Saturday, September 19, 2009

Small screen? How numerologist of you!

A friend asked me how I could watch movies on my 15" laptop screen. Why don't I connect it to my [old, CRT] 27" TV? My answer: Because the movie on the 15" laptop is much larger than on the 27" TV!

"Surely you jest. It can't be," explodes the interlocutor.

Yes, it is. The laptop sits about 50cm from me, the TV about 3.5m. So the laptop covers approximately the same fraction of my visual field as a TV seven times as large, or about 105". Since I watch both from the same slouchy bad posture on my overstuffed couch, the laptop is better. (Yes, it is linear to a first approximation; it's a simple homothetic projection with my eyes as the center.)

Talking about numbers without understanding their meaning is one of the afflictions of the modern-day citizen/consumer/audience/manager. Unthinking reactions to magnitudes (27 vs 15) without context (that the TV is much farther from my eyes than the computer screen) are common and the source of much dismay [when they affect me] or amusement [when they don't].

It's like a new form of numerology, where people use numbers as magic wands -- understanding of the underlying reality considered unnecessary. I have used the BMI as my bĂȘte noire and preferred example to motivate students about the follies of neonumerology, but I think that from now on I'll use this even simpler example first.

Numbers mean things. The things are what matters.