Amateur question

The people in this discussion group are obviously very smart so I would
like to ask a question I can never get a straight answer for. Is there a
limit to the size/power a Black Hole can be? It's just a point of
curiosity to me.

Dear belkna...:

On Dec 1, 2:46*pm, (steve mememe) wrote:
The people in this discussion group are *obviously very
smart so I would like to ask a question I can never get
a straight answer for. Is there a limit to the size/power
a Black Hole can be? It's just a point of curiosity to me.

The limitation of the size of a single black hole is probably some
function of the total mass of the Universe, say "1/10th" as a
theoretically unsupported wild guess. So it would be possible to
place the entire mass of the Virgo supercluster (of which the Milky
Way galaxy is a part) into a single black hole.

It would have a pretty large event horizon (2*10^46 kg yields a
Schwarzchild radius of about 3000 light years), and would behave
gravitationally like the Virgo supercluster at sufficient distance.

As to "power", if you fall from "infinity", at the event horizon, you
will be travelling exceptionally close to c... just like with any
black hole.

David A. Smith

steve mememe wrote:
The people in this discussion group are obviously very smart so I would
like to ask a question I can never get a straight answer for. Is there a
limit to the size/power a Black Hole can be? It's just a point of
curiosity to me.

Yes there is a limit. It is the entire universe. It can't be any bigger than
that or contain more matter than that. If you mean the other direction, ask the
physics people if any of their string things are heavy enough that they are
smaller than the radius of a hole. IIRC quarks are bigger so they aren't but I
don't know about the string things.

"steve mememe" wrote in message
...
The people in this discussion group are obviously very smart so I would
like to ask a question I can never get a straight answer for. Is there a
limit to the size/power a Black Hole can be? It's just a point of
curiosity to me.

Black holes, like bright green flying elephants, are a figment of someone's
wild imagination. As such they can have any properties the dreamer wants
them to have. Should you ever find a black hole please look inside for
bright green flying elephant's eggs. Even some broken eggshell would
go a long way in confirming my theory that the bright green flying elephant
uses black holes to nest in. It's just a point of curiosity to me.

"steve mememe" wrote in message
...
The people in this discussion group are obviously very smart so I would
like to ask a question I can never get a straight answer for. Is there a
limit to the size/power a Black Hole can be? It's just a point of
curiosity to me.

I'm interested in what you mean by the 'power' of a black hole. At anything
other than close distances a black hole has exactly the same gravitational
effect as any other object, so if the Sun was somehow converted into a black
hole, the rest of the solar system would continue to orbit it in exactly the
same way. The black hole doesn't 'suck matter into it' any more than the sun
'sucks the planets into it' now.


Despite what another contributor to this thread has suggested, there is good
evidence for Black Holes.
For example, part of the evidence for a supermassive Black Hole at the
centre of the galaxy is the observed movement under gravity of a star with
an orbit radius of about 120 AU (appx 10 times that of Saturn) and period of
about 15 years (about 1/2 that of Saturn). This implies a central mass
equivalent to 3-4 million Suns at the centre of the galaxy.

In article ,
(steve mememe) writes:
Is there a limit to the size/power a Black Hole can be?

There's no theoretical limit on black hole mass (unless you consider
"all the matter in the Universe" to be a limit). The largest black
holes known in our actual Universe have masses of a few billion suns.

I'm not sure what you mean by the "power" of a black hole. Are you
thinking of the Eddington limit?

--
Steve Willner Phone 617-495-7123
Cambridge, MA 02138 USA
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