Here is the video for this topic:
Here are the links for the video:
Calendar changes
Calendar reform: https://en.wikipedia.org/wiki/Calendar_reform
Julian calendar: https://en.wikipedia.org/wiki/Julian_calendar
Leap seconds
What slows down the Earth: https://www.discovermagazine.com/planet-earth/the-earths-rotation-is-gradually-slowing-down
Earth’s spinning faster: https://phys.org/news/2021-01-earth-faster.html
Leap seconds: https://en.wikipedia.org/wiki/Leap_second
A* Star: https://www.a-star.edu.sg/News-and-Events/a-star-tv/discover-science/a-star-tv-episode-13
GNSS affected by bad sync: https://www.spirent.com/blogs/how_leap_seconds_can_interfere_with_gnss_receivers
Stock markets worry about leap second: https://money.cnn.com/2015/06/29/technology/leap-second/
Internet affected by 2012 leap second: https://www.wired.com/2012/07/leap-second-bug-wreaks-havoc-with-java-linux/
Y2K
Y2K: https://en.wikipedia.org/wiki/Year_2000_problem
https://www.nationalgeographic.org/encyclopedia/Y2K-bug/
Accurate clocks
Quartz clocks: https://en.wikipedia.org/wiki/Quartz_clock
Atomic clock: https://en.wikipedia.org/wiki/Atomic_clock
https://www.nasa.gov/feature/jpl/what-is-an-atomic-clock
https://www.smithsonianmag.com/smart-news/new-atomic-clocks-hone-length-second-180977387/
(you can access the nature article through smithsonian if you want)
Kilogram: https://www.nist.gov/si-redefinition/kilogram-present
Metre: https://www.npl.co.uk/si-units/metre
Time.is: https://time.is/
Time zones
Businesses’ need for time zone awareness: https://www.johnkay.com/2016/02/10/the-importance-of-time-zones-to-business-and-londons-competitive-advantage/
Dateline and map:
https://www.timeanddate.com/time/dateline.html
https://www.timeanddate.com/time/map/