Asimov on Scientific Certainty.


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> Aristotle's dictum of heavier bodies falling faster than light bodies...Hell a ten year old kid could have dropped a heavy weight and a light weight from a height and proved that bodies fall at the same rate provided the air does not interfere. [baal, #20]

Actually, no Baal, you are wrong on the science - as you so often are when you post nonsense about science and nonsense about epistemology:

A ten year old kid *couldn't* "drop a heavy weight and a light weight from a height and prove that bodies fall at the same rate provided the air does not interfere". Not only because air does interfere --- hardly a trivial point which you want to proviso out of existence, and neither Aristotle or today's middle schooler would probably have a vacuum handy --- but here's another point that Baal "didn't bother to check": 2500 years ago without instruments (stop action photography, a watch that can measure tiny fractions of a second) it was NOT POSSIBLE to tell the difference in when a medicine ball and a baseball would hit the ground.

To quote the charge he aimed at Aristotle: Shame on Baal for not checking and doing the experiment himself and assessing the extremely rapid intervals involved. To fault Aristotle for not being able to measure this is like faulting him for not being able to measure the speed of sound or being able to observe whether a lightning bolt travels up from ground to sky or vice-versa.

Nor did Baal attempt to tell us what the great (instrument-free?) 7th century experiment was that was so easy a ten year old could have done it. Shame on him.

Did Baal do any checking or is this a cryptic wikisnip? If so shame on Baal.

By the way, just as an aside: Galileo a) probably did not drop actually weights from the top of the Leaning Tower of Pisa, b) could not have proven that all objects fall at the same rate from that low a height (32 ft/sec/sec, remember?), c) was able to demonstrate this using inclined planes, d) even then had to prove some propositions showing that rate of sliding down at an angle was analogous to free wall without support.

Shame on Baal, you bad overrated boy, for not knowing the actual details of the history of science !!!

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John Philoponos did an experiment in the 7th century which disproved Aristotle's dictum of heavier bodies falling faster than light bodies. Anything Philoponos did in the 7 th century Aristotle could have done. There was no technological barrier there. Hell a ten year old kid could have dropped a heavy weight and a light weight from a height and proved that bodies fall at the same rate provided the air does not interfere.

Aristotle didn't bother to check. Shame on him.

Suppose this ten year old kid drops an iron ball and a leaf or feather. How is the kid suppose to know the air interfered? Could he see a lighter object fall faster than a heavier one to thwart the conclusion heavier objects fall faster than lighter ones?

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John Philoponos did an experiment in the 7th century which disproved Aristotle's dictum of heavier bodies falling faster than light bodies. Anything Philoponos did in the 7 th century Aristotle could have done. There was no technological barrier there. Hell a ten year old kid could have dropped a heavy weight and a light weight from a height and proved that bodies fall at the same rate provided the air does not interfere.

Aristotle didn't bother to check. Shame on him.

Suppose this ten year old kid drops an iron ball and a leaf or feather. How is the kid suppose to know the air interfered? Could he see a lighter object fall faster than a heavier one to thwart the conclusion heavier objects fall faster than lighter ones?

Any kid running into the wind feels the force of air in relative motion with his body. Even so, the fact that two unequally weight balls of metal fall at the same rate (or very close to the same rate) is sufficient to disprove Aristotle's dictum that the heaver body not only falls faster but that the terminal velocities are in proportion to the weight. That is dead wrong and a ten year old kid could easily show it.

Galileo, for instance, was totally aware of the force that air exerts on very light objects with a surface area that is large in proportion to the weight., Birds flew in Galileo's time and leaves drifted to the ground as did snow flakes. But heavy spherical bodies that could roll (not slide or drift) down inclined planes rolled at the same rate regardless of weight. By the way, shipwrights in Aristotle's time could have made smooth planks for The Master if he had ordered them. Also spherical shot was available. The Greeks used ballistae in warfare. Aristotle has all the technological means of checking his pronouncements on moving bodies that Galileo did. He did not bother to check. He did not think he had to. He suffered from the "Greek Disease" and was slave to the Logos.

Ba'al Chatzaf

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Bob:

This "conclusion" that you have projected upon Aristotle is based on your reading of his original writings?

Adam

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> the fact that two unequally weight balls of metal fall at the same rate (or very close to the same rate) is sufficient to disprove Aristotle's dictum

No it isn't. Rapid acceleration. The difference could be too small to measure.

