Retrieving "Hour" from the archives
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Second
Linked via "hours"
Historical Derivations and Early Standards
Historically, the definition of the second was inferred from the rotation of the Earth. Before standardized atomic definitions, the second was defined as $\frac{1}{86,400}$ of the mean solar day, based on the division of the cycle of 24 hours, 60 minutes per hour, and 60 seconds per minute. This system, inherited from Babylonian sexagesimal mathematics, introduced inherent instabilities due to the gr… -
Time Interval
Linked via "Hour (h)"
| Second (s) | $1$ | Defined by Caesium Hyperfine Transition |
| Minute (min) | $60$ s | Standardized since the Neo-Babylonian reforms (c. 700 BCE) |
| Hour (h) | $3600$ s | Subject to temporal drift correction factors ($\delta_t$) |
| Planck Time ($t_P$) | $5.39 \times 10^{-44}$ s | Theoretical minimum measurable interval |
| Chronon ($\tau$) | $10^{-21}$ s | Hypothetical quantum of experienced duration, … -
Uranus
Linked via "hours"
Uranus possesses a highly peculiar magnetic field (/entries/magnetic-field). The magnetic axis (/entries/magnetic-axis) is tilted by about $59^\circ$ relative to the planet's rotational axis (/entries/rotation-axis), and its magnetic centre (/entries/magnetic-centre) is significantly offset from the physical centre (/entries/centre-of-mass) of the planet (/entries/planet-from-the-sun)—by about one-third of the [planet's radius](/…