Fairy tales for adults

Steve Bougerolle steveb at creek-and-cowley.com
Wed Feb 12 11:07:55 PST 2003

On Thu, 2003-02-13 at 02:44, Ian Molton wrote:

> Ok, ok. but we CAN say with a reasonable degree of certainty how far
> away other stars are. certainly more than accurately enough to disprove
> any 6000 year theory.


First, the trivial answer; it's irrelevant how long it takes light to
arrive from other stars because Genesis discusses the creation of the
earth, not them :)

Now, the real answer.  Distance measurement may seem simple from outside
but is actually still one of the most difficult fundamental problems in
astronomy.  The only cases where we can measure distance with any degree
of certainty are those where we can do it geometrically, by measuring
parallax.  All other methods involve assumptions (and generally quite
gross ones).  

Typically we measure the redshift of the star, by fairly reliable means
such as measuring the shift of spectral lines.  This gives us a
velocity, and is fairly un-controversial.  The next step is to convert
that velocity to a distance, which necessarily involves using some model
or other.  The most common one is "Hubble's Law" but don't be fooled by
the impressive name because it's extremely far from being a
well-established scientific law of any sort.  This method amounts to
plotting star data on a graph then fitting a simple line to it and using
the slope of the line to get the distance.  That slope, by the way, has
an uncertainty in the neighbourhood of 60% and it is extremely arguable
whether it should be a linear fit at all.

Now, all this is a debate about details of a theory, but on balance the
theory holds together pretty well and presents a reasonably coherent
picture of the universe, so scientists (like me) pay attention to it and
keep its predictions in mind.

However, if somebody with a critical bent and a lack of fascination with
numbers looked at the theory they would see assumption piled on top of
assumption, and they would be quite justified in rejecting the entire
thing as unproven.  It IS all unproven and that doesn't change just
because we get interesting and occasionally useful results from our
theories and speculations. 

Thus it is quite possible for an intelligent, well educated person who
is NOT scientifically inclined (or overimpressed with numbers, depending
how you want to look at it) to disbelieve cosmology and prefer a
literary account like Genesis.  Their view just seems unreasonable to us
here because we are judging it by our standards.  If anybody actually
saw cosmology as a coherent logical theory, it would be extremely simple
to punch it full of holes and ridicule it - and by the standards of,
say, a lawyer or somebody else in the humanities that would be perfectly

Steve Bougerolle
Creek & Cowley Consulting


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