Can Black Holes Really Die and What Are Their Secrets?

[Quds Akbar]

1. A black hole is not a point of infinite density. That's the singularity.
4. Black holes have a non-zero volume.
5. You do not gain mass as your velocity increases.

A black hole is formed by a singularity, the singularity is a point of infinite space time curvature, at the center of a black hole is a singularity, so if you are close enough you would approach the center you would be approaching the singularity. There is no black hole with no singularity. Also, black holes do have non-zero volumes yes, but isn't a black hole essentially a space time singularity? I also never said velocity, our mass increases with the more energy you posses, at 10% the speed of light, your mass will only be 0.5% more, at 90% the speed of light it would be more than twice the original mass.
"The energy which an object has due to its motion will add to its mass" - Stephen Hawking, A Brief History of Time

 

[Drakkith]

A black hole is formed by a singularity

No, it is not. A black hole is formed by the matter of a collapsing star.

There is no black hole with no singularity

From here: http://en.wikipedia.org/wiki/Black_hole#Singularity

The appearance of singularities in general relativity is commonly perceived as signaling the breakdown of the theory.[63] This breakdown, however, is expected; it occurs in a situation where quantum effects should describe these actions, due to the extremely high density and therefore particle interactions. To date, it has not been possible to combine quantum and gravitational effects into a single theory, although there exist attempts to formulate such a theory of quantum gravity. It is generally expected that such a theory will not feature any singularities.

As you can see, it is expected that singularities do not really exist, that they are an artifact of an incomplete theory.

Also, black holes do have non-zero volumes yes, but isn't a black hole essentially a space time singularity?

Nope.

I also never said velocity, our mass increases with the more energy you posses, at 10% the speed of light, your mass will only be 0.5% more, at 90% the speed of light it would be more than twice the original mass.

Yes, you're talking about velocity, and no, our mass does not increase, despite what Stephen Hawking says. This is because Hawking is using 'Relativistic Mass' which is not, as far as I know, standard terminology. Mass is usually used to describe what is known as 'Rest Mass' or 'Invariant Mass'. Consider that an observer moving at 0.9c relative to the Earth does not experience twice the gravity in their own frame of reference, as would be the case if their rest mass increased.

 

[Monsterboy]

Cores of very massive stars collapse when iron starts forming right ? In the discovery channel they said the core can collapse just seconds after the iron starts forming , if the core collapses so fast how did the Iron get out of the core and become available to us ?

 

[Monsterboy]

How do you answer to a lay person when he/she asks a question like this ..." If nothing can escape a black hole, not even light , how does hawking radiation escape from the black hole and eventually kill it ?".

 

[Drakkith]

Cores of very massive stars collapse when iron starts forming right ? In the discovery channel they said the core can collapse just seconds after the iron starts forming , if the core collapses so fast how did the Iron get out of the core and become available to us ?

Iron is produced both in the core of massive stars as well as in supernovas themselves.

https://en.wikipedia.org/wiki/Nucleosynthesis

Supernova nucleosynthesis within exploding stars by fusing carbon and oxygen is responsible for the abundances of elements between magnesium (atomic number 12) and nickel (atomic number 28).[1] Supernova nucleosynthesis is also thought to be responsible for the creation of rarer elements heavier than iron and nickel, in the last few seconds of a type II supernova event. The synthesis of these heavier elements absorbs energy (endothermic) as they are created, from the energy produced during the supernova explosion. Some of those elements are created from the absorption of multiple neutrons (the R process) in the period of a few seconds during the explosion. The elements formed in supernovas include the heaviest elements known, such as the long-lived elements uranium and thorium.

 

[Drakkith]

How do you answer to a lay person when he/she asks a question like this ..." If nothing can escape a black hole, not even light , how does hawking radiation escape from the black hole and eventually kill it ?".

Hawking radiation is created and emitted from outside the event horizon, so it isn't captured by the black hole.

 

[Monsterboy]

Hawking radiation is created and emitted from outside the event horizon, so it isn't captured by the black hole.

If that's the case how come the black hole loses it mass and evaporates away ?

 

[Drakkith]

If that's the case how come the black hole loses it mass and evaporates away ?

That's beyond my ability to explain. Have you read the wiki article?

