Linked from

The 14 pages that link to Scale factor, each with the reason it gives.

• Cosmological principleBroader topic: It tracks expansion once large-scale uniformity reduces cosmic evolution to one function of time.

• Friedmann equationsRelated: Its time evolution is the central quantity governed by the equations.

• Hubble's lawRelated: It describes expansion dynamically, whereas Hubble’s law gives a velocity–distance relation at an epoch.

• Comoving distanceRelated: Comoving coordinates stay fixed as this factor changes.

• Alexander FriedmannRelated: Its evolution distinguishes Friedmann’s expanding and contracting solutions.

• Hubble parameterRelated: The Hubble parameter is the scale factor’s time derivative divided by the scale factor itself.

• Accelerating expansion of the universeBroader topic: Its second time derivative distinguishes accelerated from decelerated expansion.

• Cosmological horizonRelated: Its history determines how far light can travel and whether an event horizon exists.

• Particle horizonRelated: Its history determines how far a signal could travel while space expanded.

• Horizon problemRelated: Its evolution determines how the observable horizon grew relative to cosmic distances.

• Flatness problemRelated: Curvature’s influence relative to expansion depends on how the scale factor evolves.

• Expansion of the UniverseRelated: Its growth directly represents the expansion of cosmic distances.

• Photon epochRelated: Its growth describes the expansion that diluted radiation faster than matter.

• Comoving and proper distancesRelated: Multiplying comoving distance by the scale factor gives proper distance at that time.