These are all over the place in Norway (as are they everywhere else, presumably!)
When we moved to the island we currently live on, our address was in a road called 'Solsteinen' (The Sun Stone), but I didn't think anything of it until I realized that the roughly hewn stone serving as the property limit marker was juuu-uuust touched by the sun on Winter Solstice. Aha.
A quick call to the local archaeologist confirmed my suspicion - 'Oh, so you're the new resident there, I'd planned on being in touch - that stone monument has been there for more than 2000 years, is A-listed and please, whatever you do, don't do anything with it. Seriously.'
They aren't "all over the place" in the US, and I certainly don't have a local archaeologist that I can just call up.
FWIW: The Northeastern US is quite recent with human presence. It wasn't settled until after the last ice age. Pretty much anything old is celebrated because there is so little of anything old.
Oh, he works for the county, but happened to live just up the hill from us.
There's so much old stuff around here that he is basically being called out to perform an assessment every time anyone wishes to build anything.
Where we live now, for instance, there are a handful of burial mounds from God knows when (all plundered long ago), lots of old charcoal pits, a couple of late stone age fish traps in the lake in a corner of our farm.
To exaggerate just a little - where we could build our home was basically dictated by where we could find a spot noone had claimed thousands of years ago...
I suspect most local councils in the UK have an archaeology team and failing that there are a lot of professional consulting archaeologists - a lot (all?) large scale building works often include the need for archaeological surveys and/or remediation.
e.g. Work for what is now the Queensferry Crossing bridge uncovered a 10,000 year old home:
What I find cute is that every year on the 21st of december a small number of modern day pagans and nature lovers gather at Ales Stenar here in southern Sweden and watch the sun rise over the center stone of the "ship".
We bring thermos bottles, some bring kids, pets, and we just stand there in silence watching the sun.
Afaik it's not coordinated, it's just a bunch of people having the same idea every year.
This reminded me of The Anasazi Sun Temple that catches the first light of the Summer Solstice in a specific point in the temple. I first discovered this watching Carl Sagan's Cosmos early this year (which I'd highly recommend, BTW)
How did ancient cultures know when the solstice was? If you didn't tell me it was the 21st, I don't know how I'd be able to tell you other than by carefully measuring the sunrise and sunset times
1. Go out every morning to work in your field.
2. When the Sun rises, make a note on the same fixed piece of wood, e.g., a fence.
3. Observe the leftmost and rightmost positions, these are your solstices.
4 You can now use your fence to identify and predict solstices.
I have read that the auspicious date of December 25th may have been intended to be the Solstice but that the degree of error for "making a note on a fence" is why we have the 25th.
Honestly I bet you would have at least a reasonable intuition about it if you were among them. It's pretty remarkable how much our distractions and 'being indoors' all the time dulls our senses to nature.
I started doing astrophotography about three years ago. I'd always been interested in 'space' but never really spent hours upon hours out at night over the course of months actually just studying the night sky. I remember wondering as a kid how people even thought about planets or came up with these wild stories with the constellations...to me it just kind of looked like a bright field of randomly twinkling lights.
Well, when you're out every night from 10pm to 2am looking up, it all just kind of comes alive. You see everything. The motion of the planets, the elliptic upon which they travel, the gradual shift of the entire field as the seasons change, the undulations of the moon and it's varied trajectory across the sky. The shifting of the sun's set and rise and the ebb and flow of day vs night. Everything. Your mind just starts to harmonize with the rhythm of it all. It's pretty wonderful.
It seems unintuitive today because people living in cities and towns don’t usually see sunrises and sunsets from where they live. If you had a way to easily reference the sunrise and sunset points against known horizon, it’d be very easy to tell.
> How did ancient cultures know when the solstice was
Solstice is a small thing they figured long ago, there are things they managed that are much more complex than that. In India there are whole temples dedicated to astronomy and built to align with different celestial geometries.
However if you live in the open, or have daily access to the open sky, after a while you are bound to notice.
We are so used to having a ceiling above us, so used to constructions blocking our view of the sky that this seems a feat.
I was the same till I got access to the sky. Then ... oh wait ... the sunset is shifting towards those landmarks every day. Oh wait, now its turning around to go the other way.
The total span of movement is so large, that its hard to miss unless you are on a featureless landscape or in the open sea.
