Intuitively you would think that the tide is being formed because the Moon is "lifting up" the water at the point closest to the Moon. But this contribution is actually very miniscule to the tidal effect. Instead the bulk of the tides are produced about 45 degrees away where the tidal force is parallel to the Earth's surface. This has the effect of dragging the water closer to the tidal bulge.
Thank you--the diagram you link is a better explanation of whey the tide "bulges up on the sides of the Earth closest to and farthest from the Moon"--the article left this entirely unclear.
In particular, I could understand how two satellites connected by a cable would result in the cable being stretched. But I still find it hard to wrap my mind around the fact that we get a high tide where the Earth's gravity and the Moon's add (the far side of the Earth from the Moon), but we also get a high tide on the opposite side, where the Moon's gravitational pull is subtracted from the Earth's. The centrifugal force is (I think) a much better explanation. (I realize physicists don't consider that a force, but...)
So yes, tides really are weirder than I think.
(The other facts in the article were actually familiar, e.g. the fact that the tides in Hawaii are quite small, because it's not far from an amphidromic point.)
Tides aren't caused by centrifugal force but by differing gravity. You would be ripped apart by tides falling straight into black hole.
The near part of Earth experiences more gravity from the Moon, the far part less. The Earth moves in the center so the water bulges on the ends. Important part is that the Earth pulls things out their natural orbits.
With circular orbits, gravity and centrifugal force are balanced so could be considered difference on centrifugal force. But that isn't true for all orbits.
But the water on the left is being pulled by everything to the right of it, moon, earth, other water. Why is it left behind? Every single thing is being attracted by the same centre of gravity on the right of the earth
but to develop better intuition, think of the sun's gravity as a field in space and nothing is being dragged anywhere, it's just that wherever you are feels appropriate to where you are and where you are going is the path of least resistance, and the places around you feel the same way, and where you all are in relation to each other (in this field) changes its relative position to everything else.
the water of an incoming tide doesn't feel "i'm being dragged uphill", it feels "hey, the earth is moving underneath me". it's all in freefall all the time.
you don't feel like you are rotating at 1000 mph (1600 kph) but you do feel your weight against the surface of the earth. same with the water, except it feels itself being squeezed by everything around it like you only feel that in the entrance to a crowded venue.
so, the water on the side toward the moon and the water on the side away from the moon would mostly perceive the earth as dropping away or coming closer (if they could perceive anything at all) where they are is always their point of reference
I went down a rabbit hole a few weeks back to discover this. I was so upset with so many wrong explanations including Neil de Grasse Tyson saying we're moving into the bulges.
it's very magical though discovering the beauty of it.
What really gets me is the "Map of the strength of the 12-hr lunar tide" in the Layer 4 section of the article posted, which I haven't seen discussed.
All the rest is swept away, and you have stretches of coastline with tides over one meter, and others with nearly zero, just because of landmass distribution ...
If you moved Miami Beach to the French Atlantic coast, things would get interesting.
The problem of predicting tides was so important that it attracted many Physics and Maths heavy weights. You can well imagine how important predicting tides would have been for D-day landing.
One related fascinating historical artifact is the special purpose analogue computer designed by Lord Kelvin in the 1860s based on Fourier series, harmonic analysis. Think difference engine in it's cogs and cams glory, but special purpose.
Possibly one of the first examples of Machine learning, with Machine in capital 'M'. It incorporated recent tidal observations to update it's prediction.
Note that sinusoids are universal approximators for a large class of functions, an honour that is by no means restricted to deep neural nets.
George Darwin (Charles Darwin's son) was a significant contributor in the design and upgrade of the machine.
Other recognizable names who worked on tide prediction problem were Thomas Young (of double slit experiment fame) and Sir George Airy (of Airy disk fame).
> Kelvin’s machine automates the second half of that task. As the pulleys spin, they pull on a common chain by the correct amount for each of the calculated components. A year’s worth of tidal tables can be put together in half an hour, if you know the components. Even better, you can “guess and check” the components by comparing your machine’s output to past records, and adjusting the pulleys until you get something that works correctly.
I didn't know they already had machine learning and model fitting algorithms in the 1800s, but here we are...
Sometimes we need dates attached - by the numbers (1838 of current 3176) that's probably some 5 or 6 years before ChatGTP. Or 3 or 4 years after the Netflix challenge.
"Q: I live outside of the U.S. and my location is no longer supported. What happened?
A: Many data were purged after a legal threat from the U.K. Hydrographic Office (UKHO) in January 2001. I ended maintenance of the non-U.S. data that replaced them for different reasons in early 2012."
I wonder how much money the Hydrographic Office saved by not allowing this data to be distributed?
https://www.youtube.com/watch?v=AxC770lpSLw shows one of the old tide prediction mechanical computers briefly mentioned in this article. It is effectively doing an inverse Fourier Transform, summing all the various 30+ sinusoids that affect the tides.
out the back door of my house, down through the field and woods to the water is a 12 min walk at high tide, and another 12 min + walk to the water at low tide, 53 vertical feet between the two.
I know ,not the slightest thing about tides, other than what my senses tell me when walking the shore, and I suppose the practicalities of beach walking along cliffs
are similar to planning and predicting arival times for ships loaded to the maximum draft, the money to be made there bieng the motivation behind the push to understand tides.
huge, and where else?
there are some places here where the slope is so gradual, that the low tide is over the horison
growing up we had a camp right at the end of Burnt Coat Head, in Noel, and never did make it to the low tide line
between there and Cape Split there is the full range of tidal phenominon on display, resonant standing waves, whirlpools, tidal bores(with surfing black ducks),whole bays emptied, and varios dikes and berms, dams, locks, to hold it back
there are one ot two other places on the planet that are close, and from the charts in the article, spots with NO tide, which when I think about,is very wierd indeed
Reading most of the technology articles would have you to believe that dark ages really existed and for more than thousands years, i.e from Greece to Renaissance time there is no marine technology advancement between them.
The truth of the matter is that the Arabic and muslim are the master of the sea during this so called "dark ages" time, and many advancement has been made from navigation gear of the Arabic astrolobe to the Idrisi map.
In tide prediction Al-Kindi for example, has notable work on tides in his seminal book Treatise on the Efficient Cause of the Flow and Ebb back in 9th CE [1],[2].
> In a treatise entitled as Risala fi l-Illa al-Failali l-Madd wa l-Fazr (Treatise on the Efficient Cause of the Flow and Ebb), al-Kindi presents a theory on tides which "depends on the changes which take place in bodies owing to the rise and fall of temperature."
Thanks for pointing that out but there's must some mistakes on the website. Al-Kindi contribution is on the experiment in showing that tides are caused by the expansion of water due to heat but of course later people know that it mainly due to gravity.
Other well known Arabic and muslim reseachers in the middle ages working on ocean tides are Abu Ma'shar al-Balkhi (Albumasar), Al-Biruni and Nur ad-Din al-Bitruji (Alpetragius).
Albumasar in his seminal book on tides was the first hypothesized the lunar correlation [1]. He's arguably the most important figure in the history of tidal theory between the ancient Greeks and Renaissance. His famous work namely The Great Introduction to Astrology (Kitab al-Madkhal al-Kabir) was translated into Latin in the 12th century and became the standard reference for European scholars (like Roger Bacon and Albert the Great) when they tried to understand tidal physics.
Al-Biruni was a polymath who had direct experience with the strong tides of the Indian Ocean specifically at the port of Somnath in Gujarat, India. Of the 146 books written by him, 95 are devoted to astronomy, mathematics, and related subjects like mathematical geography [2]. In his encyclopedic work Indica (Kitab al-Hind), he discussed how the moon influences "moist substances". He dismissed the common myth in the region that viewed tides as the breathing of the earth or sea monsters. He firmly established the moon as the physical cause of the tidal cycle. This observation was using data gathered from sailors and his own measurements of the shoreline.
Al-Bitruji was the very first astronomer who proposed an alternative to Ptolemy's model of the universe long before (more than 300 years) Galileo, by avoiding both epicycles and eccentrics mechanism [3]. According to him, the movement of the celestial spheres created a physical dragging force that stirred the waters of the earth, but his theory is less accurate than Albumasar's.
