Re: [Phys-l] nature of science

[John Denker <jsd@av8n.com>]

Manoranjitham Joshua wrote:

> 1. What is the basic difference between a theory and a law in science?

Previously I answered this question without reading the question
carefully enough.  Ouch!  Sorry!

As I previously mentioned, there are many near-synonyms for "law" ...
but alas "theory" is not among them, as Robert C. pointed out.

"Theory" is highly problematic, because it can be used in two radically
different ways. The first usage means something like law or rule, only
much grander, namely a system of rules giving a coherent description
and explanation of a topic. The other usage refers to a a mere speculation.
Remarkably, both versions are correct, and both have been in use for
over 2000 years. It is best to avoid the word entirely when talking
to non-scientists, and especially when debating with persons who can’t
be trusted, since if you intend one meaning they’ll use the other meaning
against you. (It sure would be nice to find a word that expresses the
idea of “coherent description and explanation” without risk of
misunderstanding.)

Robert C. alluded to:

> > ... the common
> > impression that laws are theories that have been proven to be true.  Is
> > there general agreement that this is *not* the case?

I would certainly agree that is not true.  Does it even rise to the level
of "common" misconception?

Popper had something to say about falsifiability (as opposed to proving
things "true").

I would add that predictions do not need to be super-accurate in order
to be useful.  This and related points are discussed at
  http://www.av8n.com/physics/scientific-methods.htm