A brief History of the Calendar and Time Keeping 

If only all Physicists, and other experts, could explain complicated subjects so effortlessly, precisely and interestingly we would all be a lot smarter. Thank you!

This is fantastic and so informative.... MUCH better than most TED talks IMO.

So cool. Never take things for granted in all aspects of life. What we take as simple and trivial has taken thousands of years and lifetime work of many many people

This is one of most interesting lecture, explanations of calendars/ time I have ever listened too. I have studied Astro Navigation and learned about lunar , sidereal solar time before, but I wish this lecture was available back in Navigation classes. This lecture gives a fresher deeper insight and appreciation of time and calendars. I am watching for my third time.

I shouldn't be surprised that a physicist would give an hour-long presentation on calendars and measuring time - but I am. I shouldn't be surprised that the physicist was a female as youthful as a teenager - but I am. I am not surprised that she did a damn good job. I searched for a video that would cover this topic and I was not disappointed.

I am proud to say I search for this! Was finishing my afternoon hospital shift and it just came to me to find out history of telling time.

as a marine navigator and use the sextant years ago, where time was very important. I enjoyed your lecture - A brief History of the Calendar and Time Keeping. When involved in fisheries patrol and having to go on the witness stand, i can not forget the strange looks from the judges and Lawyers when explaining different times from GMT to Newfoundland time to Atlantic time time zone and then telling about time diffenence as it involve Loran C units ( which had nothing to do with zone or mean time ). Anyway thank you for posting the lecture on RU-vid.

I've been studying calendars for many years and can verify nearly everything she has shared. Excellent work! Thank you!

WOW such a good presentation and speaker! Thanks so much for posting this for everyone.

A truly wonderful and very worthwhile… And may I add, a very excellent presentation

Amazing lecture rich with information! Thanks Dr. Carroll for putting all this knowledge together and presenting it in such and organized and articulated matter!

Thank you Donna. I've been searching for Yahs appointed times and led me to you. I know you will be of Great help to me. Glory to the Almighty.

This is a brilliant piece of presentation by a beautiful lecturer! I was a student of Philosophy at the University of Nairobi class of 2001. I sometimes will google content related to time and space and I am extremely glad to have landed on this lecture. I live and work in Nairobi, Kenya (East Africa). Good Work Dr. Carroll!

One of the best lecturers in the history of the world! I sincerely mean that!

such an outstanding lecture! thank you for sharing with us common viewers!!!

Commenting to say I was just up and randomly started researching calendars. Came across this gem. And because I'm very woo woo I think its cool this was recorded in February six years ago. Thanks for this really cool info to feed my late night randomness 🥰☺

great talk. very informative and educational i thoroughly enjoyed it and was glued the whole way through. even shared with my older two children as I know they will appreciate it as much as i did. I thoroughly recommend 👍🏼👍🏼👍🏼

Regarding 47:00, John Harrison invented the Marine Chronometer in 1761 which could determine longitude around the globe. British Captain James Cook used a John Harrison Marine Chronometer during his sea voyages of circumnavigation. Regarding 53:31, the small pocket on jeans trousers was designed to originally store a pocket watch, because pocket watches were worn by men during the 19th century. Later wrist watches superseded pocket watches and the pocket watch pocket could be used to store coins or keys, etc.

Wonderful presentation. Thank you very much!

Donna Carroll is wonderful. Truly enjoyed this.

This is the best public lecture on historical perspective of time! Fascinating. Thank you professor Carroll.

I absolutely loved this lecture! So interesting and entertaining. I learned a lot. Thanks Donna!

The best explanation of time and calendars I've seen... Thank you.

Awesome video! Good job explaining everything.

This should be good. This is a fascinating topic that is seldom explored explicitly.

absolutely, thanks for this presentation.

I know this is an old video. But, it is so fascinating ! Excellent presentation.

Magnificent presentation !

Awesome study, I need more. Thank you.

very good presentation, complete and enlightening.

28:16 brilliant! Thank you. The planets for week days. I love it.

Fantastic presentation. Dr. Carroll is a fantastic presenter. Wonderful lecture, but wished I had more control over it. Can't jump back to relisten to portions of it. Please consider this in future posts.

..absolutely brilliant lecture!

Amazing lecture. Thank you very much.

Very nice and informative lecture. Thanks 😊!

Sounds very complicated, amazing how this was all sorted out , thank you for this lecture x

Love the topic and presentation. I need a drink of water now

very informative lecture thanks!

What a fantastic and brilliant lecture

Riveting presentation, thank you for posting/sharing it.

