Re: Definition of A Field

From: Harry (harald.vanlintel_at_epfl.ch)
Date: 11/12/04 

Date: Fri, 12 Nov 2004 09:33:09 +0100

"Gregory L. Hansen" <glhansen@steel.ucs.indiana.edu> wrote in message
news:cn0rqc$qs4$1@hood.uits.indiana.edu...
> In article <419366c8$1@epflnews.epfl.ch>,
> Harry <harald.vanlintel@epfl.ch> wrote:
> >
> >"Gregory L. Hansen" <glhansen@steel.ucs.indiana.edu> wrote in message
> >news:cmtajk$jjq$1@hood.uits.indiana.edu...
> >> In article <4191ed60$1@epflnews.epfl.ch>,
> >> Harry <harald.vanlintel@epfl.ch> wrote:
> >SNIP
> >
> >> Logic has never been dumped in science.
> >
> >The question was about the kind of logic. See further.
>
> Aristotelian logic has never been dumped in science.
>
> >
> >> You'll find some people that
> >> claim logic has been dumped, but in every case I've examined carefully
> >> they've either made an error in their own analysis, or they can't
separate
> >> logical operations from their own premises. A random, but common,
example
> >> goes something like "It's illogical for a beam of light to have the
same
> >> speed for two observers in relative motion." Why? Because they assume
> >> Galilean relativity, without realizing that it's an assumption and not
an
> >> a priori logical necessity. The argument reduces to "If we assume
special
> >> relativity is wrong, then it follows that special relativity is wrong."
> >> How illuminating.
> >
> >That's an interesting one. Maybe worth to start a separate thread about
it
> >if you like.
> >It is important to be extremely precise with expressions like "to have a
> >speed", for "to have" may refer to either observation of reality (as is
> >habitual in modern physics), or to a claim about logically inferred
reality
> >itself. Obviously there is no problem with the first interpretation which
is
> >loose from metaphysical logical deductions.
>
> The closer you try to get to "reality itself", the farther you'll be from
> things that can be measured and observed. You can make models of the way
> nature works, but recognize that they're always inventions of the human
> mind.

Right. With trying out models we can at least propose possible ways that
reality may work.

> >It's not at all necessary to assume Galilean relativity to notice a big
> >problem if reality itself is claimed to be described. Only the use of the
> >foundations on which physics has been built suffices: Aristotlean logic
and
> >the existence of observer-independent nature - which implies the
existence
> >of observer-independent reality. Or do you hold that, using those
> >assumptions, the propagation of a light pulse that is sent in all
directions
> >can be claimed to _be_ (in contrast to "seem to be") both isotropic *and*
> >anisotropic with reference to the position of the source?
>
> I have no idea what the distinction is between "be" and "seem to be".

I hold that two contradictory deductions about reality can't be both
correct:
[ x1= x2 AND x1> x2 ] is erroneous in the same context.
When you look through a magnifying glass the world seems to be smaller and
upside down. There can be no denial that you observe that, it's a clear and
repeatable measurement. However, logical considerations lead to the
conclusion that likely it's your observation that is affected and not the
universe, even if this couldn't be determined with specific experiments.
Anyway, if you were unaware of the distinction between assumption of reality
vs. mere appearance in the context of relativity, then you may have missed
the point of the discussion you referred to (or maybe not, I've seen some
hopeless debates were both parties were clueless).
BTW, Feynman did address it but admitted that he didn't bother about such
things, he likely thought it too philosophical for him.

> >> There is a certain conservatism in science, and it does serve a useful
> >> purpose. Every scientist remembers N-rays, polywater, and the fifth
> >> force.
> >
> >I think that's wishful thinking.
> >N-rays were before my time and only thanks to some critical commentaries
on
> >internet I had discovered about them, and polywater and the fifth force:
I
> >am not familiar with them!
>
> Polywater:
> http://www-2.cs.cmu.edu/~dst/ATG/polywater.html
>
> Fifth force:
> http://plato.stanford.edu/entries/physics-experiment/app4.html

Thanks!

> Science presented to the public or in textbooks is only after the party is
> over, the beer cans and pizza boxes have been discarded, and the vomit
> steam-cleaned from the rugs before Mom and Dad come home.

Yeah

Cheers,
Harald

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