Okay, that's a lot to pay for an AR15, but it's not a lot to pay for the ability to make as many AR15 lowers as you want.
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Reading Betrayer of Worlds and got caught flat-footed in the first twelve pages--I definitely have not read this one before.
Today I was thinking about four-dimensional spacetime manifolds and how what we experience as the force of gravity is just such a phenomenon, and trying to reconcile that with momentum.
I've reasoned that when an object is in motion, its tendency to stay in motion is due to the curvature of spacetime. It takes work to get something moving because you're changing the shape of space, because you have to generate the "tilt" in spacetime that keeps that object moving once you let it go.
But: why doesn't it accelerate? If "tilted" spacetime is the cause of acceleration due to gravity, why doesn't an inertial "tilt" also cause acceleration?
Then it hit me: the object in motion is a single body; the object being accelerated by gravity is interacting with another object. That interaction with another object causes the acceleration; the single body cannot act on itself, so whatever motion it has is all it's going to get.
No, it's not a big revelation or anything. All I really did was think of another way to describe the workings of gravity and momentum--but in terms of four-dimensional manifolds rather than "force", "velocity", "momentum", and so on.
More one cannot ask for.