Black Holes Don’t Exist!


Well, not quite!

When a star has finished converting its hydrogen to helium, helium to carbon, etc, it runs out of fuel and collapses. If the mass of the star is less than about three solar masses, the collapse will halt when all the matter is compressed to form a neutron star. But if the mass is greater, the subatomic forces are overwhelmed by the gravitational force, and the collapse continues, right down to a point.

But another effect comes in to play. Einstein’s General Theory of Relativity tells us that when the gravitational forces are this great, time itself is slowed down, and the rate of contraction decreases more and more so that this point of infinite density and infinite gravitational force is never quite reached. In fact, General Relativity tells us that the contraction will come to a stop long before this point, when the collapsing mass reaches a radius known as the Schwarzschild radius, given by the equation

R = 2GM/c**2

Where G is the gravitational constant, M is the collapsing mass, and c the velocity of light.

So in fact, the collapse will never reach the status of a black hole, forever inching closer and closer to it. But not so, say Finkelstein, Kruskal and Szekeres, whose calculations show that in the reference frame of an observer falling in with the collapsing mass, there is no critical radius, and the collapse proceeds smoothly down to a point.

But this falling observer has a different reference frame to us distant observers. His time dimension is not our time dimension. The Black Hole astronomers produce reference frames for the falling observer with equations relating his time to ours. But these equations contain a term (1 – 2GM/c**2) in the denominator, which becomes zero at the Schwarzschild radius, and as we all learned at school, and number divided by zero equals infinity.

So the falling observer will pass through the event horizon – when our clocks read infinity! No observer, no matter, has ever fallen through an event horizon yet in our time-frame, or any of the time frames of the visible universe. The falling observer does so, but does it by leaving our universe – at the far end of time. But by the same reasoning, the collapsing star will never quite reach the status of a black hole by our clocks. The collapse will freeze just as it approaches this state.

So what we are left with in our universe is some extremely dark grey holes. One cannot tell the difference by any observations. But we have no singularities, no breakdown of the laws of physics, no gateways into other universes, no time-travel portals. Einstein’s theory works all the way. And Einstein didn’t believe in black holes either!

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Mike

Hum,
the `point` singularity is only a puzzling hypothetical mathematical description.
Most cosmologist who talk about BH singularities don't really consider them as points, they usually tend to settle for a Planck length (1.6 x 10^-35) or time period, (10^-43 seconds)...or larger (a lot larger).

The bottom line is that currently we don't really know, or need to know, what is beyond the event horizon - The `physical laws` must still work, but our usual mathematical tools break.

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`Irony` actually does mean `metal like`...

Isn't this ATM?

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Gillian

"Now everyone was giving her that kind of look UFOlogists get when they suddenly say, 'Hey, if you shade your eyes you can see it is just a flock of geese after all.'"

"You can't erase icing."

"I can't believe it doesn't work! I found it on the internet, man!"

Depends on what you mean by "ATM" (that's a general relativity joke -- the answer to even the most straightfoward question in general relativity is usually "depends on what you mean by this and that in your question). It certainly wasn't a question, though.

His tone may be ATM, but indeed, it takes infinite time on external clocks for something to cross the horizon (of a pre-existing black hole that has existed "forever" or at least since the big bang.......don't analyze that statement too closely). ANd it will indeed take an infinite time on external clocks for a collapsing spherical mass to cross its own event horizon.

In it's own frame however, it doesn't take too long at all. And when it hits the singularity, "time (and space) ends for that object". Don't ask me too much what is meant by that statement either.

In it's own frame, a singularity is formed according to current thinking. Now GR twists things so much that whether something actually happens or not is frame dependent. That's hard to swallow, but that's the way it works.

However, Abhas Mitra, and Indian physicist has challenged the cold collapse model, and says the Einstein Field Equations actuall does prevent a collpase to singularity in its own co-collapsing frame. It's called the MECO/ECO theory. That is ATM, but it is very serious ATM, not the usual fare you see here in the ATM section.

So, is the OP ATM? Well, I think you now see "it depends on what you meant by ATM", and what he is actually trying to say................


