The tricky bit is how you define a "minimum size black hole". If you mean
minimum in terms of the fundamental physics, such a black hole could have
been orbiting inside the Earth since the Solar System formed, and it still
would not have consumed enough material to make its presence known. If you
mean minimum in terms of fundamental physics, but make the thing big enough
to be stable (to consume material faster than it can evaporate)... I don't
now how long that would take to consume Earth. And if you mean minimum in
terms of how most theory (and all observation) mean it- on the order of a
stellar mass- well, clearly things will get real bad, real fast if one
intersects the Earth, no matter how fast or slow it's going.
Chris
*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com
----- Original Message -----
From: "Sterling K. Webb" <[email protected]>
To: "Carl 's" <[email protected]>;
<[email protected]>
Sent: Tuesday, September 15, 2009 3:52 PM
Subject: Re: [meteorite-list] Chicxulub Asteroid
Hi, Carl, List,
Two impactors of identical mass (not size,
because density varies, but mass), hitting with
identical speeds and at identical angles produce
virtually identical craters.
All that matters (if the object is bigger than
20-50 meters is kinetic energy. It could be iron,
it could be rock, it could be ice, it could be highly
compressed chicken feathers or a ball of fossilized
fast food --- all would have the same result.
A porous carboneaous chondrite of 10 km diameter
and an iron ball of 5.85 km, weigh the same, and at
20 km/s and a 60-degree angle, both will produce a
65 mile crater 3/4 of a mile deep.
There are high-iridium iron meteorites as well as
stony ones, but an iron impact will leave other traces
not found around Chicxulub.
Now... the fun part! What WOULD go right through
the Earth?! It would have to be very dense so that its
area was very small for its huge mass. Number one
best candidate is a small fast black hole. I specify "fast"
because if it was slow-moving, it might slow enough to
stop inside the Earth or start orbiting around inside
the planet, madly eating up mantle and core material
as it went until...
Wow! makes me want to drag that heavy John
Wheeler book off the top shelf and start scribbling.
Given a black-hole of minimum mass and size
m-sub-bh <<<< m-sub-earth, how long would it take
to eat the entire Earth? Well, even without numbers,
one can see that initially the mass consumption of
the small black hole would be very modest, but as it
grew and grew, the rate would increase by a power
curve following the exponent of the ratio of black hole
surface to black hole mass until the black hole reached
a certain fraction of the Earth's mass and then a
destructive deformation would occur in a catastrophic
fashion... It could take thousands of years. There could
be one there now. (Not true; we would hear it.)
But if it was a FAST black hole, it would go straight
through the Earth with only the equivalent of a black
hole burp and perhaps produce a massive episode of
basalt flood vulcanism as it exited. Silly notion. We don't
have massive basalt flood vulcanism... What's that?
We do? Every how often? Hmm. You don't suppose...?
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