Re: Kevin later wrote:

Brian D Harper (bharper@postbox.acs.ohio-state.edu)
Wed, 24 Feb 1999 10:58:04 -0800

At 05:28 AM 2/24/99 -0700, Kevin wrote:
>>
>>Burgy:==
>>>>
>>>>What you wrote, "But there has never, to my knowledge, been a case when a
>>>>physical law was found to be false by new evidence," is still an
>absurdity.
>>>>
>>
>>Kevin:==
>>>
>>>And yet you still cannot or will not give even one example to prove me
>>>wrong, or explain what physical law Einstein or any other scientist proved
>>>wrong. Making bald assertions you either cannot or will not defend is the
>>>height -- or should I say depth -- of absurdity.
>>>
>>
>>OK, how about Descartes' law of refraction?
>>
>
>
>I suppose that means that when Descartes' law was shown to be incorrect,
>refraction as a physical phenomenon was also shown to be false.
>
>Yeah, right, and I have seafront property for sale in Colorado.
>
>Let's not confuse the physical phenomenon itself with our abstract
>mathematical description of it, even though we tend to call both a "physical
>law". When Burgy and I talk about falsifying a physical law with new
>evidence, we mean demonstrating that the physical phenomenon itself, not
>just our abstract mathematical description of it, is false. Refraction is
>still recognized as a legitimate physical phenomenon; what's more, it is
>also recognized that it is caused by the decrease in the speed of light as
>that light passes through dense material, such that as a general rule of
>thumb the greater the density, the greater the angle of refraction.
>Descartes' attempt to describe this phenomenon may have been shown to be
>incorrect, but the phenomenon itself is still very much real.
>

But what you said was physical law, not physical phenomena. Even
if Newton's law had been overturned by Einstein (I agree with you
that it wasn't) it would have no bearing on the physical phenomena
of gravity. The absence of any mathematical description (law)
for how gravity operates would have no bearing on the physical
phenomena of gravity. As Stan so eloquently pointed out, the
previous discussion and arguments make no sense if it is indeed
physical phenomena (as opposed to our mathematical descriptions
of them) that is the issue.

Nevertheless :), I tried to pick an example that would resist all
attempts at rebuttal. You say above that "...it is also recognized
that it is caused by the decrease in the speed of light as that
light passes through dense material...". This is the whole
controversy. And it was truly a controversy on the grandest
scale, one of the most interesting in the history of science.
Imagine the furor among the Cartesians when a mathematician
(Fermat) derived the correct form of the law by making the
outrageous assumption that light travels along that path which
minimizes the time of travel. Clerselier, a well known
Caretesian of the day, wrote of Fermat's principle:

"That path, which you reckon the shortest because it is the
quickest, is only a path of error and bewilderment, which
Nature in no way follows and cannot intend to follow."

Now, returning to your description of the physical phenomena:
"...it is also recognized that it is caused by the decrease in
the speed of light as that light passes through dense material..."
This may be recognized today, but it wasn't then. Descartes
(and everyone else, including Leibniz) thought light travelled
more quickly through a dense media (a property predicted by the
law. Snell's law is obtained from Descartes' by inverting either
the right or left hand side). Not only is the law incorrect,
the physical phenomena associated with the law (that light
travels more rapidly through a dense media) is incorrect.

Brian Harper
Associate Professor
Applied Mechanics
The Ohio State University

"He who establishes his arguments
by noise and command shows that
reason is weak" -- Montaigne