The Unexpected Measure that Makes the Modern World Tick

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All of modern society relies upon a seemingly simple but surprisingly complex unit of measurement: the second. But knowing exactly what a “second” is is more complicated than you might think!
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Thank you to the following for helpful discussions and research for this episode:
Geoff Chester - U.S. Naval Observatory
Judah Levine - National Institute of Standards and Technology
Jeffrey Sherman - National Institute of Standards and Technology
Elizabeth Donley - National Institute of Standards and Technology
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[@besmart]

I really enjoyed making this video. I had the TIME of my life 😏On second thought that was a bad joke. Make sure you check out our Patreon page so you can help us make more videos like this one! www.patreon.com/itsokaytobesmart

[@michaelmayhem350]

Your video was outdated before you even got it up. The earth has started speeding up for the first time ever.

[@jackielinde7568]

Joe, you missed out on having a Chicago song as this show's theme song... or at least the background music during your "History of Time".

[@nightthought2497]

The lizard people myth is anti-Semitic. Stop using it in your videos, even as a joke. It encourages the neo-nazis.

[@geoffh4861]

Just because Americans don't use metric in their daily lives, doesn't mean the United States doesn't use the metric system. All imperial units are derived from metric units and the scientific community largely uses metric units.

[@enadegheeghaghe6369]

@@michaelmayhem350 you mean for the first time since we started monitoring and recording those changes

[@Ekevoo]

I still remember in high school a teacher going okay let's talk about the basics. Distance: unit, definition, uses. Time: unit, definition ("there is no definition. time is time. moving on…"), uses.

[@jrchannel7405]

the scary thing is that time varies depending on mass and speed

[@travcollier]

@@jrchannel7405 There's an interesting argument that time should be defined in terms of energy (including mass).

[@mrjoe332]

@@travcollier but now time defines mass, so I guess we're screwed

[@travcollier]

@@mrjoe332 But mass is energy, so just flip the definition of mass in terms of time and you have it. Well, at least that's the very basic version of the idea my brain could comprehend ;)

The rate at which events happen

[@zetsumeinaito]

Speaking of leap seconds, I thought it fascinating that there was a leap second for the earthquake that caused the Fukajima power plant to fail. It made THAT much of a difference.

[@rickintexas1584]

We are so fortunate to live in a world where all of this information is taken for granted. I remember as a kid in the 70s you could call the local bank and get an automated machine telling you the time of day precise to a minute. That is what we would use to set our watches. If our watches were precise to within 5 minutes, well that was good enough.

[@1boobtube]

Rick in Texas, uncle sam published instructions to build a radio and has been brocasting frequency standards since the 1920s, and time since 1937. N.I.S.T. still offers dial up time since 1970 in addition to the original HI and CO radio transmitters. Fwiw a billionth of a second is about a foot of distance in freedom units.

[@publiconions6313]

"At the tone the time will be.... " : )

[@boggisthecat]

We used radio broadcast. Every hour they sent three short tones then a second-long tone. At the end of the tone it was precisely(ish) the start of the hour. Radio waves propagate at different speeds dependent upon atmospheric conditions (light travelling through a medium, essentially) and there is a slight delay with the radio converting the signal to sound, and of course the sound waves then travel to our ear, and we have reaction time. So it was good to better than one second, which was fine right up until communications networks needed synchronising. (TV and air traffic control had their own thing going on.)

[@Term-0]

As someone who studies electronics and computer science as a hobby, I can assure you that I do not take it for granted.

[@Penrose707]

That's pretty cool, never thought how asynchronous time must have been without this simple central repository which is the internet to grab it from

[@LordTelperion]

Fun fact, while the Romans would measure time during the day using sundials, to keep time during the night or when it was cloudy (or during Senate meetings) they also used "water clocks" which operated by dripping water out of a vessel at a regular rate to measure the passage of time.

[@rayoflight62]

Romans also used wax candles with markings around the body to count the hours before the sixth hour and after the eighteenth hour - the nighttime basically.

[@Yomabo]

Can you imagine that you are holding a Senate meeting and there is this drip drip drip noice every second. No wonder they stabbed Julius Caesar

[@gabor6259]

How did they keep the water clock accurate? The lower the water pressure, the lower the flow rate.

[@matthewburger798]

@@gabor6259 A pendulum clock also gets inaccurate the longer it runs, that’s why you change out the water in the top.

[@annoloki]

@@matthewburger798 A pendulum is way more consistent than water. But the water doesn't have to drip at a consistent rate, just place the markings based on the time it takes to fill or drain to that particular marking. As long as it always drips at the same rate each run, the time to each marking will be the same

[@SuicV]

I would really like to know more about the candela. All throughout my graduation in Engineering I never had to use it, and it sure doesn't look like you can't express it in function of the other base units (just at face value). So yeah, feels like a bit of a mystery

[@AlanTheBeast100]

What's so unnatural about: "The candela [...] is defined by taking the fixed numerical value of the luminous efficacy of monochromatic radiation of frequency 540 × 1012 Hz, Kcd, to be 683 when expressed in the unit lm W−1, which is equal to cd sr W−1, or cd sr kg−1 m−2 s3, where the kilogram, metre and second are defined in terms of h, c and ΔνCs."? 🥴 --- source: Wikipedia candella.

