Terms - Moral’s Mark

The memos explain each term where it first appears, so nothing here is required reading. This page is for checking one you have met before, or for arriving in the middle of the series from a search result.

A term means the same thing on every page of the series. Where the precise definition differs from the everyday one, the everyday one is given here and the precise one is in the memo that needs it.

The medium

Aether: The substance filling all space. One kind of particle, packed everywhere, which light travels through and which matter is built from.
Aetheron: The single particle the Aether is made of. One mass, one size, one magnetic strength — every one identical to every other.
Lattice: The regular three-dimensional arrangement the Aetherons settle into, like atoms in a crystal. Its spacing is the one number in this framework still unknown.
The void: Empty space itself — the bare fact that there is somewhere for things to be. It has no properties and nothing can be done to it. Distinct from the Aether, which fills it.
Free lattice: Aether that is not bound inside matter. The medium between and around atoms, at roughly its natural density.
Trapped Aether: Aether held inside matter as part of its structure, at several times the density of the free lattice. Released only when the structure breaks.

Stiffness and springs

Shear stiffness: How hard a material resists being pushed sideways — one layer sliding over another. Fluids have none, which is why they cannot carry sideways waves.
Squeeze stiffness: How hard a material resists being compressed from all sides. Water has a lot; air has very little.
Bulge ratio: How much a material bulges sideways when you squeeze it. Rubber bulges a lot, cork almost none. Fixed at exactly one quarter for the Aether.
Central force: A push or pull acting straight along the line between two particles. Featureless balls can only manage this, because they have no sides to push from.
The Cauchy relation: A result from the 1820s: for identical balls on simple springs, the two stiffnesses are not independent. Their ratio is fixed by geometry alone.

Waves and light

Sideways wave: A wave where the material moves across the direction of travel, like a shaken rope. Light is one. Needs shear stiffness, so only solids carry them.
Squeeze wave: A wave where the material moves the same way the wave goes, like sound in air. Always faster than the sideways wave in the same material.
Polarisation: The orientation of a sideways wave — whether the rope is shaken up-and-down or left-and-right. Polarised sunglasses block one and pass the other. A squeeze wave cannot have it.
Refractive index: How much slower light travels in a material than in empty space. Water is 1.33, diamond 2.42. In this framework it reads the Aether density directly.
Dispersion: When waves of different wavelengths travel at different speeds. A prism splitting white light is dispersion. A lattice causes it for waves short enough to feel its grain.

Gravity and space

The metric: The set of measured relationships between events — how far apart, how long between. What physicists mean when they say spacetime is curved.
Coordinates: The labelling we impose to say where things are, like latitude lines on a map. Can be changed at will without changing anything physical.
General covariance: The requirement that physics comes out the same whichever coordinates you choose. A standard feature of general relativity, and the reason coordinates carry no physical content.
Gamma: The standard measure of how much space curvature a mass produces. Zero means gravity bends light without curving space; one is general relativity. Measured at 1.000021.
The flowing form: A way of writing the Schwarzschild solution, published 1921, in which space is flat and the medium flows inward at escape velocity. Mathematically identical to the usual form.
Pseudotensor: A near-miss substitute for an energy density. General relativity has no proper energy density for the gravitational field, only these — and they can be made to vanish by choosing coordinates.
G: Newton’s gravitational constant, the number setting how strong gravity is. Measured since Cavendish, explained by nobody, and the worst-known constant in physics.

Matter and particles

Magnetic moment: How strong a magnet something is. A circulating electric charge produces one, which is why a current loop behaves like a bar magnet.
Nuclear magneton: The natural unit for measuring the magnetism of nuclear particles, the way a metre is the natural unit for a room.
Spin: The angular momentum a particle carries in its own right, as distinct from motion in an orbit. Every neutron has exactly the same amount.
Mass excess: How much heavier something is than the sum of its parts. A neutron is 0.78 MeV heavier than a proton plus an electron, and that difference has to be accounted for.
Binding energy: The energy released when parts lock together, showing up as a reduction in total weight. In this framework it is Aether expelled rather than mass converted.
Hoop force: The outward push a current loop exerts on itself, trying to burst itself open. The same effect that makes a spinning hoop want to fly apart.
Femtometre (fm): A millionth of a billionth of a metre. A proton is about 0.84 of one across.
MeV: A unit of energy used for particles. A proton weighs 938 of them; the energy holding an atom’s electron in place is about 0.0000136.

Other terms

The Casimir effect: Two uncharged plates in a vacuum attract each other. Measured since 1997, and direct evidence that empty space is not empty.
Micropolar: A material whose particles can turn on the spot, not merely move. Gives it a stiffness against twisting that ordinary materials lack.
Parts per million (ppm): One in a million. Used for small fractional differences — a 552 ppm disagreement means the values differ in the fourth significant figure.