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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This is what Ted-Ed is for: answering random questions you’ve always wondered about.
its for answering random questions i've never wondered about until they've asked it and I think "huh, that's a good question"
Or rather, it's for : answering the questions we don't find answers to in schools because they are 'not quite important'
So why do we need to measure such small chunk of time we will almost neglect it in most part of physics?? I mean since theta is very small sin(theta) = theta to derive pendulum time period...Huh?? Well maybe because of some specific cases like GPS when neglecting difference of arrival of small unit of time can give us inaccurate data of where person is located by factor of thousand miles I guess... 😅😅
@@ishworshrestha3559 Also that sin theta= theta thing is mostly used for exams and theory I guess, while when they are really dealing with real life problems I think they must be using actual value instead most of the time.
Agreed!
The only person who decides how long Is a second is our parents counting down from 10 to clean our rooms
Underrated comment 😂😂
So when it hits 2 everything slows down
definitely 😂
True af
@@skibur848 Parents: ZA WARUDO
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. 🤯
Yes, I'd still like to know how it's done now.
SAME
@@abiryaakovalmoznino3395 computers don’t think for us, they do work instead of us
@@abiryaakovalmoznino3395 Yes they can crunch numbers that would otherwise take far far too long for a human to replicate
@@abiryaakovalmoznino3395 Wait I think I misunderstand your position here. I'm not saying that's all computers can do, but they can assist humans with doing work that is otherwise too tedious or impossible within a reasonable time frame. Obviously they can do more than crunch numbers.
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
That's brilliant quote 👍
@@veen88 you really quoted yourself
You should be a professional quote maker
"Who decides how long a second is?" Me: Mississippi.
i see
1 Mississippi 2 Mississippi 3 Mississippi...
Ross after reading this: *I'm fine*
@Grzegorz Dziedzic what
@Grzegorz Dziedzic what
It's strange to think that something so obvious like a second wasn't even a thing years ago. It makes me wonder...
yeah it is strange but not really as out of the blue. We have the same problem with economy, evolving throughout the time on what we think is useful to us.
Second has been a thing for a long time, it's the precise definition that we lacked. As pointed in the video, they used the formal definition of the second, you know 365.25x24x60x60, to arrive at a reference that's agreed and replicable all over the world. We didn't use the ticking of Cesium electrons to define second, we used the already existing definition of a second to find out how many ticks the Cesium electron makes.
while watching the video I was thinking, from where and when comes the "It will take only a second."?
Honestly, we should stop using our planets version of a second for scientific research. It works adequately enough while humans only colonize Earth, but what are we going to use once humans are living on multiple planets, or even beyond this solar system. Our version of a year/day/hour/minute/and second would seem ridiculous to others not born on Earth, since our measurements of time are based on our planets orbit and rotation around the sun. Future planets colonized by humans would find it difficult to learn and remember, especially if their time measurements are not comparable to ours. I think we should define a universal timescale based off a constant that doesn't favor one planet over another. Perhaps use the time it takes light to travel 100,000,000 meters as a new universal second (almost 1/3 of our current second). That way it will be the same no matter what timescale measurements future planets use, and we can set it to a metric system of base 10 for easier calculations. We will all have a common, accurate measurement to share future research with one another.
Hamad Hamdi nah, let em figure it out when they decide to change planets.
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.
Wow
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.
*Why does this channel know the questions I want to ask before I ask them?*
Because the one who makes this videos already asked themselves in their childhood.
By thinking it all questions get begin *Thinking of a human being can create or destroy the world* *-Albert Einstein*
Haki.
@@vas2.1025 hahaha
Have u asked them a topic before
And later on we discovered - Every 60 seconds in Africa a minute passes.
Together we can stop this
I was waiting for this
😂😂😂
wtf his fingers are the same length
RIP minute.
This question has been on my mind for far too long. Now i finally have a SECOND to look it up
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
This is the definition of “I don’t need sleep I need answers”
oh you sheldon fan !