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Anyone who wants to know what Aristotle "really" said can read the Loeb Classic Library Editions. They are bilingual Greek and English. The Introductions tell where the manuscripts came from. Aristotle's "Athenian Constitution" was only discovered partially in 1879/80 and the rest in 1890. Most of the corpus is from various medieval monasteries and the Vatican Library. Some of Aristotle came to the West via Muslim Spain. The Arabist Gerbert d'Aurillac became Pope Sylvester II in 999 CE. Many other manuscripts were given to the Vatican by the Church at Constantinople. It is an interesting story if you care.

The sad part not touched on so far here is that when the Macedonian ruling family squabbled over the spoils of Alexander, the works of Aristtole were buried. When they were exhumed, they were found to have been ravaged by worms. The reconstructions are still argued today.

As for the "Greek Disease of Logos" if you read The Protagoras by Plato, you will find Protagoras debating Socrates on whether Justice can be taught. Socrates says:

I will freely confess to you, Protagoras, that I have

a doubt whether this art is capable of being taught, and yet I know

not how to disbelieve your assertion. And I ought to tell you why

I am of opinion that this art cannot be taught or communicated by

man to man. I say that the Athenians are an understanding people,

and indeed they are esteemed to be such by the other Hellenes. Now

I observe that when we are met together in the assembly, and the matter

in hand relates to building, the builders are summoned as advisers;

when the question is one of shipbuilding, then the ship-wrights; and

the like of other arts which they think capable of being taught and

learned. And if some person offers to give them advice who is not

supposed by them to have any skill in the art, even though he be good-looking,

and rich, and noble, they will not listen to him, but laugh and hoot

at him, until either he is clamoured down and retires of himself;

or if he persist, he is dragged away or put out by the constables

at the command of the prytanes. This is their way of behaving about

professors of the arts. But when the question is an affair of state,

then everybody is free to have a say-carpenter, tinker, cobbler, sailor,

passenger; rich and poor, high and low-any one who likes gets up,

and no one reproaches him, as in the former case, with not having

learned, and having no teacher, and yet giving advice; evidently because

they are under the impression that this sort of knowledge cannot be

taught.

http://classics.mit....otagoras.1b.txt

The Greeks generally valued hands-on knowledge highly. Plato did not. His Republic is taught today by would-be philosopher-kings, Instead of beating The Republic to death, we should be reading Protagoras. After all, if Justice cannot be taught, why have universities? Would not the technical school and engineering college be the highest institutions of learning?

Why did Aristotle not count teeth or drop balls? Maybe he did. But I think that he did not because he was an observer and a cataloguer and a thinker, not an experimentalist. Consider that he did not follow his father's profession of medical doctor, an experimental field. Now Archimedes, he was an experimentalist! He wanted to know if the Earth or the Sun was at the Center, so thinking through the problem, he probably built a dioptra and attempted to measure the parallax. Not finding it, he concluded that the Earth is at the Center. Maybe in a hundred years, we will find out why Michelson and Morely failed to measure the ether ... and someone will complain that Einstein was a Kantian Idealist.

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Michael:

I know about the Athenian Constitution.

What percentage, if you know, of Aristotle's works survived. I am under the impression that it is well under thirty percent (30%), but I could be flat out wrong.

Thanks.

Adam

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Now Archimedes, he was an experimentalist! He wanted to know if the Earth or the Sun was at the Center, so thinking through the problem, he probably built a dioptra and attempted to measure the parallax. Not finding it, he concluded that the Earth is at the Center. Maybe in a hundred years, we will find out why Michelson and Morely failed to measure the ether ... and someone will complain that Einstein was a Kantian Idealist.

Archimedes was first and foremost a mathematician. He did some applied science for which he is justly famous but most of his written works in so far as they are known is pure mathematics. His masterpiece is the ur-version of differential and integral calculus formulated 1800 years before Newton and Leibniz. His manuscript -The Method- was discovered not too long ago as a scraped away text overwritten by (get this!) Christian hymns. Please see http://kottke.org/09/01/archimedes-developed-calculus. The contents of the manuscript have been teased out using advanced ultraviolet and x-ray technology. For details see -The Archimedes Codex-

http://www.amazon.com/Archimedes-Codex-Revealing-Antiquitys-Scientist/dp/0306817373/ref=sr_1_1?s=books&ie=UTF8&qid=1325119180&sr=1-1

If Archimedes (while he was in his prime) could have been brought to our time in a time-machine he would have picked up on modern mathematics in a heart-beat. His thinking was almost as modern as yesterday morning.

