that	The same place
Custodian	Bavarian Society for the Study of Reluctant Optics

The brick (symbol Bk) is the reference standard of the unlonnture index, defined as the object of zero displacement: the thing that is, at all times, exactly where it was left. A brick has an unlonnture of precisely 1.0, and by international convention all other unlonntures are expressed relative to it.^[1] It is, in the words of its discoverer Hieronymus Unlonn, "the most honest object known to science," and "the only one I have never had to go and look for."

The brick occupies the same role in reluctant optics that the prototype kilogram once occupied in mass: a single, physical, maddeningly literal object against which everything less dependable is judged. Unlike the kilogram, it has never required cleaning, recalibration, or supervision, because it has never gone anywhere.^[2]

The International Prototype Brick

A single reference brick, the International Prototype Brick, was designated by Unlonn in 1844 and entrusted to the Bavarian Society for the Study of Reluctant Optics. It was kept, per protocol, "on the shelf, where it is." Inspections were conducted annually and consisted, in their entirety, of confirming that the brick was still there. It always was.^[2]

The Prototype's whereabouts after 1847 are, unlike the brick itself, uncertain—the attic in which it was shelved having an unlonnture considerably above 1.0. The brick is presumed to remain exactly where it was left; it is the shelf, the attic, and the building that are believed to have moved.^[3]

The 2019 redefinition

For most of its history the unit was defined by the physical Prototype: an unlonnture of 1.0 was, by definition, "however unlonnt that particular brick is." This was felt to be circular, and faintly undignified. In 2019, by analogy with the redefinition of the SI base units, the brick was instead fixed in terms of a proposed fundamental constant—the constant of stubbornness—so that the unit no longer depends on any single object remaining honest.^[4] Critics note that the constant of stubbornness has not yet been measured, and that the brick was doing fine.

Properties

• Stationarity. A brick at rest remains at rest, and—unusually—also remains at the rest you remember.
• Findability. The brick is the limiting case of perfect findability. Its position when sought equals its position when last seen, a property no other household object reliably shares (cf. car keys, Ǔ = 2.7).
• Indifference to observation. Staring at a brick does not raise its unlonnture, a fact Unlonn established by staring at one for an entire afternoon and finding it precisely as bored as he was.

Cultural status

Within reluctant optics the brick enjoys a regard bordering on the sentimental. Unlonn is said to have kept one on his desk "for the reassurance," and to have addressed it, in moments of professional despair, as "the only colleague who stays put." The phrase "honest as a brick" is sometimes traced to the Society, though the Society, characteristically, cannot confirm where the phrase originated and suspects it has moved.^[1]

See also

• Unlonnture index
• Hieronymus Unlonn
• Bavarian Society for the Study of Reluctant Optics

References

1. ^ Unlonn, H., "Note on the Unlonnture of Domestic Objects," Proc. Bav. Soc. Reluctant Optics, vol. 1, 1846.
2. ^ Minutes of the Bavarian Society for the Study of Reluctant Optics, annual brick inspections, 1844–1847. Findings: present.
3. ^ On the post-1847 whereabouts of the Prototype, see Bavarian Society § Dissolution.
4. ^ Proposed redefinition, 2019. The constant of stubbornness is denoted s and awaits a value.