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From: ethan@utastro.UUCP (Ethan Vishniac)
Newsgroups: net.origins
Subject: Re: ...and yet more responses
Message-ID: <699@utastro.UUCP>
Date: Thu, 25-Oct-84 17:01:23 EDT
Article-I.D.: utastro.699
Posted: Thu Oct 25 17:01:23 1984
Date-Received: Sat, 27-Oct-84 06:25:56 EDT
References: <1432@qubix.UUCP>
Organization: UTexas Astronomy Dept., Austin, Texas
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[]
     Another quick note in response to Larry Bickford's article.
First, I note that Larry comments on how lazy those who disagree
with him are, and how they're obviously not reading his notes.
I can't speak for other people, but I'm not particularly interested
in spending time reading the creationist literature.  I spend enough
time on this as it is.  If Larry were to convince me that a valid
case could be made for creationism I'd find the time.  I *do* read 
the articles in this newsgroup carefully, even his.  I just don't
find any of the creationist submissions particularly convincing, a
possibility that Larry seems to be dismissing off hand.

>On the other hand, in _The Case for Scientific Creation_, Morris
>presents 41 separate reasons for disputing the 4.5E9 years hypothesis of
>evolution, among them:
>	Decay of earth's magnetic field (10E4 years max)
>	Influx of radiocarbon into earth system (10E4 years max)
>	Efflux of He-4 into atmosphere (1750-175000 years)
>	Decay lines of galaxies (10E6 years max)
>	Expanding interstellar gas (60E6 years max)

Allow me to extend the list:
        Thunderstorms (few days)
        Fresh flowers (ditto)
        Soap bubbles (1 minute maximum)

    Now the above is, of course, facetious, but there is a serious
point involved.  It is legitimate to invoke transitory phenomena
as a measure of the age of the universe (which is *not* the age
of the solar system) only if they clearly cannot recur.  What is one
to make of the above list?

    Decay of earth's magnetic field - The Earth's magnetic field
appears to be the natural consequence of having a hot ball of
rotating metal with convection currents running through it.  Its
precise behavior is difficult to understand because it is a very
complicated system, but any planet with the above properties
should have a magnetic field with a lot of time variation.  Note
also that the rocks near spreading rifts show variations in the
frozen magnetic field that vary systematically with the age of
the rocks (which is correlated with their distance from the rift).
They support the picture of a magnetic field whose strength and
direction have varied considerably.  

>	Influx of radiocarbon into earth system (10E4 years max)
     
     I don't understand this comment at all.  Carbon 14 is radioactive.
It is produced in the atmosphere.  Since organisms absorb carbon from
the atmosphere only while they are alive this implies that the fraction
of carbon 14 left in ancient organic material is a function of how long
it has been dead.  This can be checked by comparison with ancient
tree trunks and remains found in conjunction with historically dated
sites.  The low level of C14 found in ancient remains is a function of
its radioactivity, not a recent increase in the C14 levels in hte
atmosphere.

>	Efflux of He-4 into atmosphere (1750-175000 years)

     I have no idea what he's talking about here.  He-4 is
a trace component of our atmosphere because it can acquire escape
velocity at normal temperatures in the upper atmosphere.  The Earth
outgasses Helium at some compensating rate.  Not being a geologist,
I have no idea offhand how much of that is primordial (i.e. dating
from the origin of the Earth) and how much is the result of alpha
decay of heavy elements in the Earth's crust.

>	Decay lines of galaxies (10E6 years max)

    I was baffled by this at first (and I'm an astronomer!), but
someone suggested to me that he meant the spiral arms of spiral
galaxies which would tend to wrap up in about 10^8 years if
the objects that mark spiral arms move at normal orbital velocites
and continue to mark the spiral arms.  This seems pointless since
the bright stars that mark spiral arms are shortlived (few million
years) and the molecular clouds associated with them are probably
transient on the same time scale.  In fact, spiral arms are 
understood to be a wave phenomenon in which gas density waves
propagate in the rotating disk.  The spiral arms are the wave
crests where the gas density peaks creating molecular clouds, and
(subsequently) giving rise to star formation.

>	Expanding interstellar gas (60E6 years max)

   See above, the clouds appear to be created in the spiral arms
and to become disrupted by star formation within them.

     Nevertheless astronomy does provide some indications of the
age of the universe.  Three methods of estimation that I'm aware
of are
      1)  The universe is expanding.  Extrapolate the radial velocities
          of distant galaxies backwards and one finds that the
          universe was *much* denser about 10^10 to 2x10^10 years
          ago.
      2)  The oldest stars in the galaxy appear to be at least
          10^10 years old.  This estimate is based on noticing
          that stars in globular clusters have aged so that
          even stars with less mass than the sun have stopped
          core hydrogen burning and become Red giants (low mass
          stars age less rapidly).  The time estimates are based
          on our models of stellar structure (which produce reasonable
          agreement with the observed distribution of stars in the
          luminosity-temperature plane).
      3)  There is a deficiency of *extremely* cold white dwarf stars.
          These are very small, but massive stars that are not
          burning nuclear fuel anymore, but remain hot (presumably
          from previous nuclear fusion).  Extremely hot members
          of this class have cooling times that are measureable.
          The coolest members of this class need to have been
          cooling for at least 10^10 years.  At lower temperatures
          there is a *complete* lack of such stars (they would need
          much more than 10^10 years to cool).  Presumably the
          creationist explanation is that God decided that cooler
          white dwarfs were unesthetic.

"I can't help it if my     Ethan Vishniac
    knee jerks"         {charm,ut-sally,ut-ngp,noao}!utastro!ethan
                           Department of Astronomy
                           University of Texas
                           Austin, Texas 78712