Hugh Ross theorizes in his book "The Genesis Question" that a
Supernova may have been the instrument utilized to shorten human
life. He has a less rigorous analysis posted at:
<http://www.reasons.org/resources/skeptics/methusela.html>
Excerpt from the site:
"Until recently, we had no scientific explanation as to how the
pre-flood peoples could have lived so much longer than modern people
can. Several canopy theories have been proposed, but none of them
works. The hypothesized canopies would filter out some ultraviolet
radiation, but they offer no effective mechanism for blocking out
hard cosmic rays. These hard cosmic rays do far more to limit human
lifespans than do ultraviolet rays.
"In 1981 a possible explanation for the long lifetimes and the
subsequent shortening of them (along a geometric curve) was
unknowingly proposed. A paper entitled "Terrestrial
Paleoenvironmental Effects of a Late Quaternary-Age Supernova" was
published by geophysicist G. Robert Brakenridge in the journal Icarus
(v. 46, pp. 81-93). Dr. Brakenridge describes measurements that date
the Vela supernova as having occurred sometime between 9300 and 6400
B. C. (A supernova is the cataclysmic explosion of a massive star;
this one is called the irela supernova because it occurred in the
Vela constellation.) These dates fit well with the Biblical date for
the Genesis Flood."
Related papers can be found at:
<http://www.reasons.org/resources/skeptics.html>
David Nunes