Goin' FastReally, super, duper, extra fast — twenty measured speeds from the ground under the house to light itself, what each one costs, and where the ceilin' is.
The whole thing, dirt simple
1. Fast is always fast compared to somethin'. Pick the somethin' first.
2. Holdin' a speed is free. Changin' it costs.
3. Air fights back harder the faster you go — a lot harder.
4. Orbit ain't up. Orbit is sideways, fast enough to keep missin' the ground.
5. There is a top speed. Light. 299,792,458 metres a second.
6. Get near it and your speed quits climbin' — your watch slows down instead. That part is measured, not argued.
That is the whole page. The rest is the fun part.
Fast ain't a thing you own. It's a thing you are, compared to somethin' else. Set still on the porch with a glass of tea and you are already doin' 465.101 m/s on the spin of the Earth[15] — 1,040 mph, out at the equator — and 29,780 m/s around the Sun, and about 230 kilometres every second around the middle of the galaxy. The tea does not slosh. Nothin' hurts. Y'all been haulin' this whole time.
That is the first thing about speed and it is the thing that trips people up: a speed is measured against somethin', and you get to pick. The trooper picks the road. The bird picks the air. The physicist picks whatever makes the arithmetic shortest.
Speed is free. It's the changin' of it that costs.
Sittin' at 29,780 metres a second costs nothin' — no fuel, no noise, no wind in your hair. What costs is gettin' from one speed to another, and what you have to shove out of the way while you do it. Three bills come due, in this order:
The three bills
Air. Push through it twice as fast and it pushes back four times as hard, and you spend eight times the horsepower doin' it. The cube law is why your truck drinks at eighty.
Ground. To quit fallin' on it you have to go sideways fast enough to keep missin' it — 7,661.31 m/s at the height the space station flies. Orbit is not up. Orbit is sideways.
The ceilin'. There is one, it is 299,792,458 metres a second, and it does not haggle. Past a certain point the speed stops goin' up and your watch starts goin' slow instead. Here is what that costs.
Start here
The ladder
Twenty speeds, smallest to biggest, each one with the arithmetic and who measured it. Snail to light.
The crack of the whip
Why a bullwhip pops, why thunder lags, and why the sound barrier was never a wall — it was your own racket pilin' up in front of you.
The air tax
19 horsepower at sixty, 45 at eighty, to shove the same truck-shaped hole through the same still air.
Fallin' and missin'
Newton put a cannon on a mountain in 1728 and explained satellites a quarter thousand years before there were any.
The ceilin'
Two trucks doin' three-quarters light speed, head on, close at 0.96c. Not 1.5. Here is why, and what it does to a watch.
Things that cheat
A shadow on the barn wall can outrun light and break no rule at all. Five of these, and what is moving in each.
The reckoner
Four calculators. How fast you are goin' settin' still, what the air costs, how two speeds add, how slow your watch runs.