B Science history, falling objects before Galileo

  • Thread starter bland
  • Start date
85
9
Summary
I'm finding difficult to believe that the ancient greeks really didn't know that all objects fall at the same speed.
Aristotle further believed that objects fall at a speed that is proportional to their weight. In other words, if you took a wooden object and a metal object of the same size and dropped them both, the heavier metal object would fall at a proportionally faster speed. link

I mean these guys were in love with the math of proportions and nice neat numbers, look at the frikken detail of their observation of the world. I've heard the above so many times as it's one of those things that everyone has to mention. But it's always sounded a little bit suss to me. I mean if it already is agreed they were thinking not just that a heavier object falls faster, but crucially it would fall proportionally faster.

Wouldn't they be busting themselves to place bets that Metal for some metaphysical reason is of an important order of elemental importance compared to wood, would not one of them say, "I bet ye my goodly Aris, that the proportion will be a doubling" Nay ye pox ridden Archi, it be in the proportion of the square root of angle between something that makes sense"

So I just don't believe it, and why should I. I wasted my time finally getting a proper understanding of the tides and when I felt I nailed it to my satisfaction I see I was conned and that really really pissed me off because I didn't expect this from proper scientists. It's like the Vos Savant thing where I can't remember the numbers it's on wiki but it's worth pondering, I mean it's worse that all those early laughable hypotheses that some very smart people wish they had just waited a couple of years. Why? I mean they are so smug they're saying she must be wrong because otherwise she's saying 10,000 or whatever math professors say her analysis is a nonsense, I mean that should settle shouldn't it, I love the arrogance it's a little bit disturbing too. I never tire of that one. It's worth doing it yourself with playing cards and see it happen before your eyes.

The reasoning given is always, 'yes those Greeks eh, they just had to work it out in their mind only, always, absolutely. No argument'.

Or maybe they did do it and saw everything fell at the same rate and thought they'd better keep schtum like what happened to their irrational number discovery. How do we tell which. Does this bother anyone else, it bothers me because if it's false then it's shoring up a false narrative about the ancient Greeks. I do find that if I keep reading the same stuff or listening in my case over and over from many different source you gradually tease out little nuggets that all the others miss. I guess we'll never know.

TL:DR is it plausible that the Ancient Greeks did not drop two objects to see the proportionality of the descents?
 

BvU

Science Advisor
Homework Helper
12,321
2,742
Consult some sources ...
As opposed to believing something beforehand , something that came about in totally different circumstances
 

sophiecentaur

Science Advisor
Gold Member
23,527
3,946
Summary: I'm finding difficult to believe that the ancient greeks really didn't know that all objects fall at the same speed.
Are you saying that you would have come to a different conclusion, on the strength of everyday evidence? All objects definitely do not fall at the same speed on Earth. The actual rule is a difficult one (if you hadn't been taught it) and that idea lasted until Galileo.
It is the result of non-experimental Science.
Note. At the same time, the Greeks measured the circumference of the Earth to very tolerable accuracy. So they were were victims of the Science culture about gravity.
 

Paul Colby

Gold Member
944
196
A feather falls faster than a rock. Feathers are usually lighter than rocks. Should I publish? Clearly not. We understand air resistance is an important issue. In fact the rock-feather falling in air versus vacuum was demonstrated to me early in my training. As an ancient Greek would I have seen this issue. Doubt it, seriously.
 

sophiecentaur

Science Advisor
Gold Member
23,527
3,946
A feather falls faster than a rock. Feathers are usually lighter than rocks. Should I publish? Clearly not. We understand air resistance is an important issue. In fact the rock-feather falling in air versus vacuum was demonstrated to me early in my training. As an ancient Greek would I have seen this issue. Doubt it, seriously.
I wouldn't be surprised if Galileo followed his new line as a result of a pub conversation with mates when he decided to be a bit controversial - he was a bit of a loudmouth, I believe. He was probably as surprised as everyone else when experiments proved him right.
 
85
9
Are you saying that you would have come to a different conclusion, on the strength of everyday evidence? All objects definitely do not fall at the same speed on Earth. The actual rule is a difficult one (if you hadn't been taught it) and that idea lasted until Galileo.
It is the result of non-experimental Science.
Note. At the same time, the Greeks measured the circumference of the Earth to very tolerable accuracy. So they were were victims of the Science culture about gravity.
Yes, I concede it seems normal and obvious that all objects do not fall at the same speed, but they would be aware of air resistance, they had sails. They would not recall leaves and feathers flying around and just leave it at that. In fact with feather, I'm guessing they would postulate that they must be for trapping a bunch of elemental air that keeps them up.