[@rickkwitkoski1976]

@@AlanTheBeast100 🤣🤣🤣🤣🤣🤣🤣🤣🤣😍

[@MatthijsvanDuin]

All of the photometric units (lumen, lux, candela) measure electromagnetic energy in some way, but they integrate the electromagnetic spectrum weighted in a way that reflects how bright light of a particular wavelength looks to the average human eye. Lumen measures total light emitted from a source, so it's analogous to Watt used to measure total EM radiation emitted from a source. Lux is lumen per square meter, a measure of how much light shines on a surface. Candela is lumen per steradian, a measure of how much light a point-source emits per solid angle, i.e. if you block the light from a point source in some directions then the total amount of light emitted (in lumen) decreases but in any direction that's not blocked the brightness of the source (in candela) remains the same.

[@AlanTheBeast100]

@@MatthijsvanDuin Whoosh!!! The cynicism derives from the complexity of the definition. To be sure it's not an easy thing to define, but unlike the other base units, it's not something straightforward like the other units.

[@MatthijsvanDuin]

@@AlanTheBeast100 I was replying to the original comment, not to you

[@Beryllahawk]

I still remember the first time I ever heard about cesium-atom clocks. Great little book about naked-eye astronomy, and the author went on to discuss tachyons and all sorts of other nifty ideas and science that depend on time. He didn't get into THIS though! (Not mad about it, either, that was a fabulous book and I still own it 30 years later.) I love that the guy said "I used to think one second was "one Mississippi"..." That made me laugh a lot, especially because I recently had a discussion with an old friend about whether "one Mississippi" is more accurate than "one Hippopotamus." I have very fun friends, heh.

[@gnarthdarkanen7464]

Oh yes... the FUN friends, who delve into how "colloquial enunciation" could've screwed up a clock just enough to have doomed us to the Victorian era for ANOTHER century or two, technologically speaking... haha... ;o)

[@younghan3573]

One alligator!

[@wolfetteplays8894]

@@gnarthdarkanen7464 it would be a blessing compared to our world of endless decadence and modern degeneracy

[@mwm48]

“The Absolute Unit” was my nickname in college.

[@flamencoprof]

I wondered about this in 2014 and these were my findings: - Network Time Protocol (NTP) is a networking protocol for clock synchronization between computer systems over packet-switched, variable-latency data networks. In operation since before 1985, NTP is one of the oldest Internet protocols in use. It is amazing that although the internal clock on my laptop runs at 1.50 GHz, i.e. chops time into 1500000000ths of a second, it can't keep accurate time over a few hours. Proper NTP can tolerate and correct a PC's clock that is out by up to +/- 43 seconds a day. Wikipedia NTP page: "Future versions of NTP may extend the time representation to 128 bits: 64 bits for the second and 64 bits for the fractional-second. The current NTPv4 format has support for Era Number and Era Offset, that when used properly should aid fixing date rollover issues. According to Mills, "the 64 bit value for the fraction is enough to resolve the amount of time it takes a photon to pass an electron at the speed of light. The 64 bit second value is enough to provide unambiguous time representation until the universe goes dim." Then in 2015/11/1 I found: - The latest in atomic clocks would neither gain nor lose one second in some 15 billion years-roughly the age of the universe. (One second in 15 billion years is 1 part in 1000,000,000 x 15 x 365.25 x 24 x 60 x 60 = 473,364,000,000,000,000 = 4.73 x 10^17) Now, after taking in the almost incomprehensible accuracy this represents, one could be forgiven for thinking "Yes, but who needs clocks that accurate? What could they possibly be used for?" Well, it turns out that they can be made useful by studying what makes them INACCURATE. Once you have this steady pulse, gravity, magnetic fields, electrical fields, force, motion, temperature and other things can introduce tiny but measurable variations, such measurements becoming a proxy for measuring the actual gravity or force etc. For example, as Einstein predicted, a gravitational field causes time to pass more and more slowly as gravity increases. A clock which is higher is further from Earth, experiences less gravity, and thus runs faster. The new clock is sensitive enough to detect the time shift caused by a rise of only two centimeters! It can thus serve as an extremely accurate measure of height for mapping, and of gravity variations caused by the earth's composition and shape. (Note that gravity's effect on time is NOT relevant to GPS satellites) A reader interested in a fuller description of the intricacies involved and the influences which must be accounted for to achieve this accuracy should click here for the article "About time: New record for atomic clock accuracy", April 21, 2015 at phys.org.

[@lara_xy]

I truly love how this channel makes learning fun and give me answers to both questions I have always wanted to know the answer to, and questions I never asked myself until watching a video.

