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Black Hole, Does it realy exist?





bukaida
Quote:
Black holes might not exist - or at least not as scientists have imagined, cloaked by an impenetrable "event horizon". A controversial new calculation could abolish the horizon, and so solve a troubling paradox in physics.

The event horizon is supposed to mark a boundary beyond which nothing can escape a black hole's gravity. According to the general theory of relativity, even light is trapped inside the horizon, and no information about what fell into the hole can ever escape. Information seems to have fallen out of the universe.

But researchers argue the information may never have been cut off in the first place. Tanmay Vachaspati and his colleagues at Case Western Reserve University in Cleveland, Ohio, US, have tried to calculate what happens as a black hole is forming. Using an unusual mathematical approach called the functional Schrodinger equation, they follow a sphere of stuff as it collapses inwards, and predict what a distant observer would see.

They find that the gravity of the collapsing mass starts to disrupt the quantum vacuum, generating what they call "pre-Hawking" radiation. Losing that radiation reduces the total mass-energy of the object - so that it never gets dense enough to form an event horizon and a true black hole. "There are no such things", Vachaspati told New Scientist. "There are only stars going toward being a black hole but not getting there."

Source - http://nathanr.ca/space/do-black-holes-really-exist/
[MOD - quote tags and source added. Bikerman]
SonLight
The link is problematic -- I got a "forbidden" message. I couldn't find the page in the internet archive, but I did find the article that site apparently used as a reference:

http://www.newscientist.com/article/dn12089

That link too may have a problem. I found the article in google's cache, and found it presents more alternatives than Nathan considered. A main thrust of the article is that information may be preserved by radiation which leaves the vicinity of the black hole, or apparent-black-hole-which-never-quite-becomes-one. The choice seems to be between Hawking radiation (after the event horizon forms) or pre-Hawking radiation (which may prevent event horizon formation, though some doubt if it would be powerful enough).

The source id within the article is:

22:16 18 June 2007 by Stephen Battersby

Journal reference: Physical Review D (In press)
Xanatos
It will be interesting to see if there is any substance to this. Black holes have been studied for a long time by very famous people. If they turned out not to exist it could cause quite an uproar. Almost as much as not finding the higgs would.
Bikerman
SonLight wrote:
The link is problematic -- I got a "forbidden" message. I couldn't find the page in the internet archive, but I did find the article that site apparently used as a reference:

Well, all I can say is that the link works OK from my browser (otherwise I wouldn't have used it of course)....
I'm using Firefox 3.05. I don't understand why a 'forbidden' error should arise.
LukeakaDanish
Link works fine, however this is most likely complete nonsense. The problem with the modern scientific community is that as soon as some college grad does some basic calculations and makes a mistake somewhere and therefore finds something really amazing, he or she publishes it on his/her blog.

Therefore this is most likely bullshit. Because it's not been reviewed by other scientist yet.
Bikerman
Well, I have to agree with the sentiment. I don't support the notion expressed - I merely added the source and put the original posting in quotes, as is my role as moderator. If you want a personal opinion then I have to say that I am personally convinced that Black Holes exist. They are predicted by GR and observations seem to bear the theory out....
Xanatos
Bikerman wrote:
Well, I have to agree with the sentiment. I don't support the notion expressed - I merely added the source and put the original posting in quotes, as is my role as moderator. If you want a personal opinion then I have to say that I am personally convinced that Black Holes exist. They are predicted by GR and observations seem to bear the theory out....


Which is what would make it extremely interesting if black holes didnt exist. They are predicted and we think that we see them.
ocalhoun
bukaida wrote:
Quote:
the gravity of the collapsing mass starts to disrupt the quantum vacuum,

1: What is 'quantum vacuum'?
2: Why and how does gravity disrupt it?
3: Why do small amounts of gravity, such as Earth's, not disrupt it the same way?
LukeakaDanish
Xanatos wrote:
Bikerman wrote:
Well, I have to agree with the sentiment. I don't support the notion expressed - I merely added the source and put the original posting in quotes, as is my role as moderator. If you want a personal opinion then I have to say that I am personally convinced that Black Holes exist. They are predicted by GR and observations seem to bear the theory out....


Which is what would make it extremely interesting if black holes didnt exist. They are predicted and we think that we see them.


No, we dont think that we see them. Seeing them is, by their very nature, impossible.

On the other hand we have reliable measurements that show that, regardless of what maths some scientist might be doing, they do exist.

So if he makes a theory that says they don't exist, he is immediately wrong. They do exist. Much of the science behind them is yet to be resolved though, so this kind of work might help get a better understanding of them.
SonLight
Both views expressed in the New Scientist article agree that black holes exist, in the sense that they appear as expected to an external observer. The question is, what is their nature? The term "frozen star" was formerly applied to black holes, because from the external observer's point of view, the inward movement of matter appears to stop short of the event horizon.

If the common point of view is correct, the matter does continue to the center of the hole, approaching a single point at least to within approximately the Planck distance. The problematic areas for that theory are that the interaction of high gravitational fields and quantum mechanics have yet to be well understood, and some kind of new laws of physics appear to be necessary within the Planck distance of the center. The fact that an event horizon shields the external universe from the unpredictable interactions at the center is the only hope to preserve causality and predictablity within the rest of the universe without figuring out the totally unknown and unknowable rules of behavior at the singularity.

If the new view is correct, matter would presumably be converted to radiation, almost at the point where the event horizon would otherwise form. The radiation would reach the external universe very slowly since it would have to escape from the deep gravity well, so the difference would not be obvious.

