[MikeS (OP)]

According to the big bang theory (more or less) the our Universe started off as a singularity from which originated all the energy(/mass) that is and is contained within the Universe.

If energy (as well as mass) creates gravity then what is the difference between the above and saying the Universe originated from a black (or white) hole?

If a black hole then what mechanism can cause a black hole to effectively explode (for lack of a better way of phrasing it)?

I know this is bordering on the unknown but it would still be good to get some feedback.

[Bill S]

I imagine a lot would depend on what, if anything, preceded the Big Bang.  Presumably, in order to be a black hole it would have to exist in something.  We would then have to ask what that something might have been.

[MikeS (OP)]

Bill S
True and I have amended the question accordingly.

[Bill S]

All we need now is an answer. 

[MikeS (OP)]

That would be nice.  Anyone?

[Soul Surfer]

It would probably have to be another universe similar to ours and so on.  At the moment we do not know what goes on behind the event horizon of a black hole and are not confident enough of our knowledge of physics to try to predict it but it will probably end up as some sort of violent explosion of time and space and not a cold mathematical singularity.  The exploding black hole would of course always be behind its own event horizon because whatever it did it could not possibly explode through it. We are also reasonably confident what black holes do toward the end of their lives.  That is as long as they are in very cold empty space they evaporate extremely slowly and finally go out with a small pop (a very long way from a big bang) that represents the conversion of a few tons of matter into pure energy.

Using the standard black hole reference page  http://xaonon.dyndns.org/hawking/

In its final year an evaporating black hole works through about 70,000 metric tons of mass and radiates it away as particles and energy.  That is less than our sun gets through every second.  In its last second it gets through about 220 metric tons.  The explosion is about one and a half million megatons in nuclear terms but that is absolutely microscopic compared with a supernova in fact it would be difficult to detect an exploding black hole much further away than the nearest star.  This is a very long way away from anything like the big bang.

[Bill S]

The exploding black hole would of course always be behind its own event horizon because whatever it did it could not possibly explode through it.

Where would a naked singularity fit into this picture?

[CliffordK]

There seem to be more theories about Black Holes than actual observations.
There is some evidence that the Black Holes are capable of emitting some highly energetic matter.
http://www.theregister.co.uk/2011/05/23/extragalctic_black_hole_snap/

What we don't know is what would happen to a Black Hole if it contained all the matter and energy of a billion galaxies....  or, for that matter, just a half a dozen large galaxies.

[MikeS (OP)]

Clip
There seem to be more theories about Black Holes than actual observations.
There is some evidence that the Black Holes are capable of emitting some highly energetic matter.
http://www.theregister.co.uk/2011/05/23/extragalctic_black_hole_snap/

It is speculated that if a black hole is fed with 'food' faster than it can 'swallow' it, some is thrown out in the form of energetic jets.  These jets can be as long as the diameter of a galaxy, contain antimatter particles, be seen to be accelerating and travelling at a significant proportion of the speed of light.  This mechanism is poorly understood and seems to be counter intuitive unless the antimatter originates within the event horizon of the black hole.  It then makes perfect sense.

http://www.spacetoday.org/DeepSpace/Galaxies/MilkyWay/Antimatter.html

[imatfaal]

Clifford and Mike - I am not sure there is a mechanism for matter to go beyond EH and then be spurted out - what definitely happens is that the black hole is a very messy eater and a fair percentage of the matter and energy that is sucked towards the black hole ends up being ejected at enormous speed before it reaches the EH.  If you do have links to matter crossing in and back out I would love to read them

[MikeS (OP)]

imatfall

quote from my last post
"unless the antimatter originates within the event horizon of the black hole.  It then makes perfect sense."

I don't have any links but the idea is simply based on that is what would happen if matter and antimatter gravitationally repel each other which is certainly a distinct possibility but as yet unknown/unproven.

[CliffordK]

Interesting about the positron emissions.

Perhaps as part of the condensing matter in the black hole, the black holes must shed positive charges from the protons to prevent +/+ interactions.  Of course, that means both loosing electrons and positrons to maintain a neutral system.

Electrons and Positrons, of course, are heavy compared to photons, but light compared to protons and neutrons.  The exact mechanism and origin of the emissions needs more research. 

[CliffordK]

I don't have any links but the idea is simply based on that is what would happen if matter and antimatter gravitationally repel each other which is certainly a distinct possibility but as yet unknown/unproven.

The above discussion was specifically related to Positrons, so I'll limit my discussion to that particle.

The positrons are relatively easy to make, so I believe they've been extensively studied.

According to Wikipedia, there are specific masses attributed to each of the elementary particles:
Neutron Mass: 1.674927351(74)×10⁻²⁷ kg
Proton Mass:   1.672621777(74)×10⁻²⁷ kg
Positron Mass:9.10938215(45)×10⁻³¹ kg
Electron Mass:9.10938291(40)×10⁻³¹ kg

With a neutron being slightly heavier than a proton, and a positron being a slightly different mass than an electron.

However,
One also has the simple decays:

Neutron minus Electron --> Proton (lighter particle)
Proton minus Positron --> Neutron (heavier particle)

Which I would think takes one in a circle. 

So, is it possible that the positron mass is actually fundamentally different than the electron mass?

[Yuling]

There seem to be more theories about Black Holes than actual observations.

This is true.

In fact, Hawking radiation (an attempt to explain away the information loss paradox) has not been directly observed and as such, has no observational 'proof' to back it up. It only has math to back it up. There are stronger theories out there which are ridiculed because of a lack of observational evidence or because we lack the technology to test (e.g, string theory).

