From: maoh@phyast.nhn.uoknor.edu (Maureen O'Halloran)
Subject: Re: Are we privileged observers?
Keywords: universe,earth, paradox
Organization: Engineering Computer Network, University of Oklahoma, Norman, OK, USA
Date: Sun, 16 Aug 1992 00:12:03 GMT

julian@fraser.sfu.ca (Julian Shillcock) writes:

> . . .  But if science can be shown to
>need extra assumptions OUTSIDE the realm of science itself in order to explain
>the unvierse we observe then we might be justified in postulating God
>with some assurance.
> .....
>If one answers yes, then it is an unscientific assertion as we can by 
>definition do no experiments there, if no, then why do we hold a special
>position in the universe so that where we cannot see the laws of physics
>change?

How about answers other than yes or no, such as that its meaningless
to speculate about things that can't be measured.  That's metaphysics,
not physics, and if by definition measurement is impossible then you
can't verify or disprove any theories.  So whats the point other than
personal amusement?

>We seem to need a meta-physics to tell us where the laws of physics
hold.

Why?  What do we care if they do or don't hold in places we can't
measure.  If you have some theory about whether the physics beyond the
horizon affects whats going on in "our" universe, then it becomes
interesting, PROVIDED I BUY YOUR THEORY. 
If its measureable and reproducable, then we can do science.

>It is made even worse if the laws themselves change in time as we then
>have no idea what happens even in the parts of the universe we can
> observe.

See below.

>(Alsom if the universe is infinite then how come we are still here?)

?????????

>julian 

It probably seemed like a good idea at the time, but this dog won't
hunt. Science does not consist of compiling data, publishing it in a
book like a phone book and then refusing to speculate about anything
other than what's in the book and declaring all theories that explain
the book equally probable.

One way to choose which is the "best" theory is by its predictive
power. i.e., the proof of the pudding is in the eating.  A theory not
only explains the data, but also provides a mechanism to produce the
data and predict additional data.  You then go out and gather more
data or perform experiments in order to test your theory.  A
scientific theory has to be consistent. i.e, your theory must explain
all observations, not just a few. William of Occam put forth the
principle that given a choice among theories, the simplest and
straightforward one with the fewest unproven assumptions is the best
choice, and time and time again this has proven to be true.  Anytime
you introduce a step like "and then a miracle occured" you are
introducing an unproven assumption.

Yes, you could claim that the laws of physics have changed with time
in such a way that the physical world we live in "just happens" to
match the one predicted by a theory with a few simple forces that
don't change with time.  Be careful though because your theory will
have to require that different kinds of physical phenomena change
in the same way so that they all match up with each other today.  Your
theory should explain why things changed in the past and are not
changing now. 

I could equally well come up with a theory that the laws of physics
 change every two weeks.  It just happens that our memories change
at the same time and all physical objects rearrange themselves to make
it look like the laws of physics have been constant.  All written
records of course change to show that previous experiments and
observations agree with the current set of physical laws.  (Actually,
the only written records that don't change are the lab notebooks in
undergraduate physics courses, but the students doctor the data so as
to get the "correct" answer.)

--- Maureen O'Halloran