> My sketch of the Sun-Earth-Moon system assumes a heliocentric solar system, something that wasn’t known to the Greeks of the first century BCE.
I am not sure this is entirely accurate. According to Wikipedia:
> The notion that the Earth revolves around the Sun had been proposed as early as the 3rd century BC by Aristarchus of Samos,[1] who had been influenced by a concept presented by Philolaus of Croton (c. 470 – 385 BC). In the 5th century BC the Greek philosophers Philolaus and Hicetas had the thought on different occasions that the Earth was spherical and revolving around a "mystical" central fire, and that this fire regulated the universe.[2] In medieval Europe, however, Aristarchus' heliocentrism attracted little attention—possibly because of the loss of scientific works of the Hellenistic period.[b]
Source: https://en.m.wikipedia.org/wiki/Heliocentrism
Contrary to the recent revisionist version of the “dark ages”, they were pretty dark if you were a Greek of the Hellenistic period, an Athenian 5th century BC or a Roman the next 500-800 years. Loss of philosophical (locked in monasteries) and technical knowledge is common and Heliocentrism or the blood circulation system (Egyptians during the Ptolemy era had knowledge comparable to the one we will acquire again 18th century) are two prime examples.
You can argue semantics on this, but "wasn’t known to the Greeks of the first century BCE" is basically accurate, or certainly "accurate enough" for this context. All of the heliocentric writers were basically little more than "this idea some guy had", and geocentric views as described by e.g. Aristotle were dominant.
If that's true, then by the same reasoning you're also saying that heliocentrism wasn't known to the Europe of (insert any time before the mid 1600s), because it was little more than an idea some guy had, not dominant or accepted.
But nobody would characterize the history of the science that way, because it simply isn't true. "Wasn't known to the Greeks" is inaccurate, particularly in its historical context, since science and philosophy were often "little more than 'this idea some guy had.'"
Does geocentric go hand in hand with flat earth?
Because it was pretty common scientific knowledge that earth was round back then. A knowledge that got lost during the dark ages.
For example: In the third century BCE , Eratosthenes, a Greek librarian in Alexandria , Egypt , determined the earth's circumference to be 40,250 to 45,900 kilometers (25,000 to 28,500 miles) by comparing the Sun's relative position at two different locations on the earth's surface.
This guy Sagan's...
> A knowledge that got lost during the dark ages.
Any examples of that? I've heard it called a myth.
Google “the Galileo Affair”.
I suggest you read about it again. It was about geo-centric vs helio-centric models. It was not about flat vs globe.
The geo-centric model assumed the earth was spherical but it didn't rotate or otherwise move.
True, I didn't follow the thread closely, my bad.
I meant specifically that the Earth is roughly ball shaped.
> Egyptians during the Ptolemy era had knowledge comparable to the one we will acquire again 18th century
Citation needed, especially given the “comparable”.
The “dark age’s revisionism” afaik doesn’t claim that there was no loss of technical and philosophical knowledge (not that the average roman soldier would normally be a philosopher…), but that it’s limited to a few centuries. By the 12th and 13th century it’s very difficult to speak of dark ages.
Thisnlink is not the one that I had in mind - a Wikipedia link that talks specifically about blood circulation details explained in ancient Egyptian mummification texts rediscovered in Europe during that time - but in some sense it is more accurate[^1].
If you're in Athens, the Herakleidon museum has not only an exhibit about this, but about all sorts of other advanced Greek technology: coin-operated vending machines, drink-serving robots, water-powered telegraphs, etc. While this specific device may (or may not) have been a one-off, it's undeniable that ancient Greece was basically the real-life version of a Steampunk-based society. (With the caveat that ancient Persia probably had similar technology at one point also, but most of that has since been destroyed by the British and others throughout history.)
> water-powered telegraphs
This phrasing oversells it a bit too much: The water wasn't a power source and there was no long distance movement of it.
They signaled between users with the light of a burning handheld torch, and the duration of the light corresponded to predefined messages.
Water was used at each end for independent stopwatches, to measure the duration of the light. It's easy to imagine an equivalent system using sand hourglasses.
https://en.m.wikipedia.org/wiki/Hydraulic_telegraph#Greek_hy...
Oh damn it. Missed that one entirely. I will have to come back again.
Same!!!
I just asked chatgpt “Based on what you know about me, what do you think I would be interested in seeing in Athens?”
The Herakleidon Museum was third on the list. May have to try this again in the future.
Never thought of using it for that.
