Field notes · Nº 21 2 min read Judgment

Grace Hopper handed out nanoseconds.

By Pallav Sharma · Co-founder & CTO
On a dark background, a field of countless faint specks fills the frame. In a quiet clearing at its centre lies one straight gold length of wire, with an architectural dimension line above it reading '11.8 in'. Labels: 'A billionth of a second' and 'One nanosecond'. Headline: 'Clarity is a hard idea you can hold.' Pallav Sharma, www.pallavsharma.com.

Each was a piece of wire 11.8 inches long: the distance light travels in a billionth of a second.

A billionth of a second is beyond imagining. A length of wire fits in a hand.

Her listeners left holding the reason a fast computer has to be small. I count that wire among the great explanations.

Clarity is a hard idea you can hold.

What is the clearest explanation anyone has ever handed you?

Going deeper

Grace Hopper spent her working life bringing computers closer to the people who used them. Her early compiler translated mathematical notation into machine code, and her work shaped COBOL, a business language still in use today. Yet the object most people remember her by is a piece of wire.

When people asked her why communication by satellite took so long, she could have answered with a figure. A billionth of a second is a number nobody can picture, so she gave it a length instead: stiff wire, 11.8 inches, the distance light travels in that time. She called each piece a nanosecond and handed them out at her talks. Later she used the same wires to show why computers had to be small to be fast: every inch a signal travels costs time.

What I love about the wire is that it gives nothing away. The physics is exactly as true as before. Only its shape has changed, from something a listener has to take on trust into something a listener can feel, carry home and reason with.

That is what complete command of an idea looks like. Understanding a thing well enough to use it is common. Understanding it well enough to hand it to a stranger, intact, in a form that fits in a pocket, is rare, and it tends to come with generosity and a sense of humour. Hopper had all three, and the wire carries every one of them.

A bundle of her nanoseconds is now in the Smithsonian’s National Museum of American History: a billionth of a second, kept behind glass.

The finest explanations do not ask to be remembered. They are simply impossible to forget.

Sources

Linda Hall Library: Scientist of the Day, Grace Hopper · Open Culture: Grace Hopper shows how to visualize a nanosecond (1983) · Smithsonian: Nanoseconds associated with Grace Hopper · Wikipedia: Grace Hopper