[@kirkkohnen5050]

At 11:07, you confuse the sidereal day with the solar day. Tracking Earth's rotation with respect to a fixed star gives you a sidereal day, which differs from the 86,400 second solar day we all know and love.

[@TheEulerID]

There is a thing called the sidereal second, and there are 86,400 of those in a sidereal day, and maybe that was what was meant by an Earth second, but that is being generous as good old clock time was being used to illustrate the principle. So yes, maybe in order to keep things simple it was glossed over, which is why I can still win bets by asking people how many times does the Earth rotate on its axis per year.

[@jadonbelezos2583]

i love how this video makes such a good point about how we take knowing what time it is for granted.

[@nHans]

The metric units (or more specifically, SI) are *_not_* a realization of John Wilkins' idea of _"A standard and universal system of measurement based on the natural world."_ Those would be the *_Planck Units._* A video for another day, perhaps?

[@ShubhGG12]

"i cannot tell you what time is, but i can tell you exactly what time it is" - Geoff 2022

[@foromador9024]

6:18 I was waiting for him to mention the retro encabulator

[@bitsofgeek]

It would be fascinating if you could manage to get a chat in with David L. Mills, the inventor of Network Time Protocol and probably the most underrated contributor to technological progress over the last 40 years.

[@beargiles4062]

A fun fact is that NTP is far too coarse for cloud-native apps. Clocks are only synchronized within a second or two - that's millions of microseconds! That's been an annoyance for a long time if you're trying to merge logs across multiple servers within a data center. Unless you have a really smart merge program you'll routinely see responses occurring before their request, etc. It can make it really hard to figure out what's going on. In traditional apps you'll make a request and wait for a response, probably with a timeout. However you're unlikely to have deeply nested requests. The traditional three-tier model (presentation, business, and persistence) is a simplification but not unreasonable. With cloud-native apps you're much more likely to see deep cascades of requests and things are just a *lot* faster in a modern data center. (Think 100 Gbps network connections.) Timeouts are tighter and any effort spent to respond to a request that has already timed out is wasted. NTP is far too inaccurate to use the system time... but if you had clocks synchronized to within microseconds then you could pass the appropriate deadline in each request and drop it if you know the results will be ignored. The Precision Time Protocol (PTP) handles that. It relies on special hardware in the network device (now common in consumer gear) and only works within a data center due to network latency issues. But within those constraints it can keep clocks synchronized within a few microseconds. Even those of us running traditional apps come out ahead since we can now merge our logs and never see responses before requests. (At least if we increase the precision in the timestamp.)

[@James_Knott]

@@beargiles4062 There's also Precision Time Protocol, which is much more accurate than NTP.

[@tarabergthold6633]

I heard The Atomic Wobbles just released their Second album.

[@NioFromXbox]

"It smells like knowledge" is one of the best descriptions of a scent I've ever heard! I could actually imagine the smell!

[@fermiLiquidDrinker]

I worked on atomic clocks last year for my undergrad research, specifically 87Rb vapor CPT clocks-they're not as good as other clocks, but they're way cheaper and have the potential to be made really small. (You might know rubidium vapor clocks for their biggest hit, the GPS satellite network.) They're super interesting devices, and the physics behind them is really fascinating. That said, I do need to correct this video on something: pretty much all new atomic clocks _are_ optical clocks, and have been since the '70s-they're not the next generation. Even if they're not operating at visible wavelengths, they're still using lasers and all that to shine a beam at a sample. The next generation of atomic clocks features stuff like optical lattice clocks, which I'm super excited about myself. (Optical lattices are just super cool, though I'm mostly excited about how they can be used to simulate condensed matter systems.)

[@johnchessant3012]

Fun fact: last week the international standards bureau voted to abolish leap seconds between the years 2035 and 2135.

[@iamagi]

I missed the end date, knew there must have been a second part.

[@tma2001]

also the one thing these popular science videos get wrong is the reason for leap seconds - its not because the Earth is slowing down by a second every 2 to 3 years! the TLDR of it: That 'random' number 9,192,631,770 of cycles was based on the motion of the Moon from film camera measurements in the 50's. The second it was measuring was ET or Ephemeris Time used as the independent argument of time for calculating astonomical almanacs since 1900. And that second was itself an average of planetary observations over decade in the 1800's. We will always be comparing one average with another whether analogue or atomic --> which means even if the Earth from now on spun perfectly uniformly we would still need leap seconds, tiny differences in the tick lengths will always build up over time.

[@shanechurilla]

I live near the observatory, and I love driving past and looking at the master clock at the gates and knowing the whole world is based off of it.

[@nerd_alert927]

That's SO cool!!!

[@rickkwitkoski1976]

Hmmmm.... yeah, except that the majority of people in YOUR country don't use the base units that come from it. You do know that all US Standard Units are now based on a precise conversion from metric? And don't say the Imperial System! That is an old British system from which the US system was based. They are not exactly the same. For instance, an inch is now EXACTLY 25.4 mm Previously it was 25.4xxxxx mm out to some decimal point. Does it matter in most people's lives? No.