I am super impressed by humans noticing and separating the planet's from the stars. Look at those stars they don't twinkle and they move funny. I guess the planets drew attention because of their brightness and by their lack of twinkle.
I’m sure you’d know that this was winter. If you line 2 sticks up with sunrise, and keep adjusting them every morning, eventually you’ll see that the sun stops rising further south and starts moving north again. You don’t need complex mathematics to work it out.
Now if you disclose your local time offset from GMT, say, Palantir can send a drone carrying roses.
Of course this is meant as a joke, but wanted to emphasize how easy it is for location information to leak. And if one really doesn't care about collateral deaths how easy it is to exploit location data.
Kerala, for the curious, is also the place where the infinite series (and with it arguably calculus) was devised some 200 years before Newton's birth.
Blatant Western-centrism within academia (and the strange, almost primitive-hatred for living ancient-cultures) perhaps hasn't led either to the recognition of "ancient" monuments in India or its scientific/astronomical outputs.
The festival of Sankranti for eg. is so old that due to the Hindu Luni-Solar calendar's usage of the sidereal year, it has drifted off from the winter-solstice by 20 odd days, starting from 150 BC (amusingly as has the Julian calendar, but due to a lack of precision in arithmetic / observational accuracy).
That's regrettable yes, as any centrism. But people interested in epistemology certainly are aware of major contributions to sciences by Indian thinkers.
Biased coverage is unfortunately rather widespread in more general media. And rise of nationalisms don't help in the matter. Which is true for western and eastern countries by the way.
Regarding a case of several millennia of prior art, there is Pāṇini, who employed metalanguage long before the idea become of interest in western side.
I don’t know if it’s related to Western-centrism or not, but I recall thinking it was weird that my English-speaking colleagues do not know the formula to solve second-degree polynomials as the “Bhaskara formula”, as we call it in Brazil.
By the way, Wolfram’s website has an interesting summary of the history of this formula.[0]
Although western centrism is definitely a thing, the link you provided states that temple, for example, was started in the 16th century. The article link is about something from 2800BC
Depends on the details of how you define calculus. Archimedes was doing integration, Descartes was evaluating slopes and tangents of algebraic curves. Isaac Barrow had a good grasp of fundamental theorem of calculus -- that differentiation and integration are inverse operations. Brook Taylor did Taylor series before Newton.
Newton and Leibnitz get credit because they placed calculus as a general technique that is immensely broadly applicable not just for extrapolating the tangent function or the sin function as a series, but to any function that's smooth in some sense.
They worked out the details that do not depend on the specifics of the function and called them out as rules/results of broad applicability. Especially how to push the differential and integral operations through +,-,×,÷ and function composition sign. It did not matter what the function was as long as it was built up from those operations.
I am familiar with the work of Kerala school and also of Aryabhatta's work on using differential coefficients to extrapolate the sin function (this being much before Kerala school), his work on difference equations.
Rather than getting caught up with us versus them narratives , spend some time learning about the beauty of math and how different cultures have thought about them in such creative ways. Otherwise you risk sounding ignorant and rageful conspiracy monger.
The inaccuracies in the Hindu calendar is and was a lot more than the Julian calendar. The Julian calendar assumed that a year was 365 1/4 the day. This is slightly inaccurate and therefore there was a need to correct for the leap day that's added every 4 years by skipping it every 100 years, adding it back every 400 years. At time of Gregorian correction it was off by 10~11 days because of an error of 10 minutes in their estimate of the length of an year.
Hindu civilization's estimate of the length of an year, although remarkably accurate for its time, was less accurate than the estimate of 365 1/4th. Usually the length of an year has been overestimated, making the Hindu calendar lose accuracy quicker. These errors were order of a day per year versus off by about 10 minutes like the Julian calendar.
This was less of a problem historically because Ujjain observatory would correct the calendar time time using accurate observation of the Equinox. Since the fall of Ujjain observatory the Hindu calendar has been accumulating drift error for centuries.
The current state is such that we can, with great authority, give an exact measure of each "years" length, with every one bieng unique.
You touch on but dont quite state that math is a usefull game, but miss that reality does not use math consistantly, and we force arbitrary units and measures onto what we are trying to understand, but are still clueless as to what the nature of reality is, and how it works.
