half-life
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half-life
In physics and chemistry, the period of time in which half of the atomic nuclei of a radioactive substance decay. It is a measure of the stability of an isotope.
Die Halbwertszeit von Kohlenstoff-14 beträgt etwa 5730 Jahre.
The half-life of carbon-14 is about 5,730 years.
The word is a clear compound of 'halb' (half), 'Wert' (value), and 'Zeit' (time). So it literally describes the time in which something is only worth half as much, or in which half of a quantity remains.
Die Halbwertszeit dieses Medikaments im Körper ist sehr kurz.
The half-life of this medication in the body is very short.
In a scientific context, the half-life is often stated with the verb 'betragen' (to amount to / to be) in order to name an exact duration.
Die Halbwertszeit von Uran-238 beträgt etwa 4,5 Milliarden Jahre.
The half-life of uranium-238 is about 4.5 billion years.
You can recognize the meaning from the context: if it is about physical or chemical substances (e.g., isotopes, medications), the scientific meaning is intended. If it is about abstract things (knowledge, trends, jokes), the figurative meaning is intended.
Die Halbwertszeit eines Witzes ist oft nur wenige Tage.
The half-life of a joke is often only a few days.
In the figurative meaning, the word is often used for things that become outdated quickly. Typical phrases are 'die Halbwertszeit von Wissen' (the half-life of knowledge), 'von Informationen' (of information), 'eines Trends' (of a trend), or 'politischer Versprechen' (of political promises).
In der IT-Branche ist die Halbwertszeit von Fachwissen besonders kurz.
In the IT industry, the half-life of specialist knowledge is especially short.
lifespan
'die Lebensdauer' and 'die Halbwertszeit' both describe how long something exists or remains effective. 'die Lebensdauer' means the entire time during which a person lives or an object works. 'die Halbwertszeit' more specifically means the time in which something drops to half, for example with radioactive substances or figuratively with value, relevance, or usefulness. The words can be confused because both have to do with duration. 'Lebensdauer' fits when talking about the whole useful life. 'Halbwertszeit' fits when the topic is decrease, decay, or loss of effect.
Die Halbwertszeit dieser Nachricht ist kurz, weil morgen schon neue Zahlen kommen.
The half-life of this news story is short because new figures will already come out tomorrow.
Die Lebensdauer der Batterie hängt stark von der Nutzung ab.
The lifespan of the battery depends heavily on how it is used.