Understanding Aristotle's Physics in Newtonian Terms

[utunumsint]

Hi Folks,

I have to say this is a very interesting article.

The author believes that Aristotle’s observations are all empirically based and substantially correct in terms of Newtonian physics within its sphere of validity, in much the same way as Newtonian physics is empirically based and substantially correct in terms of Modern physics within its sphere of validity.

Here is a quote:

Aristotle’s physics is the correct approximation of Newtonian physics in a particular domain, namely, the domain where we, humanity, conduct our business. This domain is formed by objects in a spherically symmetric gravitational field (that of the Earth) immersed in a fluid (air or water) and the main celestial bodies visible from Earth. The fact that Aristotelian physics (unlike the physics of most of his commentators) is to be properly understood as the physics of objects immersed in a fluid, air, or water, has been emphasized by Monica Ugaglia (2004, 2012b), and in my opinion this is the key to understanding Aristotle’s physics in modern terms.

And on its weakeness here:

Obviously, Aristotle’s physics is far from being perfect. In this, too, it is similar to Newton’s and Einstein’s physics, which are far from being perfect either (the first wrongly predicts the instability of atoms, and the second predicts implausible singularities, for example). Among the various limitations of Aristotelian physics, I illustrate here a few, of a different nature.

From this perspective Aristotle’s physics deserves a sharp reevaluation. With all its limitations, it is great theoretical physics. Its major limitation is that it is not mathematical. Aristotle failed to absorb the Pythagorean visionary faith in the power of mathematics, which Plato recognized and transmitted to his school and from which the great ancient mathematical physics of Alexandria, in particular as applied to astronomy, developed. But Aristotle was able to construct a powerful account of physics that is the ground on which later physics has built. When Galileo realized that the missing ingredients were the notion of acceleration and the use of formulas, thus opening the way to Newton, Galileo’s interlocutor was Aristotle. Not because Aristotle was the stupid dogma that intelligence should overcome, but because Aristotle was the best of the intelligence of the world that thirty centuries of civilization had so far produced in this field.

God bless,

Ut

 

[utunumsint]

Just wanted to add this last quote:

The bad reputation of Aristotle’s physics is undeserved and leads to widespread ignorance. For instance, think for a moment—do you really believe that bodies of different weight fall at the same speed? Why don’t you just try: take a coin and piece of paper and let them fall. Do they fall at the same speed? Aristotle never claimed that bodies fall at different speeds ‘if we take away the air’. He was interested in the speed of real bodies falling in our real world, where air or water is present. It is curious to read everywhere: ‘Why didn’t Aristotle do the actual experiment?’ I would retort: ‘Those writing this, why don’t they do the actual experiment?’ They would find Aristotle right.

God bless,
Ut

 

[inocente]

Just wanted to add this last quote:

The bad reputation of Aristotle’s physics is undeserved and leads to widespread ignorance. For instance, think for a moment—do you really believe that bodies of different weight fall at the same speed? Why don’t you just try: take a coin and piece of paper and let them fall. Do they fall at the same speed? Aristotle never claimed that bodies fall at different speeds ‘if we take away the air’. He was interested in the speed of real bodies falling in our real world, where air or water is present. It is curious to read everywhere: ‘Why didn’t Aristotle do the actual experiment?’ I would retort: ‘Those writing this, why don’t they do the actual experiment?’ They would find Aristotle right.

Interesting paper, although I think he does Aristotle a disservice there. Paper wasn’t invented yet, but it would be obvious to Aristotle that a leaf blows around, and wouldn’t make a valid comparison against a coin. A better experiment would be to compare the speeds of two things which he knew fall directly to ground, say a block of wood and a block of clay. But history doesn’t record him making that experiment. It seems it took a long time before the birth of the principle that “It doesn’t matter how beautiful your theory is, it doesn’t matter how smart you are, if it doesn’t agree with experiment, it’s wrong”.

Science is about making guesses, and modern science tested Aristotle’s guesses and found a number of them were wrong. But so what, almost all guesses are wrong. He was methodical, and he wanted to explain, he didn’t just take the world for granted, and it’s no big deal if he made mistakes, everyone does. I think Rovelli underestimates the orthodoxy though. Aristotle had been admired for so many centuries that it must have seemed impossible that all those books in all those libraries might be wrong.

