On Expanding - Cosmological Expansion · Dark Energy the Cosmological Constant Λ

Do you remember the first line they taught you in school? This lyric-philosophical essay begins with y = mx + b and finds it standing up as Hubble's law, then follows the expansion of the universe through its tangents, its bend, and its inflection some five or six billion years ago, when the energy of empty space began to set the pace. Read alongside its companion essay on gravity, it holds a single picture: gravity is coherence holding close, and bound things — atoms, planets, galaxies — take no part in the expansion, while the expansion itself is reach. The essay corrects a common picture of dark energy (negative pressure is a tension, and acceleration comes from pressure's own weight in general relativity), traces Λ from Einstein's static universe to Lemaître's vacuum energy, and sets the framework's floor beneath the reading beside it as a resemblance, not an identity — a floor the author calls grace, as what remains. It states plainly that a person's share of a crowded room thins, though the line for what a person lives holds no term for the room's size, and closes on the far-future horizon past which the universe's history will no longer be legible.