Testable theorys are thin on the ground now,Newton and his peers, past,present,here, and there, would be and are, unsatisfied with the meager conclusions we have, sure we can sincronise, and our tools and toys are wonderfull, but the universe remains,theoretical.
It takes my breath away how consistent the mean length of a day is and how accurately we can measure it. So accurately that if it deviates by mere tens of milliseconds, and it does, we can notice it.
It boggles my mind that a hunk of rock made up of differing densities, with so much of salty water sloshing around, Moon exerting her brakes, bombardments by extraterrestrial matter, Earth still remains so consistent. Of course, this is not surprising if one does the math.
Yes math and physics are different. It's the the fact that math can model the physics so accurately at all that it's breathtaking.
ha ha ha!, we state the same thing, I think, maybe, but it's the "10's of milliseconds" of inconsistancy that I am refering to, we can measure things in as you well state, a "breathtaking" way, but are then reduced to bieng reality's mad, overworkered, note keepers, and ALL of the clocks are still ALWAYS wrong, with the very definition of time becoming something that we must descibe as "realitys ongoing mistake, that we must correct for".
I will indulge myself and go a bit farther into woooooo, teritory, in that this new ability to keep time so accuratly is something that resists entropy by creating order, where there is none.
Even without venturing into the realms of Quantam Mechanics or Chaotic Dynamics, all measurements are, by physical definition, upto the resolution of the measuring instrument. So it always come with inherent +/- error bars. Sometimes these error bars are made explicit, at other times they are elided, often with the assumption that it's obvious.
Models are always simplifications. That is precisely why they are useful. ( A 1:1 scale map is not very useful, especially when we already have one). Models are obtained by ignoring the effect of many known disturbances, but whose effect one deems not to exceed a tolerance bound.
> Blatant Western-centrism within academia (and the strange, almost primitive-hatred for living ancient-cultures) perhaps hasn't led either to the recognition of "ancient" monuments in India or its scientific/astronomical outputs.
Enough with this bullshit please? There are genuine reasons why the knowledge of the calculus of ancient Kerala didn't travel outside India during the late middle ages.
It is a fact that Madhava a mathematician and astronomer from the late middle ages, came up with calculus, and established the Nila School of Mathematics in Kerala. For some reason, the book (Yuktibhasa) that discusses this math is written in the local language Malayalam. Most scholars at the time only understood Sanskrit, including later Western scholars who were unable to find good Malayalam book. Because of this, it was difficult to have the works translated, especially since the works describe formal proofs of concepts like series expansion, which was not even known in the Northern India at the time.
Kerala was also under Portuguese rule at the time and was frequently faced with wars, so the school gradually declined and the math culture sort of died out.
The Mathematics of India by P.P. Divakaran discusses these themes.
P.S: Most of what I've said here is taken from this Numberphile video of another mathematician discussing the life and work of P.P. Divakaran (who recently passed away)
https://www.youtube.com/watch?v=G23Jx0kPCSI
When an aperture is aligned to the winter solstice, it is also aligned to avoid light the rest of the year. An early attempt at air conditioning? Keep the heat out.
When we moved to the island we currently live on, our address was in a road called 'Solsteinen' (The Sun Stone), but I didn't think anything of it until I realized that the roughly hewn stone serving as the property limit marker was juuu-uuust touched by the sun on Winter Solstice. Aha.
A quick call to the local archaeologist confirmed my suspicion - 'Oh, so you're the new resident there, I'd planned on being in touch - that stone monument has been there for more than 2000 years, is A-listed and please, whatever you do, don't do anything with it. Seriously.'
They aren't "all over the place" in the US, and I certainly don't have a local archaeologist that I can just call up.
FWIW: The Northeastern US is quite recent with human presence. It wasn't settled until after the last ice age. Pretty much anything old is celebrated because there is so little of anything old.
There's so much old stuff around here that he is basically being called out to perform an assessment every time anyone wishes to build anything.
Where we live now, for instance, there are a handful of burial mounds from God knows when (all plundered long ago), lots of old charcoal pits, a couple of late stone age fish traps in the lake in a corner of our farm.
