minute
mintime · International · Mixed
1 minute = exactly 60 s.
Converter
time · International · Modern
second
sexact
- Record
- M018
- Definition quality
- Standardized
- Conversion mode
- multiplicative
- Calculator
- Fully calculable
None identified for current SI definition; name etymology not researched in this batch.
Definition
SI base unit of time. The caesium-133 hyperfine transition frequency is fixed exactly at 9,192,631,770 Hz.
Reference value
One second is equal to 1 second.
History & use
The second was historically treated as 1/86,400 of a mean solar day. In 1967 it was redefined using a caesium-133 atomic transition.
Modern use
International SI base unit for time and the foundation for frequency and many derived SI quantities.
Did you know?
Modern timekeeping defines the second from more than nine billion cycles of a specific caesium-133 transition.
Sources & evidence
Source tier Tier A · confidence High
- Definition Source — https://www.bipm.org/en/measurement-units/si-defining-constants
- History Source — https://www.nist.gov/nist-museum/defining-international-system-units-si
- Modern Use Source — https://www.bipm.org/en/measurement-units/si-base-units
- Trivia Source — https://www.nist.gov/si-redefinition/definitions-si-base-units
Related measurements
hour
htime · International · Mixed
1 hour = exactly 3600 s.
day
dtime · International · Mixed
1 day = exactly 86,400 s for unit-conversion purposes.
week
wktime · International · Mixed
1 week = 7 days = 604,800 s when used as a fixed duration.
shake
shaketime · International · Mixed
One shake = 10 nanoseconds = 10^-8 s.
informaltime · International · Mixed
Documented physics usage: light-travel time over 1 cm; other jiffy meanings exist.
approx.informaltime · International · Mixed
Planck time, 2022 CODATA: 5.391247(60)×10^-44 s.
approx.time · International · Mixed
Based on July 21–31, 2017 tenure; Scaramucci himself uses 11 days as the unit.
informal