One natural cycle which I've never seen mentioned in histories of time keeping is the tidal cycle. Yet tides too need to be logged and kept track of in order to make decisions, particularly of course when to enter or leave port, with reference not only to water depth but also flow speed. To this day there's a rule of thumb called the "rule of twelths" used by mariners for this purpose, but I suggest that the convention of dividing clock faces into twelve segments originates with the convenient properties of this number in logging and therefore predicting rise and fall in water height and speed. 1 o'clock tells you that 1/12 of the tidal range (whether spring or neap) has been reached, 2 o'clock that another 2/12's has been added, then 3/12's more at 3 and again at 4. By 5 only another 2/12's, so speed is diminishing, and by 6 only another 1, at which time we have high water and slack water, and the process then goes into reverse over the next 6 hours. The changes in flow speed are represented by the sequence 1 2 3 3 2 1, which sums to 12, and at 6 the water is twice as deep as it was at 3. I don't think other numbers fit as well here as 12 does, except possibly 6, and of course integer multiples of 12. One difficulty that's often associated with using sundials is the inconvenient daylight time length changes over the year, but the tide goes in and out over the same period at a given spot on the coast or tidal river bank throughout the year, maintaining the time length of the hour unit, even though the range changes from spring to neap with the lunar cycle. Moreover, the period between spring and neap tides is roughly 7 days, which might have been the origin of another conventional time unit, the week. If ancient maritime and trading civilisations developed astronomy for navigation, they might have invented this means of time logging too.

This was so worth it. Thanks.

I really enjoyed this. It was very informative indeed and has so much depth of knowledge :)

This was awesome, thank you. I've taken notes

Wow - Thank you From South Africa

Thanks ! I always wondered from where week came from. Fyi the babylon system of assigning planets to each hour is still in use in hora astrology practiced in India.

Inciteful. Spurns interest for further research. Thank you. She's quite charming...could unconfuse me about physics any day.

If we hadnt been adding any extra days for the last 2000 yrs it would now be Nov 2018 in summertime. Glory to God.

Currently studying gematria and heard it mentioned that the gregorian calendar was created to also fit the language of numerology. Your excellent lecture gave me deeper clarity into the way the Romans would also count backwards, which is a used cipher within gematria. So interesting, especially as its still being used today by the Society of Jesus and freemasonry.

The real second, or what one might call a natural second, is still 1/86400th of a day, and is a tiny bit longer than an Atomic Time second.

Very informative.

I wish you'd have added the qumran-enoch/zadok priestly calendar (derived from Scripture) to your list. Great survey thank you

Great example How a consept evolv over time and gets better and better

Mind blown! WOW!

just great!

excellent presentation

Thank U so much 💓👍⏳⌚⏲️⏱️🕗🌒🌞

If Science was understood to become important around 450 AD, it was too late to realise it. On the contrary, the Eastern calendars that originated in India for almost 1000s of years earlier were very scientific with absolutely no selfish names to months or weeks. The world needs to know that every name was associated with nature and every year in a cycle of 60 years also have unique names.

Thank you.

fabulous!

Actually, the calendar we use is the _Roman Catholic_ calendar - or the Gregorian Calendar. The names of some months *are* Roman and 3 weekdays. The rest is a bit of a hodge-podge. en.wikipedia.org/wiki/Gregorian_calendar

Good presentation. One item she did not discuss was the adoption of an international date line, and why we have one in the first place. Would be interesting to hear her take on it.

Thanks a lot.

Incredible presentation! Now I feel like I'm accidentally dropped in a random location in a space rock that wobbles at irregular intervals around a fire rock, and that every order ever percieved by my senses is but a mere illusion.

I have watched this more than I can I can remember. I knew about the calendar back untill Gregory times but now it's refreshing to go far back as to it's origin. The first king of Rome kingdom in 731BC.

Thank you for this lecture :) I loved it! I just would like to see the images authors mentioned on them. A good day to everyone :)

Great talk thanks

Me who used this video just to listen and clean my room at the same time for one hour 😐😐

Very nice, thanks.

Time is the Motion of Objects in a given area of Space in Our Vacuum Under the firmament subject to Decay . The Sky is a Clock . Time is the Result of Observation of Biological Life , Like persistence of a Heartbeat , It's a Love beat , and when we Meet , It's a Good Vibration :) QC

I'm glad to see that I'm not the only one that researches for fun. Thank you for mentioning the 8th day that got lost when the Pope assigned Sunday as the day of worship. Nobody mentions that so not many people know the 8th day ever existed. People celebrated twice because people were sticking to ancient traditions. I still believe we are out of alignment. Winner is always later every year in Florida. Winter was November when I was a child. Now it's February March.

Very educative

It is an interesting narrative but as a trained historian I have some difficulty accepting Romulus as an existing historical figure. On Roman religion you can read my grandfather's La Religione Romana (G.B. Pighi) supplemented by more modern research.

The fact that we still use September/October/etc., but for the months 9-12, just goes to show how much humans have a habit for hacking systems together on top of older, flawed systems. We do this everywhere if you look hard enough.