Ironic... I should be asleep
Yeah lol it's like half past twelve in the morning but I'm watching this
@@stef511 it’s 3 am and I just read your comment
@@mala967 I read this at exactly 02:59 am
"With precision that's _second_ to none." We all saw what you did there.
I didn't...
That's what a good writing is..
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!
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.
The dislikes are from chemists who were rooting for a different element to be chosen
Actually, Yterrbium or Lutetium are actually used to make the world’s most accurate atomic clock. This will allow for GPS to be accurate within 1 mm which has vast implications for self-driving cars and even store product stock locations.
What if I disliked this comment?😡
@@Micahsaurus Then I'd keep on going with life
Lol
What if i liked this comment like i just did?!😄
Fun fact: second is called second because it is second division of an hour. i.e 1second = ((1/60)/60) hour
Brilliant fact!
@@mrafi7166 ...it's minute compared to a day?
@@mung_pi lmao
@@mrafi7166 Everything is made up of minute particles. Every hour is made up of minutes.
@@mrafi7166 the word "minute" comes from the Latin "pars minuta prima" , meaning "first small part"... in fact minutes are also called "primi" (firsts) in Italian, idk about English
I always wondered why such a seemingly random number was picked to define a second! But now I'm wondering how we were ever able to measure an atom's ticking, especially back in the 60's. This video gave me a rough idea about that, but how do those machines work? And how are you able to put a single atom inside? And how do we know if it works the way we think it does?
The answer is the most used word in physics "probably "
@@farziltheweebo4841 Since I made this comment I did find out how the number was picked! It's because it approximately equalled 1/60 of 1/60 of 1/24 of a day. So just use it to redefine a second, and you're gold. Still not sure how they measure it, though.
This used to be my question as child. Thank you for answering. Ted Ed is a great initiative. Keep up the good work.
I like how the intro turns on the thinking machine in our head
TED-Ed asking the real questions.
The illustration and animation in this one are amazing
once again the animations are perfection!!! they really accompany what's going on and allow you to understand things so much easier, thanks to all the ted team who put these vids together 🥺💕
Last time I was this early, a second wasn’t properly defined
Wow you must be old
@@jerickoposs3747 LMBO
Wait a second
The animations are so good. The animator has done an incredible job.
Amazing job on animation always!
Mashallah
@@astgfrallah771 Jesus died for your sins.
Oh pls be quiet 😒
@@tomfooIeryzReligion is one's choice. Respect it and accept it.
I never seen such a simple and effective explaination about measuring second.
"Atomic clocks allow us to measure time with precision that is second to none" Oh my god, i love this channel
"Who decides how long a second is?" Uploaded 53 seconds ago *I don't understand*
🤣🤣🤣 nice one
Good one
KZhead
I guess the same PERSON who decides " which AD can be skipped and which can't be! "
Smart answer and TRUE
that is one of the most interesting knowledge i ever known and never have i thought of it. good job Ted-Ed
This channel answers questions that I never knew I wanted answered
I love how this video is about seconds, and it just appeared to me in seconds.
Lol, same as well
Same
Lol same
Lmao same
Abosulutly
The animation never fails to amaze me!
I learn so much by watching these videos! Thank you!
At 3:35 TED-Ed said that there are 118 elements to choose from but back in 1967 (The time that the conference took place) there were only 105 discovered elements.
Perhaps it also included different isotopes of the same element, which explains why Caesium-133 is specified, and not just "Caesium."
Thank you Ted-Ed for teaching me so much. You've really made my 2020 knowledgeable. I look forward to watching all of your future videos.
The definition of a second is defined in 1967, based on a measurement of the number of cycles of the radiation from a particular cesium-133 transition with reference to the second commonly used in civilian timekeeping, which at that time was based on astronomical observations.
it says it got measured in 1967 and created another definition for the second, acording to this it was already based on "a day/24/60/60" in late 1500s
this narrator's voice is one of my favorite. thank you narrator!