Ocean tides was a significant area of study for Arab and Muslim reseachers during the middle ages (Islamic Golden Age), had extensive access to the Persian Gulf, the Red Sea, and the Indian Ocean, where tides are far more dramatic. The Greeks and Romans however, had a very limited exposure to ocean tides since they mostly observing the tide-less Mediterranean sea.
> Thanks for pointing that out but there's must some mistakes on the website.
You were the one who suggested that web site.
> Al-Kindi contribution is on the experiment in showing that tides are caused by the expansion of water due to heat but of course later people know that it mainly due to gravity.
Where is the mistake? That is what I quoted.
Your original premise is "Reading most of the technology articles would have you to believe that dark ages really existed and for more than thousands years".
That is, IMO, quite an exaggeration. In the European context, the "Dark Ages" is a dated and inaccurate term for the early middle ages, so the period of about 500 years after the fall of Rome - far from even a single thousand years that you wrote, which would exclude the Carolingian Renaissance.
The term also contains both anti-Catholic and anti-religion attitudes, by Protestant and Enlightenment thinkers who regarded the Roman Church and religion in general as the oppressors of intellectual thought.
I therefore can't help but think you are listening to some very misinformed writers, which is probably why they are writing about technology and not history.
Like, you wrote "Romans however, had a very limited exposure to ocean tides since they mostly observing the tide-less Mediterranean sea" but the Romans had access to the Atlantic coastline from Gibraltar up to modern day Netherlands, plus the modern English coastline .. and those have tides. Famously so, given Julius Caesar's problems with tides during his invasions of Britain.
For that matter, the Roman Empire also reached the Red Sea, with maritime routes to India all the way to the Ganges. Hardly "limited"!
You wrote "Albumasar in his seminal book on tides was the first hypothesized the lunar correlation" but that correlation was made well before. Quoting https://en.wikipedia.org/wiki/Theory_of_tides#History "An ancient Indian Purana text dated to 400-300 BC refers to the ocean rising and falling because of heat expansion from the light of the Moon." (sounds familiar, yes?), and "Ultimately the link between the Moon (and Sun) and the tides became known to the Greeks, although the exact date of discovery is unclear; references to it are made in sources such as Pytheas of Massilia in 325 BC and Pliny the Elder's Natural History in 77 AD."
Your [1] even says he rejected "rejected Greek thought that moonlight influenced the tides and considered that the Moon had some astrological virtue that attracted the sea." How do you conclude his book was the first to hypothesize the lunar correlation?
You also wrote "Al-Bitruji was the very first astronomer who proposed an alternative to Ptolemy's model of the universe" but that is also not true. The very same paragraph on that Wikipedia page points out "Seleucus of Seleucia is thought to have theorized around 150 BC that tides were caused by the Moon as part of his heliocentric model." and https://en.wikipedia.org/wiki/Heliocentrism adds "a moving Earth was proposed at least from the 4th century BC in Pythagoreanism, and a fully developed heliocentric model was developed by Aristarchus of Samos in the 3rd century BC."
What your [3] says is that he was first "to present the concentric spheres model", it points out how it "was a modification of the system of planetary motion proposed by his predecessors, Ibn Bajjah (Avempace) and Ibn Tufail (Abubacer). He was unsuccessful in replacing Ptolemy's planetary model, as the numerical predictions of the planetary positions in his configuration were less accurate than those of the Ptolemaic model" . It links to https://en.wikipedia.org/wiki/Concentric_spheres which points out that model dates back to the Ancient Greeks.
These far predate the start of Islam, much less the Islamic Golden Age.
The Islamic Golden Age was a fantastic era of scholarship, architecture, and research. Making incorrect claims of primacy tarnishes that glory.
My point is that the article is devoid of the significant contributions made in the so called dark ages as so many technical and technology articles with historical background posted in HN [1].
>What your [3] says is that he was first "to present the concentric spheres model", it points out how it "was a modification of the system of planetary motion proposed by his predecessors, Ibn Bajjah (Avempace) and Ibn Tufail (Abubacer). He was unsuccessful in replacing Ptolemy's planetary model, as the numerical predictions of the planetary positions in his configuration were less accurate than those of the Ptolemaic model" .
Imagine if in the future scholars were dismissing Newton's novel contributions to astronomy because his physics model is not that accurate compared to Einstein's. Or even more ridiculous if their future articles point to Ptolemy and straight to Einstein skipping Newton.
>Making incorrect claims of primacy tarnishes that glory.
We can debate about the accuracy later but your comments were missing the forest for the trees, of western biased scholars making their scientist/engineers/technologist contributions even more significant or using your own word "more primacy". The idea is that they (Renaissance scholars) came up with the so called novel and great ideas (pardon the pun) that were originated from the Greek very simple elementary ideas and jump straight into Renaisance era sophisticated ideas, and conveniently skipping the true lineage of knowledge and scholarship in between them.
In research and scholarship this mentallity is frowned upon and illegal. The proper name of this immoral activities is plagiarism by not mentioning the prior reseachers who are you doing the same work and proposing valid ideas even if their work is less accurate than yours [2]:
"Plagiarism is the representation of another person's language, thoughts, ideas, or expressions as one's own original work."
[1] The Myth of the ‘Dark Ages’ Ignores How Classical Traditions Flourished Around the World [1]:
Don't use the term "Dark Ages". The article does not. Use "early European medieval period". Repeating it perpetuates the myth. If you must use it, say "European Dark Ages", and be aware that you are still perpetrating a false anti-religion narrative.
> if in the future scholars were dismissing Newton's novel contributions to astronomy because his physics model is not that accurate compared to Einstein's.
Newton's came first. Einstein improved on Newton.
The example you point to came after the Ptolemaic system and made worse predictions. Plus, there are no compounding rotations of homocentric spheres. And there were other heliocentric models.
> of western biased scholars making their scientist/engineers/technologist contributions even more significant
Sure. And you didn't mention ancient Indian contributions to tides either, like the one I quoted from Wikipedia.
"In earlier versions of this narrative, its European propagators claimed that the Islamic scholars who appropriated Greek knowledge in the eighth-century and then passed it back to their European successors, beginning in the twelfth-century, only conserved that knowledge, effectively doing nothing with it and not increasing it. ... a later generation of historians of science began to research the work of those Islamic scholars, reading, transcribing, translating and analysing their work and showing that they had in fact made substantial contributions to many areas of science and mathematics, contributions that had flowed into modern European science along with the earlier Greek, Babylonian and Egyptian contributions ... Unfortunately the hagiographic, amateur, wannabe pop historians of science now entered the field keen to atone for the sins of the earlier Eurocentric historical narrative and began to exaggerate the achievements of the Islamic scholars to show how superior they were to the puny Europeans who stole their ideas, like the colonial bullies who stole their lands."
You believe I am solidly in the first camp, and you in the second. I believe your comments strongly support my belief that you belong in the third category - a part of the forest you should be aware of because that comment was directed to you.
If I were in the first camp then it should be very easy to refute me by pointing to concrete examples, but your examples fall apart under simple scrutiny, often even by reading the references you give.
If your knowledge were deep, you never would have written "Romans however, had a very limited exposure to ocean tides" as if that were meaningful - or you would have explained why I was wrong, rather than ignoring the problem.
Even now, you write "In research and scholarship this mentallity is frowned upon and illegal."
Plagiarism is NOT illegal per se. Your own [1] says "Plagiarism and copyright infringement functionally overlap, depending on the copyright law protection in force, but they are not equivalent concepts,[19] and although many types of plagiarism may not meet the legal requirements in copyright law as adjudicated by courts, they still constitute the passing-off of another's work as one's own, and thus plagiarism. "
Nor is it always plagiarism to not mention the prior researchers who did the work before you. That's actually quite common, because 1) finding previous work can be hard, and 2) people don't like digging into the literature. If you don't know about previous work then that's called independent re-discovery, not plagiarism. Ramanujan rediscovered known theorems. He did not plagiarize them.
I'm not sure why you keep replying to my post since I believe you understand my original point that most of these historical article were jumping straight from old Greek to Renaissance era.
