I am under the impression that most scientests take for granted Black Holes exist, and seen some things “caused” by them. Have we, however, proven that they do exist? I know that it would be tough to see one, since they are, well, black, but I’ve seen some pictures from Hubble that say something like “this jet of material is caused b a super-large black hole in the center of this galaxy… yadda, yadda” Or this light is refracted because of… a black hole nearby yadda, yadda…
Are they just “assuming” that a black hole exists there as nothing else they can think of could cause the effects that they are seeing or do they know with extremely little doubt that it is a black hole?
Nothing in science is every absolutely proven beyond doubt.
Black holes provide the best explanation for several phenomena. The jets you spoke of, for example, must be created by a spinning, extremely compact object with a very strong magnetic field, and black holes are the best candiate for that. The best evidence for black holes are the extremely fast orbits of stars at the centers of some galaxies. The only thing that we know of that could be massive enough to cause the stars to orbit so fast, but not be cranking out tons of light, is a black hole.
For example, there is something at the center of the Milky Way with a mass of 2.6 million Suns–and it’s not 2,600,000 stars, 'cause it isn’t putting out that kind of light.
Black holes are also predicted by the theory of general relativity. GR is a good theory, in the sense that it has made many useful predictions and has been tested rigorously for 'bout a century, now, and has stood up well.
So, while nothing in science is absolutely certain, the evidence for the existence of black holes is pretty good. That doesn’t mean that somebody won’t figure out a brand new kind of object that could explain these observations tomorrow, of course, but black holes are a reasonably good bet.
If you’re looking for a feeling for the consensus of the astronomical community, well, you’d have to do a little digging to find someone who argues against the existence of black holes, though there are a few–mostly it’s in a devil’s advocate kind of a way, bending over backwards to try to break the theory.
Nothing’s ever proven, though. Heck, we’ve been just assuming for quite some time now that those pinpricks of light in the night sky are actually big balls of hydrogen and helium with fusion happening at the center, 'cause, well, they act the way we thing big balls of hydrogen and helium with fusion happening at the center would act . . . but we could be wrong. After all, we’ve never seen one close up. Whazzat? You say we’ve got one right here in our Solar System? Well, yeah, theoretically that’s true . . . but are you sure that it’s exactly the same sort of thing as those distant pinpricks? I’m not. (Well, you know, pretty sure, but not absolutely sure.) Never know when a better model might come down the pike. . .
So, when I see pictures of some phenomena and the caption says something about “a supermassive black hole is causing this” it is because, well, a “supermassive black hole” would theoritically cause that and nothing else that science can think of would? Is that a safe assumption?
(And when I say science, I mean mainstream. Lets leave the wingnuts and fringe out of the picture for the purposes of this discussion).
PS - I am not trying to pick apart any theories or anything, I was just under the impression that black holes were still “theory” (albeit likely) but not <cringe> “proven” yet… (and yes, I know proven is a strong word! )
That’s an fairly safe assumption, yes. But then, that’s a fairly safe assumption when any theory is discussed. Belaboring the example I gave above, when you read “the Sun is composed of hydrogen and helium,” what that means is “All the evidence seems to indicate that the Sun is composed of hydrogen and helium, and the evidence seems to indicate that it goes all the way down, but to be perfectly honest, it is possible, albeit highly unlikely, that it could be something else.”
When a scientist says, “I believe X,” they are really saying that “I believe X is the best current explanation for the data,” and moreover, he believes it with a certain level of confidence that you must be very familiar with his field of study to grasp precisely. That’s one of the reasons why science is sometimes very difficult for laymen to grasp. You need to know the context. You need to understand how well accepted various theories are, and see how they build on one another. It’s like a house of cards. The further up you go, the shakier the conclusions are. Oftentimes, how reliable each theory is will be a personal judgement, based on your own knowledge, experience and reading of the data. It’s impossible to convey the exact shakiness of any given idea in a short picture caption.
Among mainstream media, there’s a wide variety in the quality of reporting. When scientists are unsure about something, they typically pepper their explanations with “weasel words”–“may be,” “might be,” “seems to be,” “appears to be”, “apparently,” “suggests”, “implies”, &c.
A good science reporter will pick up on those and carry them through. A less experienced or knowledgable journalist will tend to filter them out, making the scientists’ statements much more certain than they meant to be. And the people who write the headlines–
Well, the less said the better.
Assuming that you don’t want to become a scientist who specializes in absolutely every field of science the best you can do is try to read widely about the topics you’re interested in. Choose good sources, like reputable websites and science magazines.
I can understand your confusion. A great deal of the evidence for the existence of black holes has been amassed in, say, the last 5-10 years or so. This is one of the “curses” of modern life–we keep getting better at collecting data in greater quality and quantity, so it is harder and harder to keep up with it.
And, yes, proven is indeed far too strong a word. You can only prove a theory false. And even the best theory may be proven false–indeed, it almost certainly will be proven false, given time, in the sense that we will find new data that will require us to discard, or at least to revise, any given theory. The Universe is infinitely complex, so science at any given time must be a radical oversimplification. Science as simply the process of adding detail to this simplified picture of how things work and, most importantly, weeding out the incorrect bits.
Saying that something is a theory in science does not imply that it is unsupported. Quite the opposite! For something to be called a theory, its predictions have to been tested and there must be a large body of evidence that agrees with the theory. Of course, even among theories, some are better-supported than others, which is the real trick.
An idea that has little evidnece to back it up is a hypothesis–which may be the word you’re looking for. The everyday use of the word theory is more along the lines of what scientists would call a hypothesis.
I’ve been awfully long-winded, sorry. But this is an aspect of the philosphy of science that is very interesting to me.