The new idea is a major change in our understanding of black holes, and should be looked at skeptically, as should all new scientific theories. Nevertheless, the New Scientist article makes it clear that this is based on a research paper in progress. Once it has been examined by referees and published, it is entitled to be looked at seriously. The beauty of it is that there should be some observable difference between the two models. If we are lucky, this issue could be resolved within our lifetime. More probably, it will take us a few hundred more years before we can actually measure the difference. There will be little practical effect of the difference, especially if it is so hard to measure, so we will continue to speak of black holes and they will leave pretty much the same "fingerprints" in space regardless of which theory is more accurate.
Xrave
the existence of blackholes is proven, right?

I mean, even though you can't 'see' it, the black hole is distinctively outlined as a abnormality in background radiation, since everything is sucked up by it.

if you have a stealth aircraft so stealthy that it can evade infrared/normal/radiowaves/xray scans/radar/sound and other stuff, how do you detect it? by detecting abnormal emptiness of course.
Blazole
yes there are millions of blackholes in the universe. Some of them are millions times bigger than earth. Fearless Planet a program on the discovery channel was talking about this the other day. A great program to watch.
ocalhoun
Blazole wrote:
Some of them are millions times bigger than earth.

Wouldn't a singularity be much smaller than the Earth?
LukeakaDanish
ocalhoun wrote:
Blazole wrote:
Some of them are millions times bigger than earth.

Wouldn't a singularity be much smaller than the Earth?

Yep, if definitely would be.

But the event horizon around it (the area that we "see" as the black hole") can be VERY large. Indeed it may be much larger than the earth.

Thats the way I understand it anyway.
Xanatos
LukeakaDanish wrote:
ocalhoun wrote:
Blazole wrote:
Some of them are millions times bigger than earth.

Wouldn't a singularity be much smaller than the Earth?

Yep, if definitely would be.

But the event horizon around it (the area that we "see" as the black hole") can be VERY large. Indeed it may be much larger than the earth.

Thats the way I understand it anyway.


The singularity in itself should be near infinitesmal. As to the size of the black hole we have one at the center of our galaxy that is about 10^7 times more massive than our sun.
nathanr
SonLight wrote:
The link is problematic -- I got a "forbidden" message. I couldn't find the page in the internet archive, but I did find the article that site apparently used as a reference.


The only reasons a 'forbidden' error would arise would be:
a) I've blocked the referer (which is not the case here) or
b) due to malware attacks.

I have a total of 82 IPs & subnets blocked due to malware attacks, exploits and the like. It's a precautionary measure so they don't attack a second time. It's only a matter of time before I start banning whole countries.

If you're creative with a Google search, you can probably pull up a cached version there.

Otherwise, let me know and I'll send you a screenshot.
Johnsenesque
Interesting, though I do hope it gets disproven so that I can still hold onto my childish fantasy of finding a way to create a wormhole, tugging one side of it to the edge of a black hole, just before the event horizon, waiting several thousand years and traveling through it to see what's on the other side.

Sad
BigGeek
I'm sure Bikerman will have a few things to say that refute what I'll claim here, but I don't think Black Holes exist.

Besides the fact that they refute General Relativity and I was never able to accept that GR supported their existance. There is just so much about the math (that I've seen) that seem adhoc, like they are trying to convince themselves and others by throwing in disjointed arguments whenever necessary to try and prove something improvable.

I've pointed to this website before, www.thunderbolts.info, I've been told that it is a website that is of no interest as the authors are just trying to sell their books. This may be so, but I do find some of the articles very insightful, and the math fairly easy to understand.

It is articles like these that have me questioning if Black Holes even exist. Have a read yourself and let me know what you think, just some food for thought.

And Bikerman, what do you think of the following articles, even though they come from a website that does not interest you? Oh and no I haven't gotten around to "The Elegant Universe" yet, but as soon as I do, we can start up another topic about it.

http://www.thunderbolts.info/thunderblogs/guest.htm
http://www.thunderbolts.info/thunderblogs/guest1.htm
http://www.thunderbolts.info/thunderblogs/guest3.htm

Enjoy, and if you are gonna refute what they say let's hear some constructive arguments, because I'm not good enough with the math to prove or disprove them either way, I have to follow my sense of logic with what I've learned, and the above articles (I think) cast enough doubt on astrophysicists claims FOR black holes, that I'm leaning toward the idea that they just aren't real!!
Bikerman
But what would be the point? On the one hand you say that you don't think that GR supports the notion of BHs, whilst on the other you say that you don't have sufficient maths to be able to follow the argument.
As I have already said, I have no interest in debunking a commercial website dedicated to selling a particular book or set of books. If I spent my time doing so then I would have no time for anything else - the internet is full of kooks and numpties with a 'theory', and there simply are not enough hours in the day. We already have a process to sort out the crap from the credible - it is called peer review. The fact that the thunderbolt site seems to offer no peer-reviewed papers means, to me, that it is not worth serious consideration. The fact that it also heavily pushes commercial books, rather than proper peer-reviewed science, merely confirms my opinion.
It is easy to set-up a website which apparently confutes modern science. Indeed it is even fairly easy to quote lots of authentic sounding facts and figures in support. It is the job of peer-reviewers to sort this stuff out - they are paid to do so and have the knowledge in the particular field to enable them in the task. I am not a theoretical physicist, though I have a basic understanding of some elements of that subject.
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