To exaggerate just a little - where we could build our home was basically dictated by where we could find a spot noone had claimed thousands of years ago...
e.g. Work for what is now the Queensferry Crossing bridge uncovered a 10,000 year old home:
https://www.bbc.co.uk/news/uk-scotland-edinburgh-east-fife-2...
We bring thermos bottles, some bring kids, pets, and we just stand there in silence watching the sun.
Afaik it's not coordinated, it's just a bunch of people having the same idea every year.
https://en.wikipedia.org/wiki/Casa_Rinconada
https://daylight.franzai.com/
today - 07:18:59 → 16:24:29 = 9:5:30. yesterday - 7:18:23 → 16:23:53 = 9:5:30
You can use an js SVG animation to have it run in real time: https://tomchen.github.io/animated-svg-clock/clock.svg
I have no idea why we stuck with the 12 hour clocks once we stopped using sundials and variable hours: https://en.wikipedia.org/wiki/Unequal_hours
https://en.wikipedia.org/wiki/Manhattanhenge
0. https://drive.google.com/file/d/1FB3Ofl4mUvOO4gGqARro9cO_kjJ...
/edit: Looks like noscript blocks the p5 thing.
Does the math fail because of not considering (i) equation of time and (ii) oblateness of the Earth ?
Merry Sun-Fence Day everyone. ;-)
I started doing astrophotography about three years ago. I'd always been interested in 'space' but never really spent hours upon hours out at night over the course of months actually just studying the night sky. I remember wondering as a kid how people even thought about planets or came up with these wild stories with the constellations...to me it just kind of looked like a bright field of randomly twinkling lights.
Well, when you're out every night from 10pm to 2am looking up, it all just kind of comes alive. You see everything. The motion of the planets, the elliptic upon which they travel, the gradual shift of the entire field as the seasons change, the undulations of the moon and it's varied trajectory across the sky. The shifting of the sun's set and rise and the ebb and flow of day vs night. Everything. Your mind just starts to harmonize with the rhythm of it all. It's pretty wonderful.
The sheer amount of _stuff_ in the sky is mind boggling, the silence is deafening.
That we spend all of human existence until little over a century ago living like that is something I have a hard time wrapping my head around.
Solstice is a small thing they figured long ago, there are things they managed that are much more complex than that. In India there are whole temples dedicated to astronomy and built to align with different celestial geometries.
Edit: Obviously somewhere like here in Scotland observing the sunrise is easier said than done - particularly at this time of year!
However if you live in the open, or have daily access to the open sky, after a while you are bound to notice.
We are so used to having a ceiling above us, so used to constructions blocking our view of the sky that this seems a feat.
I was the same till I got access to the sky. Then ... oh wait ... the sunset is shifting towards those landmarks every day. Oh wait, now its turning around to go the other way.
The total span of movement is so large, that its hard to miss unless you are on a featureless landscape or in the open sea.
I am super impressed by humans noticing and separating the planet's from the stars. Look at those stars they don't twinkle and they move funny. I guess the planets drew attention because of their brightness and by their lack of twinkle.
December: https://www.timeanddate.com/sun/uk/kirkwall?month=12&year=20...
June: https://www.timeanddate.com/sun/uk/kirkwall?month=6&year=202...
Now if you disclose your local time offset from GMT, say, Palantir can send a drone carrying roses.
Of course this is meant as a joke, but wanted to emphasize how easy it is for location information to leak. And if one really doesn't care about collateral deaths how easy it is to exploit location data.
https://www.etvbharat.com/english/bharat/padmanabha-swamy-te...
Kerala, for the curious, is also the place where the infinite series (and with it arguably calculus) was devised some 200 years before Newton's birth.
Blatant Western-centrism within academia (and the strange, almost primitive-hatred for living ancient-cultures) perhaps hasn't led either to the recognition of "ancient" monuments in India or its scientific/astronomical outputs.
The festival of Sankranti for eg. is so old that due to the Hindu Luni-Solar calendar's usage of the sidereal year, it has drifted off from the winter-solstice by 20 odd days, starting from 150 BC (amusingly as has the Julian calendar, but due to a lack of precision in arithmetic / observational accuracy).
Biased coverage is unfortunately rather widespread in more general media. And rise of nationalisms don't help in the matter. Which is true for western and eastern countries by the way.