> Don't use the term "Dark Ages". The article does not. Use "early European medieval period". Repeating it perpetuates the myth. If you must use it, say "European Dark Ages", and be aware that you are still perpetrating a false anti-religion narrative.
The knowledge lineage need to to be taken into account, it's not my job to do that it's the author of the article responsibility, I just pointing the European and western biased here. The biased even more profound in the medical history literature whether they mentioned "dark ages" or not.
>Newton's came first. Einstein improved on Newton
Newton came earlier then Einstein improved on Newton, fixed that for you.
Before Newton there were many other Arabic and muslim scholars working on the physics of planetary problems, or even Indian and Chinese scholars, but I think you get my point.
> "Romans however, had a very limited exposure to ocean tides" as if that were meaningful - or you would have explained why I was wrong, rather than ignoring the problem.
Necessity is the mother of invention.
For example now we have western and European based wireless modulation and standards including Wi-Fi by IEEE and 5G by 3GPP that cannot work reliably with tropical region with lush trees, foliage and heavy rain (in certain spectrum). For satellite communication on certain popular wireless spectrum that means you don't get the signal most of the time during the day. Where in most European countries rain is exotic with minimum rain year around but in tropical countries there's frequent rain, and during rainy season like now it rain practically everyday.
Currently I'm working on the improvement of the wireless modulation that can work much better in this environment due to the western researchers do not experiencing much of this challenging and harsh propagation environment of the tropical trees/rain/etc. Thus they can sympathized but not empathized on the situation. There's no urgent need for them to improve on the situation unlike us although now we're in the Wi-Fi 7 going to 8, and 5G going to 6G for cellular.
However back to the article, the European scholars later found ocean tides is something that need to be calculated, analyzed and predicted due to their colonization effort around the world during the Renaissance time, hence the need to explore and research them further.
Because I want to encourage you to read your sources in more detail. Good scholarship is important, and yet so very hard. And because I want to know new things, and this exchange has lead to some fruitful readings for me.
> it's the author of the article responsibility
You haven't pointed out what's missing from the article that would be relevant to the reader. Rather, what you have pointed out hasn't been correct, or hasn't been relevant.
> working on the physics of planetary problems
Sure. Absolutely. And how would mentioning more of them improve the article? The tides are not caused by the heat of the moon. The tides are not caused by astrological forces. The tides are not caused by undersea monsters. The moon's orbit is not described by a sphere. Listing tidbits about all the people who worked on tides is far outside the scope of this article.
> the European scholars later found ocean tides is something that need to be calculated, analyzed and predicted due to their colonization effort around the world during the Renaissance time, hence the need to explore and research them further.
Sure. And they built on a long history of earlier research in understanding tides.
"Much has been said about the nature of waters ; but the most wonderful circumstance is the alternate flowing and ebbing of the tides, which exists, indeed, under various forms, but is caused by the sun and the moon. ... There is a difference in the tides, depending on the moon, of a complicated nature, and, first, as to the period of seven days. For the tides are of moderate height from the new moon to the first quarter ; from this time they increase, and are the highest at the full: they then decrease. On the seventh day they are equal to what they were at the first ... After an interval of eight years, and the hundredth revolution of the moon, the periods and the heights of the tides return into the same order as at first"
Not bad for someone from the Mediterranean .. except, wait! Not only would he have read about tides, he was the procurator of Hispania Tarraconensis, which has an Atlantic coastline, and may have been the procurator of Gallia Belgica, also on the Atlantic.
"The next advances were made in the Thang. Tou Shu-Mêng, about +770, who wrote the Hai Thao Chih (or Hai Chiao Chih) (On the Tides), seems to have been one of the first to deal with the lunar theory of the tides with any scientific detail. When the moon is passing through hsi-mu and ta-liang, he said, the water rises higher. ... In +850 came a short tractate which was to be famous, Lu Chao’s Hat Chhao Fu (Essay on the Tides). From this we know that regular tide tables (thao chih) were already in use, and that the association of neaps with the moon’s quarters was fully accepted."
Tides calculated, analyzed, and predicted long before Europe's greedy immoral ventures.
Needham suggests the necessity was even greater in China because "The coasts of China, however, have tides of considerable range, for example, about twelve feet in spring off the mouth of the Yangtze. Moreover, China possessed one of the only two great tidal bores or eagres in the world, that on the Chhien-Thang River near Hangchow".
If you really believe your necessity hypothesis, then you should stress Chinese tidal studies, not Muslim/Arabic ones.
Still, it's all interconnected. Europeans needed a better way to handle bookkeeping. Fibbonacci's Liber Abaci introduced the Indo–Arabic numeral system to Europe. The resulting improved of banking and accounting abilities would later help fund Europe's exploitative efforts.
China developed gunpowder. European researchers improved on it both for internal wars and their wars of subjugation.
The Needham Question - yes, the very same Needham - asks and tries to answer the question of why modern science did not develop in Chinese or Indian civilization (or during the Muslim Golden Age), but only in later Europe.
> Rather, what you have pointed out hasn't been correct, or hasn't been relevant.
According to your biased conjectures.
>Fibbonacci's Liber Abaci introduced the Indo–Arabic numeral system to Europe
Please don't further propagate this fake story, this is just another European biased narratives and lies.
Arab and muslim were in Europe well before Fibonacci, and were using Arabic numbers 1 to 10, etc. Toledo and Spain were fluorishing as one of world knowledge centers alongside Baghdad under muslim empires. Then Toledo fall the to Reconquista in 1085 CE (11th century). Please note that this event happened well before Fibbonacci time [1].
Mediterranean sea was under the auspice of muslim including Sicily even before the latter conquered by Normans. I suppose Normans learnt many civilization stuff with their interaction with muslim in the Mediterranean area, and later the same Normans conquered Britain.
>China developed gunpowder. European researchers improved on it both for internal wars and their wars of subjugation
This another jumping of history narrative from China straight to European contribution missing on the significant contributions lineage of muslim reseachers.
Tipu Sultan of Mysore in India was inventing the rocket using existing knowledge of gunpowder and beating British Empire several time in the wars [2]. Then when he was defeated the British created Arsenal research centers at Woolwich to study further the rockets and the ammunitions. Now England has the Arsenal football club.
>I want to know new things, and this exchange has lead to some fruitful readings for me.
Please do your scholarship properly or better try to get publish in the reputable journals rather then lurking too much in HN if you are really interested in the idea. Time and tides wait for no man.
Also read the Bible and Quran, the Truth will set you free.
According to the very citations you link to. I note you haven't pointed to additional supporting evidence for your arguments.
Nor have you said what's missing from the article that would be relevant to the reader, other than providing a list of names.
"Arab and muslim were in Europe well before Fibonacci"
I am using "Europe" in the same meaning that you did with "became the standard reference for European scholars (like Roger Bacon and Albert the Great) when they tried to understand tidal physics." and "the European scholars later found ocean tides is something that need to be calculated, analyzed and predicted due to their colonization effort around the world during the Renaissance time".
Should I say "Christian Europe"? What then of the Jews in Europe? I really don't like saying "the West" or "Western Civilization" as those are terms white supremacists prefer to use.
You can also include Sicily and Malta as part of Muslim Europe.
"This another jumping of history narrative from China"
That was me telling you that you have been ignoring Chinese history in your focus on Muslim history. If you want the author to include all the contributions you mentioned, then surely you want the author to also include the examples from China, right? I believe you said that doing otherwise would be
"immoral" and "plagiarism".
"Please do your scholarship properly"
I pointed you to Pliny to show that Romans know the Moon and Sun affected tides, and how to make tide predictions.
I pointed you to Needham so you could read about Chinese knowledge of tides and tide prediction, and to highlight how weak your "necessity" argument was.
You haven't pointed to any primary or secondary sources, only encyclopedia entries, and you think there must be mistakes in Wikipedia when it disagrees with your understanding.
I have read the Bible twice and taken a college course in the Bible. I also know the world was not covered by a great flood, that the story of the Exodus is not historical, and that Christian apologetics can justify anything as "the Truth" while they claim the Bible is 100% accurate.
Nor are they alone in promising "the Truth".
