Equations · equation

Half-Life

Nuclear Physics · 1904

Equation: t½ = ln 2 / λ
Field: Nuclear Physics
Named After: Ernest Rutherford
Symbols: t½ time for half of any sample to decay · λ decay constant · ln 2 ≈ 0.693
Year: 1904

Significance

Every radioactive nuclide has a signature clock: after one half-life, half remains; after ten, a thousandth. Carbon-14's 5,730 years dates archaeology; uranium-238's 4.5 billion years dated the Earth itself.

Minerals

Muscovite Monazite Biotite Zircon

Timeline

Proton Decay, If It Happens

Theories

Grand Unified Theories Nuclear Shell Model

Machines

Radioisotope Thermoelectric Generator Chicago Pile-1 Pressurized Water Reactor

Related

Radioactive Decay Law Chandrasekhar Limit

Requires

Radioactive Decay Law

Elements

Carbon Uranium Rubidium Potassium Plutonium

Referenced by

element

Carbon Plutonium Potassium Rubidium Uranium

equation

Chandrasekhar Limit Radioactive Decay Law

event

Proton Decay, If It Happens

machine

Chicago Pile-1 Pressurized Water Reactor Radioisotope Thermoelectric Generator

theory

Grand Unified Theories Nuclear Shell Model

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From the Equations database in Notion, last edited 2026-08-18. This page is the row, rendered by the build; nothing on it is written by hand.