In
sci.astro.seti,sci.astro,uk.sci.astronomy,sci.phys ics.relativity,rec.arts.sf.science,
On Thu, 08 Sep 2005 00:41:12 GMT, Matt Giwer
wrote:

AA Institute wrote:
Okay, this is a light hearted question... but serious answers are
equally invited!

Suppose a black hole enters a binary system or a triple star system or
even a small, tightly-packed open cluster. Once it's finished
swallowing the first star, can it go onto swallowing a second star, and
then a third star, and so on... as it continues along its destructive
path?

Matt's response (quoted at the end of this post) indicates that,
due to orbital paths, it is unlikely that more than one star would be
'swallowed' by a black hole going through the system. However, if you
'aim' the black hole carefully, you can have it intersect the orbits
of two or perhaps even three stars, and with the right timing, they
will all be swallowed up.

What is the *limit* (if any) as to how much theoretical mass that
can go into a black hole, before it's 'filled to capacity' as it were?

It's one of those questions that's been bugging me for a while, and I'm
not certain what the latest theoretical assumptions are about black
holes.

What we don't know about black holes could fill one so to speak.

There is no "capacity" in any sense we would think of it. There is no reason to assume there is a
limit.

The known universe is said to have something like 10^80-odd
particles (I forget the "exact" number, and what's a few powers of 10
among Usenet posters?), so there is a "practical" upper limit to the
mass a black hole could consume.

The practicality of swallowing more than one would appear limited to the very few binaries which
are very close and rapidly revolving around each other, most binaries are not. But then we have to
ask how a BH could hang around long enough to eat even one. Even relativistic mechanics says it is
going to pass near, if near enough swing around a common center of gravity and leave again. There is
no conceivable way to decelarate it so it could take up close orbit. Even in a universe this size a
"head on" collision may have never occurred.

A sufficiently massive BH might pass by a rapid binary and pull them along and slowly feed on both
but again one of those rare events as such dynamics tend to expell one -- at least by playing a
simple simulation many times.

Also close binaries are themselves a likely source of BHs as the larger feeds on the smaller.

"Ben Bradley" wrote in message
...
| In
|
sci.astro.seti,sci.astro,uk.sci.astronomy,sci.phys ics.relativity,rec.arts.sf.science,
| On Thu, 08 Sep 2005 00:41:12 GMT, Matt Giwer
| wrote:
|
| AA Institute wrote:
| Okay, this is a light hearted question... but serious answers are
| equally invited!
|
| Suppose a black hole enters a binary system or a triple star system
or
| even a small, tightly-packed open cluster. Once it's finished
| swallowing the first star, can it go onto swallowing a second star,
and
| then a third star, and so on... as it continues along its
destructive
| path?
|
| Matt's response (quoted at the end of this post) indicates that,
| due to orbital paths, it is unlikely that more than one star would be
| 'swallowed' by a black hole going through the system. However, if you
| 'aim' the black hole carefully, you can have it intersect the orbits
| of two or perhaps even three stars, and with the right timing, they
| will all be swallowed up.

Sheesh.... and what happens if two quite ordinary stars, never mind the
black holes, collide? I'd call that a supernova, but of course nobody
has ever seen that so supernovae must be old dying stars that become
swallowed by black holes and collisions like Shoemaker-Levi don't
happen. If it ever did we'd see it about to, as we can with those two
stars here.
http://antwrp.gsfc.nasa.gov/apod/ap950724.html
Which two stars did you ask?
The two on the right, near the middle. See then moving toward each
other?



|
| What is the *limit* (if any) as to how much theoretical mass that
| can go into a black hole, before it's 'filled to capacity' as it
were?
|
| It's one of those questions that's been bugging me for a while, and
I'm
| not certain what the latest theoretical assumptions are about black
| holes.
|
| What we don't know about black holes could fill one so to speak.
|
| There is no "capacity" in any sense we would think of it. There is
no reason to assume there is a
| limit.
|
| The known universe is said to have something like 10^80-odd
| particles (I forget the "exact" number, and what's a few powers of 10
| among Usenet posters?), so there is a "practical" upper limit to the
| mass a black hole could consume.

And a strong possiblity of 5 collisions a century, but black holes are
far more exotic.
Androcles

|
| The practicality of swallowing more than one would appear limited to
the very few binaries which
| are very close and rapidly revolving around each other, most binaries
are not. But then we have to
| ask how a BH could hang around long enough to eat even one. Even
relativistic mechanics says it is
| going to pass near, if near enough swing around a common center of
gravity and leave again. There is
| no conceivable way to decelarate it so it could take up close orbit.
Even in a universe this size a
| "head on" collision may have never occurred.
|
| A sufficiently massive BH might pass by a rapid binary and pull them
along and slowly feed on both
| but again one of those rare events as such dynamics tend to expell
one -- at least by playing a
| simple simulation many times.
|
| Also close binaries are themselves a likely source of BHs as the
larger feeds on the smaller.
|

"Erik Max Francis" wrote in message
...
Paul Harman wrote:

snippage

All that being said, that's not particularly relevant to
the question of
maximum black hole size (since Hawking radiation limits
the minimum
mass, not the maximum mass), and, as Aaron was kind enough
to remind us,
maximum black hole mass could only come into play only in
particularly
queer universes, of which ours does not to seem to be one.

