# Operational knowledge

A few days ago in my computer graphics class at NYU, I was talking about why we can often get away with assuming that light rays are parallel. It’s because we are used to seeing things lit by the Sun, and the Sun is so far away that its rays are extremely close to parallel.

In the spirit of class participation, I introduced the topic by asking the 30 students in the class how far away the Sun is from the Earth. “Can someone tell me?” I asked.

One student volunteered that it takes 8 minutes from the light from the Sun to reach the Earth. To her credit, that was correct. To get the distance to the Sun from that, you would just need to multiply 186,300 miles per second times 60 seconds per minute times 8 minutes. But I was still hoping somebody would give me a direct answer.

Finally, after another minute or so of silence, another student piped up. “Google says about 93 million miles,” she said.

In that moment I became very sad. I tried to explain to the class the enormous difference between factoids and actual operational knowledge.

Now I worry that this is generational. Are we getting a crop of students who are being discouraged from having working operational knowledge? Is Google inadvertently destroying a generation of thinkers and potential innovators?

Frankly I am worried.

## 4 thoughts on “Operational knowledge”

1. I’m surprised nobody popped up with the trivial answer: “one AU”

Ha ha, that’s a funny idea!

I suspect that anyone who knows the term “Astronomical Unit” would also know the answer to the question I asked.

One person’s factoid is another person’s operational knowledge, and vice versa.

In California, when you ask how far away something is, the answer is invariably given in units of time, accounting not only for the distance and assumed mode of travel, but also for the most efficient route and the usual traffic delays. That’s operational knowledge to a Californian.

To a pre-digital photographer, the sun and the moon are both about 1 mm in diameter on a 35 mm slide or negative, assuming a standard lens. The distance is “infinity” according to the focus ring on the lens. That’s operational knowledge.

To a radio operator, the 8-minute answer may be the most useful operational knowledge.

To a spacecraft engineer plotting a slingshot maneuver, the distance is probably in meters rather miles, with error bars. It’s probably the result of a numerical integration along a flight path over time for a specific launch window as the sun and earth drift closer and farther apart due to the slight eccentricity of earth’s orbit. Knowing which factors are significant is operational knowledge. Calling up the values from a computing device is pretty much expected.