Foundations

An inverse-square force models attraction between point masses.

Rock materials can change through multiple geological pathways.

Moving lithospheric plates organize many large-scale geological processes.

Water moves among reservoirs above, on and below Earth's surface.

Carbon moves through biological, oceanic, atmospheric and geological reservoirs.

Earth's energy storage changes when incoming and outgoing energy differ.

Infrared absorption and emission affect how Earth loses heat to space.

Weather describes short-term conditions; climate describes their longer-term patterns.

An orbiting body can remain in continuous gravitational free fall.

Main-sequence stars release energy by fusing hydrogen into helium.

Expansion and relic radiation support an earlier hot, dense Universe.

Homogeneity and isotropy reduce gravitational expansion to two balances.

A bound nucleus has less rest mass than its separated nucleons.

A fixed decay probability per time gives a population timescale.

Nuclear rearrangement can release or require energy.

Mineral identification combines structural and physical evidence.

Isotopic measurements estimate an age only with a suitable geological model.

Wave travel, refraction and transmission constrain an interior model.

Fluid motion in the outer core maintains much of Earth's magnetic field.

A defined area's water storage changes with total inflow and outflow.

Groundwater flow is often approximately linear in hydraulic-head gradient.

Wind, buoyancy changes and mixing contribute to ocean transport.

Unequal heating and rotation organize broad circulation patterns.

External changes can disturb climate's radiation budget.

Climate responses can amplify or damp a change.

Attribution compares observed changes with plausible drivers and variability.

Stellar structure changes as core fuel and conditions change.

Different evolutionary outcomes leave different compact remnants.

Changing observing position permits geometric distance inference.

Spectral stretching carries expansion information but is not one universal distance ruler.