[@shanechurilla]

@@rickkwitkoski1976 our country is wacky like that. Your system is better than ours by a mile 😆

[@meneeRubieko]

Absolutely loved the dutch guys face pronouncing the name the correct dutch way!, thank you!

[@nerd_alert927]

Your guys' videos are always so fun and educational (obviously)! 😆 I can't wait until my son is old enough so he can watch and understand, instead of just randomly skipping the videos I'm watching.

[@alex.g7317]

Yup, gettem off of sis vs bro!

[@jucom756]

Color is just a frequency, so the second is about a quadrillion green

[@TheOriginalFaxon]

I just want to point out that the US does actually legally rely on the metric system at this point. The only reason you still see Imperial used was because they didn't want to force all our industrialized manufacturing capacity to completely retool (which would have set the US back decades at the time), but that was over a century ago, and while we actually still use some of those same machines in production of stuff today, modern machinery for manufacturing has been universal for a long time, basically since we started making everything using CnC operated machines. Even decades old CnC lathes can be used in both imperial and metric. Imperial as it currently stands today is effectively considered an extension of the metric system, because all the base units we use to define what imperial is today, are based on metric measurements.

[@housellama]

TMW all of the Imperial unit people learn that all of that stuff is defined in metric units. :D

[@James_Knott]

You can thank Ronnie Reagan for the U.S. still being stuck in the dark ages. Carter had set up the switch to using the metric system, but Reagan killed it. Also, international trade has forced U.S. industry to use metric measure. Check the wrench sizes for any car these days. It's pretty much all metric.

[@whimsythecrypto-hippy-wolf1900]

Guess how many times MY BRAIN wobbles per second when i watch this channel?! Love it!

[@Term-0]

60

[@SherilRKirshenbaum]

Love this video Joe! Thanks for the shout out and sending folks our way. As you know, we’re all big fans of Be Smart! 💫

[@anime5h_m1shr4]

Your channel has become perhaps my favourite on all of KZbin. Thank you for everything you've done. Keep up the great work! Greetings from India!

[@thebullet7874]

This was absolutely fascinating. I almost skipped over this video as I thought it’d be dull. I was wrong. Well done!

[@NeonVisual]

The UK doesn't really use the metric system across the board either. Pints of beer, miles per gallon, stones and ounces, etc

[@mythreepants]

But those are now defined in terms of SI units

[@dannysulyma6273]

Stones is one that kills me, slightly archaic.

[@kianharris7783]

Depends on context. Canada uses a mishmash of metric and imperial as well but officially and scientifically we use metric

[@CarFreeSegnitz]

@@kianharris7783 Yes. Fellow Canadian here. I’m completely comfortable with kilometres and metres… sometimes. I still prefer feet & inches when talking about how tall a person is. Weirder: outside temperatures need to be in centigrade for me, but indoor temperatures I need to hear in Fahrenheit.

[@oldcowbb]

the internet is just a cult of metric system

[@greguchiha3]

Really thought provoking episode.....love what you guys do, my son and I like watching and learning together...can you guys do an episode how specific crystals are made.. Example.. Besides heat and pressure , what are needed for cystrine... And so on

[@Lambda01]

I was having a conversation about a topic related directly to this with my partner last night. I get up today, and I just so happen to see this video, and it was perfect because it was quite literally keeping me up as well hahaha. Great content as always :)

[@systemofapwne]

That excellent video basically recalls the introductory chapter of my PhD thesis about an optical clock. Thank you so much :)

[@sphakamisozondi]

02:39 I can't tell you what time is, but I can tell you exactly what time it is. Socrates, Hume, Descartes, Plato etc would love to have your location, sir

[@charlotteparadis4754]

I believe this is the most fascinating episode I’ve watched so far. Thank you for making us a little less ignorant with each video! I really enjoy them.

[@florian2442]

"I can't tell you what time is, but I can tell you exactly what time _it_ is" nice

[@iancompton6494]

That was a fascinating episode. It has to make you think about alien civilizations that evolve a sense of time. The way they tell time would be totally different than what we do. They might understand math really well but if our timescales are off it would be really hard commucate.

[@paddington1670]

They probably use a function of the speed of light instead of how long it takes for a random planet to spin 360 on its axis and how long it takes that random planet to circumnavigate a random star. lololoollo1oonelol

[@ABC-vv4cm]

@@paddington1670 that’s already what we do. Literally all it would take is a conversion the same way we convert imperial to metric. 9 billion and something césium résonances to however many speed of light units they use. It really wouldn’t be that big of a deal

[@renato360a]

great show, I wish you would talk about how we're abolishing leap seconds.

[@Spo8]

Absolute unit. In awe of the precision of this lad.

[@chrisxsterling]

Really makes me rethink just complicated it is to build rollback netcode into a fighting videogame, and all of the science that makes characters dance on screen. Everything is SO complicated that we literally do not have time for war.

