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Re: F=ma: law or theory?



Re: "ultimate nature of the universe" - A nifty read is Martin
Rees, <Just Six Numbers>. Chapter 11 is "coincidence, providence - or
multiverse", which captures current thinking on the subject.
Regards,
Jack

On Tue, 16 Oct 2001, Kossom wrote:

Howdy-

Robert Cohen wrote:
I know there are no universally accepted definitions. I am only asking
for those definitions that support F=ma being a theory.


[Ooo! Ooo! I get to use all those history and philosophy of science courses
I took!]

Not only do physicists have no universally accepted definitions of "theory",
"law", "principle", and so on, neither does anyone else. The use of one or
another depends on the people proposing the idea in the first place, the
language they wrote in, and the politics of the time.

Why are some things laws and other theories? Says more about the people
doing the naming than the science. A theory is not necessarily something
that explains. A law is not necessarily purely describe.

F = m a is not explanatory. That is, it doesn't say why mass resists
acceleration. Many people have explanations (I think that I read something
about the Higg's boson, but I don't remember for sure) but in the end all
explanations eventually finish with, "That's just the way the uniiverse
seems to work."

When I ask my students to explain some phenomenon, I ask them to keep on
explaining until they reach the "That's just the way it seems to work"
level.
----

The philosophy of science respects to big schools of thought on the
ultiimate nature of the universe. One camp claims that the structure of the
universe is arbitrary, that a universe could have formed with different sets
of laws that internally consistant and work to make a coherent whole.
Another camp argues that the set of laws that we see or not just sufficient
for describing the universe, but they are the only possible set that would
work.

Don't ask me. I don't know.

----

In terms of F = m a, I actually like to introduce it as a = sum F / m total,
but I always was a rebel. Many students do find it kind of arbitrary, but on
further inspection, their problem usually ends up dealing with how to
measure F (most ways end up needing Hooke's Law which seems like cheating to
them) and mass. Mass after all is arbitrary. One kilogram is just a chuck of
expensive metal in a vault. Everything else is just a comparison to it.

Marc "Zeke" Kossover


--
Franz Kafka's novels and novella's are so Kafkaesque that one has to
wonder at the enormity of coincidence required to have produced a writer
named Kafka to write them.
Greg Nagan from "The Metamorphosis" in
<The 5-MINUTE ILIAD and Other Classics>