"Hinduism, the world’s oldest religion, has no beginning–it precedes recorded history. It has no human founder. It is a mystical religion, leading the devotee to personally experience the Truth within, finally reaching the pinnacle of consciousness where man and God are one." - https://www.hinduismtoday.com/hindu-basics/nine-beliefs-of-h...
I know this is unrelated to the actual content, but I have such a visceral reaction to any headline in the "x is different than you think"... how do you know what I think? I am sure many people who read this will be experts on tides, and the title is completely wrong.
For me, the worst are posts about scale and things I won't need, like "You don't need kafka" or "your data isn't actually big data" or "don't horizontally scale, just get a bigger server"
I get that I am not the target audience and there are people for whom those statements are true, but I am running Kafka clusters with data from 10s of thousands of servers, I absolutely can't move that to a single machine.
I wish they would phrase it as "Tides are weirder than most people think", although that probably doesn't drive as much engagement.
What you are actually having is a visceral reaction to your misunderstanding of how the English language works with the word ‘you’ in this circumstance.
It is property of English language where "you" is used in place of "one" very often. This is particularly common in American English which has less formality to it; less Frenchiness. No 'on' etc. Everyone is 'tu'.
It is language quirk, but you can probably use LLM to replace HN headlines like this. Pretty cheap and one will no longer have visceral reaction that one does not wish.
Odd weather wasn't mentioned. While weather does not create tides, but it can significantly modify the actual water level compared with the purely astronomical tide that the article describes.
I see I'm not the only geek fascinated by the tide. I knew all the stuff in the article already, of course. It seems it's like railways or something, seems to trigger something in geeky brains. I live in the UK so see some of the largest "swings" in the world. It never ceases to amaze me that it all happens in the space of 6 hours. I've also gone to see spring tides just to see what it looks like. It's cool, and scary.
It took most of this summer to get my tide clock to predict accurately, using NOAA harmonic constituents data crammed into an Arduino, a GPS module, and published formulas.
A detail not included here, but important for people interested in the sea level, is the effects of the wind. Lots of places along the east coast of the US experience mild tides, but a steady wind in the right direction will push sea levels up in various bays and inlets. The storm surge of a hurricane turns it up to 11.
I live near a river that flows backwards for some 50km or so with tides. The first time I saw it, I thought I'd gotten turned around because surely water can't flow uphill, right? It's fun to find out that one is so wrong about basic physics.
Jeanne Rousseau, who passed away in 2012, asked in an interview [1]:
Why are the syzygy tidal coefficients equal when the quadrature tidal coefficients are at opposite extremes?
Why are the syzygy coefficients at opposite extremes when the others are equal?
Who can explain this using the laws of universal gravitation?
Her point is that you can't.
Earlier in that interview she says:
I was put in touch with the Institut de Physique du Globe [2]. In April 1953, I met with Professor Coulomb [3], who was the director at the time, and asked him about the ionic variations that might occur during the lunar phases. His formal response was that there were none. However, I had already been observing them for some time. I must say that in 1953 I had already begun to observe the phenomenon of the tides. Being told that, apart from a minimum of atmospheric ionization at 4 a.m., there is nothing else that can have an impact on the biological, human, or other levels, I said: but there is the phenomenon of the tides! And that's when I got this response, which marked a break with the scientific community for me:
The phenomenon of the tides is a phenomenon that is beyond us. We waste our time when we take an interest in phenomena that are beyond us. If you don't want to waste yours, focus on other things.
Jeanne Rousseau demonstrated through observation that tidal phenomena are not solely gravitational but primarily electromagnetic. One can read more about this in English in this paper [4].
This is, not to put too fine a point on it, crank science. Opening up the linked document, the DOI fails to resolve, the paper investigates pH variations in urine during tide cycles, and also skimming over it doesn't appear to make a single prediction. This is at best unfalsifiable, and a "break with the scientific community" is an accurate assessment.
The physics of tides is largely well-understood, and the moon and sun provide the primary forcing. Accurate tide tables are regularly computed the world over, with measurements regularly made. Without even looking at measurements, the shipping industry demands accurate tide forecasts for navigating efficiently. The claim that "tidal phenomena are... primarily electromagnetic" requires some serious evidence to back it up, with calculates to boot, rather than invoking mysticism that tides are "beyond us". Many things are beyond our current scientific understanding, and that is humbling, but tides are quite well understood.
I would not dismiss this as crank science so quickly, first and foremost because it's not claiming to be science, not theoretically at least. It's observation of likely correlation. Also I would not say tides are "quite well understood" because it's misleading. I'd say sufficiently understood so that models are precise enough to be useful, but they're still an approximation to a few cm. For now water levels, costal geography, terrain, and weather seem to be the main parameters they attribute to the small variations observed, but who can say there aren't more parameters to take into account? Also what doesn't help in having a "well understood" feeling is that you can find different explanation of the bulges on either side of the earth.
I don't have the scientific knowledge to assess all this. I'm not even sure how to understand properly the questions Jeanne Rousseau asks saying newtonian physics can't answer. What I hear however are competent people observing small variation in the properties of water and living systems that seems to be related to cosmic phenomenon, including moon phases. Variations we can also find in the atmosphere/ionosphere with more recent measurements of their ionic polarities. Adding to that are all the new discoveries that link weather phenomenon to electromagnetic influences from the sun, with water significantly influencing the electromagnetic properties of the atmosphere. Finally more people question the true molecular structure of water, as H2O seems to be a crude simplification over a dynamic mixture of isotopes and ions.
Overall the tidal theory is not a done deal, we only have approximate models, and this topic can be discussed for years to come. That's probably why she was told the tides is a phenomenon that is beyond us.
You may have seen diagrams of the tidal force of the Moon on the earth (like this one: https://www.oc.nps.edu/nom/day1/tide_force_diagram.gif).
Intuitively you would think that the tide is being formed because the Moon is "lifting up" the water at the point closest to the Moon. But this contribution is actually very miniscule to the tidal effect. Instead the bulk of the tides are produced about 45 degrees away where the tidal force is parallel to the Earth's surface. This has the effect of dragging the water closer to the tidal bulge.
Thank you--the diagram you link is a better explanation of whey the tide "bulges up on the sides of the Earth closest to and farthest from the Moon"--the article left this entirely unclear.
In particular, I could understand how two satellites connected by a cable would result in the cable being stretched. But I still find it hard to wrap my mind around the fact that we get a high tide where the Earth's gravity and the Moon's add (the far side of the Earth from the Moon), but we also get a high tide on the opposite side, where the Moon's gravitational pull is subtracted from the Earth's. The centrifugal force is (I think) a much better explanation. (I realize physicists don't consider that a force, but...)
So yes, tides really are weirder than I think.
(The other facts in the article were actually familiar, e.g. the fact that the tides in Hawaii are quite small, because it's not far from an amphidromic point.)
Tides aren't caused by centrifugal force but by differing gravity. You would be ripped apart by tides falling straight into black hole.
The near part of Earth experiences more gravity from the Moon, the far part less. The Earth moves in the center so the water bulges on the ends. Important part is that the Earth pulls things out their natural orbits.
With circular orbits, gravity and centrifugal force are balanced so could be considered difference on centrifugal force. But that isn't true for all orbits.
Simple illustration of what you are explaining in 1D. Imagine a simplified Earth:
Water -- Ground -- Water
Now let's add a Moon with gravitational pull. The pull stretches the system, because gravity is stronger the closer you are to the Moon.
Water ---- Ground ---- Water -//- Moon
The water is farther away from the ground on both sides now, since both sides stretched.
so why is left water further away from ground? this example make 0 sense
The Earth is being pulled away from that water, just as the water on the right is being pulled away from the Earth.
