Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: syhprum on 17/11/2010 13:13:14
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There is ample evidence that stellar mass and super large blackholes exist but is there any evidence that small ones exist ?, the universe is not old enough or cool enough for stellar mass ones to have lost any of their mass so the only way small ones could exist is if they were created at the time of the 'bigbang'.
Have any been detected ?.
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I believe that they have been looked for but have not yet been detected. The problem is that an evaporating black hole in its last few years is not very powerful when you consider the radiation produced by a typical star like the sun so it must be quite close before it would be detected.
From http://xaonon.dyndns.org/hawking/
A black hole at the start of the last year of its life weighs around 72,000 metric tons
and has a luminosity of 1.7 e -10 of the sun most of which would be in energetic particles like cosmic rays. If this energy was in the form of light it might be just be detectable at a distance of around 1 light year
remember the sun converts about 4 million tons of mass into energy per second to keep up its current luminosity
It is a avery far cry from a big bang like a supernova
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Great question! I think Soul Surfer answered it pretty well, but in Googling around for it, these tiny black holes are generally referred to as primordial black holes, i.e. those stemming not from the collapse of stars, but rather from the hot, dense matter that existed shortly after the big bang. Just to add a little to the question, for a star to collapse into a black hole requires that it have about 22 times the mass of our sun. These primordial black holes, as you note, could be much smaller.
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Hopefully, some may find this of interest:- http://en.wikipedia.org/wiki/Black_hole_electron (http://en.wikipedia.org/wiki/Black_hole_electron) [:I]