[@housellama]

I'm a game designer with a pretty heavy tech background and just enough knowledge of coding to understand what a god-damn nightmare network rollback code is. It's hard enough to design around, I can't even imagine what it would be like to actually WRITE. You have my respect.

[@alexlandherr]

Ever since I started to learn programming I’ve become quite the time infrastructure nerd. I even set up a crude Stratum 1 NTP server using a high quality GNSS receiver.

[@MrT------5743]

If it truly is a stratum 1 clock, then it isn't crude.

[@alexlandherr]

@@MrT------5743Crude as in “costs less than 200 USD & can actually be repaired“.

[@B_Van_Glorious]

I was hoping you'd go into the Planck second and how close we are with measuring that and our limitations.

[@safaiaryu12]

This was fascinating, thank you!

[@protonmaster76]

It would be really interesting to see more of the interview with Geoff

[@byronwatkins2565]

Actually, rubidium clocks are more common than cesium clocks, but, cesium is the basis for standard time because its frequency is about twice as high (and its resolution is half as big).

[@MrT------5743]

They are way cheaper too, so more common since.most people do not have to be as precise as cesium clocks.

[@Mixxd_Gaming]

If you took a synchronized, identical time server to an orbiting space station, would you have to occasionally re-sync the times because of time dilation?

[@flopdoodle8056]

Yes and this happens often

[@TheEulerID]

GPS satellites are continually adjusted for time dilation or the system would fairly rapidly start producing the wrong coordinates

[@michaelfulson390]

Great presentation as always

[@alexisalvarez6336]

It's not so much that the "2nd" unit (it's the 3rd if you consider hours) got called "second", but that "secundo" has the dual meaning of "2nd" and "following", the adaptation of which is "sequencing" (i.e., determining what follows what), so while arguable, the etymology gives "second" in this context the connotation of "sequencer" or "pacesetter".

[@h7opolo]

4:35 not quite. the latin is describing two magnitudes of minutia aka minute, i.e., first and second, not that one is called a "minute" and the other a "second." "minute" refers to minutia, i.e., the result of dividing a whole into parts.

[@MrT------5743]

Yeah the first division called a minute and the second division is called a second.

[@h7opolo]

@@MrT------5743 wrong, troll. but you still can't grow any braincells cuz the types of drugs you abuse.

[@MrT------5743]

@@h7opolo hahahha nice argument. Second word you call me a troll but you are the one who disagrees with this video and the names of minutes and seconds. So an hour is divided into 60 what? 60 unicorns? And each of those are divided into 60 rainbows? In your world what do you call minutes and seconds? You are the troll! Haha

[@MrT------5743]

@@marvinmallette6795 the original post disagrees with the video and here you come along and say the answer is in the video and the OP is correct. The OP and video state the opposite so they both can't be correct. hahahaha

[@rparl]

When I was at MIT, the two common scientific measuring systems were cgs and mks. The profs said that they wouldn't specify what we used. So one cocky freshman decided to use fsf (furlong stone fortnight). It was a lot more work, but the TA would have to follow his work rather than just check the final answer.

[@RogerWKnight]

I remember the foot-pound-second and used it while working at Boeing. Using it is one thing. Explaining it to a Boeing supervisor, let's just say that reducing the entropy of the Universe is easy by comparison! Along with explaining to him that there are 254 Angstroms in a microinch, or that there are 1 billion cubic mils in a cubic inch, or that 5/8 inch is 1/8 of 5 inches. In my college physics lab, I liked to joke that Archimedes used the cubit-shekel-second system.

[@findystonerush9339]

FORTNITE BATTLE PASS!!!!

[@Xnoob545]

Why don't people use mgs Meter - gram - seconds No prefixes, just the base units

[@rparl]

@@Xnoob545 That's not a thing because the derived units are unmanageable.

[@rickkwitkoski1976]

@Ross Parlette I thought MIT students used "smoots" for length? 😂😂😂😂😂

[@rickintexas1584]

We are so fortunate to live in a world where all of this information is taken for granted. I remember as a kid in the 70s you could call the local bank and get an automated machine telling you the time of day precise to a minute. That is what we would use to set our watches. If our watches were precise to within 5 minutes, well that was good enough. Now my iPhone and computers know precisely what time it wand I never need to think about it.

[@MrM1729]

POPCORN am I right?

[@iolalopesdarosa7736]

The most interesting video from the whole channel, for sure! The best subject ever.

[@HebaruSan]

The CuriousMarc channel recently uploaded some videos of getting an old cesium clock working, worth checking out if you're interested in this

[@edreusser4741]

Perhaps inadvertently, but certainly casually, you just mentioned the number one problem of being smart. When you said these things keep me up at night, you spoke truth to my heart. These really ARE the things that keep me up at night.

[@spencershapiro1022]

Sleep patterns and current obsessions have never been used to determine intelligence.

[@Term-0]

I don't know about intelligence but definitely curiosity and that is good even if it does keep you up at night.

