The kilogram is the unit of mass; it is equal to the mass of the International Prototype of the Kilogram.
—the Third General Conference on Weights and Measures, 1901
Her polished body does not
weigh a kilogram. She is the kilogram,
definitive artefact (nine parts platinum,
one part iridium) that rests
in a darkened Paris vault
beneath three nested bell jars.
She does not weigh fifty-three
millionths of the total steel
used to erect the Sydney Harbour Bridge,
nor does she weigh three times as much
as the average human heart—
these and all else take their measure
from her cylindrical precision.
declares her eternal,
immutable arbiter of mass
that shall never know the indignity
of any gain or loss.
Unbreakable law gives her the right
to remain the kilo
even should she fluctuate—
a laughable prospect
on the day she was set
so immaculately in place.
But very real is the minute
yet significant decline
proclaimed by the balance
at scheduled unveilings
(perhaps the very source
of her deterioration)
when she’s weighed against
six true and perfect daughters
cast in gleaming exactitude
for this task alone.
Lost across a life of more than a century
is only a dust-speck’s amount of her matter,
so little of something as to be nothing.
But as she diminishes by any degree,
the universe puts on weight.