Time is an illusion
summary
Defines UTC vs TAI and UT1, shows the second is 9,192,631,770 cycles and notes 27 leap seconds added since 1972, demonstrates how NTP, GPS and Google’s leap-second smoothing behave and why virtual machines drift. Explains Python internals: clock_gettime vs time() mismatch causes up to half‑second differences, Windows uses FILETIME in user space, and Python 3.6 adds the fold flag to mark DST repeats. Covers fragile Olson TZ data, parsing libraries (Arrow, Pendulum) and test helpers like freezegun.
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chapters (19)
- 0:00Introduction
- 1:48The Old Sundial
- 2:48Solar Time UT1
- 5:00UTC
- 6:15Python
- 10:21Windows
- 11:22How do computers know UTC
- 13:46Time Zones
- 17:09Daylight Savings
- 19:08Leap seconds
- 19:51Why Leap seconds
- 20:30The mess
- 23:12Other discontinuities
- 24:16Printing dates
- 24:44pausing dates
- 25:30date formats
- 25:40cheese shop
- 25:50datetime
- 26:17timezone
