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James Blodgett
Jul16-04, 09:19 AM
<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no,location=no,scrollbars=yes,resizable=yes,status=no,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>\nFrank Hellmann and Alan Lewis have made useful assertions. It is =\npossible that a mini black hole could be so dormant that it could sit at =\nthe center of earth for the next few billion years and not cause =\ntrouble. I would like to see a convincing model that demonstrates this. =\nBut it is a problem to model this object convincingly. It has strange =\nproperties. Such a model could also be theoretically rewarding. A mini =\nblack hole is a quantum gravitational object; a convincing model might =\nlead to a quantum theory of gravity.\n\nThe key is accretion. This is difficult to model. Greg Landsberg modeled =\naccretion by calculating the volume "swept out" by the black hole. The =\nblack hole would slow down as it accretes mass, and the volume swept out =\nwould decrease asymptotically to zero, at which point given this model =\nthe black hole accretes no mass at all. This suggests that it will be =\ndormant.\n\nBut other things are going on. Presumably the black hole ends up more or =\nless stationary at the center of the earth. It may be stationary, but =\nsurrounding matter is moving with heat energy. Also, when the black =\nhole moves into electron orbitals, they are moving at light speed. When =\nit moves into an atomic nucleus, nuclear components are also moving with =\nrelativistic velocity. For\nvolume swept out calculations, we need to calculate volume relative to =\nthese movements. We are assuming multiple dimensions, so we need to =\ncalculate hyper volume in multiple dimensions of radii which could vary =\nfrom very small to the limit set by current observations of an inverse =\nsquare law for gravity, which I think is in the range of a few =\nmillimeters.\n\nVolume swept out arguments assume that the black hole hits something, or =\nis hit by something, directly, so gravity is not yet an issue. (That is, =\nit hits something from a quantum point of view--the probability of =\naccretion is the quantum probability of a particle being in that =\nvolume.) Angular momentum is also not yet an issue. But they need to be =\nincluded. In a Newtonian system, angular momentum would make everything =\nnot aimed directly at a body move in a hyperbolic orbit, and be gone. =\nHowever there is an area around a black hole, outside of the =\nSchwarzschild radius, where centrifugal force does not work. This is =\nbecause space is bent so much that, from the point of view of a particle =\nin that area, a circle around the black hole is a straight line. There =\nwas an article in Scientific American about this a few years back. I =\nthink the result is only to increase the effective capture cross section =\na bit beyond the Schwarzschild, but this effect needs to be included.=20\n\nThere are other effects that need to be included. The string theories =\nthat permit mini black hole formation are attempts to unify forces. They =\ninvolve multiple dimensions, with gravity as strong as other forces at =\nthe center. These need to be included.\nAlso accretion involves quantum gravity. What happens to a particle =\nprobability wave when a mini black hole moves into it? Is the =\nprobability of capture as simple as volume swept out? Or does a field of =\ninfinite gravity stretch the probability wave in some way?\n\nEven given a model, we need to demonstrate that nature actually works =\nthat way.\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form">&nbsp;&nbsp;View this Usenet post in original ASCII form </a></div><P></jabberwocky>Frank Hellmann and Alan Lewis have made useful assertions. It is =
possible that a mini black hole could be so dormant that it could sit at =
the center of earth for the next few billion years and not cause =
trouble. I would like to see a convincing model that demonstrates this. =
But it is a problem to model this object convincingly. It has strange =
properties. Such a model could also be theoretically rewarding. A mini =
black hole is a quantum gravitational object; a convincing model might =
lead to a quantum theory of gravity.

The key is accretion. This is difficult to model. Greg Landsberg modeled =
accretion by calculating the volume "swept out" by the black hole. The =
black hole would slow down as it accretes mass, and the volume swept out =
would decrease asymptotically to zero, at which point given this model =
the black hole accretes no mass at all. This suggests that it will be =
dormant.

But other things are going on. Presumably the black hole ends up more or =
less stationary at the center of the earth. It may be stationary, but =
surrounding matter is moving with heat energy. Also, when the black =
hole moves into electron orbitals, they are moving at light speed. When =
it moves into an atomic nucleus, nuclear components are also moving with =
relativistic velocity. For
volume swept out calculations, we need to calculate volume relative to =
these movements. We are assuming multiple dimensions, so we need to =
calculate hyper volume in multiple dimensions of radii which could vary =
from very small to the limit set by current observations of an inverse =
square law for gravity, which I think is in the range of a few =
millimeters.