Ba'al Chatzaf

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> the fact that two unequally weight balls of metal fall at the same rate (or very close to the same rate) is sufficient to disprove Aristotle's dictum [baal]

> No it isn't. Rapid acceleration. The difference could be too small to measure. [Phil]

Notice how Baal simply ignores it when he's been refuted and simply changes the subject. Archimedes, anyone?

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> the fact that two unequally weight balls of metal fall at the same rate (or very close to the same rate) is sufficient to disprove Aristotle's dictum [baal]

> No it isn't. Rapid acceleration. The difference could be too small to measure. [Phil]

Notice how Baal simply ignores it when he's been refuted and simply changes the subject. Archimedes, anyone?

Not refuted. The hammer and the feather landed at the same time on the Moon.

And my bowling ball and my golf ball landed on the lawn within a hundreth of a second. The velocities were NOT proportional to the weight.

One counterexample disproves a general statement. Logic 101. Even Aristotle knew that.

Aristotle was almost completely wrong about motion of bodies.

Ba'al Chatzaf

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One counter example disproves a general statement. Logic 101. Even Aristotle knew that.

The velocity of falling objects when air resistance is neglegible is not proportional to their masses. All masses are accelerated equally in a gravitational field if no other forces are acting on them. This has been proved by simple experiments and complicated experiments. The Etvoes experiments show the velocities are equal to within on part in 100 million. The simple experiment of dropping two heavy balls of unequal weight will show the velocities are equal to within one part in 100. So simple a ten year old kid can do it.

Ba'al Chatzaf

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The hammer and the feather landed at the same time on the Moon.

Do you expect any ten-year old to know that? Do you think Aristotle should have known that?

Did you read about the golf ball and the bowling ball which immediately followed. That a ten year old kid could do.

Face it; Aristotle was just plain wrong about falling bodies; mistaken, in error, mislead by appearances, incorrect. Got it?

the mass of experimentation from simple experiments good to within a percent to the Etvoes type of experiments good to within one part in a 100 million all say the same thing. Aristotle was wrong. Which is no sin. We all make mistakes. What he did not bother to do (apparently) was to check his work. That is a sin.

Ba'al Chatzaf

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Now Archimedes, he was an experimentalist! He wanted to know ...

Archimedes was first and foremost a mathematician. He did some applied science for which ... His masterpiece is ... The Method ... - was discovered not too long ago as a scraped away text overwritten by (get this!) Christian hymns.

Whether Archimedes was primarliy a mathematician depends on which materials and stories you have. His "Method" is, indeed, a startling work. But he did much more. It is most likely that he experienced no dichotomy between mathematics and engineering. By analogy, I liong knew John Kemeny from his invention with Thomas Kurtz of BASIC. His biographjy is much richer, of course. Was he "primarily" an applied mathematician or an administrator?

We know so little about Aristotle, Archimedes, and the others. Much of their works were lost. To understand this, realize that the Emperor Claudius wrote a multi-volumne history of the Etruscan people because his wife was Etruscan. The language was spoken and written in their time. Now, the work is lost and the language is known from perhaps 200 words and two short bilingual texts. If a book written by the emperor of Rome for his wife can disappear from history, we must pause before we declare what Aristotole should have done or known or thought.

Also, you will find few defenders of the Christian religion here, so you are free to heap scorn on someone else's credo. Personally, I think that we are lucky for the happenstance that superstitious Jews saved scrap paper because it might have the name of god on it somewhere, or might allude to a reference to the unnamed and unnameable name of G*d or Y??#h, and as a consequence, we have this huge corpus of legal documents and supporting ephemra from the Cairo Genizah. They open the door to another time and place. Chrisitan prayers do that, also: illuminated manuscripts, the Book of Kells, stuff like that.

