When a black hole has evaporated > critical mass

[six_strings]

What happens when, through Hawking Radiation, a black hole has evaporated to a mass below that which was critical to form it?<br /><br />Will it become something like a neutron star?<br /><br />Does it become violently unstable and explode, like a super-nova? <br /><br />Or is it an issue of density? Even once it has passed critical phase (in regards to mass) its density won't release its grip on space-time till it's completely evaporated?<br /><br />Sorry if it’s a dense question, or already been asked…<br /><br />Oh, and to add yet another question to the tally of black hole questions ;-) <br /> <div class="Discussion_UserSignature"> </div>

 

[six_strings]

I'm thinking we would observe (if we could) the event horizons diameter just get smaller an smaller till its just gone? <div class="Discussion_UserSignature"> </div>

 

[alokmohan]

What you mean by critical mass?Less than 3 solar masses?

 

[yevaud]

^what he said^<br /><br />And once this occurs, the singularity detaches from our space time, which is to say it vanishes, never to be seen again. <div class="Discussion_UserSignature"> <p><em>Differential Diagnosis:  </em>"<strong><em>I am both amused and annoyed that you think I should be less stubborn than you are</em></strong>."<br /> </p> </div>

 

[six_strings]

alokmohan; Yes<br /><br />eburacum45, Yevaud,<br />So the singularity would be emitting light at this phase?? (confused) Or the hawking radiation is glowing? <div class="Discussion_UserSignature"> </div>

 

[yevaud]

It would, as previously described, suddenly emit most of it's stored energy, and then detach. Might as well chum up with a Fusion bomb for the effect. A very large explosive event indeed. <div class="Discussion_UserSignature"> <p><em>Differential Diagnosis:  </em>"<strong><em>I am both amused and annoyed that you think I should be less stubborn than you are</em></strong>."<br /> </p> </div>

 

[alokmohan]

Black hole evaporation is only a theoritical conception.I have never seen it being described glowing.According to certain principles of quantum mechanics, the probability of any event occurring is always greater than zero. One of the stranger consequences of this idea is that what we think of as 'empty' space isn't really empty at all; it's filled with 'virtual particles', bits of matter and energy that are almost, but not quite, real. Despite being unreal, virtual particles play a vital role in the descriptions of how the universe works on the quantum scale; they're necessary to explain how photons and electrons interact, for example.<br /><br />Under normal conditions, virtual particles rarely have any noticeable effects. In certain unusual environments, such as the intense gravitational fields generated by black holes, they can 'borrow' energy from their surroundings and temporarily become real. When virtual particles manifest themselves, they must always do so in pairs of particles and anti-particles, which cancel each other out and release their energy back into the void. However, it is possible for the particles to materialise just on the edge of the event horizon, the boundary that separates the 'inside' and the 'outside' of the black hole. When this occurs, one particle is sometimes consumed by the black hole while the other escapes. The escaping particle carries away a tiny fragment of the black hole's mass, the extra energy that allowed it to become real. Over long periods of time, the black hole will eventually evaporate, losing all of its energy to escaping particles. These particles are the Hawking radiation.<br /><br />An unusual aspect of Hawking radiation is that it may be a proof of the 'arrow of time'. According to classical physics, the universe is time-reversible; anything that happens in the universe could just as easily happen 'backwards' as 'forwards'. For instance, it's possible in theory to reconstruct the content of a burnt newspaper by examini

 

[nexium]

Most everthing about black holes ranges from slightly speculative to very speculative, so there is a very slight probability that alokmohan and BBC is exactly correct. It is thought that the black hole does not revert suddenly to ordinary matter (or radiation) until it has much less than 1% of a solar mass remaining. We have not found any blackholes with less than about one solar mass, but there may be millions of them crusing our galaxy.<br />In theory a black hole with 1% of a solar mass is evaporating much faster than the bigger blackholes, but still has thousands, if not millions of years left before the final spirt of evaporation. Part of the reason is the intense gravity eventually recaptures many of the virtual particles which escape the event horizon, plus most blackholes capture at least an occassional bit of matter and thus are becoming more massive inspite of a small amount of Hawking radiation mass loss. Neil

 

[derekmcd]

I think we have a better chance of witnessing the evolution of a black dwarf, than we do witnessing a 'natural' black hole evaporating into non-existence. We can hypothesize mathematically endlessly, but the timescales to actually witness the processes are beyond anything we can currently realize. <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>

 

[dragon04]

<font color="yellow">It would, as previously described, suddenly emit most of it's stored energy, and then detach. Might as well chum up with a Fusion bomb for the effect. A very large explosive event indeed.</font><br /><br />Would this perhaps explain some of the prodigious GRB events we've observed?<br /><br />I'm not a physicist, so I don't have the training or the math to figure it out on my own, but I've always had a problem with this "evaporation" thing.<br /><br />Evaporation describes a <b>gradual</b> process regardless of time scale.<br /><br />I hope you indulge me in what I'm about to say while understanding that I'm not a trained physicist, and humor me with a response because while I'm clearly in deep water here, I'm trying to learn from you guys.<br /><br />We know that a black hole forms very rapidly. We know that there is a specific "window" of mass required for one to form.<br /><br /><b>IF</b> a black hole "evaporates", it does so on an infinitely longer time scale than the implosion event that creates it.<br /><br />Further, we know (or theorize?) that at less than "critical mass", we get a Neutron star.<br /><br />So if a black hole is "evaporating" at a specific rate over time rather than in a time frame equal to the event that caused it, why wouldn't a BH simply lose enough mass to convert to a Neutron star?<br /><br />If the evaporation theory is correct, it would seem intuitive to me that there would be no titanic explosion and that we'd simply see Neutron stars where there were none previously.<br /><br />I'm assuming that "evaporation" would be a misnomer? But if it is, and as old as the Universe is, shouldn't we have seen at least a few prodigious explosions that defy conventional explanation by now?<br /><br />Inquiring minds want to know. <img src="/images/icons/wink.gif" /> <div class="Discussion_UserSignature"> <em>"2012.. Year of the Dragon!! Get on the Dragon Wagon!".</em> </div>