But the water on the left is being pulled by everything to the right of it, moon, earth, other water. Why is it left behind? Every single thing is being attracted by the same centre of gravity on the right of the earth
but to develop better intuition, think of the sun's gravity as a field in space and nothing is being dragged anywhere, it's just that wherever you are feels appropriate to where you are and where you are going is the path of least resistance, and the places around you feel the same way, and where you all are in relation to each other (in this field) changes its relative position to everything else.
the water of an incoming tide doesn't feel "i'm being dragged uphill", it feels "hey, the earth is moving underneath me". it's all in freefall all the time.
you don't feel like you are rotating at 1000 mph (1600 kph) but you do feel your weight against the surface of the earth. same with the water, except it feels itself being squeezed by everything around it like you only feel that in the entrance to a crowded venue.
so, the water on the side toward the moon and the water on the side away from the moon would mostly perceive the earth as dropping away or coming closer (if they could perceive anything at all) where they are is always their point of reference
This explanation is a lot more thorough and detailed (and there are no tidal bulges.. Common myth)
https://physics.stackexchange.com/questions/121830/does-eart...
I went down a rabbit hole a few weeks back to discover this. I was so upset with so many wrong explanations including Neil de Grasse Tyson saying we're moving into the bulges.
it's very magical though discovering the beauty of it.
What really gets me is the "Map of the strength of the 12-hr lunar tide" in the Layer 4 section of the article posted, which I haven't seen discussed.
All the rest is swept away, and you have stretches of coastline with tides over one meter, and others with nearly zero, just because of landmass distribution ...
If you moved Miami Beach to the French Atlantic coast, things would get interesting.
Relevant
https://news.ycombinator.com/item?id=44065458
(92 comments)
Also https://content.teachastronomy.com/taweb/images/textbook/hrt...
Inlining my comment that I had posted there:
The problem of predicting tides was so important that it attracted many Physics and Maths heavy weights. You can well imagine how important predicting tides would have been for D-day landing. One related fascinating historical artifact is the special purpose analogue computer designed by Lord Kelvin in the 1860s based on Fourier series, harmonic analysis. Think difference engine in it's cogs and cams glory, but special purpose.
https://en.m.wikipedia.org/wiki/Tide-predicting_machine
Possibly one of the first examples of Machine learning, with Machine in capital 'M'. It incorporated recent tidal observations to update it's prediction.
Note that sinusoids are universal approximators for a large class of functions, an honour that is by no means restricted to deep neural nets.
George Darwin (Charles Darwin's son) was a significant contributor in the design and upgrade of the machine.
https://en.m.wikipedia.org/wiki/George_Darwin
Other recognizable names who worked on tide prediction problem were Thomas Young (of double slit experiment fame) and Sir George Airy (of Airy disk fame).
> Kelvin’s machine automates the second half of that task. As the pulleys spin, they pull on a common chain by the correct amount for each of the calculated components. A year’s worth of tidal tables can be put together in half an hour, if you know the components. Even better, you can “guess and check” the components by comparing your machine’s output to past records, and adjusting the pulleys until you get something that works correctly.
I didn't know they already had machine learning and model fitting algorithms in the 1800s, but here we are...
https://news.ycombinator.com/item?id=44066091
https://xkcd.com/1838
Sometimes we need dates attached - by the numbers (1838 of current 3176) that's probably some 5 or 6 years before ChatGTP. Or 3 or 4 years after the Netflix challenge.
No later than 17 May 2017 - https://www.explainxkcd.com/wiki/index.php/1838:_Machine_Lea...
Mobile view
https://m.xkcd.com/1838/
Nice article!
Any talk of tide prediction should always mention xtide:
https://flaterco.com/xtide/
I've used it with great accuracy in a number of locations around the world.
Another one of those free software packages that's been meticulously maintained by one person for decades...
Here we go (quote from the xtide Web page)
"Q: I live outside of the U.S. and my location is no longer supported. What happened?
A: Many data were purged after a legal threat from the U.K. Hydrographic Office (UKHO) in January 2001. I ended maintenance of the non-U.S. data that replaced them for different reasons in early 2012."
I wonder how much money the Hydrographic Office saved by not allowing this data to be distributed?
https://www.youtube.com/watch?v=AxC770lpSLw shows one of the old tide prediction mechanical computers briefly mentioned in this article. It is effectively doing an inverse Fourier Transform, summing all the various 30+ sinusoids that affect the tides.
out the back door of my house, down through the field and woods to the water is a 12 min walk at high tide, and another 12 min + walk to the water at low tide, 53 vertical feet between the two. I know ,not the slightest thing about tides, other than what my senses tell me when walking the shore, and I suppose the practicalities of beach walking along cliffs are similar to planning and predicting arival times for ships loaded to the maximum draft, the money to be made there bieng the motivation behind the push to understand tides.
That seems huge. Are you in Fundy’s bay in Canada?
huge, and where else? there are some places here where the slope is so gradual, that the low tide is over the horison growing up we had a camp right at the end of Burnt Coat Head, in Noel, and never did make it to the low tide line between there and Cape Split there is the full range of tidal phenominon on display, resonant standing waves, whirlpools, tidal bores(with surfing black ducks),whole bays emptied, and varios dikes and berms, dams, locks, to hold it back
there are one ot two other places on the planet that are close, and from the charts in the article, spots with NO tide, which when I think about,is very wierd indeed
Veritasium made a great video on Kelvin's Tide-predicting machine in 2021.
Title: The Most Powerful Computers You've Never Heard Of
URL: https://www.youtube.com/watch?v=IgF3OX8nT0w
https://en.wikipedia.org/wiki/Tide-predicting_machine
Basically, a summation of sinusoids.
Reading most of the technology articles would have you to believe that dark ages really existed and for more than thousands years, i.e from Greece to Renaissance time there is no marine technology advancement between them.
The truth of the matter is that the Arabic and muslim are the master of the sea during this so called "dark ages" time, and many advancement has been made from navigation gear of the Arabic astrolobe to the Idrisi map.
In tide prediction Al-Kindi for example, has notable work on tides in his seminal book Treatise on the Efficient Cause of the Flow and Ebb back in 9th CE [1],[2].
[1]al-Kindi:
https://en.wikipedia.org/wiki/Al-Kindi
[2] Al-Kindi:
https://muslimheritage.com/al-kindi/
From [1]
> In a treatise entitled as Risala fi l-Illa al-Failali l-Madd wa l-Fazr (Treatise on the Efficient Cause of the Flow and Ebb), al-Kindi presents a theory on tides which "depends on the changes which take place in bodies owing to the rise and fall of temperature."
Thanks for pointing that out but there's must some mistakes on the website. Al-Kindi contribution is on the experiment in showing that tides are caused by the expansion of water due to heat but of course later people know that it mainly due to gravity.
Other well known Arabic and muslim reseachers in the middle ages working on ocean tides are Abu Ma'shar al-Balkhi (Albumasar), Al-Biruni and Nur ad-Din al-Bitruji (Alpetragius).
Albumasar in his seminal book on tides was the first hypothesized the lunar correlation [1]. He's arguably the most important figure in the history of tidal theory between the ancient Greeks and Renaissance. His famous work namely The Great Introduction to Astrology (Kitab al-Madkhal al-Kabir) was translated into Latin in the 12th century and became the standard reference for European scholars (like Roger Bacon and Albert the Great) when they tried to understand tidal physics.
Al-Biruni was a polymath who had direct experience with the strong tides of the Indian Ocean specifically at the port of Somnath in Gujarat, India. Of the 146 books written by him, 95 are devoted to astronomy, mathematics, and related subjects like mathematical geography [2]. In his encyclopedic work Indica (Kitab al-Hind), he discussed how the moon influences "moist substances". He dismissed the common myth in the region that viewed tides as the breathing of the earth or sea monsters. He firmly established the moon as the physical cause of the tidal cycle. This observation was using data gathered from sailors and his own measurements of the shoreline.
Al-Bitruji was the very first astronomer who proposed an alternative to Ptolemy's model of the universe long before (more than 300 years) Galileo, by avoiding both epicycles and eccentrics mechanism [3]. According to him, the movement of the celestial spheres created a physical dragging force that stirred the waters of the earth, but his theory is less accurate than Albumasar's.
Ocean tides was a significant area of study for Arab and Muslim reseachers during the middle ages (Islamic Golden Age), had extensive access to the Persian Gulf, the Red Sea, and the Indian Ocean, where tides are far more dramatic. The Greeks and Romans however, had a very limited exposure to ocean tides since they mostly observing the tide-less Mediterranean sea.