 

[mfb]

Physics cannot answer "how"-questions on a fundamental level. You can calculate it with quantum field theory, but I don't think some pages of calculation are a proper answer of "how".

 

[rootone]

If that's the case how come the black hole loses it mass and evaporates away ?

In simple terms without going into virtual particles and etc...
The Hawking radiation is emitted from very slightly outside of the event horizon and is thus is able to escape.
Since mass and energy are equivalent, the lost energy is equivalent to lost mass.

 

[Monsterboy]

In simple terms without going into virtual particles and etc...
The Hawking radiation is emitted from very slightly outside of the event horizon and is thus is able to escape.
Since mass and energy are equivalent, the lost energy is equivalent to lost mass.

Drakkith said the same thing, the mass of a black hole is the mass and/or energy that has entered the singularity or atleast entered the event horizon right ? So, for it to lose mass something will have come out of the event horizon and/or the singularity that is impossible right ? That goes against the definition of event horizon right ? Without using virtual particles and negative energy things etc (which I don't really understand), it's not possible to explain right ? like mfb said physics doesn't answer "how" questions on a fundamental level or maybe its more appropriate to say that our current understanding of physics cannot answer some "how" questions.

 

[rootone]

It took somebody of the calibre of Stephen Hawkins to deduce from quantum math how it is that these virtual particle (pairs) could pop into existence and some of them end up becoming real particles emitted as radiation.
It took quite a while for him to convince others at his own level that this is likely.
Without the complicated math, and I am no math genius anyway, the key point to grasp is that the particles are not particles which have traveled from inside of the horizon to outside.
They literally just appear outside the horizon 'from nowhere', pairs of them having equal and opposite properties.
Yes, quantum mechanics is weird like that.

 

[PeterDonis]

the mass of a black hole is the mass and/or energy that has entered the singularity or atleast entered the event horizon right ?

Not quite. To an observer 'hovering" anywhere outside the horizon, the "mass" of the hole is whatever mass is at a smaller radial coordinate than he is. So if matter falls into the hole, you, as an observer "hovering" outside the horizon, will measure the hole's mass to be larger as soon as the falling matter passes you.

for it to lose mass something will have come out of the event horizon and/or the singularity

No. See below.

Without using virtual particles and negative energy things etc (which I don't really understand), it's not possible to explain right ?

Not really, but the quantum explanation of Hawking radiation does violate key assumptions of the theorem (due to Hawking, btw) that says a classical black hole can't lose mass and a classical event horizon can't decrease in area. That theorem requires that certain conditions called "energy conditions" are assumed to hold. The quantum fields that produce Hawking radiation violate the energy conditions, so the theorem no longer applies and it is possible for Hawking radiation to cause a black hole to lose mass and its event horizon to decrease in area. This is a quantum effect and it doesn't involve anything classical "coming out" of the horizon.

Violating the energy conditions does not require "virtual particles and negative energy things" (those are just interpretations of the quantum physics involved, and other interpretations are possible), but it does create some counterintuitive possibilities--though no more counterintuitive, IMO, than anything else in QM.

 

[mfb]

like mfb said physics doesn't answer "how" questions on a fundamental level or maybe its more appropriate to say that our current understanding of physics cannot answer some "how" questions.

It is not just a limit of our current understanding, it is a fundamental limit. You can replace theories by theories that are more fundamental, unify more effects, require fewer free parameters and so on, but they will always stay theories.

 

[Monsterboy]

It is not just a limit of our current understanding, it is a fundamental limit. You can replace theories by theories that are more fundamental, unify more effects, require fewer free parameters and so on, but they will always stay theories.

Is that because we have not been able to test these theories with a real black hole ? If we manage to create micro black holes in LHC then will those fundamental "how" questions be answered ?

 

[Chronos]

Even if [a very big if] the LHC could produce a micro black hole, it is believed they would instantaneously evaporate. Any testing would be like trying to play ping pong in a hurricane

 

[mfb]

Is that because we have not able to test these theories with a real black hole ? If we manage to create micro black holes in LHC then will those fundamental "how" questions be answered ?

It is a general limit of physics everywhere. You cannot describe "how" things are attracted by Earth on a fundamental level, for example. You can say "spacetime curvature!" but then the follow-up question is "how does mass bend spacetime?" and you are back to the same type of question.