Serious Units Fables: mass and momentum

Part 13 — Neon Lights Planet

In a dream you are in orbit over the night side of a chrome and black leather-upholstered planet, lit by neon lights. You tumble slowly through the dream air, holding in one hand a remote that controls the planet's accessories. According to the user's manual, if you want to change the direction of your orbit you should press the orange button on the remote. Then somewhere ahead of you a lustrous metal pod will slowly open to reveal a trampoline. This, according to the manual, will then tilt up vertically, intercepting and reflecting you into a new surface-skimming orbit aimed in some other direction.

You find that you can control the lights along the way with your remote. Some tubes must contain other gases besides neon, because you can make them glow with other colors than red. A lot of the tubes shine green and a lot purple. The planet's dream air is chilly.

There are billboards on this planet — even more than on previous ones — but it never seems possible to read them. Most seem to be advertising novel styles of body piercing and metal jewelery. The signs are unlit and always seem to be in shadow. At the hotel someone told you they measure mass in talents on this planet—a thousand ounce unit which also happens to equal a billion times the mite-sized natural mass.

You see other people in orbit turning trampoline corners — mops of oddly colored hair flopping as they change direction. It is always the same story: Someone in orbit approaches a silvery metal bulge in the planet's surface, a pod opens; a trampoline rises vertical as if on edge, the orbiter bounces and is suddenly traveling in a new direction. Then, as the reflector retracts into the metal bulge again, a billboard (one of the few kinds you can read here) flashes:

Surface orbit speed on this planet is a tenth of a mile per minute. Your mass is ____ talents. Your momentum is ____ talent mileperminute.

More jargon! Talent of mass, mile per minute of speed, and now a unit of momentum? Enough of these artificial units. Why not translate everything into nature's own terms? Get real, you say to yourself, this planet's skimspeed is simply 10 billionths of the speed of light, and a talent of mass? Simply a billion times the natural unit.

After flying a while you begin to feel chilly and realize that you have no clothes on. What a nuisance! Just the kind of thing that is always happening in dreams! It's time to return to the hotel and find your pyjamas. So you decide to press the orange button and get reflected. A metal bulge ahead of you opens and there, rising vertically before you and facing you directly like a black mirror, is the trampoline. As you sommersault into it and bounce off again, a billboard to one side flashes (apparently the trampoline has sensed your momentum as you bounced):

Surface orbit speed on this planet is a tenth of a mile per minute. Your mass is 4 talents. Just multiply. Your momentum is 4 tenths of a unit.

At least it would be if your mass is the same as mine. My mass, I know, is very close to 4 billion of the universe's unit. Maybe this dream didn't happen to you but happened to me instead? Or is your mass the same as mine? That's the trouble with mass — it's so individual that it can disturb the illusion of sharing a dream.