[1] Abu Ma'shar al-Balkhi:
https://en.wikipedia.org/wiki/Abu_Ma%27shar_al-Balkhi
[2] Al-Biruni:
https://en.wikipedia.org/wiki/Al-Biruni
[3] Nur ad-Din al-Bitruji:
https://en.wikipedia.org/wiki/Nur_ad-Din_al-Bitruji
> Thanks for pointing that out but there's must some mistakes on the website.
You were the one who suggested that web site.
> Al-Kindi contribution is on the experiment in showing that tides are caused by the expansion of water due to heat but of course later people know that it mainly due to gravity.
Where is the mistake? That is what I quoted.
Your original premise is "Reading most of the technology articles would have you to believe that dark ages really existed and for more than thousands years".
That is, IMO, quite an exaggeration. In the European context, the "Dark Ages" is a dated and inaccurate term for the early middle ages, so the period of about 500 years after the fall of Rome - far from even a single thousand years that you wrote, which would exclude the Carolingian Renaissance.
The term also contains both anti-Catholic and anti-religion attitudes, by Protestant and Enlightenment thinkers who regarded the Roman Church and religion in general as the oppressors of intellectual thought.
I therefore can't help but think you are listening to some very misinformed writers, which is probably why they are writing about technology and not history.
Like, you wrote "Romans however, had a very limited exposure to ocean tides since they mostly observing the tide-less Mediterranean sea" but the Romans had access to the Atlantic coastline from Gibraltar up to modern day Netherlands, plus the modern English coastline .. and those have tides. Famously so, given Julius Caesar's problems with tides during his invasions of Britain.
For that matter, the Roman Empire also reached the Red Sea, with maritime routes to India all the way to the Ganges. Hardly "limited"!
You wrote "Albumasar in his seminal book on tides was the first hypothesized the lunar correlation" but that correlation was made well before. Quoting https://en.wikipedia.org/wiki/Theory_of_tides#History "An ancient Indian Purana text dated to 400-300 BC refers to the ocean rising and falling because of heat expansion from the light of the Moon." (sounds familiar, yes?), and "Ultimately the link between the Moon (and Sun) and the tides became known to the Greeks, although the exact date of discovery is unclear; references to it are made in sources such as Pytheas of Massilia in 325 BC and Pliny the Elder's Natural History in 77 AD."
Your [1] even says he rejected "rejected Greek thought that moonlight influenced the tides and considered that the Moon had some astrological virtue that attracted the sea." How do you conclude his book was the first to hypothesize the lunar correlation?
You also wrote "Al-Bitruji was the very first astronomer who proposed an alternative to Ptolemy's model of the universe" but that is also not true. The very same paragraph on that Wikipedia page points out "Seleucus of Seleucia is thought to have theorized around 150 BC that tides were caused by the Moon as part of his heliocentric model." and https://en.wikipedia.org/wiki/Heliocentrism adds "a moving Earth was proposed at least from the 4th century BC in Pythagoreanism, and a fully developed heliocentric model was developed by Aristarchus of Samos in the 3rd century BC."
What your [3] says is that he was first "to present the concentric spheres model", it points out how it "was a modification of the system of planetary motion proposed by his predecessors, Ibn Bajjah (Avempace) and Ibn Tufail (Abubacer). He was unsuccessful in replacing Ptolemy's planetary model, as the numerical predictions of the planetary positions in his configuration were less accurate than those of the Ptolemaic model" . It links to https://en.wikipedia.org/wiki/Concentric_spheres which points out that model dates back to the Ancient Greeks.
These far predate the start of Islam, much less the Islamic Golden Age.
The Islamic Golden Age was a fantastic era of scholarship, architecture, and research. Making incorrect claims of primacy tarnishes that glory.
My point is that the article is devoid of the significant contributions made in the so called dark ages as so many technical and technology articles with historical background posted in HN [1].
>What your [3] says is that he was first "to present the concentric spheres model", it points out how it "was a modification of the system of planetary motion proposed by his predecessors, Ibn Bajjah (Avempace) and Ibn Tufail (Abubacer). He was unsuccessful in replacing Ptolemy's planetary model, as the numerical predictions of the planetary positions in his configuration were less accurate than those of the Ptolemaic model" .
Imagine if in the future scholars were dismissing Newton's novel contributions to astronomy because his physics model is not that accurate compared to Einstein's. Or even more ridiculous if their future articles point to Ptolemy and straight to Einstein skipping Newton.
>Making incorrect claims of primacy tarnishes that glory.
We can debate about the accuracy later but your comments were missing the forest for the trees, of western biased scholars making their scientist/engineers/technologist contributions even more significant or using your own word "more primacy". The idea is that they (Renaissance scholars) came up with the so called novel and great ideas (pardon the pun) that were originated from the Greek very simple elementary ideas and jump straight into Renaisance era sophisticated ideas, and conveniently skipping the true lineage of knowledge and scholarship in between them.
In research and scholarship this mentallity is frowned upon and illegal. The proper name of this immoral activities is plagiarism by not mentioning the prior reseachers who are you doing the same work and proposing valid ideas even if their work is less accurate than yours [2]:
"Plagiarism is the representation of another person's language, thoughts, ideas, or expressions as one's own original work."
[1] The Myth of the ‘Dark Ages’ Ignores How Classical Traditions Flourished Around the World [1]:
https://www.smithsonianmag.com/history/the-myth-of-the-dark-...
[2] Plagiarism:
https://en.wikipedia.org/wiki/Plagiarism
Don't use the term "Dark Ages". The article does not. Use "early European medieval period". Repeating it perpetuates the myth. If you must use it, say "European Dark Ages", and be aware that you are still perpetrating a false anti-religion narrative.
> if in the future scholars were dismissing Newton's novel contributions to astronomy because his physics model is not that accurate compared to Einstein's.
Newton's came first. Einstein improved on Newton.
The example you point to came after the Ptolemaic system and made worse predictions. Plus, there are no compounding rotations of homocentric spheres. And there were other heliocentric models.
> of western biased scholars making their scientist/engineers/technologist contributions even more significant
Sure. And you didn't mention ancient Indian contributions to tides either, like the one I quoted from Wikipedia.
I see from your posting history that you posted https://news.ycombinator.com/item?id=37184786, with someone else posting a comment linking to https://thonyc.wordpress.com/2014/10/03/the-unfortunate-back... . Quoting from it:
"In earlier versions of this narrative, its European propagators claimed that the Islamic scholars who appropriated Greek knowledge in the eighth-century and then passed it back to their European successors, beginning in the twelfth-century, only conserved that knowledge, effectively doing nothing with it and not increasing it. ... a later generation of historians of science began to research the work of those Islamic scholars, reading, transcribing, translating and analysing their work and showing that they had in fact made substantial contributions to many areas of science and mathematics, contributions that had flowed into modern European science along with the earlier Greek, Babylonian and Egyptian contributions ... Unfortunately the hagiographic, amateur, wannabe pop historians of science now entered the field keen to atone for the sins of the earlier Eurocentric historical narrative and began to exaggerate the achievements of the Islamic scholars to show how superior they were to the puny Europeans who stole their ideas, like the colonial bullies who stole their lands."
You believe I am solidly in the first camp, and you in the second. I believe your comments strongly support my belief that you belong in the third category - a part of the forest you should be aware of because that comment was directed to you.
If I were in the first camp then it should be very easy to refute me by pointing to concrete examples, but your examples fall apart under simple scrutiny, often even by reading the references you give.
If your knowledge were deep, you never would have written "Romans however, had a very limited exposure to ocean tides" as if that were meaningful - or you would have explained why I was wrong, rather than ignoring the problem.
Even now, you write "In research and scholarship this mentallity is frowned upon and illegal."
Plagiarism is NOT illegal per se. Your own [1] says "Plagiarism and copyright infringement functionally overlap, depending on the copyright law protection in force, but they are not equivalent concepts,[19] and although many types of plagiarism may not meet the legal requirements in copyright law as adjudicated by courts, they still constitute the passing-off of another's work as one's own, and thus plagiarism. "
Nor is it always plagiarism to not mention the prior researchers who did the work before you. That's actually quite common, because 1) finding previous work can be hard, and 2) people don't like digging into the literature. If you don't know about previous work then that's called independent re-discovery, not plagiarism. Ramanujan rediscovered known theorems. He did not plagiarize them.