So what would the 'everyday' evidence be, to the philosophers not the general population. Feathers and anything else seems obvious but we don't see anything else fall with this sort of discrepancy in our everyday lives. I'm finding it difficult to picture anything falling with enough obvious discrepancy of a feather and any other solid object. When saying it's obvious that all objects don't fall at the same speed, it's *always* a feather that is used, which seems fine if one was explaining to a child.

Apart from feathers and leaves and similar, what other obvious signs that heavier object fall faster does the ordinary person see, even today?

A feather falls faster than a rock. Feathers are usually lighter than rocks. Should I publish? Clearly not. We understand air resistance is an important issue. In fact the rock-feather falling in air versus vacuum was demonstrated to me early in my training. As an ancient Greek would I have seen this issue. Doubt it, seriously.
Forgive me suggesting that appears a little disingenuous to me. If the Ancients decided there was a proportion in this falling rate difference would they run to get a random feather, that a feather falls faster than a rock might bamboozle an eight year old but I see nothing in your argument that convinces me of anything.

I think a subtle point has been missed here, I'm suggesting that they would have their theory of elements and they would be interested in not just objects but they'd probably think in terms of wooden things and metal things and the like. Maybe not I'm just putting this out there.

Consult some sources ...
As opposed to believing something beforehand , something that came about in totally different circumstances
Yeah fair enough, I've asked the question and I've gotten some answers, you all seem to have no concerns about this, so that satisfies me for the time being. I might look into this a bit more now, and revive this thread at a later date.
 

Paul Colby

Gold Member
944
196
Forgive me suggesting that appears a little disingenuous to me. If the Ancients decided there was a proportion in this falling rate difference would they run to get a random feather, that a feather falls faster than a rock might bamboozle an eight year old but I see nothing in your argument that convinces me of anything. You seem to be implying that modern
Well, I'm doing my best to understand your point which remains elusive. If measurements were made by "the ancients" supporting a fall rate proportional to weight then they were wrong, right? My argument was if I was there at the time I would likely have been confused as well or, more likely, go with the current theory just based on my own limitations.
 

sophiecentaur

Science Advisor
Gold Member
23,527
3,946
they would be aware of air resistance, they had sails.
Using sails has nothing to do with a knowledge of Physics. You are trying to impose modern ways of thinking on the ancients. You need not go back as far as ancient Greece to read "Nature abhors a vacuum" or that "disease spreads by miasmas".

There is no reason to expect people to be thinking in the way you think - after your personal education and what you have since learned.
Hundreds of years ago, people smelted iron yet they had no idea of modern Chemistry. Our 'Modern thought' is ------ Modern.
 
697
147
I think what the OP is saying is that: if they thought things of different masses fell at different rates they would've tried it, not with a feather but with a camel and a coconut or similarly dense objects.

Cheers
 

Nugatory

Mentor
12,328
4,804
I think what the OP is saying is that: if they thought things of different masses fell at different rates they would've tried it, not with a feather but with a camel and a coconut or similarly dense objects.
I expect that’s what OP is thinking as well, as it’s what anyone growing up in or after the 19th century would naturally do. But it would not have been so natural before then; the empiricism we take for granted today is a recent and hard-won invention.

Consider that as late as the 18th century we didn’t have scientists, we had “natural philosophers” and in medicine and biology the word “empiricist” was pejorative. Empiricists were people who allowed themselves to be distracted by the effects of the texture of the walls of Plato’s cave; these effects only muddle the Platonic ideals that natural philosophers should be reasoning about.
 

Paul Colby

Gold Member
944
196
But it would not have been so natural before then; the empiricism we take for granted today is a recent and hard-won invention.
Very true. I also might suggest the OP read up on what Galileo actually did, not that cartoon version involving leaning towers but the real one, using incline ball tracks he used to slow the fall rate down to where it could be measured accurately under controlled conditions.
 

sophiecentaur

Science Advisor
Gold Member
23,527
3,946
as it’s what anyone growing up in or after the 19th century would naturally do.
I appreciate what you're saying but even that is not true. "Anyone" doesn't do experiments, even today (PF members are a big exception). People still believe in what the current authority tells them. How many people actually do experiments in the home with cookery or DIY? It takes a lot of confidence to do something other than the book / internet says.
"It is written" has always been the dominant input for most people. That applied, even to the Science community before the Enlightenment.
 

