Is there a maximum mass for a black hole?

[CCWilson]

How about minimum mass for black holes caused by gravitational collapse. Isn't it something like three solar masses?

 

[mfb]

3 solar masses is the mass limit for the star in the calculations, the remaining black hole would have a lower mass (I think something like 2 solar masses?). However, no black holes of this size were detected yet, so this is a bit speculative.

 

[hubble_bubble]

3 solar masses is the mass limit for the star in the calculations, the remaining black hole would have a lower mass (I think something like 2 solar masses?). However, no black holes of this size were detected yet, so this is a bit speculative.

I assume you mean that the other mass is ejected before or during the collapse.

I am looking at a modified Schwarzschild calculation for the data I need. I want to work in the effects on time too. The fact that e=mc2 leads onto a calculation where c becomes negative and mass compression becomes a component. What does mass compression do to energy levels? Could energy form around a singularity. As you have the event horizon could you have another band near the singularity where time is running at a comparable rate to that of light elsewhere and light itself is stationary?

Imagine a collision of particles within the event horizon. this initiates an energy release in the form of a photon which wants to head toward the event horizon. It will be impossible for the photon to do this. The particle is no longer "experiencing " light as it normally acts. As light may now appear static, time may take its place in the environs of a singularity. Now if c is zero this makes no sense. If c however is negative then this may indicate that time is negative, but this is not necessarily so. If time was negative then particles would be attracting light rather than emitting it. This would indicate an increase in energy which is counter intuitive near the singularity.

 

[hubble_bubble]

Have a think about this.

"Objects in a gravitational field experience a slowing down of time, called time dilation. This phenomenon has been verified experimentally in the Scout rocket experiment of 1976 [2], and is, for example, taken into account in the GPS system. Near the event horizon, the time dilation increases rapidly. From the point of view of an external observer, it takes an infinite amount of time for an object to approach the event horizon, at which point the light coming from it is infinitely red-shifted. To the distant observer, the object, falling slower and slower, approaches but never reaches the event horizon. The object itself might not even notice the point at which it crosses the event horizon, and will do so in a finite amount of proper time."

This postulation must be false. If everything falling into a black hole appears to take an infinite amount of time to reach the horizon these things would be lit up like christmas trees. Not exactly black. So if one million spacecraft were sent into the event horizon we would see 1 million static spaceships around the horizon for ever. Discussion welcome.

 

[phinds]

This postulation must be false.

I'm sure you'll be able to back that up with something other than your opinion, yes?

I'm waiting.

 

[hubble_bubble]

I'm sure you'll be able to back that up with something other than your opinion, yes?

I'm waiting.

I will post any calculations. Of course.

 

[CCWilson]

"From the point of view of an external observer, it takes an infinite amount of time for an object to approach the event horizon, at which point the light coming from it is infinitely red-shifted. To the distant observer, the object, falling slower and slower, approaches but never reaches the event horizon."

This is one of those brain-twisters. I agree with Hubble - that the statement above is incorrect. Doesn't seem likely that an object approaching a black hole would move slower - to an external observer - than it would approaching a planet, say. If we had a really good telescope and were able to watch the people inside a spacecraft approaching a black hole, we would see them moving slower and slower and their clock running slower and slower. But the spaceship itself, I believe, would proceed faster and faster into the abyss and disappear. If there were any way to watch a clock inside the event horizon (which there isn't), it would, for all practical purposes, have stopped - but until they were destroyed, any passengers still alive inside the event horizon would see the clock running normally.

 

[phinds]

"From the point of view of an external observer, it takes an infinite amount of time for an object to approach the event horizon, at which point the light coming from it is infinitely red-shifted. To the distant observer, the object, falling slower and slower, approaches but never reaches the event horizon."

This is one of those brain-twisters. I agree with Hubble - that the statement above is incorrect.

And I'm sure that you, too, will be able to back this up with more than just your opinion.

Since you are both wrong, this is going to be interesting.

 

[hubble_bubble]

Also it is believed that inside a black hole things would be destroyed quite quickly. Under various gravitational strengths it must be possible for life to survive. As long as the lifeform has developed under the gravity in question. A lifeform that has developed within the confines of a neutron star, think Robert L Forward's Dragon's Egg, would be quite at home within the confines of a black hole up until reaching the singularity. If time inside the singularity, instead of slowing, speeds up then it may take an infinitely long time for travelers to reach the singularity. The boundary for this change would be the event horizon itself. This would be a very strange world with little light available as all the waves would be traveling away from the observer in two directions. Visibilty would be restricted to the band of the collapsing spherical wavefront at either side of this observer. Any movement would be restricted due to the effects of the intense gravity. Thus space within this reference fram is effectively static and balanced by a modification of the speed of time.