Volume swept out arguments assume that the black hole hits something, or =
is hit by something, directly, so gravity is not yet an issue. (That is, =
it hits something from a quantum point of view--the probability of =
accretion is the quantum probability of a particle being in that =
volume.) Angular momentum is also not yet an issue. But they need to be =
included. In a Newtonian system, angular momentum would make everything =
not aimed directly at a body move in a hyperbolic orbit, and be gone. =
However there is an area around a black hole, outside of the =
Schwarzschild radius, where centrifugal force does not work. This is =
because space is bent so much that, from the point of view of a particle =
in that area, a circle around the black hole is a straight line. There =
was an article in Scientific American about this a few years back. I =
think the result is only to increase the effective capture cross section =
a bit beyond the Schwarzschild, but this effect needs to be included.=20

There are other effects that need to be included. The string theories =
that permit mini black hole formation are attempts to unify forces. They =
involve multiple dimensions, with gravity as strong as other forces at =
the center. These need to be included.
Also accretion involves quantum gravity. What happens to a particle =
probability wave when a mini black hole moves into it? Is the =
probability of capture as simple as volume swept out? Or does a field of =
infinite gravity stretch the probability wave in some way?

Even given a model, we need to demonstrate that nature actually works =
that way.

Alan
Jul19-04, 04:09 AM
<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no,location=no,scrollbars=yes,resizable=yes,status=no,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>\n\n\n"James Blodgett" &lt;bjames1@nycap.rr.com&gt; wrote in message\nnews:001201c46b1f\\$e7322d40\\$471dc318@nycap.rr.com...\n&gt;\n&gt; Frank Hellmann and Alan Lewis have made useful assertions. It is =\n&gt; possible that a mini black hole could be so dormant that it could sit at =\n&gt; the center of earth for the next few billion years and not cause =\n&gt; trouble. I would like to see a convincing model that demonstrates this. =\n&gt; But it is a problem to model this object convincingly. It has strange =\n&gt; properties. Such a model could also be theoretically rewarding. A mini =\n&gt; black hole is a quantum gravitational object; a convincing model might =\n&gt; lead to a quantum theory of gravity.\n\nWhat did you think of Frank Hellmann\'s calculation, (recently) posted above\nthat suggests it takes \'forever\' to accrete anything significant?\n\nIf mini-Black holes are easily produced in colliders, don\'t radiate, and\nhave\nsuch benign accretion behavior, then intuitively they make great\ndark matter candidates. Primordial black holes are an old\ndark matter, but perhaps someone can give us another\n"back of the envelope" estimate to the following question.\n\nNamely, suppose a mini-Black Hole has a significant chance of being\nproduced in a 1 Tev collision, and survives from that point to infinity\n(let\'s say without accreting anything) -- then,\nwhat percentage of today\'s universe\'s mass would consist of such objects\nproduced early after the big bang?\n\nThere was an nice interesting review related to this in astro-ph/0407207,\nwhich assumed the Hawking radiation scenario, however.\n\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form">&nbsp;&nbsp;View this Usenet post in original ASCII form </a></div><P></jabberwocky>"James Blodgett" <bjames1@nycap.rr.com> wrote in message
news:001201c46b1f$e7322d40$471dc318@nycap.rr.com...
>
> Frank Hellmann and Alan Lewis have made useful assertions. It is =
> possible that a mini black hole could be so dormant that it could sit at =
> the center of earth for the next few billion years and not cause =
> trouble. I would like to see a convincing model that demonstrates this. =
> But it is a problem to model this object convincingly. It has strange =
> properties. Such a model could also be theoretically rewarding. A mini =
> black hole is a quantum gravitational object; a convincing model might =
> lead to a quantum theory of gravity.

What did you think of Frank Hellmann's calculation, (recently) posted above
that suggests it takes 'forever' to accrete anything significant?

If mini-Black holes are easily produced in colliders, don't radiate, and
have
such benign accretion behavior, then intuitively they make great
dark matter candidates. Primordial black holes are an old
dark matter, but perhaps someone can give us another
"back of the envelope" estimate to the following question.

Namely, suppose a mini-Black Hole has a significant chance of being
produced in a 1 Tev collision, and survives from that point to infinity
(let's say without accreting anything) -- then,
what percentage of today's universe's mass would consist of such objects
produced early after the big bang?

There was an nice interesting review related to this in http://www.arxiv.org/abs/astro-ph/0407207,
which assumed the Hawking radiation scenario, however.