[@bbbl67]

you should do a video about how the precision of clocks has gone up from swinging pendulums to quartz watches to cesium clocks, and what's coming after cesium.

[@MonkeySimius]

Fun fact:. The US is on the metric system. It is the official measurement system. The imperial system is also the official measurement system. We officially use both. Which is to say, being intentionally pedantic, your graphic pointing to the US saying "not metric" is wrong. In fact measurements like "feet" are officially defined as conversions from metric units.

[@autemiclessons3054]

Great video! You could have added that the French Revolutionaries tried to change the definition of the second to fit decimal time. 100 sec/min. 100 min/hr. 10 hrs/day.

[@bob456fk6]

It's too bad that was not accepted. Of course, if it were accepted, in the USA we would still be using the Babylonian method.

[@Term-0]

the decimal system is overrated. From a technological point of view, it would make things more simple if people were accustomed to use something like the octal or maybe hex number system. this would allow us to much more easily convert to binary, which could be really helpful for even just doing math on paper.

[@TriAngles3D]

As someone of US/Dutch (multilingual) origin it was an absolute milestone to witness the acknowledgment after so many decades that the name Huygens was perhaps being mispronounced. That time was taken to get things Absolutely right.

[@wandaperi]

Still no consensus on (Vincent) Van Gogh!

[@TriAngles3D]

@@wandaperi That is indeed so. One step at a time. :)

[@DaveTexas]

This is the kind of pedantry that really excites me. I would LOVE to have a job that dealt with these types of measurement. My job right now is cool, but the divisions of time are whole, half, quarter, eighth, sixteenth, etc., all controlled be someone beating time with a baton.

[@rubenlazosmartinez8774]

Thanks for your good video. May I suggest for the next versión to visit the US National Institute of Standards and Technology facilities in Denver, Co.

[@killaken2000]

My mobile office had a cesium beam clock and I always thought it was pretty awesome and some pretty impressive tech.

[@cynic5581]

Is the US really not using the metric system? Last time I visited the US I was a bit worried about this but everything was in metric. Food, medicine etc…the friend I was staying with specifically referred to a bottle of soda as a “two liter”, even her drug dealer used “grams”😂. Only thing I obviously noticed was the speed limit which was in MPH and thermostats were in Fahrenheit and I was told construction workers use imperial. I was doing CAD there and myself and the Americans I was working with were using entirely metric. If anything I found Americans to be able to freely use both imperial and metric without skipping a beat…I was impressed because I had to look up conversions 100% of the time.

[@housellama]

It honestly depends on what is being measured. We buy soda in 2-liter bottles, but milk and gas are in gallons, and dry solids are usually measured in cubic ounces. We measure temperature in F and distance in inches and miles. Weights are usually in pounds and ounces, but medication is milligrams. The LEGAL standard is metric and has been for years, but as mentioned in a comment above, they have legally defined Imperial units in terms of the metric system so that industry didn't have to spend billions of dollars retooling all the things. So while legally we are on the metric system, Imperial units are still used day to day by most people.

[@sambhavjain2641]

Amazing work!!!

[@jsfbr]

Fantastic video! Thanks!

[@FloozieOne]

As usual you have come up with a long and complex answer to a question I hadn't thought of. Still, I think time is sneakier than those ultra-accurate clocks. In my world, and, I suspect, yours too, time can stretch out (like when you are bored) or speed up (like when you are late for something) so I will never be sure what a second is.

[@shadowgattler]

I don't think its entirely fair to say the US doesn't "rely" on the metric system. It's still a non negotiable unit in all sciences and in fields of study that require exact detail and measurements. In general fields where "close enough" measurements are acceptable is where imperial is used. A lot countries operate in a similar matter, the UK being a notable example.

[@davidadams421]

A great video, about time.

[@maxdon2001]

Great video!

[@JJ-ji9xx]

What an absolute unit

[@reddcube]

Every unix user know time starts at 1 January 1970

[@pontiuspilatus7900]

Thank you for this insight

[@Dfperez]

Nicely done

[@zymurgist8844]

Interesting timing of the video as it coincides with the scrapping of the leap second by 2035 for the next 100 years announced yesterday. Just causes way too many technical problems.

[@MichiganPeatMoss]

Upward of 9 billion units per second. That's awesome.

[@ryanwaege7251]

"This is where time begins" ... 🤣😄😁 Joe, the camera operator and all of us.

[@Crevtout98]

Good episode, thanks !

[@Crevtout98]

Strangely enough this link goes to a channel with 2 subscribers.... this smells like a scam.

[@LabyrinthMike]

You say that the vibrations of the cesium atom is the same everywhere, but I would think that the strength of the gravitational field it is in would affect it. Also, the time that is transmitted over the internet, how do they account for propagational delay of the message through the network itself? Do they measure it so that it can be taken into account? (These are the things that keep me up at night!)

[@rayoflight62]

The NTP Internet time protocol is expressly defined mathematically, so to exclude the transit times from the time signal...

