Black Holes

[mickoking]

Do you Believe in black holes or are you unsure?

[davidpretorius]

there is an escape velocity to leave the earth, so there must be an escape velocity from a massive enough object that it greater than the speed of light. hence a black hole!!!

[ving (David)]

I saw a lil' movie at a presentation at my last astro club meet that showed the movement of stars around an otherwise invisible object.... interesting and that along with numerous other studies i have seen but since forgotten is proof enough

[barees63]

I heard an interesting interview on the "Universe Today" podcast with a physicist who claims black holes are a mistake and what they really are is "Dark Energy Stars", it was all very technical but his theory apparently explained several "holes" in black hole theory (such as why stars supernova instead of simply collapsing), sounded convincing to me.. but I'm no cosmologist ;-)

[ving (David)]

black holes, dark energy stars.... its all just names to describe one phenomenon.
Nor am I am expert...

have to try one of these pods casts. I like nothing more than to listen to some expert waffle on about something that may or may not exist which cannot be seen visually but the effects of said object ca bee see.... makes my head spin

[JohnH]

Big call from the 100% ers there.

A black hole's existance is deduced by observing its effects on the environment and comparing those against effects of known phenomena such as white dwarfs and neutron stars. If the simplest explanation is a black hole then, using Occam's razor, we have a winner.

This is not so much a "proof" as the best explanation we have for a number of observations such as active galaxy's jets and objects such a Cygnus X-1 :

http://spaceflightnow.com/news/n0101/11hubblehole/

and stars behaving badly:

http://www.space.com/scienceastronom...ay_021016.html

This does not preclude other explanations but the case is pretty strong.

[Yuzza]

i believe they exist, haven't they also got proof of something (black hole, dark star, whatever) when a star passed behind one of them, can't remember what the name of the show was but i think it was one from the BBC

[barees63]

have to try one of these pods casts.

The two that I enjoy are Slacker Astronomy (short and entertaining) and Universe Today which is longer and more in depth with really good interviews with mad scientists..

They definately exist, in the form of boats and cars, you pour money in, and nothing ever comes out. And as absolute proof, I present the Visa card.

My thought is this, when humans dont have absolute proof they speculate, the objects that cause gravatational lensing and have effects on near by stars etc that we cant see certainly exist, until we can actually fly to one and observe it face to face we can only speculate, same as the big bang, it's a theory, for each advocate we can find someone who dispells it, I'm a fence sitter, it's an attractive theory that helps explain some phenomena we humans dont understand, my gut feeling is they probably don't exist and I say that without any scientific support.

[AGarvin]

They definately exist, in the form of boats and cars, you pour money in, and nothing ever comes out. And as absolute proof, I present the Visa card.

Man, ain't it the truth ... not to mention my latest black holes, the kids ...

My thought is this, when humans dont have absolute proof they speculate, the objects that cause gravatational lensing and have effects on near by stars etc that we cant see certainly exist, until we can actually fly to one and observe it face to face we can only speculate, same as the big bang, it's a theory, for each advocate we can find someone who dispells it, I'm a fence sitter, it's an attractive theory that helps explain some phenomena we humans dont understand, my gut feeling is they probably don't exist and I say that without any scientific support.

On the subject of black holes, they are not speculation but rather a prediction of General Relativity ... and GR is a remarkably successful theory. Not to mention the fact that it underpins most of our current understanding of the universe. And there is really no one out there that dispells it.

[Sonia]

Originally Posted by Yuzza

i believe they exist, haven't they also got proof of something (black hole, dark star, whatever) when a star passed behind one of them, can't remember what the name of the show was but i think it was one from the BBC

The Sky At Night with Patrick Moore?


Black holes i think are mysterious objects, but their existence is predicted as a quite straightforward consequence of the way we know matter behaves - they are not science fiction. Since the light cannot escape from them, they are for us difficult to observe.

[Adrian-H]

ive seen alot of steven hawkings things on black holes, so i think they may exist. even more so interesting theories to a hollow or sun fiilled earth core.

On the subject of black holes, they are not speculation but rather a prediction of General Relativity ... and GR is a remarkably successful theory. Not to mention the fact that it underpins most of our current understanding of the universe. And there is really no one out there that dispells it.[/QUOTE]

Ahhh but the prediction of a theory IS speculation, after all, it is a theory, as is all science until it is proven beyond doubt, space is full of doubt and theories, call me a scinic but only the proven is fact, ask any court of law.

[acropolite (Phil)]

I'd say they exist, it's a logical enough concept and there's more and more evidence every day for their existence.

[Robert_T]

Originally Posted by nightshift

Ahhh but the prediction of a theory IS speculation, after all, it is a theory, as is all science until it is proven beyond doubt, space is full of doubt and theories, call me a scinic but only the proven is fact, ask any court of law.

This is a common misconception about scientific theory, that it equates to "speculation" or opinion. It certainly can't be regarded as fact, but nor can it be really regarded as simply speculation. There seems to have been a conflation in many peoples minds of the meaning of scientific theory and the term "theory" as used in everyday speech (e.g. I've got a theory why the weekend days always seem shorter than workdays). In common usage the word "theory" has come to mean opinion or speculation (or just plain running off at the mouth), often of a single individual, and is often used to describe something that has been said (or believed) in a way that casts doubt on it's validity or basis.

Scientific theory does differ in some important ways from this common usage meaning. First, and most fundamentally, scientific theory is phrased so as to be testable, perhaps not always with the current technology available, but there must at least be the potential for testing and the criteria for testing and confirmation or refutation should be made explicit. Scientific theory should also be based on and be consistent with repeatable observations, generally from a range of different individuals. In short, scientific theories are based on stated evidence from observations and they invite challenge by others, and from fresh observations, that seek to test the theory, also from testable and repeatable observations and the evidence they generate. Again, they're not fact, but should a theory stand the test of time and the multiple challenges thrown at it, it should be regarded with considerable more respect than that embodied in the term "speculation".

[gaa_ian (Ian)]

IMHO there has been enough observational Astronomy done & tests by GR theory to show they exist.
Even if we do not know everything about them !