Why does your phone change its clock for daylight saving time but your microwave doesn’t? Pause and guess. Your phone asks the network for the time and carries the rules for every time zone, so it switches by itself. Your microwave has no one to ask: you reset it by hand.
Which clock in your house is still an hour off?
Watch next: Why Is Microwaved Food Still Frozen in the Middle?
0:00 Your phone asks the network
0:11 2 a.m. becomes 1 a.m.
0:21 The rules for every time zone
0:34 Your microwave has no one to ask
0:42 60 Hz and quartz
0:50 Is that “atomic clock” atomic?
Sources for every claim in the video:
• Daylight saving time ends the first Sunday in November at 2 a.m.: at 2 a.m. it becomes 1 a.m.; many cell phones update automatically: NIST, Local Time FAQs,
• The dates are federal law: 15 U.S. Code § 260a,
• Android gets the time from a network source: internet time servers (NTP) or the carrier’s signal (NITZ), re-checked every 18 hours by default: Android Open Source Project, Time overview, Network time detection,
• Android carries the rules for every time zone (Los Angeles: 7 hours in summer, 8 in winter), and they arrive as updates: Android Open Source Project, Time overview, Time zone rules,
• iPhone: Set Time Automatically sets the date and time based on your time zone: Apple Support,
• A microwave is reset by hand for daylight saving time, and a flashing 0:00 means a power failure: GE Appliances, Whirlpool,
• Many electric clocks count the 60 Hz power line, others a quartz crystal (usually 32,768 Hz): NIST, Time and frequency from electrical power lines, NIST, Timekeeping and clocks FAQs,
• Radio-controlled clocks aren’t really atomic clocks: their radio hears NIST’s WWVB near Fort Collins, Colorado, and they fall back on their own: NIST, Help with WWVB Radio Controlled Clocks,
Music: “Pizzicato” by Ehma (Jamendo), licensed under CC BY 3.0, Sound effects: CC0 from Freesound (Jummit).
Voice is synthetic (text-to-speech).
#daylightsavingtime #howitworks #ohthatshowworks
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