Regarding a case of several millennia of prior art, there is Pāṇini, who employed metalanguage long before the idea become of interest in western side.
https://en.wikipedia.org/wiki/P%C4%81%E1%B9%87ini
By the way, Wolfram’s website has an interesting summary of the history of this formula.[0]
[0]: https://mathworld.wolfram.com/QuadraticEquation.html
In India and also in general it's called Sridharacharya formula or method. It's named after the Indian algebraist Sridhar
https://en.wikipedia.org/wiki/Sridhara
whom Bhaskara quotes extensively.
Newton and Leibnitz get credit because they placed calculus as a general technique that is immensely broadly applicable not just for extrapolating the tangent function or the sin function as a series, but to any function that's smooth in some sense.
They worked out the details that do not depend on the specifics of the function and called them out as rules/results of broad applicability. Especially how to push the differential and integral operations through +,-,×,÷ and function composition sign. It did not matter what the function was as long as it was built up from those operations.
I am familiar with the work of Kerala school and also of Aryabhatta's work on using differential coefficients to extrapolate the sin function (this being much before Kerala school), his work on difference equations.
Rather than getting caught up with us versus them narratives , spend some time learning about the beauty of math and how different cultures have thought about them in such creative ways. Otherwise you risk sounding ignorant and rageful conspiracy monger.
The inaccuracies in the Hindu calendar is and was a lot more than the Julian calendar. The Julian calendar assumed that a year was 365 1/4 the day. This is slightly inaccurate and therefore there was a need to correct for the leap day that's added every 4 years by skipping it every 100 years, adding it back every 400 years. At time of Gregorian correction it was off by 10~11 days because of an error of 10 minutes in their estimate of the length of an year.
Hindu civilization's estimate of the length of an year, although remarkably accurate for its time, was less accurate than the estimate of 365 1/4th. Usually the length of an year has been overestimated, making the Hindu calendar lose accuracy quicker. These errors were order of a day per year versus off by about 10 minutes like the Julian calendar.
This was less of a problem historically because Ujjain observatory would correct the calendar time time using accurate observation of the Equinox. Since the fall of Ujjain observatory the Hindu calendar has been accumulating drift error for centuries.
unless you bump your toe on part of it.
It takes my breath away how consistent the mean length of a day is and how accurately we can measure it. So accurately that if it deviates by mere tens of milliseconds, and it does, we can notice it.
It boggles my mind that a hunk of rock made up of differing densities, with so much of salty water sloshing around, Moon exerting her brakes, bombardments by extraterrestrial matter, Earth still remains so consistent. Of course, this is not surprising if one does the math.
Yes math and physics are different. It's the the fact that math can model the physics so accurately at all that it's breathtaking.
Even without venturing into the realms of Quantam Mechanics or Chaotic Dynamics, all measurements are, by physical definition, upto the resolution of the measuring instrument. So it always come with inherent +/- error bars. Sometimes these error bars are made explicit, at other times they are elided, often with the assumption that it's obvious.
Models are always simplifications. That is precisely why they are useful. ( A 1:1 scale map is not very useful, especially when we already have one). Models are obtained by ignoring the effect of many known disturbances, but whose effect one deems not to exceed a tolerance bound.
Enough with this bullshit please? There are genuine reasons why the knowledge of the calculus of ancient Kerala didn't travel outside India during the late middle ages.
It is a fact that Madhava a mathematician and astronomer from the late middle ages, came up with calculus, and established the Nila School of Mathematics in Kerala. For some reason, the book (Yuktibhasa) that discusses this math is written in the local language Malayalam. Most scholars at the time only understood Sanskrit, including later Western scholars who were unable to find good Malayalam book. Because of this, it was difficult to have the works translated, especially since the works describe formal proofs of concepts like series expansion, which was not even known in the Northern India at the time.
Kerala was also under Portuguese rule at the time and was frequently faced with wars, so the school gradually declined and the math culture sort of died out.
The Mathematics of India by P.P. Divakaran discusses these themes.
P.S: Most of what I've said here is taken from this Numberphile video of another mathematician discussing the life and work of P.P. Divakaran (who recently passed away) https://www.youtube.com/watch?v=G23Jx0kPCSI
We jump so quickly to religious significance.
In the northern latitudes, doubtful. It would be cool enough year round.