

Starquakes: maybe we can be a little frightened (2009) - markmassie
http://blogs.discovermagazine.com/badastronomy/2009/06/18/ok-so-maybe-we-can-be-a-little-frightened/

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pavel_lishin
So, does this mean that any intelligent life that might have been closer to
SGR 1806-20 is now extinct?

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rl3
I would imagine it depends on how intelligent.

On the other hand, I suppose life forms could exist that aren't bothered by
massive amounts of radiation.

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TeMPOraL
I read once about gamma ray bursts [0] which happen pretty frequently out
there; we detect them every day in other galaxies. If any such event occurred
near us (by near I mean anywhere in the vicinity of our galaxy) and the Earth
was in the path of the beam, it could do anything from destroying the ozone
layer to burning away every trace of life from the surface.

The scary thing is that, like with starquakes, we can't dodge it. The effect
moves with the speed of light; when we detect it, it's already too late for
us.

So between GRBs and starquakes, what else is there that can snuff us out
without warning?

[0] - [http://en.wikipedia.org/wiki/Gamma-
ray_burst](http://en.wikipedia.org/wiki/Gamma-ray_burst)

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jballanc
If you're into worrying about catastrophic existential threats, you'd be hard
pressed to do better than Vacuum Instability:
[http://en.wikipedia.org/wiki/Vacuum_instability#Vacuum_metas...](http://en.wikipedia.org/wiki/Vacuum_instability#Vacuum_metastability_event)
...especially worrying because the recently confirmed mass of the Higgs puts
us firmly in the realm of "well, it _could_ happen".

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gliese1337
It is worth noting, however, that a region of lower vacuum energy does not
actually expand at lightspeed- merely _near_ the speed of light (and exactly
how near depends on the details of the vacuum inside the bubble), due to the
fact that domain walls have mass-energy. So, if it happens sufficiently far
away, we could in theory actually notice it happening before it killed us,
unlike a gamma-ray burst.

~~~
jballanc
Yes, but unlike a gamma-ray burst, there is _literally_ no hope of survival.
With a gamma-ray burst one could, in theory, survive given an ultra-shielded
structure with full life support (to offset the lack of atmosphere and any
other life on the surface once the burst passed). If a region of lower vacuum
energy were headed our way, it would _completely change the very physics we
know of down to the sub-subatomic level_. Ain't nothin' standing in the way of
that...

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BrandonMarc
Would it be possible to tell when such events happened far into our past? I'm
curious if such an event could trigger a mass extinction [1] on Earth ... and
if any of the 5 previous mass-extinctions [2] might coincide with one.

[1]
[http://en.wikipedia.org/wiki/Extinction_event#A_nearby_nova....](http://en.wikipedia.org/wiki/Extinction_event#A_nearby_nova.2C_supernova_or_gamma_ray_burst)

[2]
[http://en.wikipedia.org/wiki/Extinction_event#Major_extincti...](http://en.wikipedia.org/wiki/Extinction_event#Major_extinction_events)

~~~
throwaway_yy2Di
Probably not from one of these magnetar quakes. The one described in the
articled released 10^39 J of x-rays; the typical gamma-ray burst is estimated
to be 10^44 J, and moreover, concentrated in a narrow beam. If you're in the
path of a GRB, it's looks as bright as a 10^45 - 10^47 J isotropic source.

[https://en.wikipedia.org/wiki/SGR_1806-20](https://en.wikipedia.org/wiki/SGR_1806-20)

[https://en.wikipedia.org/wiki/Gamma-
ray_burst#Energetics_and...](https://en.wikipedia.org/wiki/Gamma-
ray_burst#Energetics_and_beaming)

[http://arxiv.org/abs/astro-ph/0102282](http://arxiv.org/abs/astro-ph/0102282)
(ref [69] from the previous; page 20 in particular)

So, if the article you link to estimates a GRB would be an extinction event
within <6,000 light years or so, you could extrapolate that a magnetar quake,
10^7 times weaker, would need to be 10^3.5 times closer, that is, within 2
light years. There's zero magnetars in that range for sure.

~~~
throwaway_yy2Di
Then again, Phil Plait is taking about much lesser effects like damaged
satellites. He calculates this could happen at 5,000 light years from a
magnetar; that implies (flipping my calculation around) that a GRB could do
that _all the way from another galaxy_ (..if it's a "nearby" galaxy).

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jameswilsterman
Does this imply that the 1806-20 event occurred ~50,000 years ago and only
just reached us ten years ago?

"In December 2004, the magnetar SGR 1806-20 underwent such a starquake." <\-
Makes it sound like the effect on Earth was instantaneous but I imagine that
is impossible.

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saintgimp
Relativity kind of messes with our notions of time.

Any event that happens outside of our lightcone
([http://en.wikipedia.org/wiki/Light_cone](http://en.wikipedia.org/wiki/Light_cone))
cannot have any casual effect on us, even theoretically, until it enters our
lightcone. Before then, the event literally doesn't exist from our point of
view. Because of this, it's reasonable and valid to take the position that
distant events "happen" when we're first able to see them happen. It's not the
only perspective you could have, of course, but it can be a useful one and
astronomical events are often discussed this way.

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Houshalter
That's not true if faster than light travel is possible (e.g. wormholes,
warpdrives, any form of time travel, etc.) And even so, it doesn't make a lot
of sense to redefine time that way. It would be like a pre-electricity
civilization declaring that things outside their mail-cone (how fast mail can
travel) haven't actually happened yet.

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zaroth
Civilization destroying starquakes, wow! It's amazing to consider that since
such a thing could theoretically happen, then in the infinite stretch of time
and space, then such a thing certainly has happened, many times over.

Doesn't the fact that we have actually observed this happening anywhere in the
universe mean it's basically a "regular every day" event?

The universe is seriously incredibly hostile to life... and yet here we are!

~~~
zaroth
But then again, how about another way to try to gauge the treat in terms we
can actually comprehend... What percent of the known universe would be within
the 'kill zone' of a starquake over the course of, let's say, 1 billion years?