While likely correct, until we observe Hawking radiation, I think people need to stop talking about it as if it's already fact.

Nobody knows what goes on inside a black hole - quantum mechanics and relativity both break down at the singularity so no predictions can be made. Everything everyone says about what happens at the singularity is pure speculation.

[MikeS (OP)]

Clifford

When I talk about antimatter emissions from black holes I am referring to positron emission as you observed.  It is speculated that the intense energy and gravitational forces at work within the event horizon would create electron positron pairs.  If matter and antimatter are gravitationally repulsive then the electron is bound by the intense gravitational field whilst the positron is gravitationally expelled through the event horizon and accelerates away.

[CliffordK]

If matter and antimatter are gravitationally repulsive then the electron is bound by the intense gravitational field whilst the positron is gravitationally expelled through the event horizon and accelerates away.

Which could be a problem because one would quickly develop a large negative charge within the black hole, and a large positive charge in the surrounding space where electrons are annihilated. 

It is apparently possible to make a positron beam, so I would think the reaction of a positron beam to Earth's gravity (vs electron beam control) could be observed in a linear particle accelerator (using it like a large vacuum tube).  The Stanford Linear Accelerator Center is 1.9 miles long, with CERN planning to make a 20 mile linear accelerator in the future if they can justify the $6.7 billion dollar price tag.

[imatfaal]

I don't have any links but the idea is simply based on that is what would happen if matter and antimatter gravitationally repel each other which is certainly a distinct possibility but as yet unknown/unproven.

The above discussion was specifically related to Positrons, so I'll limit my discussion to that particle.

The positrons are relatively easy to make, so I believe they've been extensively studied.

According to Wikipedia, there are specific masses attributed to each of the elementary particles:
Neutron Mass: 1.674927351(74)×10⁻²⁷ kg
Proton Mass:   1.672621777(74)×10⁻²⁷ kg
Positron Mass:9.10938215(45)×10⁻³¹ kg
Electron Mass:9.10938291(40)×10⁻³¹ kg

With a neutron being slightly heavier than a proton, and a positron being a slightly different mass than an electron.

However,
One also has the simple decays:

Neutron minus Electron --> Proton (lighter particle)
Proton minus Positron --> Neutron (heavier particle)

Which I would think takes one in a circle. 

So, is it possible that the positron mass is actually fundamentally different than the electron mass?

Clifford - I am not sure this is quite what you are getting at - but your two "simple decays" are a little misleading.  They seem to be over-simplified versions of and but they are missing neutrinos antineutrinos and and Energy input for .  Natural proton decay - ie without a boost of energy is predicted, but very rare, halflife is 10^32 years and is via pions.

I will put more detail in for the two forms of beta decay when I get my keyboard sorted out (my new linux distro has defaulted my keyboard to a wrong setting and I cannot find the slash and backslash which makes typing latex equations very labourious)

[imatfaal]

There seem to be more theories about Black Holes than actual observations.

This is true.

In fact, Hawking radiation (an attempt to explain away the information loss paradox) has not been directly observed and as such, has no observational 'proof' to back it up. It only has math to back it up. There are stronger theories out there which are ridiculed because of a lack of observational evidence or because we lack the technology to test (e.g, string theory).

While likely correct, until we observe Hawking radiation, I think people need to stop talking about it as if it's already fact.

Nobody knows what goes on inside a black hole - quantum mechanics and relativity both break down at the singularity so no predictions can be made. Everything everyone says about what happens at the singularity is pure speculation.

Yuling - firstly welcome to the forum!

second - Hawking Radiation was not an attempt to explain away the information loss paradox, it was the cause of the information loss.  According to the theory of Hawking and Bekenstein the information in the radiation (a mixed quantum state) could not include the pure quantum information of the particle that fell into the black hole.  Hawkings postulated solution was quantum fluctuations in space time emanating from the EH - this is by no means agreed.

And although Hawking Radiation has never been observed (we are looking through the GLAST programme) it relies on the same set of axiomata and preconditions as the rest of mainstream physics and the maths and logic flow from the body of work that is experimentally supported.  Other less accepted theories use new and difficult preconditions.  String Theory is a strange one - it is mathematically beautiful and self-consistent, but at present it is not linked to reality enough; it does not use the same lean and simple axiomata, and it is not open to empirical testing.  There are so many variants of string theory ( ie changable variables that will produce different physical predictions) that it is a matter of tuning to reproduce particle masses etc - until some more non-string theory reasons for these particular tunings and assumptions can be shown string theory will continue to be interesting but not mainstream.


regarding your last paragraph - totally agree.  Any theories about the singularity or past the event horizon even are fundamentally divorced from our reality and must be treated with skepticism.

[MikeS (OP)]

If matter and antimatter are gravitationally repulsive then the electron is bound by the intense gravitational field whilst the positron is gravitationally expelled through the event horizon and accelerates away.

Which could be a problem because one would quickly develop a large negative charge within the black hole, and a large positive charge in the surrounding space where electrons are annihilated. 

Clifford
Why is this a problem?

[imatfaal]

If matter and antimatter are gravitationally repulsive then the electron is bound by the intense gravitational field whilst the positron is gravitationally expelled through the event horizon and accelerates away.

Which could be a problem because one would quickly develop a large negative charge within the black hole, and a large positive charge in the surrounding space where electrons are annihilated. 

Clifford
Why is this a problem?

For a start the like charge of the black hole and the electron will repel and the electrons will stop falling into the hole at some point - the opposite charge of the BH and the positron will attract and eventually overcome gravitational repulsion.  BUT please can we keep speculative theories to NEW THEORIES