Dark Matter, demystified

Say you’re up in space looking down at the night-side of earth. Due to a few quirks of orbital velocities, you only get to look at earth’s night-side, perfectly eclipsing the sun forever.

It could happen.

With the naked eye, you can make out lit-up areas on earth and see how they change with time. You nail down the rotation of the earth with no problem. Axial tilt too. Sure.

We’re ignoring the rest of space for the instant, but you’ll see it makes no difference in this example.

You have materials and know-how, however. You make telescopes. It takes you no time to start making out that the bright smears you’re seeing are made up of lots of tiny little lights.

Your scopes get bigger and tighter, and you figure out spectroscopy. Pretty soon you can make out manufacturer labels on the lightbulbs. You work out LEDs. The spectral lines of incandescent tungsten are no stranger to you. Mercury vapor? Sodium? Neon? Carbon arc? Child’s play. Lightning? Bonfires in people’s back yards? Absolutely. Combustion, incandescence, fluorescence, laser emissions—and eventually you can throw in radio, microwaves, X-rays … you can see and catalog every single antenna and cell tower and their emissions. You’ve discovered mirrors down here and you use the knowledge to improve your telescopes. Eventually you can make out, by carefully blocking out the glare of the bulbs, little illuminated patches of ground, of pavements, of rooftops….

You know it all now, right?

Not a chance. You don’t know about anything in houses or underground. You don’t know about whales or anything that lives in jungles. You’d only know a giraffe if it was on fire. Obviously there’s something about mountaintops and glaciers and the middles of oceans that repel lightbulbs. But yeah, you know everything about light there is to know.

That, my friends, explains Dark Matter. Feel free to take the capital letters off at any time.


January 23, 2007 · by xalieri · Posted in Everything Else  


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