Sometimes I wonder how good schools could be if they incorporated KZhead 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.
When Ted-Ed teaches you more than school.
When Ted ed doesn't teach you more than school " Wait that's illegal"
I actually learnt this before. Arrest Ted Ed. It broke the law!
Always did
No it doesn't
@@nopenope8369 You must study in a great school
Ted-ed always manages to make me watch videos on topics I've never given thought to but never really understood!
What a great platform !👌🏻
I have been wondering my whole life. thank you.
Had read about it years agoin brief but didn't seep into mind , only knew that it's related to Cs atom , but now understood it fully . Very well explained.
When we count as kids we say tick-tick one, tick-tick two so that we don't count too fast when playing hide and seek lol
What country was that? Haven't heard that before in Australia.
@@classicambo9781 Im from India Im pretty sure it's just an Indian thing
Mississippi!
@@dhruvasoyantar9656 yeah it like saying Mississippi Ive heard some people say that
@@shreya...007 I know about about tick tick as well.. I'm an Indian too.. but mississippi just sounds great 😅
Ted Ed answers the questions I never knew I wanted answers for!!!!
I think heard the narrator's happiness at the "...second to none" joke at the end 5:23
“Dr Strange would like to know your location”
Why do people say "I'll be back in a second" when they didn't?
Truly big brain
“I’ll be back in a moment.”
@@matikashu6033 me too
Me too #Matikashu
Due to Heisenberg's uncertainity principle.
Awesome knowledge just right in time.
This is actually really impressive. I never even wondered about the topic, mad
I kinda love those quotes that they put at the beginning.
While it is fantastic that we have figured out how to standardize the second, what’s arguably just as mind blowing is the fact that even though we’ve figured out atomic clocks, it doesn’t change the fact that from a physics perspective, we can’t actually prove that time exists
Neither can you prove that it doesn't exist
Its subjective exist and not exist from different perspectives
@@professorx3060 you cant prove anything doesnt exist with certainty
We have used time in billions of experiments without problems. That should be enough proof of its existance...
Another thing you missed: the length of the atomic second was indeed based on the length of the day... but the average length of the day between 1750 and 1892, as determined by Simon Newcomb. This was the basis for Ephemeris Time, a uniform scale of time based on the motions of the Earth and the other planets, and it was the second of Ephemeris Time, not 1/86,400 of the solar day in 1967, that was the basis for how many Cesium oscillations were in a second. That's why they needed leap seconds as soon as the switch to atomic time was made. And this, of course, is central to answering the question in the title.
This was an amazing video and information. I never knew this historical decision. And I thought a second was decided for much earlier.
My mom did this thing when she was mad and counted down until I had to have started doing what she wanted me to do. When she came to ONE she would drag it out so long, just to give me a last chance. That's how long I wish a second was, because then I could brag about so many things I do in one second. Just ask my wife.
😂😂😂
"I killed 70 people in a second!"
The Gregoria Calendar was made in the university of Salamanca, Spain. The British colonies started around XVII, a hundred years later.
Video said it was *spread* by the British, not invented by them.
The animation is sooo clean !
Great video again! I love the animation. Also, please make a video about D.I.D (Dissociative Identity Disorder). People need to learn more about it.
I didn’t know electrons orbited the nucleus of an atom. I was under the impression that instead of it being in orbit around an axis, the electrons existed as a cloud surrounding the nucleus. I also thought these seconds came from the ancient Sumerians who use the number 60 instead of 100 or 10 in their measurements. And the second represented a heartbeat.
It is a cloud, but it only appears that way because they move so fast. Just like how rain cloud is only a cloud when viewed far away but up close you can see every individual water particle in suspension. You are also right about the Sumerians however they never defined anything smaller then a day. The ancient Egyptians defined hours as 1/12 of the day and 1/12 of the night using a sun dial (hence 24 hours in a day, which is not base-60). The Greeks then made a whole solar day 24 hours and defined an hour as 1/24 of a solar day. It wasn't until the invention of pendulum clocks that sundials were replaced and minutes and seconds could be defined. Because of the math of hours, days, and months; minutes and seconds had to be base-60 in order to be properly geared to have 24 hours in a day. That pendulum swing (or one second) was defined as one swing of the pendulum over one meter of length over the Earth's surface.
