Ask A Scientist© Physics Archive

 
>
> >  name       Rachel
> >  status     student
> >  age        20s
>
> >  Question - How would you explain, according to evolutionary theory,
> > the existence of many millions of atomic decay halos found in granite
> > that begin their decay sequence with polonium? My understanding is that
> > polonium is not a naturally occurring element. The phenomenon of
> > finding decay halos beginning with polonium in solid granite extending
> > over 20 feet into the earth would be analogous to finding Alka-Selzer
> > bubbles preserved in an slowly-frozen glass of solid ice--the granite
> > should have taken too long to cool for there to be any polonium remaining
> > to decay, especially in the quantities that have been found. The granite
> > would have to have been formed instantaneously. So how did this happen?
>
>Aah, polonium halos. Another favorite creationist argument. The halos in
>some rocks that supposedly arise from the rapid decay of many polonium atoms
>in the same place supposedly show that the rocks in which they formed had to
>solidify in three minutes or less, proving that the earth was created in an
>instant.
>
>Well, it's not so simple as that. You can find a much more detailed
>explanation at the website http://jblanton.home.mindspring.com/apr1999.htm;
>I'll give you a brief version. Polonium is a decay product of radon, which
>is formed in several steps from the radioactive decay of uranium. All of
>these polonium halos have been found in uranium-rich rocks, so there is
>plenty of raw material fom making polonium available over geologic time.
>The key thing about radon is that it is a gas, and thus can be fairly mobile
>in rock. Say, for instance, that a uranium-bearing rock has a small crack
>in it. Over hundreds of millions of years, radon atoms that form from
>uranium decay diffuse to the crack, migrate along the crack, and then are
>trapped at the end of the crack. The radon decays to polonium, which
>settles out on the wall of the crack. The polonium atom then decays,
>leaving a trail of damage in the rock. As large numbers of polonium atoms
>are deposited in the same spot, the trails of radiation damage form a sphere
>- the "polonium halo." So it is not necessarily true that "the granite
>would have to have been formed instantaneously."
>
>Richard E. Barrans Jr., Ph.D.
>Assistant Director
>PG Research Foundation, Darien, Illinois

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