At 02:30 PM 10/23/98 -0400, Randy wrote:
[...]
>
>I would certainly agree with this point but it seems a bit tautological to
>me. The scientists seem to be saying "The only reason we know the universe
>exists is because we exist to perceive it." True, but how does this
>insight explain why the physical constants in the universe favor life's
>existence instead of it's non-existence?
>
Short answer: it doesn't.
Long answer: I believe that Kevin was using the so-called
Weak Anthropic Principle (WAP). This was introduced by
Brandon Carter who defined it thusly:
"... what we can expect to observe must be restricted by
the conditions necessary for our presence as observers"
-- Brandon Carter (1974). "Large Number Coincidences
and the Anthropic Principle in Cosmology,"
in <Confrontation of Cosmological Theories with
with Observational Data>, M.S. Longair (ed.),
pp. 291-298.
This seems completely non-controversial and almost
(not quite) tautological as you suggest. The thing to
understand about the weak principle is that it is very
weak :). As you suggest, it provides no explanation of
fine tuning nor does it even predict that there should
be fine tuning.
There are, as far as I know, three primary explanations
that have been offered for the existence of fine
tuning, summarized nicely by Dennis Sciama:
===================================================
This simple but powerful argument leads us to ask the question:
*how much* can I deduce about the universe from the fact that
I exist? It turns out that various elementary particle, nuclear,
atomic and molecular properties of matter have to be very finely
tuned for conditions in the universe to have permitted my
development--many examples are given by Barrow and Tipler and
elsewhere in this book. These finely tuned properties will
probably also eventually be accounted for by fundamental
theory. But why should fundamental theory _happen_ to lead
to these properties?
There seem to be three possible answers to this question:
(a) It is a complete chance.
(b) God regards me as such a desirable product of the universe
that he has fine-tuned it so as to guarantee my development.
(c) There exist other, disjoint, universes with other laws
and constants of nature.
-- D.W. Sciama, "The Anthropic Principle and the Non-Uniqueness
of the Universe," in _The Anthropic Principle_, Proceedings
of the Second Venice Conference on Cosmology and Philosophy,
F. Bertola and U. Curi, ed., Cambridge University Press,
1993, pp. 107-109.
===============================================
I say "primary" explanations above to exclude a very common
"explanation" based on a misunderstanding of the WAP. I
call this the "we're here because we're here" argument :).
One of the things that makes the Anthropic Principle (AP)
so difficult is that different people use the term AP
with completely opposite meanings. IOW, for some the
AP is considered as an answer to the design argument,
for others, AP *is* the design argument.
Here are a couple of quotes illustrating both views:
"The anthropic principle is the design argument in scientific
costume" --Timothy Ferris <The Whole Shebang>
==========================================
There does exist a line of thinking that _is_ in direct
competition with the anthropic principle. Edward Harrison,
in his textbook _Cosmology_, advises his readers early on:
"We shall occasionally refer to the anthropic principle,
and the reader may, if it is preferred, substitute the
alternative theistic principle." The theistic principle
is quite straightforward: the reason the universe seems
tailor-made for our existence is that it _was_ tailor-made
for our existence; some supreme being created it as a home
for intelligent life. Of course, some scientists, believing
science and religion mutually exclusive, find this idea
unattractive. Faced with questions that do not neatly fit
into the framework of science, they are loath to resort to
religious explanation; yet their curiosity will not let
them leave matters unaddressed. Hence, the anthropic principle.
It is the closest that some atheists can get to God.
-- Pagels, H. (1985). "A Cozy Cosmology," <The Sciences>
25(2):35-38. also in <Physical Cosmology and Philosophy>,
Ed. J. Leslie, Macmillan, New York, 1990, pp. 174-180.
==============================================
[...]
>But if evolution is "descent with modification" how does it explain the
>fine tuning of the universe? The universe is not a replicating system so
>unless the only universe that exists supports life there will never be a
>subsequent universe that supports life. At least that's how it seems to
>me.
>
Evolution would not explain fine-tuning, rather, most fine-tuning
has to do with the required conditions for life to evolve.
IOW, fine-tuning seems to me to fit in nicely with design from
evolutionary creationist perspective :).
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