-Richard

Well, but it is Q&A. So what's the question?

Maybe Mike Holland's dyslexic and thinks this is Answers and Questions.

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Thank you for the well-thought-out answer, Publius. I hope I always show a willingness to learn. (Would you be horribly offended if I told you that you're pretty consistently using the wrong "its"?)

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Gillian

"Now everyone was giving her that kind of look UFOlogists get when they suddenly say, 'Hey, if you shade your eyes you can see it is just a flock of geese after all.'"

"You can't erase icing."

"I can't believe it doesn't work! I found it on the internet, man!"

No, I wouldn't be offended because I know I do that and it makes me mad at myself. It just comes out that stupid way when I'm typing fast. When I re-read my posts, they stick out like a sore thumb, but darned if I ever notice them when I'm typing.

I will do that with "their" and "there" and some others as well. I need an editor.....

-Richard

Publius, your refusal to look at it too closely is precisely the problem. You agree with me that according to our (the outside universe) time frames, nothing has ever fallen through an event horizon. I think you also agree that by our time frames, no collapsing body has yet collapsed beyong its event horizon radius.

So why do youi not agree that according to all the external time frames of the universe, there are no black holes - yet! And won't be until all our clocks read infinity?

This is a very simple and obvious step in my argument. If it hasn't happened according to any clock that we can know of in our universe, then it hasn't happened full stop. If it only happens according to clocks that convert to our time by adding infinity to the readings, then it still hasn't happened.

I agree that an observer falling with the collapsing mass will pass beyond the event horizon. But he is then no longer in our universe!

Mike

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Mike

Heres another thought, if a entity which we call a black hole is rotating in anyway, would not the contraction of the black hole spin it faster and faster as it approaches the singularity, and again at a point of singularity the rotation would become infinitely fast (because again you divide by zero).
If this were the case then the forces of gravity would be counteracted by the centrifugal forces http://en.wikipedia.org/wiki/Centrifugal due to the energy of the spinning particles so a rotating BH could never come to be?

I cannot imagine a massive object in the universe which wouldn't be rotating (even just a little) and such a rotational velocity would be amplified by the collapse. But please correct me if I'm mistaken in any of this speculation.

I was proposing some ideas for debate, and possibly shooting down. If Q and A is the wrong forum, which would be the correct one?

Does debate happen here, or do we all just sit in awe of the boffins who run the show?

Mike

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Mike

"Against the Mainstream" is the correct forum for an idea that is not in accordance with mainstream science. You can request one of the moderators to move it.

In no forum is it correct to use cute insults.

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I calculated the odds of this succeeding versus the odds I was doing something incredibly stupid...and I went ahead anyway. - Crow T. Robot

Godspeed, John Glenn. - Scott Carpenter

And these atomic bombs that science burst upon the world that night were strange even to the men that used them.
- H.G Wells, The World Set Free

To the conspiracy crowd, radiation is a big Boogey Man that inspires terror and death in all who encounter it. - JayUtah

I don't think BAUT is a debating society - if you have an idea which goes against commonly-held astronomical theory, then the Against The Mainstream (ATM) section would be the place to post it; if it's mainstream, then why a debate?

I have the impression that you are proposing an ATM idea, and will move this thread to the ATM section (unless you say that it's not, in the next few hours).I'm not sure who you thinks runs the show, nor why you think they are boffins - perhaps you'd be kind enough to explain?

Alex; I'll take astronomy for $500.

Anyway; I appreciate the discussion and don't understand why it is ATM.
Being a lay person trying to grasp the complexities of a BH, this sounds very reasonable to me. In fact I've always wondered along the lines of the OP.
If the collapsing mass is speeding up (velocity) and slowing down (time) then why would it not be forming a shell?

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Numbers are not case sensitive. (me)

Look up the Kerr metric, Kerr black holes, etc. A rotating black hole is very, very, very different from Schwarzschild. Indeed, General Relativity will not allow something with angular momentum to collapse to a point. The singularity there (which are based on a particular model) is a "ring" not a point -- it's like a line mass, the density is infinite in only two dimensions, and that line gets bent into a circle.

