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Re: [Phys-L] JUSTIFICATIONS OF CLAIMS (was force-pair question)



Is this similar to the question --- Why do springs have two ends? ---?

On Tue, Jan 6, 2015 at 1:45 PM, Ludwik Kowalski <
kowalskil@mail.montclair.edu> wrote:

There are at least three kinds of justifications of claims made by
investigators: theological, mathematical and scientific.

I wrote about this in an article published in American Atheist (February
2012). You can read it online at:

http://csam.montclair.edu/~kowalski/theo/atheist.html

Fell free to share this link with students (and other people), if
appropriate.

Ludwik Kowalski (see Wikipedia)
===========================================

On Jan 6, 2015, at 1:26 AM, John Denker wrote:

On 01/05/2015 11:03 PM, Ludwik Kowalski wrote:

In other words, what evidence do we have that Newton's 3rd law is
valid?

Sorry, no, that's not quite the same question.

I would say that this scientific generalization is "supported by
numerous experimental data."

Right. However:

a) That is a partial answer to the question of /whether/
forces always occur in pairs. On the other hand, the
data has error bars. Furthermore, fact that you can publish
data on the subject at all means that intelligent people are
willing to consider the possibility that the discrepancy
might be nonzero, and they want to see the evidence.
Kreuzer (1968)
Bartlett and van Buren (1986)

b) Be that as it may, that's a long way from addressing
the question of /why/.

Why did Jones break his leg?
"Because his tibia hit the kerb," says the surgeon.
"Because some fool dropped a banana skin on the road," says
Mrs. Jones.
"Because he never looks where he goes," says a colleague.
"Because he subconsciously wanted a holiday," says a
psychiatrist.
- Otto R. Frisch

Evidence that the leg is or is not broken does not even
begin to address the question of /why/.

===============================

On 01/05/2015 11:08 PM, David Marx wrote:

The problem lies with the word "why." We do not know why. We just
know, as
you point out, that this is one of the properties of forces in the
universe.
We know how forces behave, not the reason they behave as they do.

Exactly. Galileo made this point in 1638. He divorced physics from
metaphysics and speculative philosophy. Some historians consider this
the epoch, i.e. Day One of modern science.

The present does not seem to me to be an opportune time to enter
into the investigation of the cause of the acceleration of natural
motion, concerning which various philosophers have produced various
opinions .... Such fantasies, and others like them, would have to
be examined and resolved, with little gain. For the present, it
suffices .... to say that in equal times, equal additions of speed
are made.

Galileo Galilei,
_Discorsi e Dimostrazioni Matematiche intorno à due nuoue scienze_
_Attenenti alla Mecanica & i Movimenti Locali_
(page 203 of the National Edition)

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Clarence Bennett
Oakland University
Dept. of Physics, (retired)
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