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What percentage, if you know, of Aristotle's works survived. I am under the impression that it is well under thirty percent (30%), but I could be flat out wrong. Thanks. Adam

I have no idea. I never looked into it. You know that we guess these things because from Diogenes Laertius or someone we have a reference that So-and-So said this thing, which I refute or agree with... Aristotle himself began many of his lectures this way, summarizing what was said before by others. Then, we don't have those others... so we know that something was lost. But beyond that, how would you know, if a certain work was never referenced or if all references to it were lost? See below about Claudius.

As for everyone else on this other discussion, Aristotle or Thales or Hipparchus could have done many things, perhaps, to discover modern physics. Shoot an arrow and drop one at the same time. They both hit the ground and the same time. The Greeks drove piles into soft soil. The pile driver is a big rock dropped from a height. A little work with those and you might think they would have realized... Shipbuildiers, architects, shoe makers... anyone who works with their hands, works with forces... and that was at one time so miraculous a skill that they called the Cutter "Daedalus" and made up myths about his skills. We know they had the discus because we have the statue of the Discus Thrower. So, why did they not invent the airfoil, the turbine or the hovercraft?

What if the South had won the War Between the States? It's an interesting question perhaps. One problem with y'all's attempting an answer is that y'all come from a world where they did not. Y'all cannot know what did not happen. Y'all can imagine, true enough, but what y'all imagine is based on what y'all do actually know from the world in which the North won the war.

I have pointed before to Stuart Hayashi's essay here on OL on "The Argument from Arbitrary Metaphysics." You wake up on a ledge... Wait a minute! How did that happen? What Aristotle "should have" done or known or said or thought or eaten is in the realm of the metaphysically arbitrary: you can argue "anything" because nothing about it is real.

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I have pointed before to Stuart Hayashi's essay here on OL on "The Argument from Arbitrary Metaphysics." You wake up on a ledge... Wait a minute! How did that happen? What Aristotle "should have" done or known or said or thought or eaten is in the realm of the metaphysically arbitrary: you can argue "anything" because nothing about it is real.

Was it technologically feasible for Aristotle to have checked his conclusions (by experimental or empirical means) concerning falling bodies? Answer: Yes.

In his day, shipwrights knew how to make smooth planks. The Greeks also knew how to make cylindrical molds so rolling objects could be made.

Ba'al Chatzaf

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> Do you expect any ten-year old to know that? Do you think Aristotle should have known that? [Merlin, #37]

Not only that but (1) Baal talks about experiments being conducted on the moon, an experimental option not available to Aristotle.

Plus, (2) he claims simple experiment shows velocity of a falling object is not proportional to weight, something even harder to measure without instruments and stopwatches 2500 years ago (a point I've already made and which he keeps dodging).

Moreover, yet another logical mistake: (3) Aristotle only claimed by observation heavier objects fall faster. He didn't claim velocity was proportional to weight.....He couldn't, Baal, no instruments remember?

???!!!!!???!!!

(Jesus Fucking Christ. How much do you have to hammer on someone's head before he'll admit "well, maybe I overstated my case against Aristotle - at least a teensy bit - on this one point?????)

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> In his day, shipwrights knew how to make smooth planks.

I've already pointed out to you he didn't know the proportionality would hold: rolling and falling are not identical phenomena and unless you are a rationalist, you can't -assume- the laws of acceleration and velocity are the same.

(I thnk I made this point in a previous post.)

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Ba'al,

Before making any more claims about what Aristotle got wrong, I think you should check what he said/wrote in Physics. You can easily search for terms like heavy and speed here. Relying on second-hand sources and what medieval Aristotelians held are suspect.

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> In his day, shipwrights knew how to make smooth planks.

I've already pointed out to you he didn't know the proportionality would hold: rolling and falling are not identical phenomena and unless you are a rationalist, you can't -assume- the laws of acceleration and velocity are the same.

(I thnk I made this point in a previous post.)

The now did Galileo hit on the notion of using rolling bodies as surrogates for free falling bodies?

It was the study of rolling things that led Galileo to what acceleration was.

Ba'al Chatzaf

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Ba'al,

Before making any more claims about what Aristotle got wrong, I think you should check what he said/wrote in Physics. You can easily search for terms like heavy and speed here. Relying on second-hand sources and what medieval Aristotelians held are suspect.

Lookee here. http://www.calstatel...a24-216a21.html

This has quotes directly from book IV of -Physics-.

He regarded falling bodies in connection with the medium through which they fell. He denied the existence of a vacuum.

