Who decides how long a second is? - John Kitching

Discover how scientists developed atomic clocks, which use the vibrations of atoms to measure and maintain a globally consistent time.

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In 1967, researchers gathered to answer a long-running scientific question: just how long is a second? It might seem obvious at first. A second is the tick of a clock, the swing of a pendulum, the time it takes to count to one. But how precise are those measurements? And what is that length based on? John Kitching digs into how we scientifically define this fundamental unit of time.

Lesson by John Kitching, directed by Tjoff Koong.

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[abbyf]

This is what Ted-Ed is for: answering random questions you’ve always wondered about.

[Kenjinu]

The only person who decides how long Is a second is our parents counting down from 10 to clean our rooms

[XEinstein]

As an engineer I wonder: how the heck did engineers in the sixties make a device that apparently was able to count something more than 9 billion times in one second. 🤯

[essee]

The Mahabharat written in 400 BCE defines the smallest unit of time as the wink of an eye. Surya Siddhanta, the Sanskrit Text on Astronomy written a century later clearly defines the smallest units of time from 1 breath (inhale-exhale of 4 sec) to hour, days, months, year, century. Quite fascinating.

[glorysky]

"Who decides how long a second is?"
Me: Mississippi.

[omarhanif]

It's strange to think that something so obvious like a second wasn't even a thing years ago. It makes me wonder...

[beactivebehappy]

This is how I want everything to be taught in schools. Not the other way around. Like telling first, we have Cs-atomic clocks and then justifying it.

"The best explanations of human phenomena lie in story-telling and not justifications." - me

[noyn]

This question has been on my mind for far too long. Now i finally have a SECOND to look it up

[mala]

This is the definition of “I don’t need sleep I need answers”

[ead]

*Why does this channel know the questions I want to ask before I ask them?*

[brianking]

These videos are incredible. The animation and narration, plus the way the science is distilled and easier to understand makes these such a valuable resource.

[JustyRBLX]

TED-Ed is the best. It answers all questions you've always wondered about, but never found an exact answer to it. Keep the good work, you help people!

[Mswordx]

"With precision that's _second_ to none." We all saw what you did there.

[gajendrasonare]

Fun fact: second is called second because it is second division of an hour. i.e
1second = ((1/60)/60) hour

[neonWHALE]

I love these videos, they are simultaneously educational and relaxing; it is certain that they will either teach me something or send me to sleep, depending on which I need more at the time.

[AnkitYadav-ilfo]

Wow, what a work this channel is doing, I am so emotional by it's work. I would like to give a special thank to them for spreading free knowledge to us. Thank you so much

[MeekOmni]

I like how the intro turns on the thinking machine in our head

[captainvane]

And later on we discovered - Every 60 seconds in Africa a minute passes.

[pathikdesai]

This used to be my question as child. Thank you for answering. Ted Ed is a great initiative. Keep up the good work.

[esmirspace]

Sometimes I wonder how good schools could be if they incorporated YouTube as a main source of teaching. So many bad teachers distracted me from learning in the past .If I could use my own mentors here, I would never be bored.There would be no pressure of bad grades, lame books, lame definitions and forced learning word by word...Learning should be fun, not strict...Same goes for testing...Appreciated the smart people that figured these things out, and I'm thankful for pasionated educators who are so underrated and smart of course.