meekerdb wrote:
On 6/5/2015 4:29 PM, Bruce Kellett wrote:
meekerdb wrote:
On 6/5/2015 12:22 PM, John Clark wrote:
On Fri, Jun 5, 2015 , meekerdb <[email protected]
<mailto:[email protected]>> wrote:
>> It's very relevant if you want to know what is a simplified
approximation of what. And we both agree that a electronic
computer is vastly more complex than it's logical schematic,
so why can we make a working model of the complex thing but
not make a working model of the simple thing when usually it's
easier to make a simple thing than a complex thing? The only
answer that comes to mind is that particular simplified
approximation is just too simplified and just too approximate
to actually do anything. That simplification must be missing
something important, matter that obeys the laws of physics.
> The trouble with this argument is that the laws of physics are
mathematical abstractions.
Mathematicians are always saying that mathematics is a language, but
what would be the consequences if that were really true? The best
way known to describe the laws of physics is to write then in the
language of mathematics, but a language is not the thing the
language is describing.
I agree the laws of physics are descriptions we invent; but even so
they are abstractions and not material and what they define is only
an approximation to what happens in the world. That's what makes
them useful - they let us make predictions while leaving out a lot of
stuff.
So what is this "lot of stuff" that the mathematical abstractions
leave out? In response you your initial point that "the laws of
physics are mathematical abstractions", the obvious questions is
"Abstractions from what?"
Abstractions from physical events. We find we can leave out stuff like
the location (and so conserve momentum) and the position of distant
galaxies and the name of the experimenter and which god he prays to
etc. Of course what we can leave out and what we must include is part
of applying the theory. Physicists work by considering simple
experiments in which they can leave out as much stuff they're not
interested in as possible in order to test their theory. Engineers
don't get to be so choosy about what's left out; they have to consider
what events may obtain. But they also get to throw in "safety factors"
to mitigate their ignorance.
In other words, in this account, the pre-existing physical world is
taken as a given, from which laws are simplified abstractions. Fine,
that's the way I think it is.
Bruce
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