The sun radiates about four hundred trillion trillion watts. Everything humanity has ever built, lit, moved, computed or fought over runs on around twenty trillion — so the sun emits roughly twenty trillion times our total use, every second, almost all of it pouring into the dark. Capture one part in a hundred thousand — a rounding error of a rounding error — and you command about two hundred million times the energy of present civilization. Dyson pointed out in 1960 that a mature species should be expected to do exactly this: not a solid shell but a swarm of collectors. We now know how the swarm starts — solar-power satellites and orbital data centers, built from the moon and the asteroids, which sit at the top of Earth's gravity well holding prefabricated construction material and free vacuum. No new physics appears anywhere in this paragraph. It is launch costs, robotics, and patience.
Compare the other direction. Starflight is not forbidden, but physics prices it without mercy: one kilogram to a tenth of light speed costs a small city's year of energy, the destination is decades away, and the freight of your civilization's meaning is reduced to the payload. A solar collector starts paying the moment it unfolds and never stops. Which raises the question the essay actually cares about: when energy and computation become effectively unlimited, what does a civilization buy with them? The next chapter suggests every civilization before us already answered.
Show the engineering error — a physical reason sun, moon and asteroids cannot yield this energy and computation — and chapters five through seven fall together.