Very true, except that, if what we now know is correct,
there is a sort of de facto "pseudo-upper-limit" on the mass
of BHs simply
due to the now accepted "hyper-expansion" of our universe
due
its so-called vacuum, or dark energy. Presumably, in deep
time, distant galactic superclusters will travel so far
apart (at relative velocities greater than c) they will,
each in turn, become causally disconnected from each other.
Local galactic superclusters may, or may not, remain
causally connected (we apparently don't know exactly yet
which of several theories is correct,) but in any event,
this would place the maximum amount of mass-energy a BH
could accrete (in arbitrarily deep time) at about that of
the largest superclusters we know of. In near-infinite time
though, even such large BHs would eventually decay by means
of emission of Hawking radiation. Still though, this
"maximum
pseudo-limit" would represent an awful large mass!
....tonyC

--
Erik Max Francis && &&
http://www.alcyone.com/max/
San Jose, CA, USA && 37 20 N 121 53 W && AIM
erikmaxfrancis
I don't like principles. I prefer prejudices.
-- Oscar Wilde

AA Institute wrote:

That's of course just a theoretical assumption. I wonder what the
equations are that leads one to that conclusion? Isn't it a wonderful
puzzle when we speculate that limitless amounts of mass can disappear
through these things, without knowing where it all goes to...

Since we don't have a black hole in front of us to experiment with, yes,
obviously the answer has to come from theory. You asked "What is the
_limit_ (if any) as to how much theoretical mass that can go into a
black hole, before it's 'filled to capacity' as it were?" [1]. If you
didn't want a theoretical answer, why did you ask for one? Furthermore,
now that you got your answer, why are you disputing it? On what basis
do you have to think that you got the wrong answer?

If memory serves me right, I seem to recall from one of the 'Space'
series (with Sam Neill), a while back, that a black hole gets bigger
and more powerful as more material gets sucked into it. So,
theoretically speaking, given an unlimited length of time and an
endless supply of matter, wouldn't a supermassive black hole like the
one thought to reside at the core of our galaxy, just grow big, big and
bigger... until there's only a dark cinder of the Milky Way left as
every last one of its stars has winked out by spiralling in?

That a black hole might have gobbled up all the handy matter locally
doesn't mean it's "filled to capacity" to its "theoretical mass."

Another interesting scenario comes to mind, where two black holes
swallow one another... something really bizzarre must happen there,
with space-time continuums and the like?

You get a larger black hole, with the emission of some gravitational
radiation.

..

1. .com


--
Erik Max Francis && && http://www.alcyone.com/max/
San Jose, CA, USA && 37 20 N 121 53 W && AIM erikmaxfrancis
Life is an effort that deserves a better cause.
-- Karl Kraus

Anthony Cerrato wrote:

Very true, except that, if what we now know is correct,
there is a sort of de facto "pseudo-upper-limit" on the mass
of BHs simply
due to the now accepted "hyper-expansion" of our universe
due
its so-called vacuum, or dark energy. Presumably, in deep
time, distant galactic superclusters will travel so far
apart (at relative velocities greater than c) they will,
each in turn, become causally disconnected from each other.

Sure. If we live in an open universe, eventually there will be no more
matter for black holes to swallow, and black holes will emit Hawking
radiation and evaporate slowly since the cosmic background radiation
will drop below their Hawking temperatures.

And if the Universe were closed, then black holes would be able to grow
only so large before the Big Crunch (although right at the last moment
they might all merge into a super black hole).

And if a black hole ate its local Galaxy and there was nothing else
nearby, it would stop growing.

These are all, in some sense, practical limits. To answer to the
theoretical question (which was asked), if you kept feeding a black hole
matter, it would never reach a maximum limit, presuming it could still
fit in the Universe.

--
Erik Max Francis && && http://www.alcyone.com/max/
San Jose, CA, USA && 37 20 N 121 53 W && AIM erikmaxfrancis
Life is an effort that deserves a better cause.
-- Karl Kraus

"Androcles" Androcles@ MyPlace.org wrote:
"Ben Bradley" wrote in message
.. .
[snip]
| Matt's response (quoted at the end of this post) indicates that,
| due to orbital paths, it is unlikely that more than one star would be
| 'swallowed' by a black hole going through the system. However, if you
| 'aim' the black hole carefully, you can have it intersect the orbits
| of two or perhaps even three stars, and with the right timing, they
| will all be swallowed up.

Sheesh.... and what happens if two quite ordinary stars, never mind the
black holes, collide? I'd call that a supernova [...]

Why would you call that a supernova? Are you saying you have evidence
that supernovae are caused by stellar collisions?