Stephen Tashi

Science Advisor
6,741
1,086
Apart from feathers and leaves and similar, what other obvious signs that heavier object fall faster does the ordinary person see, even today?
Try dropping a balloon inflated with air vs a balloon filled with a heavier gas - or a ballon filled with water if you can get it to be the same shape. If you can make precise measurements, try dropping a ping pong ball versus dropping a ping pong ball filled with lead pellets.
 

sophiecentaur

Science Advisor
Gold Member
23,527
3,946
The OP is missing empathy with the ancients by assuming they thought the same as educated Scientists these days. He is also missing the point that (real) Scientists are in a minority, even today. (Perpetual motion and Who Killed Kennedy? demonstrate that.

Other contributors are, I feel, missing the point by quoting dozens of good experiments to demonstrate Galileo's ideas. PF already knows all this. But some members seem not to realise it's not 'obvious' for someone who is not of the 'experimental persuasion'.

I really think we're done, aren't we? We (smugly) know we are right.
 
248
99
The concept of steam power was around in ancient times as well, but they never seemed to make the leap to actually harnessing it. So, I'd say that what's "obvious" to us is a contextual domain space. Tracks in the sand might be obvious to Saan peoples of the Kalahari, but won't be to me, and they might wonder why I can't see what they can see.

Also, we've only limited content from which to assess the past. Perhaps the concept was known, but not accepted or widely promoted? The whole 'feather and brick' analogy looks to be common sense if you're taking the world at face value, perhaps heretics were booed down and the records we have are not the ones that recorded that.
 
85
9
The concept of steam power was around in ancient times as well, but they never seemed to make the leap to actually harnessing it. So, I'd say that what's "obvious" to us is a contextual domain space. Tracks in the sand might be obvious to Saan peoples of the Kalahari, but won't be to me, and they might wonder why I can't see what they can see.

Also, we've only limited content from which to assess the past. Perhaps the concept was known, but not accepted or widely promoted? The whole 'feather and brick' analogy looks to be common sense if you're taking the world at face value, perhaps heretics were booed down and the records we have are not the ones that recorded that.
That's a good point well made, you also leave some wiggle room for me too.


OK now we're done.
 

kith

Science Advisor
1,278
396
Aristotle further believed that objects fall at a speed that is proportional to their weight. In other words, if you took a wooden object and a metal object of the same size and dropped them both, the heavier metal object would fall at a proportionally faster speed.
Your basic intuition is correct: the old Greeks weren't so dumb as to believe that heavier bodies fall proportionally faster. Your quote above cites an urban myth which can't be found in Aristotle's texts (see this 1946 Nature comment and the references within).

I'm finding difficult to believe that the ancient greeks really didn't know that all objects fall at the same speed.
Note that you automatically assume a vacuum here. When Aristotle writes about falling objects, he equally automatically assumes that a medium is present. I think that's an interesting cultural observation by itself: what we consider to be basic physical statements are often concerned with extreme conditions far from everyday experience while the Greeks' reasoning is built upon situations which are nearer to everyday experience.

That Aristotle only talked about motion in a medium isn't a coincidence: he gave a sophisticated argument (involving quantitative relationships) why he thought that a vacuum was impossible. I think that the notion that when the old Greeks turned out to be wrong it was because they didn't bother to compare their thoughts with everyday experience, i.e. it was for simple reasons, is mostly false. Galilei's arguments and experiments were not trivial and there's also technological progress (Torricelli's vacuum experiments happened in Galilei's lifetime). The people who were wrong for simple reasons were Galilei's contemporaries who blindly believed in Aristotle's statements without applying reason to evaluate the arguments by Copernicus, Galilei and others.

So given that Aristotle was only concerned with motions in a medium, how accurate was his physics? Here's Rovelli steelmanning him. Money quote: "I show that Aristotelian physics is a correct and non-intuitive approximation of Newtonian physics in the suitable domain (motion in fluids), in the same technical sense in which Newton theory is an approximation of Einstein's theory. Aristotelian physics lasted long not because it became dogma, but because it is a very good empirically grounded theory."
 
Last edited:

Want to reply to this thread?

"Science history, falling objects before Galileo" You must log in or register to reply here.

Related Threads for: Science history, falling objects before Galileo

  • Posted
Replies
5
Views
2K
Replies
3
Views
6K
  • Posted
Replies
22
Views
2K
  • Posted
Replies
2
Views
2K
  • Posted
Replies
5
Views
3K
  • Posted
Replies
3
Views
518
  • Posted
Replies
16
Views
5K

Physics Forums Values

We Value Quality
• Topics based on mainstream science
• Proper English grammar and spelling
We Value Civility
• Positive and compassionate attitudes
• Patience while debating
We Value Productivity
• Disciplined to remain on-topic
• Recognition of own weaknesses
• Solo and co-op problem solving
Top