MadSci Network: Physics

Re: Could we ever detect a mountain sized mini black hole?

Date: Mon Aug 7 07:55:31 2006
Posted By: Jim Guinn, Staff, Science, Georgia Perimeter College
Area of science: Physics
ID: 1150754563.Ph

“Could we ever detect a mountain sized mini black hole in our solar system 
(if they exist)? Will we ever be able to do it? Could we ever detect a 
large 1 Ton Strangelet in the solar system?”

Dear Yevgeniy,

These are some great questions!  

First, the size of a black hole, the radius of its event horizon that is, 
depends on its mass.  If we take a mountain-sized black hole to have an 
event horizon with a radius of about 5km, then we can use the 
Schwarzschild radius equation to determine what the mass of the black hole 
is.  The radius in terms of the mass is

R = 2 G M / c^2

where G is Newton’s Gravitational Constant and c is the speed of light.  
Putting M in terms of R we have

M = R c^2 / 2G = (5x10^3m) (3x10^8m/s)^2 / 2(6.67x10^-11 N m^2/kg^2) ,

or M = 3.37x10^30kg .

This is about 1.69x the mass of the Sun!  This is actually a rather large 
mass!  If a body this massive was floating around our solar system, all of 
the planets (and the sun) would have their orbits drastically affected and 
there would be no way that we could miss it.

Whether we could detect a smaller black hole would depend on just how 
small it is, and where it is.  The closer the black hole is to another 
body, the easier it would be to notice irregularities in the body’s 
motion, and so predict the location the black hole.

Another thing that a black hole would do is to bend light around it.  If a 
black hole passed between us and another object, a star or planet for 
instance, the light from that object would be distorted by the presence of 
the black hole.  If that object was being observed at the time, this 
distortion could be detected.

If the black hole passed close enough to another body to actually draw the 
body, or some of it, into the black hole, the energy released by the in-
falling material would be another way to detect the black hole.

A strangelet, a theorized particle of strange matter, with a mass of one 
ton, would be very small, only about 10-20 microns in size.  If it didn’t 
collide with anything, the best way to detect it would be to notice the 
gravitational affects that it might have on a near-by object.  With a mass 
of one ton, it would have to be fairly close to the other body, though, to 
detect its presence.  Some people have postulated that some anomalous 
Earthquakes were actually caused by the Earth being struck by a 
relativistic strangelet, so we may have already detected them in our solar 

Below are a couple of links that you might look at.  They have some more 
information about strange matter and strangelets that you might find 

Well, Yevgeniy, I hope I have answered your questions to your 
satisfaction.  Please let us know if you would like some more information,
with a followon question at the usual MadSci Question Page.


Jim Guinn
Georgia Perimeter College

Current Queue | Current Queue for Physics | Physics archives

Try the links in the MadSci Library for more information on Physics.

MadSci Home | Information | Search | Random Knowledge Generator | MadSci Archives | Mad Library | MAD Labs | MAD FAQs | Ask a ? | Join Us! | Help Support MadSci

MadSci Network,
© 1995-2006. All rights reserved.