time · International · Modern
SI base unit of time. The caesium-133 hyperfine transition frequency is fixed exactly at 9,192,631,770 Hz.
Converter
time · International · Mixed
Planck time
tPapprox.
- Record
- M298
- Definition quality
- Approximate
- Conversion mode
- multiplicative
- Calculator
- Approximately calculable
Definition
Planck time, 2022 CODATA: 5.391247(60)×10^-44 s.
Reference value
One Planck time is understood to be about 5.391247 × 10^-44 seconds.
History & use
A natural-unit timescale formed from fundamental constants rather than a human-scale measuring convention.
Modern use
Used in theoretical physics and quantum-gravity discussions.
Did you know?
Its SI value is not exact because it depends on the measured Newtonian gravitational constant G.
Sources & evidence
Source tier Tier A · confidence High
Related measurements
minute
mintime · International · Mixed
1 minute = exactly 60 s.
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
Based on July 21–31, 2017 tenure; Scaramucci himself uses 11 days as the unit.
informal