T wrote:
> I got to thinking about my recent 'Gamma Ray Bursts might be a reason
> for less intelligent life filled planets' thread awhile back, and then
> considered NASA spotted some recent explosions in space that _might_
> lead to real supernova or even gamma ray burst as described before.
> (We
> are lead to believe that these particular events are no threat to our
> own existence.)
They occurred in other galaxies, so there's not exactly a big worry
there.
> What this lead to was wondering if events in the past, in ancient or
> near modern history might be explained by stellar events that went
> unrecorded, either to their basic nature being off the visible
> spectrum
> and/or being unrecorded by something like the Hubble, because it
> hadn't
> yet been invented.
Note that the x-ray bursts are just a sequence of bursts that happened
to take place in the same region of the sky; they aren't gamma ray
bursts, and it's _hypothesized_ that they are "foreshocks" to
supernovae, but that is unknown. (One of the bursts was close in
magnitude to a gamma ray burst.)
X-ray bursts are not new; what is allegedly new here is the supposition
that these might presage supernovae. Considering that was weeks ago,
and the final stages of a type II supernova take a lot less time than
that, and there's no followup story, one can only assume that that
supposition turned out to be false.
> Mass Irradiations might be the root cause behind plateau mutations or
> massive die-offs that led to climatic changes (lots of carbon gets
> tied
> up in biomass, if let go all at once it can alter the atmosphere.)
> etc, etc.
It has been proposed that gamma ray bursts might be the cause, or
contribute to, the Fermi paradox. Since that suggestion, we're pretty
sure that gamma ray bursts are caused by hypernovae (a particular type
of explosion associated with a massive dying star), and that they are
highly directional. (This explains both why they're so powerful and so
far away; you have to look out to large distances to happen to find a
hypernova whose beam is pointing toward you, and the directional nature
of the burst concentrates the energy in those beams so that they look
much brighter than they would be if they were isotropic.) Since they're
anisotropic, that makes it much, much harder for a gamma ray burster to
sterilize a galaxy, even one it's located in.
There are several abstracts on arxiv.org dealing with the possibility of
catastrophic galactic events contributing to the Fermi paradox; so far,
they have all the same shortcomings of the Fermi paradox itself, namely
that we're not really sure what the nature of those events would be and
whether they'd really be able to fit the bill as galactic killers. It
seems not, especially with the recent theories about gamma ray bursters
being caused by hypernova.
> I know this isn't Niven specific, but lots of knowledgeable folks
> here,
> just a little gist for the mill.
rec.arts.sf.science would probably be a better newsgroup.
--
__ Erik Max Francis && max.DeleteThis@alcyone.com && <a style='text-decoration: underline;' href="http://www.alcyone.com/max/" target="_blank">http://www.alcyone.com/max/</a>
/ \ San Jose, CA, USA && 37 20 N 121 53 W && AIM erikmaxfrancis
\__/ Life is a zoo in a jungle.
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