Roughly: slower through a thicker medium than a thinner medium with weights equal. Through the same medium the heavier body falls faster than the lighter. See article reference above. Mr. A. was very aware that the air dragged on things.

What he said was true for goo, but not in general. For very dense bodies the effect of the medium (the air) is negligible.

The correct relation between terminal velocity (from rest) and the viscosity of the medium and the shape of the body is very complicated. This was not worked out until latish in the 19th century (c.e.). There is no way Aristotle or even Galileo or Newton could have figured it out, given what they knew.

Here are the details on terminal velocity as a function of the medium (viscosity) and the shape of the bodies.

http://en.wikipedia....rminal_velocity.

Terminal velocity is proportional to the square root of the mass of the object all other things being equal. Aristotle was roughly right where the medium hand to be reckoned. That means falling bodies with lots of air resistance (such a a parachute or a blunt shape).

For bodies falling in water and even stickier goo Aristotle was closer to being correct in a very rough qualitative way, which is all he had to hand when he lived.

He was remiss in dealing with falling bodies in air. He did not check and he could have.

Ba'al Chatzaf

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Reply to #46. When are you going to start showing us Aristotle's own words -- straight from the horse's mouth and where readers can find them -- before making more claims about what Aristotle said? You have completely avoided that so far.

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Reply to #46. When are you going to start showing us Aristotle's own words -- straight from the horse's mouth and where readers can find them -- before making more claims about what Aristotle said? You have completely avoided that so far.

I don't have access to the Greek text. Translations and references to translations is all you get.

This reference: http://www.calstatel...a24-216a21.html

uses the standard numbering of the works of Aristotle to point directly into -Physics-. Short of a Greek text it does not get any better than that.

Did you see 216a11-21. This is a standard reference to ANY translation of Aristotle physics. For a very good translation of -Physics- I recommend the translation done by Joe Sachs available from the Rutgers University Press.

Ba'al Chatzaf

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Bob:

This "conclusion" that you have projected upon Aristotle is based on your reading of his original writings?

Adam

I am not fluent in Attic Greek. I rely on a set of translations. I favor the translations by Joe Sachs because he does not go in for heavy Latin derived English translations. Read Saches' introduction to Aristotle's -Physics- published by the Rutgers University Press to see how Latin translations and English translations forced into the Latin straight-jacket have obscured what Aristotle wrote.

It is highly unlikely that the translations are wrong when so many translators highly agree in the translations from Greek.

I have relied on -Physics- book IV for what (the received) Aristotle had to say about bodies moving through resisting media. Bodies of equal weights go through different media in inverse proportion to the drag (viscosity, density) of the media. Two bodies of unequal weights going through the same medium have velocities in proportion to the weights. The heavier not only falls faster but the velocities are in proportion to the weights. Body A ten times heavier than Body B will fall ten times faster through the same medium.

It is the inverse relation of velocity to medium drag that led Aristotle to deny the existence of a vacuum. To get the velocity in a vacuum one would have to divide by zero, since a vacuum would have zero drag. His premise was wrong, but his reasoning was not absurd at all. It turns out light goes through a vacuum (regions of space devoid of matter) and it has a finite velocity. But Aristotle could not have known that in his day.

Aristotle was incorrect on his general law about media but his did not have the technology or the mathematics to state a correct law. Nor was the technology available to accurately gauge velocities. However it is trivial to tell if two bodies hit the ground at the same time or nearly the same time. That is the test a ten year old kid could have done.

The relation between terminal velocity and drag is complicated. See http://www.grc.nasa....lane/termv.html. There is no way Aristotle could have gotten the actual relation correctly. In any case a relatively simple experiment would have shown his basic laws to be incorrect (although there are intuitively very reasonable). Drop a one pound round shot and a ten pound round shot from a building say 50 feet high. The two shots will land within a split second of each other. The ratio of the terminal velocities is NOT 10:1.

No. You do not have to drop a hammer and a feather on the Moon to show that Aristotle's laws of falling bodies is wrong.

Ba'al Chatzaf

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On one thread, Baal claims that we don't have Aristotle's words so we have *no ideaat all* what he actually said or did as opposed to his followers.

On another thread he castigates Aristotle for his bad scientific method.

You can't claim both: Simple (Aristotelian) logic.

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