Rovelli may also have a sub-plot. There are some who see Aristotle as being on religion’s side against Galileo and modern science. According to his Wiki article, Rovelli thinks “the source of the conflict is not the pretense of science to give answers—the universe, for Rovelli, is full of mystery, and a source of awe and emotions—but, on the contrary, the source of the conflict is the acceptance of our ignorance at the foundation of science, which clashes with religions’ pretense to be depositories of certain knowledge”. Maybe that’s got something to do with him wanting to align Aristotle with Newton. Or maybe not, just a thought.

 

[utunumsint]

Interesting paper, although I think he does Aristotle a disservice there. Paper wasn’t invented yet, but it would be obvious to Aristotle that a leaf blows around, and wouldn’t make a valid comparison against a coin. A better experiment would be to compare the speeds of two things which he knew fall directly to ground, say a block of wood and a block of clay. But history doesn’t record him making that experiment. It seems it took a long time before the birth of the principle that “It doesn’t matter how beautiful your theory is, it doesn’t matter how smart you are, if it doesn’t agree with experiment, it’s wrong”.

Science is about making guesses, and modern science tested Aristotle’s guesses and found a number of them were wrong. But so what, almost all guesses are wrong. He was methodical, and he wanted to explain, he didn’t just take the world for granted, and it’s no big deal if he made mistakes, everyone does.

Agreed. Rovelli tries to go against the stereotypes that paint Aristotle as an unthinking idiot by showing the many ways in which is theory was right but also to show how the mistakes he made served as indispensable stepping stones to better theories, such as those developed by Galileo and Newton.

Also, the point about dropping a paper and a stone as being a bad example, and how things would have been self evident had he just use some different materials, Rovelli has this to say:

Aristotle’s detailed theory, however, as well as his detailed observations leading to it, refer mostly to the steady regime of falling where observation is easier. His theory disregards the initial transient phase. This phase is either too short (in water) or too rapid (for very heavy objects in air) for any careful observation. This phase, on the other hand, is relevant for the short fall of heavy objects, which is the regime on which Galileo (fruitfully) concentrated, circumventing the difficulty of observation by the ingenious trick of the incline. For this regime, as was already pointed out as early as the sixth century by Philoponus, the speed of fall is not proportional to the weight: a ball of lead doesn’t reach ground from a specific height in half the time of a ball of half its weight. The buoyancy force and the resistance of the medium do not have the time to become effective in these short falls. (Two heavy balls with the same shape and different weight do fall at different speeds from an airplane, confirming Aristotle’s theory, not Galileo’s.)

If you read through this example carefully you will see that it was no easy feat for Galileo to figure out.

I think Rovelli underestimates the orthodoxy though. Aristotle had been admired for so many centuries that it must have seemed impossible that all those books in all those libraries might be wrong.

Rovelli admits as much when he comments that Galileo strongly believed Aristotle would have been the first to accept him over the Scholastics in his day.

Rovelli may also have a sub-plot. There are some who see Aristotle as being on religion’s side against Galileo and modern science. According to his Wiki article, Rovelli thinks “the source of the conflict is not the pretense of science to give answers—the universe, for Rovelli, is full of mystery, and a source of awe and emotions—but, on the contrary, the source of the conflict is the acceptance of our ignorance at the foundation of science, which clashes with religions’ pretense to be depositories of certain knowledge”. Maybe that’s got something to do with him wanting to align Aristotle with Newton. Or maybe not, just a thought.

Maybe.

God bless,
Ut

 

[Linusthe2nd]

Hi Folks,

I have to say this is a very interesting article.

The author believes that Aristotle’s observations are all empirically based and substantially correct in terms of Newtonian physics within its sphere of validity, in much the same way as Newtonian physics is empirically based and substantially correct in terms of Modern physics within its sphere of validity.

Here is a quote:

And on its weakeness here:

God bless,

Ut

And excellent article by a qualified theoretical physicist that refutes much of the ill formed greviences of modern philosophers of science against Aristotle. I think I will save it for future reference. Thanks.

Linus2nd

 

[thinkandmull]

Maybe the “common ‘knowledge’” that Aristotle thought that in a vacuum a moving thing need force in order to maintain motion is wrong. I don’t think he talked about vacuums in the modern sense. He did say at the end of his Physics that an arrow from a bow moves because of the air. Was he denying that they bow was the main cause?