min black holes.....

[Kokatha man]

NASA's latest report is of a "mini black hole" with less than a quarter the mass of our sun, and "about the size of a large city."

J1650 is "really pushing the limits" according to spokesperson Nikolai Shaposhnikov: perhaps IIS members' reports of "micro black holes" in their offsprings' bedrooms are now more credible?!?

[Trido (Justin)]

A bit more info can be found here: http://www.news.com.au/story/0,23599...-23109,00.html

[CoombellKid]

"mini black hole" nah nah nah the silly buggers have been pointing that
telescope at my ex again. At least they gave her a better name than
I do.

regards,CS

[Trido (Justin)]

lawl Ouch.

[Quark (Trevor)]

Hi All,
The subject of black holes in general and micro black holes is an interesting one.

Adding to this discussion I thought I might define some interesting properties of black holes. Taking the example of a theroretical non-rotating black hole.

German physicist Karl Schwarzschild was the first to determine the distance from the centre of a non-rotating black hole to it's event horizon. This distance is known as the "Schwarzchild Radius" and depends only on the mass of the black hole.

The Schwarzchild Radius can be calculated as follows.

R Sch = 2GM / C squared

G = The Universal Gravitational Constant 6.67 x 10 to the power of -11
M = The mass of the object expressed in kg
C squared = A constant. The speed of light expressed in m/sec 3 x 10 to the power of 8

The result of this equation will give R Sch in metres.

EG: The mass of the Sun is 1.99 x 10 to the power of 30 kg
Therefore calculating the radius to which the Sun would have to collapse to creat a black hole. From the above equation.

R Sch for the Sun = 2949.6 m about 3km

Taking this to the extreme, the mass of a proton, a hydrogen nuclei is
1.67 x 10 to the power of -27 kg
If the mass of a hydrogen nuclei is applied to this equation we can calculate the R Sch it would have to collapse to to create a trully micro balck hole.

R Sch for a proton = 2.47 x 10 to the power of -54 metres.

Another vital point to remember, when considering the R Sch of a black hole.
The radius is the distance from the centre to the event horizon and as black holes have high mass, they distort spacetime.

Due to this distortion (think of it as a well) the distance from the centre back up to the event horizon will be greater than the actual diameter of the event horizon.

Wouldnt it be great to be able to park a micro black hole in the back yard to swallow up all of our excess rubbish, certianly would cut back on trips to the local dump.

Regards
Quark

[Terry B]

Originally Posted by Quark

Wouldnt it be great to be able to park a micro black hole in the back yard to swallow up all of our excess rubbish, certianly would cut back on trips to the local dump.

Regards
Quark

The black hole in the backyard would be very good but when looking at it from the outside time slows to a stop as items get closer to the black hole and are never seen to enter. This would be a problem with the garbage. You would throw it at your garbage eating blackhole in the back yard and the garbage would get closer and closer to it but never disappear. WHAT A MESS!
I think I will keep going to the tip.

[Jazza (Jay)]

That and it would eat the Earth...

[Ian Robinson]

Originally Posted by Kokatha man

NASA's latest report is of a "mini black hole" with less than a quarter the mass of our sun, and "about the size of a large city."

J1650 is "really pushing the limits" according to spokesperson Nikolai Shaposhnikov: perhaps IIS members' reports of "micro black holes" in their offsprings' bedrooms are now more credible?!?

If a star with less than 1/4 the sun's mass can become a blackhole , then something is seriously wrong with our understanding of the mechanisms required for solar mass and subsolar mass blackholes to form.

Gravitationally , I thought , based on my readings over the years that the star of "simlar" mass as the sun could not become a blackhole , a neutron star maybe. Radiation pressure and subnuclear forces become important in counteracting the formation of a blackhole.

Perhaps mini (-subsolar mass) blackholes are fossil blackholes (that once were much more massive) left over from universe before our's ?

[Paddy (Patrick)]

Originally Posted by Ian Robinson

If a star with less than 1/4 the sun's mass can become a blackhole , then something is seriously wrong with our understanding of the mechanisms required for solar mass and subsolar mass blackholes to form.

Gravitationally , I thought , based on my readings over the years that the star of "simlar" mass as the sun could not become a blackhole , a neutron star maybe. Radiation pressure and subnuclear forces become important in counteracting the formation of a blackhole.

Perhaps mini (-subsolar mass) blackholes are fossil blackholes (that once were much more massive) left over from universe before our's ?

Is it the case that a black hole weighs less than the star from which it formed as much of the star is converted to energy before and during the collapse? Could this mean that a star larger than our sun becomes a black hole with comparable or less mass? Or would that be just too much mass released as energy?

[Ian Robinson]

Originally Posted by Paddy

Is it the case that a black hole weighs less than the star from which it formed as much of the star is converted to energy before and during the collapse? Could this mean that a star larger than our sun becomes a black hole with comparable or less mass? Or would that be just too much mass released as energy?

Even supernovae only jettison only a minute part of the star's mass during the supernova explosion. Most the mass remains.

[renormalised (Carl)]

I'll say it's pushing the limits.....considering that, normally, a massive object has to exceed ~3Ms to form a black hole, the only way one around 1/4Ms could form is either as a primordial one during the Big Bang or from explosive compression of a body of that size (during a supernova or similar explosion), but that seems unlikely.