Half-life is a term used in various scientific fields, most commonly in physics and chemistry, to describe the time it takes for half of a substance to decay or be eliminated. Here are some contexts in which half-life is used: 1. **Radioactive Decay**: In the context of radioactive materials, half-life is the time required for half of the radioactive atoms in a sample to decay into a different element or isotope.
The half-life of radioactive decay, which as discovered a few years before quantum mechanics was discovered and matured, was a major mystery. Why do some nuclei fission in apparently random fashion, while others don't? How is the state of different nuclei different from one another? This is mentioned in Inward Bound by Abraham Pais (1988) Chapter 6.e Why a half-life?
The term also sees use in other areas, notably biology, where e.g. RNAs spontaneously decay as part of the cell's control system, see e.g. mentions in E. Coli Whole Cell Model by Covert Lab.
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