[@hamjudo]

Correct on both points. NTP compensates for network delays, and time is defined based on an undisturbed cesium atom at _sea level._ Without enhancements, NTP explicitly assumes that packets travel at the same speed in both directions, a perfectly symmetric internet connection. Using that assumption, NTP compensates for the network delay. Before we can switch to the next generation of time keeping, we need something more precise than _sea level._ The new clocks can be used to precisely measure altitude relative to other such clocks. We haven't defined sea level that precisely.

[@seanspartan2023]

I always wonder if base 10 time / decimal time would have been accepted more if it had been introduced and tied to the metric system of measurement. The day would have 10 hours with the 5 hour mark being high-noon. It would never happen now because a decimal second is different than the current second and so many other things in physics rely on its current value. 1 decimal second = 0.864 seconds.

[@thetaomega7816]

We can see with US system that switching is hard. The rest of the world started with metric, thats why they adopted it. Changing time now will be impossible, we will joke about non-adaptives like we do about US imperial system but people will not change

[@NoNameAtAll2]

decimal system is good at multiplication but time needs division - third of hour = 20 minutes, third of day = 8 hours

[@CarFreeSegnitz]

@@thetaomega7816 “…the rest of the world started with metric…”. ?? The ancestral home of the imperial system of measures, England, bit the bullet and switched. I live in Canada, we completed the switch to metric in 1985. And we have the mill-stones of historical ties to England and geographic & economic proximity to the US. The ultimate source of the metric system, Napoleonic France, had to start with systems of measure that varied from village to village. For those Americans who say they’re not hurting anyone by sticking to imperial I like to repeat the story of the Mars Climate Orbiter. A metric/imperial mix up resulted in either a new crater on Mars or the orbiter is orbiting the sun.

[@sammiller6631]

@@CarFreeSegnitz Americans do not use Imperial. Imperial is from the 19th century. The US broke away in 1776. Stop repeating the same tired orbiter meme to justify your nationalistic bigotry. Metric has its roots in French politics. The old system based on strong mathematics of "superior highly composite numbers" (12,60,360) was thrown out because it was seen as "King's units" which were bad optics after overthrowing the King. There's also the French and Prussians/Germans battling over geodesy as an extension of the Franco-Prussian War.

[@sammiller6631]

@@CarFreeSegnitz The ancestral home of the imperial system of measures, England, switched due to a bribe. The French would stop claiming the Prime Meridian passed through Paris if the British Empire would consider using the metre.

[@mkkundal]

Informative and fun video as always. Thanks Joe!

[@Tanishdutt0007]

I love your videos, U always make the best ever

[@chrisg3030]

3:30 "Our species has marked the passage of time using various cycles . . . even tides" I think tides could have played a very important part in the history of timekeeping, and may explain how we came to divide the clock face into twelths. Starting with low tide this could tell you successively what proportion of the tidal range had been reached at a given time until 6 at high tide, and while it recedes until 12 again. 1 o'clock tells you that 1/12 of the range has been reached, 2 o'clock that another 2/12 has been added (so increase in height and water flow is speeding up), at 3 o'clock that another 3/12 has been reached and we're now at maximum flow speed. By 4 another 3/12 has been added. The speed would be diminishing but the height would still be increasing till 6 when the tide starts to recede again. This change in flow speed is represented by the sequence 1 2 3 3 2 1, which of course sums to exactly 12. If the clock face were divided into 16 say, then the sequence would be 1 2 3 4 4 3 2 1 which sums to more than 16, and if 10 the sequence would be 12321 which sums to less than 10. The high tide to high tide cycle seems to roughly match the midday to midday cycle at 2:1, so 2 lots of 12 covers the latter. Tide, both high water and flow speed, must have been of immediate practical importance to early shore based and many riverine civilizations, enough to decide the number of time division units you were going to use over the tidal cycle, though probably not down to the second.

[@trevinbeattie4888]

But are the hyperfine transitions of caesium affected by the warping of spacetime in the presence of massive objects or while under reletavistic acceleration, or is its period constant in all frames of reference?

[@besmart]

Atomic clocks will vary between frames of reference just like any other clock. In fact, the next generation of optical atomic clocks will be so precise that they will be able to track the relativistic difference between two clocks just a few meters different in elevation

[@seraphik]

😒 are you trying to sound smart or something by cramming all those words in there instead of just saying relativity? answer is yes, of course caesium is affected by relativity. why wouldn't it be?

[@ShlokParab]

@@seraphik I think he had a genuine doubt

[@thebemabogale3439]

@@seraphik It's Okay To Be Smart

[@seraphik]

@@thebemabogale3439 lmao well played sir

[@WAMTAT]

This video was a long time coming, it's about time.

[@jenhalbert3001]

Thanks, this was lots of fun.

[@thetaomega7816]

Didnt they just decide a few days ago to get rid of leap seconds? Would be a nice addition to this video!