There is massive frame dragging going on there, and the space-time is no longer spherically symmetric, but axis, or cylindrical symmetric.

Coming in radially, frame dragging produces something called a "stationary limit". You can't go past that without moving. The force on a stationary observer would go to infinity. But this is not an event horizon, because if you move in the direction of hole rotation, the force remains finite. You can see this in terms of gravitomagnetic forces. So past the stationary limit, sometimes called the "ergosphere", you can be stationary, but you can be radially stationary.

Moving on in, there is an event horizon, where you can no longer remain radially stationary, and it's a point of no return.

There is actually another event horizon further in. This space-time gets very weird. Closed time-like curves are actually possible in between the two horizons.

And finally, there is a limit to how much angular momentum a Kerr Hole can have -- it is the limit on the L/M ratio. This works roughly like your centrifugal force reasoning. If something has L greater than this limit, then the centrifugal force prevents further collapse -- it exceeds gravity at some point. However, below the limit, gravity has the edge, and it collapses to the ring singularity thing.


-Richard

Ok, so since this is Questions and Answers after all, I do have two questions:

1. Is it really correct to say that since objects never reach the event horizon with respect to our own frame, that this means it really never happens?

2. This will need a little setup, and a cheesy diagram. Let's assume that black holes are actually ECOs instead. Let's also assume that two massive particles, A and B, are approaching an ECO, O from opposite sides:

A O    B

Assume that B is far enough from O so that B will have a negligible gravitational effect on A, and assume that A is near enough to O to experience strong relativistic effects. In A's frame, O does not have an event horizon, because we are treating O as an ECO.

Suppose that B is now much closer to O, so that the gravitional effect between A and B is significant:

A O B

Can the proximity B increase the gravitational strength that A is feeling enough to "kick over" O, so that O will have an event horizon, and A will be inside it, as measured by an external observer?

Edited to comment: The posting engine has removed some spaces in my goofy diagrams, unable to compensate for that.

It's actually your refusal to look at things closely and expand your horizons about the meaning of this. Yep, inside the event horizon of a black hole is "Elsewhere", it does not exist in the coordinates of external observers. Crossing the horizon and on "inside" (inwhenside would be better) doesn't happen at any time or any place on external clocks and rulers.

However, the Elsewhere does exist in full space-time -- we just have to switch to other coordiantes, other rulers and clocks to describe it. That's the question.

Now, the same thing happens to a Rindler observer, which is one who is accelerating at some constant proper acceleration, call it 'g'. An event horizon exists for him as well. If that observer leaves earth, fires his rocket at 1 earth 'g', an event horizon will form behind him at a distance of c^2/g, which for 1 earth g is just about 1 light-year.

He will see earth accelerate away, reach a peach speed, then slow down and freeze at that Rindler horizon 1 LY away. He sees the clock of earth just stop there, freezing that last moment in time. Nothing ever crosses the horizon in finite time for him, either.

But what of those on earth? Well, they can calculate when they've crossed his horizon, and in their frame, all that is happening is the Rindler observer's clock is running so slow, and continuing to slow down that it will never catch up and our events just won't happen. And we'll notice that at that exact point, a light signal we sent after him would never catch him.

All he has to do is let off the gas, and that horizon recedes away, and all those frozen clocks and later events slowly begin to happen.

Now, I ask you, what is the reality there?

Everything we can say about external observers in Schwarzschild applies to the Rindler observer.

-Richard

This is funny. The proper GR answer to the question, "Do Black holes exist?", is truly "Depends on what you mean by exist."

And finally for any lurkers perhaps confused by all this, the external gravitational field is the same. The collapsing mass, even though it takes infinite time by our clocks to reach its own horizon, makes the same external field as a pre-existing Schwarzschild black hole that has been there forever.

General Relativity has space and time doing things that are well, almost obscene, but it is mathematically and physically consistent. It will blow your mind trying to understand it sometimes, but it does work. One question is "how does the gravity escape". Well, it doesn't have to, it's already there. The Schwarzschild field was "made" as that mass collapsed.

-Richard