But one heartbeat is variable according to heart rate
@@DoomFinger511 thank your so much!! Your response was very informative and has given me much to think about!
To add to DoomFinger's comment, the clouds are effectively a way of saying how likely an electron is to be there. We know that the electrons are moving in an orbit around the electron, but it's very hard to know exactly where. The electron cloud analogy is how we know where exactly the electron is going to be orbiting most of the time.
So if I will be late again in my classes, I can actually reason out that the length of our second was drastically different.
This video is so informational and underated
Mann! The animation and the way of explanation are too good on this channel. am a student of 11th grade and these videos helps me a lot to understand some typical writing in HC VERMA book.
You forgot that a second is also defined as the distance that light travels in free space in one second, and is equal to exactly 299,792,458 metres (983,571,056 ft)
KZhead determined that this video was sent a second ago
Ted ed has the best animation ever. Period.
Great video!
So if I will be late again in my classes, I can actually say that the length of our second was drastically different.
Ok, I had this question in mind for a very long time😂😂
1:46 that transition is absolutely genius
Amazing explanation 👌
Can I please know what Software was used for this awesome animation ? The animation and the explanation were Fabulous! I love to watch TED videos, always answering some unique questions!
and I thought who invented second was just the observer of his heart-beat and was a very calm person.
And he was most likely 50+ years old at that time.
The entire video was a build up for the pun in the last line. Brilliant work 💯
Wow. So when my parents were born, seconds didn't exist. Mind-blowing. Thanks for the lesson Ted Ed.
I mean literally, everyone knows it's TVA who decides how long a second is.
You mean Kang
I like how you said Britain started spreading Gregorian calendar in 1500s when they adopted it in 1752, actually...
and also the second dates back way before 1500, as far back as Babylon. It’s not from the British
Well done 👍🏿 this was fun
Absolutely fascinating
British colonialism had nothing to do with the spread of the Gregorian calendar early on as Britain was quite late to adopt it in 1752.
I've heard the adoption of the Gregorian calendar is a sign of submission to Rome.
"Time is what we want most but what we use worst" -William Penn Just use time wisely Time won't stop for anyone.........
The animation is absolutely beautiful
Video's can't be hold by ADVERTISEMENT. That's a true value of TED-ED.
Actually, in 1967 there were several elements that hadn't been synthesized yet, so their choice was a little easier!
Who decides how long a second is? Ans: John kitching
Wtf Ted?!? I have always wander this thing! Thank you bro.
Nicely explained
Them: How long is a second? Me: Why did I never thought of this? ;-;
i guess something like this is needed for other units of measurements too. like how much exactly is a gram
Actually... yeah...
They already exist for those units.
A gram is 1000 time smaller than a kilogram. A kilogram is the weight of a cubic meter of water at the temperature of 4 degree celsius
@@bovardgabriel5335 not that's not how a kg is defined anymore. It was changed like 2 years ago. It is completely reliable and based on constants now.
@@bovardgabriel5335 Cubic meter of water is a TON, you're thinking of decimetre...
I second that. Thanks for this info
Thanks Ted-Ed for theory of relativity animation there, It means a lot to me ❤👍
i learn more from TED-Ed than school sighhh
I'm interrsted to know how they counted the 9Bn+ ticks of the Caesium atom.
elves...
Wow really interesting, love the animation too!
The animation is just perfect
Me while counting : 1,2,3,4 Oh I think it's fast 1...,2.....,3.....4.... Too slow 1,2,3,4 aah! where is my phone
Others: That would take 30 seconds. The TED in me: Well, actually, that would take 275,778,953,100 ticks of a Cesium-133 atom.
Great vid
Its about TIME someone made a vid about it