 

[hubble_bubble]

And I'm sure that you, too, will be able to back this up with more than just your opinion.

Since you are both wrong, this is going to be interesting.

Well concerning time dilation there has to be a balance. If you live slower approaching the speed of light what happens when approaching a singularity where light no longer behaves in the normal manner?

 

[hubble_bubble]

Also we must remember that wave frequency should increase as we reach the singularity. This balances the frequency decrease at or near the speed of light. As this frequency increases we should get an energy band around the singularity. And to be even more controversial, this energy should be lost as darlk matter/energy emissions from the black hole at faster than light speeds.

 

[phinds]

Well concerning time dilation there has to be a balance. If you live slower approaching the speed of light what happens when approaching a singularity where light no longer behaves in the normal manner?

You seem to completely misunderstand time dilation. If you fall into a black hole, then I see you time dilated as you approach the event horizon. I see you approaching the EH asymptotically and never reaching it. You, on the other hand, are not even aware that there IS an EH and you pass through it not noticiing a thing.

As for your statement about what happens at the singularity, that is useless speculation. "Singularity" means "the place where our models break down and we don't know WHAT is happening" so any statement about what photons do there is spreculation and in any even it doesn't matter since we can never observe it anyway.

 

[phinds]

Also we must remember that wave frequency should increase as we reach the singularity. This balances the frequency decrease at or near the speed of light. As this frequency increases we should get an energy band around the singularity. And to be even more controversial, this energy should be lost as darlk matter/energy emissions from the black hole at faster than light speeds.

I REALLY have no idea what you are talking about here but it sure sounds like utter nonsense. FTL ? Really ?

 

[hubble_bubble]

A way I believe dark matter could be detected would be to lower a mass to as near as absolute zero as possible and detect any energy released. This should be detected BEFORE the event that caused it.

 

[phinds]

Also it is believed that inside a black hole things would be destroyed quite quickly. Under various gravitational strengths it must be possible for life to survive.

nonsense.

As long as the lifeform has developed under the gravity in question. A lifeform that has developed within the confines of a neutron star, think Robert L Forward's Dragon's Egg, would be quite at home within the confines of a black hole up until reaching the singularity.

Clearly you dont' understand tidal forces

If time inside the singularity, instead of slowing, speeds up then it may take an infinitely long time for travelers to reach the singularity. The boundary for this change would be the event horizon itself. This would be a very strange world with little light available as all the waves would be traveling away from the observer in two directions. Visibilty would be restricted to the band of the collapsing spherical wavefront at either side of this observer. Any movement would be restricted due to the effects of the intense gravity. Thus space within this reference fram is effectively static and balanced by a modification of the speed of time.

Nearly as I can tell this is just a bunch of words strung together as blather.

 

[phinds]

A way I believe dark matter could be detected would be to lower a mass to as near as absolute zero as possible and detect any energy released. This should be detected BEFORE the event that caused it.

Once again, what appears to be just a string of words with no relationship to actual physics.

 

[hubble_bubble]

I REALLY have no idea what you are talking about here but it sure sounds like utter nonsense. FTL ? Really ?

Why do you think it is so hard to detect.

 

[phinds]

Why do you think it is so hard to detect.

Why do I think WHAT is so hard to detect?

EDIT: if you are talking about dark matter, then I have to ask, why did you suddenly bring dark matter into a discussion about black holes? You do realize, I hope, that there is zero relationship between the two.

 

[CCWilson]

"If you fall into a black hole, then I see you time dilated as you approach the event horizon." Yes. As I said above, if we could see what's going on inside a spaceship approaching an event horizon, their clocks would appear to us to be running slowly. If those chaps inside the ship could see us, an external observer, our clocks would appear to them to be running fast. That's time dilation. It sure doesn't mean that something approaching an event horizon moves more slowly. The opposite is true. As to what we would see as an object approaches the event horizon, I believe that we would see a redshifted image of it and then it would become invisible almost immediately. Now maybe there would theoretically be a prolongation of the image but the intensity would fall off rapidly so that it would not be visible very long. Regardless, the object will pass through the event horizon quickly; we might be able to see images of it for a short time, but that's just a quirk of observation. The actual object, from our point of view, is quickly in the clutches of the black hole; it's gone, baby, gone.

 

[hubble_bubble]

Dark matter is hard to detect. If you look at galactic rotation curves they are flat. Unlike those of the solar system. As well as this implying dark matter driven rotation it also indicates that this dark matter must be spinning in the direction of galactic rotation. As dark matter is said to be expanding the universe then this implies that the dark matter is moving away from the galactic centre. Now what do you think may be theoretically at the galactic centre and spinning?