I'm not sure why you keep replying to my post since I believe you understand my original point that most of these historical article were jumping straight from old Greek to Renaissance era.
> Don't use the term "Dark Ages". The article does not. Use "early European medieval period". Repeating it perpetuates the myth. If you must use it, say "European Dark Ages", and be aware that you are still perpetrating a false anti-religion narrative.
The knowledge lineage need to to be taken into account, it's not my job to do that it's the author of the article responsibility, I just pointing the European and western biased here. The biased even more profound in the medical history literature whether they mentioned "dark ages" or not.
>Newton's came first. Einstein improved on Newton
Newton came earlier then Einstein improved on Newton, fixed that for you.
Before Newton there were many other Arabic and muslim scholars working on the physics of planetary problems, or even Indian and Chinese scholars, but I think you get my point.
> "Romans however, had a very limited exposure to ocean tides" as if that were meaningful - or you would have explained why I was wrong, rather than ignoring the problem.
Necessity is the mother of invention.
For example now we have western and European based wireless modulation and standards including Wi-Fi by IEEE and 5G by 3GPP that cannot work reliably with tropical region with lush trees, foliage and heavy rain (in certain spectrum). For satellite communication on certain popular wireless spectrum that means you don't get the signal most of the time during the day. Where in most European countries rain is exotic with minimum rain year around but in tropical countries there's frequent rain, and during rainy season like now it rain practically everyday.
Currently I'm working on the improvement of the wireless modulation that can work much better in this environment due to the western researchers do not experiencing much of this challenging and harsh propagation environment of the tropical trees/rain/etc. Thus they can sympathized but not empathized on the situation. There's no urgent need for them to improve on the situation unlike us although now we're in the Wi-Fi 7 going to 8, and 5G going to 6G for cellular.
However back to the article, the European scholars later found ocean tides is something that need to be calculated, analyzed and predicted due to their colonization effort around the world during the Renaissance time, hence the need to explore and research them further.
> I'm not sure why you keep replying to my post
Because I want to encourage you to read your sources in more detail. Good scholarship is important, and yet so very hard. And because I want to know new things, and this exchange has lead to some fruitful readings for me.
> it's the author of the article responsibility
You haven't pointed out what's missing from the article that would be relevant to the reader. Rather, what you have pointed out hasn't been correct, or hasn't been relevant.
> working on the physics of planetary problems
Sure. Absolutely. And how would mentioning more of them improve the article? The tides are not caused by the heat of the moon. The tides are not caused by astrological forces. The tides are not caused by undersea monsters. The moon's orbit is not described by a sphere. Listing tidbits about all the people who worked on tides is far outside the scope of this article.
> the European scholars later found ocean tides is something that need to be calculated, analyzed and predicted due to their colonization effort around the world during the Renaissance time, hence the need to explore and research them further.
Sure. And they built on a long history of earlier research in understanding tides.
Like, Pliny described how the tides are influenced by both the Sun and the Moon - https://archive.org/details/naturalhistoryof01plinuoft/page/... - something I presume that every educated scholar of the Golden Era would have known about. Pliny wrote:
"Much has been said about the nature of waters ; but the most wonderful circumstance is the alternate flowing and ebbing of the tides, which exists, indeed, under various forms, but is caused by the sun and the moon. ... There is a difference in the tides, depending on the moon, of a complicated nature, and, first, as to the period of seven days. For the tides are of moderate height from the new moon to the first quarter ; from this time they increase, and are the highest at the full: they then decrease. On the seventh day they are equal to what they were at the first ... After an interval of eight years, and the hundredth revolution of the moon, the periods and the heights of the tides return into the same order as at first"
Not bad for someone from the Mediterranean .. except, wait! Not only would he have read about tides, he was the procurator of Hispania Tarraconensis, which has an Atlantic coastline, and may have been the procurator of Gallia Belgica, also on the Atlantic.
Or we can read about China from Needham, at https://archive.org/details/cftri.9621sciencecivilisat0000jo...
"The next advances were made in the Thang. Tou Shu-Mêng, about +770, who wrote the Hai Thao Chih (or Hai Chiao Chih) (On the Tides), seems to have been one of the first to deal with the lunar theory of the tides with any scientific detail. When the moon is passing through hsi-mu and ta-liang, he said, the water rises higher. ... In +850 came a short tractate which was to be famous, Lu Chao’s Hat Chhao Fu (Essay on the Tides). From this we know that regular tide tables (thao chih) were already in use, and that the association of neaps with the moon’s quarters was fully accepted."
Tides calculated, analyzed, and predicted long before Europe's greedy immoral ventures.
Needham suggests the necessity was even greater in China because "The coasts of China, however, have tides of considerable range, for example, about twelve feet in spring off the mouth of the Yangtze. Moreover, China possessed one of the only two great tidal bores or eagres in the world, that on the Chhien-Thang River near Hangchow".
If you really believe your necessity hypothesis, then you should stress Chinese tidal studies, not Muslim/Arabic ones.
Still, it's all interconnected. Europeans needed a better way to handle bookkeeping. Fibbonacci's Liber Abaci introduced the Indo–Arabic numeral system to Europe. The resulting improved of banking and accounting abilities would later help fund Europe's exploitative efforts.
China developed gunpowder. European researchers improved on it both for internal wars and their wars of subjugation.
The Needham Question - yes, the very same Needham - asks and tries to answer the question of why modern science did not develop in Chinese or Indian civilization (or during the Muslim Golden Age), but only in later Europe.
> Rather, what you have pointed out hasn't been correct, or hasn't been relevant.
According to your biased conjectures.
>Fibbonacci's Liber Abaci introduced the Indo–Arabic numeral system to Europe
Please don't further propagate this fake story, this is just another European biased narratives and lies.
Arab and muslim were in Europe well before Fibonacci, and were using Arabic numbers 1 to 10, etc. Toledo and Spain were fluorishing as one of world knowledge centers alongside Baghdad under muslim empires. Then Toledo fall the to Reconquista in 1085 CE (11th century). Please note that this event happened well before Fibbonacci time [1].
Mediterranean sea was under the auspice of muslim including Sicily even before the latter conquered by Normans. I suppose Normans learnt many civilization stuff with their interaction with muslim in the Mediterranean area, and later the same Normans conquered Britain.
>China developed gunpowder. European researchers improved on it both for internal wars and their wars of subjugation
This another jumping of history narrative from China straight to European contribution missing on the significant contributions lineage of muslim reseachers.
Tipu Sultan of Mysore in India was inventing the rocket using existing knowledge of gunpowder and beating British Empire several time in the wars [2]. Then when he was defeated the British created Arsenal research centers at Woolwich to study further the rockets and the ammunitions. Now England has the Arsenal football club.
>I want to know new things, and this exchange has lead to some fruitful readings for me.
Please do your scholarship properly or better try to get publish in the reputable journals rather then lurking too much in HN if you are really interested in the idea. Time and tides wait for no man.
Also read the Bible and Quran, the Truth will set you free.
[1] Siege of Toledo:
https://www.britannica.com/event/Siege-of-Toledo
[2] Tipu Sultan:
https://en.wikipedia.org/wiki/Tipu_Sultan
According to the very citations you link to. I note you haven't pointed to additional supporting evidence for your arguments.
Nor have you said what's missing from the article that would be relevant to the reader, other than providing a list of names.
"Arab and muslim were in Europe well before Fibonacci"
I am using "Europe" in the same meaning that you did with "became the standard reference for European scholars (like Roger Bacon and Albert the Great) when they tried to understand tidal physics." and "the European scholars later found ocean tides is something that need to be calculated, analyzed and predicted due to their colonization effort around the world during the Renaissance time".
"Europe" is also the term used by your preferred source: https://en.wikipedia.org/wiki/Liber_Abaci
Should I say "Christian Europe"? What then of the Jews in Europe? I really don't like saying "the West" or "Western Civilization" as those are terms white supremacists prefer to use.