[@robgrabowski2572]

An island in Norway north of the arctic circle, Sommaroy, wants to abolish time on the island due to the stress and depression it causes in peoples lives. I'm inclined to agree!

[@SioxerNikita]

Good luck running a society without time. Also measuring time is not what leads to stress and depression. That is like saying alcohol leads to alcoholism... It only does when misused.

[@robgrabowski2572]

@@SioxerNikita Firstly, it's not my idea. Secondly, have you ever heard of being facetious? Or humour?

[@SioxerNikita]

@@robgrabowski2572 And I was commenting on the sentiment, and you said you are inclined to agree, and humour is not easy to read without obvious markers.

[@wolfetteplays8894]

@@SioxerNikita so you’re saying Adam and Eve were using atomic clocks in the Garden of Eden 🤣 that’s beyond laughable

[@SioxerNikita]

@@wolfetteplays8894 Pretty sure I said nothing of the sort. Beyond that Adam and Eve would not be a society

[@tragically.rachel]

wow never knew this before.. Awesome!

[@bryankirk3567]

I am glad I took the time to watch this beautious introduction to seconds, minutes, hours, days, years and centuries.

[@tonyhinderman]

As a person with ADHD, assigned and quantified time is the bain of my existence

[@psoridian]

Joe is an absolute unit

[@matthewsecord7641]

I was blessed to have top tier teachers in a multitude of disciplines that used time as a teaching method. Time mattered in History, English, Maths, Chemistry, Political Science, Philosophy, Physics, Biology, Music. Now if everyone had my dumb luck for the absolutely amazing teachers I fell into in publicly funded Canadian schools...we wouldn't have to have discussions about educational problems. I was absolutely blessed by having educators that really were passionate about critical teaching. And even in University found a fee, bit that was a wake up call. Regardless, all my best teachers were very interested in time, in all subjects.

[@13thravenpurple94]

Great work Thank you

[@travcollier]

US customary units are defined based on metric units. An inch is literally just 2.54 cm, and so on. We just include lots of extra coefficients to keep people practicing their multiplication ;)

[@davidruss7702]

This has been the case since 1893.

[@killaken2000]

since 1959 in the US anyway in Federal Register Notice 59-5442 (June 30, 1959)

[@sammiller6631]

But US customary units still use the better mathematical structure of superior highly composite numbers. An inch isn't "just 2.54 cm". It's 1/12th a foot. 12 is better than 10 because you can divide it evenly more ways.

[@travcollier]

@@sammiller6631 only for one unit step of distance, inch per foot. 2, 3, 16, 1760, ect. are not so useful. US customary units are really pretty crap

[@sammiller6631]

@@travcollier The small differences between a yard and meter or a liter and quart makes metric like the old system with the serial numbers scraped off. 12 Inches and 60 seconds aren't the only highly composite numbers in US customary units. Temperature uses 180 degrees between freezing and boiling. See a pattern? 60...180...

[@Ramndom]

Love it

[@danielt5464]

I have been thinking a lot about time as well. Especially this interaction between the times we have created (time out of sync with the Earth, DST) and our Circadian rhythms. Is there such thing as a Circadian clock? Is it even possible for our rhythms to be in sync with time as we know it?

[@Term-0]

The circadian rhythm bases itself off of light level. Without it, the circadian rhythm would very quickly fall out of sync. the circadian rhythm is very inaccurate and miniscule changes is chemicals and temperature in our brain skews it.

[@lesleyghostdragon3149]

"I cannot tell you what time is, but I can tell you exactly what time it is..." Whoa...🤯Dude...🤯Excellent!!!🤙🤙

[@ScrapPalletMan]

I wish we could measure care. How much someone cares would be a wonderful amount to know. It would help with relationships, business, and friendships. It sure would take the guesswork out of life's grand decisions 🙂

[@likebot.]

Good morning Ralph. Good morning Sam. Mrs. Bot and I will agree that the unit of measurement for care is the Paul. Why not?

[@ScrapPalletMan]

@@likebot. awww 💚

[@joxterthemighty]

The U.S. is on the metric system and has been since the 70's, the imperial units in popular usage are defined in metric units and metric measures are on all products next to the imperial units.

[@joxterthemighty]

@@OfficialBeSmart. How do I do that, have installed it on my phone (v20) but do not know how to connect to you

[@just_kos99]

I'm a quadruple Virgo, so needless to say, I'm very a-r about some things. Eg, I always set my clocks and watch to the US Naval Observatory's Master Clock. I've never been there, but I'd LOVE to go! I'm such a geek that the first tourist site I went to in London was the Royal Greenwich Observatory, and yes, I stood over the Prime Meridian!

[@mrbundlestuff]

7:44 This guy took his time to memorize such a long number, RESPECT! Oh wait… this video was about one second? I remember a teacher telling me “a second is how long it takes you to say ‘Mississippi’ and now your telling me it needs over 15 minutes of explanation??? I mean, ‘Mississippi’ is good enough for me. And then you say you have to be more precise?