32:10 what i really wanted to know how did people talk about years before AD BC very interesting lecture

The Roman calendar appears so unscientific. The high priests practically dictated the terms to the ignorant masses.

Nature has and always will disrupt man made models. This is the power point I took away from this observational discussion, because anyone who has lived any length of so called time knows that change is a constant, and why models are reformulated at a feeble attempt to compensate for the unknown variables nature puzzles science with.

I have a physics question for you. If a quarts watch runs on frequencies, and people can have different frequencies depending on the individual wearing the watch. Can the time on quarts watch be effected by the frequency of the person wearing the watch? Does a person's magnetic field or frequency mess with the way they perceive the concept of time. is dragging or time is flying by in a 24 hour period. Always been super curious about it.

The Sumerians had equal minutes. Actual one USh was exactly 1° of Earth rotation, almost exactly 4 modern clock minutes. And they divided an USh by six or sixty. Our word "minute" and "second" are primary minutae and secondary minutae.

At time 4:57 How does the height of the nile flood give an indication of the length of a year?

I have two questions. 1) Why are there 13 days marked as "XVIII Kal." in her Roman Calendar example? 2) According to her, the offset is: - 11 minutes (appx.) every 4 years; - A day has 1440 minutes; - It'd take 130,90 leaps (523 years) for the delay to reach 1 day. How could the Gregorian Calendar be 10 days out of synch (and 11 on England 200 years later)? Even if that 11 is an approximation, 10 or 12 minutes wouldn't make such a difference. Am I missing something?

Saints celebration in Roman times? It would only happen (though dubious) during AD Christian period. And then they already used a 7 day week (although it was also used an eight day week until Constantine time). Julius Cesar did use a leap year every 3 years! It was Augustus (the next year of the Julian Calendar setting) who modified it to one leap year every 4 years. I think that the subject of name changing from Quintilius to Iuluis was sort of imperial egotism.

I always wondered why December is 10th month. Would have made sense to add two additional months after December rather than before March.

the Romulus calander was actually a set of dates for activities such as when marketdays were held, when the Senate could gather or not and more. in wintertime there just were no activities , so no calender was needed in that time of the year. The Early Romans probably kept tally of the days that had past, the start of the years did not drop out of nowhere, but it still was a political decision to let the year start. The Pontifex Maximus or upper priest had great authority about it. It was bcause Ceasar was Pontifex Maximus ( and gained more power) in the capacity of P.M. he could reform the Roman calender.

I have a question since you are a physics field. Why does my satellite clock and my manual car clock have to adjusted to match the time on my cell phone. This has be a reoccurring problem for years

Brilliant

Very interesting

Michelson & Moreley Experiment clearly proves we do not move !

not really correct to say they didn't have fractions. No they didn't have decimal-fractions (0.75) , but they did have whole number fractions such a 3/4 means 3 divided by 4, is three-quarter, 3 of 4. They prove this when they do things like roll a one-cubit stone radius to get length that we then think was a ruler of pi.

July and August is what set things off from Julius and Augustus January and February were very much the first two months

Guess I'm not the only one who noticed that she picks up the cup every now and then and keeps it back again without drinking from it. Lol

So this is a talk given AT Maastricht University in the Netherlands, BY a faculty member of that university, and it's in English? Is this typical of Dutch universities that the lectures are given in English, or is this just a special talk given in English?

A 'brief' history? Triple like smash.

This is a great lecture! But can someone help me out, did I miss something? On her “Romanized calendar” for February 2016, all the days after VIII Kal. March are VIII Kal. Until the Ides. Shouldn’t they be IX Kal., X Kal., XI Kal., etc.? Did I miss something or is her slide messed up? It happens when she asks the person when their birthday is this month.

What about the Haab calendar?

Nice going. Very well presented. I wonder would a glass of wine have lasted as long as that water though.

Daylight savings time idea originated with Benjamin Franklin. It would not be implemented util the twentieth century.

Lecture had some factual errors. Romulus and Numa are legendary figures who may or may not have existed. So it's far from certain they had anything to do with the Roman calendar. Also, the notion that August had an extra day added to match July is generally believed to be a myth. The seven day cycle named after the first hour's planet was around well before Constantine. Dennis the Small (actually Dionysius Exiguus) did NOT invent the concept of 'BC' and 'AD'. He merely computed a table of Easter dates in which he numbered the years from the nativity of Jesus. It was a later scholar, the Venerable Bede who introduced the 'BC' concept in his historical writings. While it was known that spring equinox was falling several days before March 21 centuries before the Gregorian reform, the statement that it led to Christians being mocked seems a bit much.

I didn’t see Celaliye Calendar by Hayyam. His calendar is the most accurate better than Gregorian and Roman calendars

Has the discovery of the sun also moving and the earth "spirals" around it such that the earth never ends up where it starts taken into consideration for the year?