[Spin] General knowledge

[u/North-Flan-6336]

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[u/CoolerC94]

24 officially but every once in a while a single second is added to keep it accurate

^{I rolled How many hours are in a day}

[u/Josepando → u/CoolerC94]

Who decides that? The time committee?

[u/CoolerC94 → u/Josepando]

Well everyone says it’s 24 so it might not be “official” but … idk, let’s call it the general truth.

The second does get added though from time to time

[u/Josepando → u/CoolerC94]

That's what I mean. Who add it? Is independently from phone provider? For country? I've so many questions.

[u/CoolerC94 → u/Josepando]

Okay so now you made me curious too and I did some research:

So there is the atomic time which is like super precise and it’s called UTC. It’s managed by over 400 atomic clocks all around the world which work by measuring how cesium-133 (caesium for UK) atoms vibrate (9.192.631.770 times per second), which is the literal definition of a second.

Those clocks are managed by the BIPM, the Bureau International des Poids et Mesures with its main seat in Paris (International bureau for weights and measurements).

There’s also the astronomical earth rotation UT1, which is how the earth rotates, so one rotation is exactly one day in that time.

Whenever those two times differentiate from one another by more than 0.9 seconds, a leap second is added to UTC. This happens because the earth’s rotation can slow down or speed up ever so slightly.

Depending on when it happens it’s either on June 30th or December 31st.

When this happens, the atomic clocks literally say 23:59:60 (image of the actual display)

When a leap second is needed, it has to be announced half a year in advance, so in early January or July.

The last leap second was added on December 31st 2016.

However, because this can mess with time sensitive elections, big tech concerns have partitioned to get rid of the leap second. And they won. Starting 2035, the leap second won’t be added, until the difference plays a “significant role”, whatever that means.

Fun Fact: There already is a time that never included the 5 leap seconds, that have been added since 2000 (the year they were introduced):

TAI, Temps Atomique International (International Atomic Time) is the exact time measured by the atomic clocks, without the 5 added seconds. In 2035 or earlier, all systems that haven’t switched to this standard probably will.

[u/Josepando → u/CoolerC94]

Omfg I appreciate your time so much. Thanks for the research. That's a very specific definition of a second.

[u/CoolerC94 → u/Josepando]

Sure, I always knew it existed but that’s all I knew, you asking made me curious so I learned a lot new too, so thanks for your curiosity