Annoyingly I’m in Athens right now but flying back tomorrow way too early to sneak a visit in :(
That airport is a bit of a haul. :/
Was even worse last week. Got off plane and metro was on strike.
what does chatgpt know about you?
As you chat with it, it'll pick up random details from conversations (eg owns a cat) and stick it into a limited memories folder, which can be manually inspected and cleared out as desired.
I’m just here to fulfill the Hacker News rule that any post mentioning the Antikythera Mechanism must have a comment linking the excellent Clickspring build videos.
https://youtube.com/playlist?list=PLZioPDnFPNsHnyxfygxA0to4R...
Excellent videos - and the one thing that sticks with me was the speculation that watchmaking and the processes that it requires eventually leads to the type of technology we have today. I think the line goes if the greeks of that era had been allowed to progress another 300-400 years, they may have been able to land on the moon...
This is why I love HN, thanks for sharing
Thank you! I was waiting for it so I could click on it again. :-)
https://www.bbc.co.uk/programmes/m0024x0g
Up to date and with a very good discussion of the 254:19 gearing.
Also much more detail on the history of the mechanism.
> I’ve always liked blogging about calendrical things, but I don’t remember doing anything on the Metonic cycle before. If I had written faster, I could’ve published it on Friday the 13th. Too bad.
On the other hand, you published it during a full moon. That's at least slightly appropriate given the subject matter :)
Reminds me of finding a pair of gears in a box of lathe accessories, with 50 and 127 teeth.
For anyone who isn't aware: that's the pair of gears with the smallest number of teeth (and by extension, largest teeth for a given size pair of gears) in the ratio of 2.54:1.
As I'm not a machinist, I'm not going to try to explain just where in the geartrain you'd use this pair to convert your metric machine lathe into a US customary lathe, but that's what they're for.
There's typically a gear train that communicates the rotation of the spindle to the threading mechanism. This is so that you can turn a precise number of threads per unit length, and to take multiple passes to reach the desired thread depth. There's a multi-ratio gearbox that sets the thread pitch.
The 2.54 ratio lets you turn metric threads on a US machine, with the help of tables in the manual for how to set all of the levers. Machinists hate it, and these days will prefer to buy a die for the occasional threading job.
The remaining problem is that metric threads are specified by the mm between peaks, whereas US customary threads are specified by threads/inch.
It's not immediately obvious to me (not a machinist) that the 127/50 ratio gets you the ability to cut metric threads without a mess of other head-scratching because you're now dealing with period instead of frequency.
Indeed, the charts for cutting metric threads are complex, and I'm not sure all of the standard pitches are even possible.
The lathe that I use hasn't had its threading gears installed in ages.
A weird historical tidbit is that after WWII a couple of standards emerged for bicycle parts in Europe, where they used metric diameters and inch thread pitches.
The Italian bottom bracket threading standard is completely insane. Like, how do you even cut that, and why would anyone come up with that in preference to literally anything else?
The only thing I can imagine was a supply of American machine tools from the rebuilding of Europe after a WWII. You can always cut any diameter, only the thread pitches are ruled by the capabilities of the lathe.
Also, left handed threads involve their own issues since the spindle chuck wants to unscrew itself.
I think if I had to do metric threads often, I'd switch to an electronic leadscrew, like the one from Clough42.[1]
I was living in Athens, and visiting the museums, and I had no idea - I walked around a corner in the National and pow - the Mechanism, THE Mechanism, was there, right in front of me.
WOW.
Also, Elgin marbles need to be returned. Parthenon is defaced by their absence.
They’re not putting them outside again; they’d be inside in the Acropolis museum. The Parthenon (blown up as it is) would still be missing them.
Speaking of which, where's the apology from Türkiye for storing ammo there ?
Elgin marbles don't need to be returned and are safer in the UK.
> In 2021, UNESCO concluded that the UK government had an obligation to return the marbles and called upon the UK government to open negotiations with Greece.
> Asked about the possible return of the Marbles, the British Culture Secretary, Michelle Donelan replied: "I can sympathise with some of the arguments but I do think that is a very dangerous and slippy road to embark down."
> ..Fulfilling all restitution claims would empty most of the world's great museums – this has also caused concerns among other European and American museums.
Ha literally just saw that this morning in the National Archaeological Museum in Athens! Lurking here paid off. A good read.
Hah - I watched that Veritasium video the other day.
I once heard that the mechanism was too fine/the gear train too large that it could not possibly actually work without stripping the gears or seizing due to friction.
Does anyone know if Clickspring ever finished making a copy of the mechanism? Seems like the last update was from ~2 years ago.