You can also include Sicily and Malta as part of Muslim Europe.
"This another jumping of history narrative from China"
That was me telling you that you have been ignoring Chinese history in your focus on Muslim history. If you want the author to include all the contributions you mentioned, then surely you want the author to also include the examples from China, right? I believe you said that doing otherwise would be "immoral" and "plagiarism".
"Please do your scholarship properly"
I pointed you to Pliny to show that Romans know the Moon and Sun affected tides, and how to make tide predictions.
I pointed you to Needham so you could read about Chinese knowledge of tides and tide prediction, and to highlight how weak your "necessity" argument was.
You haven't pointed to any primary or secondary sources, only encyclopedia entries, and you think there must be mistakes in Wikipedia when it disagrees with your understanding.
I have read the Bible twice and taken a college course in the Bible. I also know the world was not covered by a great flood, that the story of the Exodus is not historical, and that Christian apologetics can justify anything as "the Truth" while they claim the Bible is 100% accurate.
Nor are they alone in promising "the Truth".
"Hinduism, the world’s oldest religion, has no beginning–it precedes recorded history. It has no human founder. It is a mystical religion, leading the devotee to personally experience the Truth within, finally reaching the pinnacle of consciousness where man and God are one." - https://www.hinduismtoday.com/hindu-basics/nine-beliefs-of-h...
We have a "King Tide" today in SoCal where the local swing is +7/-1.5. Get to see normally hidden tidepools and a bunch of cobbles...
I know this is unrelated to the actual content, but I have such a visceral reaction to any headline in the "x is different than you think"... how do you know what I think? I am sure many people who read this will be experts on tides, and the title is completely wrong.
For me, the worst are posts about scale and things I won't need, like "You don't need kafka" or "your data isn't actually big data" or "don't horizontally scale, just get a bigger server"
I get that I am not the target audience and there are people for whom those statements are true, but I am running Kafka clusters with data from 10s of thousands of servers, I absolutely can't move that to a single machine.
I wish they would phrase it as "Tides are weirder than most people think", although that probably doesn't drive as much engagement.
Because if someone says "one" it sounds affected.
If one says "someone" it may seem too targeted.
Methinks thou shouldst tame thine viscera lest they lead thee unto distraction
What you are actually having is a visceral reaction to your misunderstanding of how the English language works with the word ‘you’ in this circumstance.
It is property of English language where "you" is used in place of "one" very often. This is particularly common in American English which has less formality to it; less Frenchiness. No 'on' etc. Everyone is 'tu'.
It is language quirk, but you can probably use LLM to replace HN headlines like this. Pretty cheap and one will no longer have visceral reaction that one does not wish.
Most people might think that someone doesn't need LLM for that.
Most people don’t have visceral reaction. The world is full of tools. You can bend your experience of it to your will.
Odd weather wasn't mentioned. While weather does not create tides, but it can significantly modify the actual water level compared with the purely astronomical tide that the article describes.
I see I'm not the only geek fascinated by the tide. I knew all the stuff in the article already, of course. It seems it's like railways or something, seems to trigger something in geeky brains. I live in the UK so see some of the largest "swings" in the world. It never ceases to amaze me that it all happens in the space of 6 hours. I've also gone to see spring tides just to see what it looks like. It's cool, and scary.
I know!
It took most of this summer to get my tide clock to predict accurately, using NOAA harmonic constituents data crammed into an Arduino, a GPS module, and published formulas.
Take a look:
https://digitalhorology.etsy.com/listing/4345582508
A detail not included here, but important for people interested in the sea level, is the effects of the wind. Lots of places along the east coast of the US experience mild tides, but a steady wind in the right direction will push sea levels up in various bays and inlets. The storm surge of a hurricane turns it up to 11.
Relevant xkcd: https://xkcd.com/3135
Reminds me of the time that Bill O'Reilly argued on national television that tides were inexplicable.
https://www.youtube.com/watch?v=NUeybwTMeWo
I live near a river that flows backwards for some 50km or so with tides. The first time I saw it, I thought I'd gotten turned around because surely water can't flow uphill, right? It's fun to find out that one is so wrong about basic physics.
All of these explanations are talking about “pulling” from gravity.
What they should really be saying is that spacetime is being affected as the moon orbits.
Jeanne Rousseau, who passed away in 2012, asked in an interview [1]:
Why are the syzygy tidal coefficients equal when the quadrature tidal coefficients are at opposite extremes? Why are the syzygy coefficients at opposite extremes when the others are equal? Who can explain this using the laws of universal gravitation?
Her point is that you can't.
Earlier in that interview she says: I was put in touch with the Institut de Physique du Globe [2]. In April 1953, I met with Professor Coulomb [3], who was the director at the time, and asked him about the ionic variations that might occur during the lunar phases. His formal response was that there were none. However, I had already been observing them for some time. I must say that in 1953 I had already begun to observe the phenomenon of the tides. Being told that, apart from a minimum of atmospheric ionization at 4 a.m., there is nothing else that can have an impact on the biological, human, or other levels, I said: but there is the phenomenon of the tides! And that's when I got this response, which marked a break with the scientific community for me:
The phenomenon of the tides is a phenomenon that is beyond us. We waste our time when we take an interest in phenomena that are beyond us. If you don't want to waste yours, focus on other things.
Jeanne Rousseau demonstrated through observation that tidal phenomena are not solely gravitational but primarily electromagnetic. One can read more about this in English in this paper [4].
[1] https://youtu.be/ytWerrYTBLs
[2] https://en.wikipedia.org/wiki/Institut_de_Physique_du_Globe_...
[3] https://en.wikipedia.org/wiki/Jean_Coulomb
[4] https://www.researchgate.net/publication/384443419_Cosmic_Re...
This is, not to put too fine a point on it, crank science. Opening up the linked document, the DOI fails to resolve, the paper investigates pH variations in urine during tide cycles, and also skimming over it doesn't appear to make a single prediction. This is at best unfalsifiable, and a "break with the scientific community" is an accurate assessment.
The physics of tides is largely well-understood, and the moon and sun provide the primary forcing. Accurate tide tables are regularly computed the world over, with measurements regularly made. Without even looking at measurements, the shipping industry demands accurate tide forecasts for navigating efficiently. The claim that "tidal phenomena are... primarily electromagnetic" requires some serious evidence to back it up, with calculates to boot, rather than invoking mysticism that tides are "beyond us". Many things are beyond our current scientific understanding, and that is humbling, but tides are quite well understood.
I would not dismiss this as crank science so quickly, first and foremost because it's not claiming to be science, not theoretically at least. It's observation of likely correlation. Also I would not say tides are "quite well understood" because it's misleading. I'd say sufficiently understood so that models are precise enough to be useful, but they're still an approximation to a few cm. For now water levels, costal geography, terrain, and weather seem to be the main parameters they attribute to the small variations observed, but who can say there aren't more parameters to take into account? Also what doesn't help in having a "well understood" feeling is that you can find different explanation of the bulges on either side of the earth.
I don't have the scientific knowledge to assess all this. I'm not even sure how to understand properly the questions Jeanne Rousseau asks saying newtonian physics can't answer. What I hear however are competent people observing small variation in the properties of water and living systems that seems to be related to cosmic phenomenon, including moon phases. Variations we can also find in the atmosphere/ionosphere with more recent measurements of their ionic polarities. Adding to that are all the new discoveries that link weather phenomenon to electromagnetic influences from the sun, with water significantly influencing the electromagnetic properties of the atmosphere. Finally more people question the true molecular structure of water, as H2O seems to be a crude simplification over a dynamic mixture of isotopes and ions.
Overall the tidal theory is not a done deal, we only have approximate models, and this topic can be discussed for years to come. That's probably why she was told the tides is a phenomenon that is beyond us.
> When they’re least lined up (First and Last Quarter Moon), tides are more smoothed out. This is a “Neap Tide”.
And when they're the "most lined up" you get the "King Tide."
https://en.wikipedia.org/wiki/King_tide
We had one of these today in Sausalito!
Tides. The OG gravitational wave detectors.
Tides are gravitational waves, as it were.