 

[hubble_bubble]

Also there must be significant energy driving this flat rotation. A slow moving dark matter/energy would not be enough so the speed must be significant and at a universal constant speed. What this speed is is yet to be determined, but can be calculated based on the force needed to maintain the rotational velocity.

 

[Drakkith]

Hubble, dark matter is not driving expansion. Expansion is *possibly* being accelerated by dark energy. Although I think I remember some talk about how dark energy isn't necessary since we already have the cosmological constant or something.

Dark matter is also not causing galaxies to rotate. What it does is provide extra gravity to hold the outside areas of the galaxies together and allow the matter there to orbit the galactic center at a speed that would be too quick otherwise. Dark matter forms a spherical "halo" around the galaxy where it spends most of its time.

 

[hubble_bubble]

Hubble, dark matter is not driving expansion. Expansion is *possibly* being accelerated by dark energy. Although I think I remember some talk about how dark energy isn't necessary since we already have the cosmological constant or something.

Dark matter is also not causing galaxies to rotate. What it does is provide extra gravity to hold the outside areas of the galaxies together and allow the matter there to orbit the galactic center at a speed that would be too quick otherwise. Dark matter forms a spherical "halo" around the galaxy where it spends most of its time.

But surely a stationary halo of dark matter would impede the rotation. As I said before finding things happen before expected, As in the rotation being faster than expected implies a force not yet described. Take e-mc2. If we have e=m(c+n)2 then we not only have a unit of length that has been stretched but also a gain in energy and speed faster than light, but what is n? It is believed that dark matter is increasing or am I wrong?

 

[Drakkith]

But surely a stationary halo of dark matter would impede the rotation. As I said before finding things happen before expected, As in the rotation being faster than expected implies a force not yet described.

How would it impede the rotation? Dark matter does not interact with normal matter through any force other than gravity. It can pass right through normal matter unimpeded.

Take e-mc2. If we have e=m(c+n)2 then we not only have a unit of length that has been stretched but also a gain in energy and speed faster than light, but what is n? It is believed that dark matter is increasing or am I wrong?

What are you talking about? The unit c is not a unit of length, but of velocity. I have absolutely no idea what you are trying to get across. You can't just insert new things into equations like this. Nor do I know what n is, as dark matter is not increasing.

 

[hubble_bubble]

We have the Schwarzschild radius rs = 2GM/c2. We also have the detected dark matter halo. Is the distance from the halo proportional to the size of the galactic black hole and its radius? Has anyone calculated this? If there is no relationship then I would agree that there is no connection. At first it was thought that Galaxy M33 had no central black hole but it is just small in comparison. It does have a halo. If there is a relationship between the black hole and the halo and this is proportional then this could be similar to the Schwarzschild radius only further out.

I don't know if this has been confirmed .

http://www.guardian.co.uk/science/2011/sep/22/faster-than-light-particles-neutrinos

Aren't neutrinos considered a type of dark matter.

 

[hubble_bubble]

Maybe the n in e=m(c+n)2 stands for neutrino

 

[hubble_bubble]

Does the percentage increase found at Gran Sasso tie in in any way with the rate of expansion found for the universe?

 

[hubble_bubble]

How would it impede the rotation? Dark matter does not interact with normal matter through any force other than gravity. It can pass right through normal matter unimpeded.

How do you know there is no interaction between matter and dark matter?

 

[Drakkith]

I don't know if this has been confirmed .

http://www.guardian.co.uk/science/2011/sep/22/faster-than-light-particles-neutrinos

Aren't neutrinos considered a type of dark matter.

Neutrinos do not travel FTL. There was an error in the setup of the detectors and clocks. I believe one of the cables was incorrectly installed. And while neutrinos may be a type of dark matter, they are not the type that we normaly talk about if my memory is correct.

Maybe the n in e=m(c+n)2 stands for neutrino

Are you making this up or did you get this from somewhere?

Does the percentage increase found at Gran Sasso tie in in any way with the rate of expansion found for the universe?

No, that was a faulty experiment.

How do you know there is no interaction between matter and dark matter?

Observations have been made and we have reason to believe that dark matter doesn't interact with normal matter. Look at the Bullet Cluster for example.

 

[Nabeshin]

Aren't neutrinos considered a type of dark matter.

Indeed they are, but they fall under the subcategory of 'hot' dark matter, whereas most of what we're looking for is 'cold' dark matter. Google around if you want to know more about the distinction.