Tim
--
You are being watched. This gives you power.

Tim Auton writes:

"Androcles" Androcles@ MyPlace.org wrote:

Sheesh.... and what happens if two quite ordinary stars, never mind the
black holes, collide? I'd call that a supernova [...]

Why would you call that a supernova? Are you saying you have evidence
that supernovae are caused by stellar collisions?


The odds of stars just wandering along and smacking into each other is
really really really really really small. The universe is a big
place, but that does not happen often.

Considering that a rather common form of supernovae is the accretion of
mass onto a white dwarf provided by a close neighbor in a binary, one
could argue that stellar "collisions" cause a lot of SNe, for a broad
minded definition of collision.


--
Bradford Holden
"When your wife tells you you can buy a power tool, you listen."
- RR

"Tim Auton" wrote in message
...
| "Androcles" Androcles@ MyPlace.org wrote:
| "Ben Bradley" wrote in message
| .. .
| [snip]
| | Matt's response (quoted at the end of this post) indicates that,
| | due to orbital paths, it is unlikely that more than one star would
be
| | 'swallowed' by a black hole going through the system. However, if
you
| | 'aim' the black hole carefully, you can have it intersect the
orbits
| | of two or perhaps even three stars, and with the right timing, they
| | will all be swallowed up.
|
| Sheesh.... and what happens if two quite ordinary stars, never mind
the
| black holes, collide? I'd call that a supernova [...]
|
| Why would you call that a supernova? Are you saying you have evidence
| that supernovae are caused by stellar collisions?

Why do you snip when I've presented the evidence of a collision and
the resultant light burst right in our own backyard?

ftp://ftp.seds.org/pub/astro/SL9/ima...ALL/HST_R1.gif
Hubble Space Telescope Image of Fragment
BDGLNQ12R Impacts

Ultraviolet image of Jupiter taken by the Wide Field Camera of the
Hubble
Space Telescope. The image shows Jupiter's atmosphere at a wavelength of
2550 Angstroms after many impacts by fragments of comet Shoemaker-Levy
9.
The most recent impactor is fragment R which is below the center of
Jupiter (third dark spot from the right). This photo was taken 3:55 EDT
on
July 21, about 2.5 hours after R's impact. A large dark patch from the
impact of fragment H is visible rising on the morning (left) side.
Proceding to the right, other dark spots were caused by impacts of
fragments Q1, R, D and G (now one large spot), and L, with L covering
the
largest area of any seen thus far. Small dark spots from B, N, and Q2
are
visible with careful inspection of the image. The spots are very dark in
the ultraviolet because a large quantity of dust is being deposited high
in Jupiter's stratosphere, and the dust abosrbs sunlight. Scientists
will
be able to track winds in the stratosphere by watching the evolution of
these spots.

Credit: Hubble Space Telescope Comet Team

ftp://ftp.seds.org/pub/astro/SL9/ima.../ALL/LCP_B.gif
Io Spectrum During Fragment B Impact

Description from Rabinowitz and Butner:

This image shows the spectrum of Io versus time during the impact of
fragment B. The data are those reported by Harold Butner and I on July
17.
The image represents wavelength on the x axis (the range is 0.4 to 0.6
microns), time on the y axis (02:47:31 to 03:07:02 UT 1994 July 17 UT)
and
intensity on the z axis (blue, red, yellow and white are increasing
intensity values). The signal clearly shows an increase in relative
intensity from 0.5 to 0.6 microns near the time of the B impact, and a
subsequent decrease in the intensity a few minutes later.

We obtained these observations with the 2.5m Dupont Telescope at Las
Campanas using a coronograph/spectrograph built by Steve Larson of the
University of Arizona.

D. Rabinowitz
H. Butner Las Campanas
1994 July 21

Can it be that you are a phuckwit?
Androcles.

Alfred A. Aburto Jr. wrote:
The universe cannot be a black hole because it is expanding, and the
expansion rate appears to be accelerating!

But isn't one of the principles of superstring theory that through
mirror symettry, you can't tell the difference between a universe
that's getting increasingly bigger from one that has shrunk down to
less than a Planck length?

Yousuf Khan

"Androcles" Androcles@ MyPlace.org wrote:
"Tim Auton" wrote in message
.. .
| "Androcles" Androcles@ MyPlace.org wrote:
[snip]
| Sheesh.... and what happens if two quite ordinary stars, never mind
the
| black holes, collide? I'd call that a supernova [...]
|
| Why would you call that a supernova? Are you saying you have evidence
| that supernovae are caused by stellar collisions?

Why do you snip when I've presented the evidence of a collision and
the resultant light burst right in our own backyard?

You posted a link to this image of M31:

http://antwrp.gsfc.nasa.gov/apod/ap950724.html

With this comment:

"Which two stars did you ask? The two on the right, near the middle.
See then moving toward each other?"

That's all the evidence I can see that you've posted in this thread.
It's not convincing. Perhaps I've missed some posts.


Tim
--
You are being watched. This gives you power.