Sorry for the hijack - but can you even prove a theory false ? I think I know your reasoning. For example the theory says, all protons have a positive charge. All it takes to prove the theory false is to find one single proton with a negative charge, right? Well, suppose one day we discover one; but it’s actually an anti-proton. Or our detector wasn’t working correctly. Or we misinterpreted the results. Do you see the same argument can apply to disproving a theory as proving it?
I think the upshot is, all we ever do is accumulate more and more evidence for the truth or falsehood of a theory. As we obtain more evidence, the conclusion swings one way or the other, but never quite reaches 100%. As far as I can see, the only place where absolute truth or falsehood can be proved is in mathematics, and then there still remains the possiblity of human error… (e.g. Wiles’s first (flawed) proof of Fermat’s Last Theorem).
DarrenS, the scientific community has probably been too influenced by Popper. Falsification is a natural extension of one interpretation of inductive reasoning, but implicit in the back of everyone’s mind is verification instead. If it doesn’t work as it has before, something must be wrong with the way I’m looking at the data. Indeed, most of the time, that’s the case, but this is also how great discoveries were thrown away. There is something of a bias in the scientific community toward seeing small little changes to theory, but people get suspicious when someone actually presents a falsification that demands an entirely different theory.
They told us in science class that balck holes are just rocks with so much gravity that everything around them gets sucked onto it and becomes part of the surface. The stuff is compacted so tightly that it seems to have been sucked into a hole. The rocks(which, btw, are apparently black and cannot be seen) grow in size as more junk is added to the surface. Additionally, the teacher said that the “black holes” will continue to grow until the entire universe is destroyed.
My school isn’t that great, so there’s a good chance they’re just feeding us b.s. It seems as though educated people like you would have known this already if it were true. But then again, you could just be a bunch of old people(no offense) who learned something different a long time ago and didn’t get the recent black hole memo.
Sorry if that wasn’t helpful. Keep up the good work! After all, I depend on this place to enrich my mind after it’s been chewed up and spit out at school^_^
They told us in science class that balck holes are just rocks with so much gravity that everything around them gets sucked onto them and becomes part of the surface. The stuff is compacted so tightly that it seems to have been sucked into a hole. The rocks(which, btw, are apparently black and cannot be seen) grow in size as more junk is added to the surface. Additionally, the teacher said that the “black holes” will continue to grow until the entire universe is destroyed.
My school isn’t that great, so there’s a good chance they’re just feeding us b.s. It seems as though educated people like you would have known this already if it were true. But then again, you could just be a bunch of old people(no offense) who learned something different a long time ago and didn’t get the recent black hole memo.
Sorry if that wasn’t helpful. Keep up the good work! After all, I depend on this place to enrich my mind after it’s been chewed up and spit out at school^_^
Umm… you need to make sure you realize that a black hole is not a rock in the formal sense of the definition of a rock. Black holes continuing to grow is one theory (pretty much untestable)… another is that black holes will leak away via Hawking Radiation. We really don’t have confirmation of either. Most astronomers are fairly convinced of the black hole at the center of most large galaxies, and no one I’ve read can explain how the largest stars won’t end up as black holes, but nevertheless, these things are particularly hard to detect.
You can do a search on the message board for such topics. This isn’t the first time black holes have come up and it certainly won’t be the last. Fight ignorance in any case, tsukinotenshi, fight it hard and don’t let it get back up. We need all the help we can get.
You can make a black hole out of any sort of matter at all, but you’re much more likely to make one out of hydrogen and helium than out of rock, just because there’s a lot more hydrogen and helium in the Universe than there is rock. Once it’s a black hole, it doesn’t matter what it was made out of originally: The only things a black hole remembers about its origin are its mass, electric and magnetic charge, and angular momentum, so one made from hydrogen would behave exactly like one made from rock.
It’s a common misconception about black holes that they eat matter voraciously. Unless you’re extremely close to them, they behave just like any other object of the same mass. Were the Sun to instantly become a black hole, all of the planets would just keep on orbiting in exactly the same way. If something does happen to hit the hole, it’ll fall in and increase the mass of the hole, but things aren’t any more likely to hit the hole than they are to hit anything else of the same mass. Less likely, in fact, becase a black hole will be a smaller target than anything else of the same mass.
I don’t know about the whole school but it certainly sounds as if your science teacher needs some serious help (or at the very least serious help regarding astronomy and cosmology).
A Black Hole is by no means a rock in any sense that we are familiar with. The ‘rock’ portion of a Black Hole is a Singularity…essentially an infinitely dense and incredibly tiny (much much smaller than an atom) point. The singularity itself may not be black at all (I have no idea) but the gravitational field it generates is so strong that nothing can escape it. Something could fly around it for awhile but sooner or later it all comes back to the singularity. The distance at which you have absolutely NO HOPE of escaping the singularity is called the Event Horizon. This is the point where not even light can escape. Given that NOTHING may travel faster than the speed of light the Event Horizon is truly a point of no return. Since light cannot escape people outside of the Black Hole cannot see into the Black Hole hence the name…it really would look like a black hole in space (although in-falling matter…if there is any…may emit prodigious amounts of light before passing the event horizon).
Black holes will almost certainly NOT swallow the entire Universe and probably not even swallow a galaxy. However, while the singularity in any black hole is essentially a point the event horizon can vary in size depending on how much matter the black hole has swallowed. The more matter comprising the black hole the bigger the event horizon. I think the black hole at the center of our galaxy is considered to be the equivalent of several million solar masses (i.e. several million of our sun’s worth of matter). Our Universe will likely putter out in a cosmic whimper and not be sucked into a black hole or crash back in a Big Crunch (that is, the Universe will likely just continue to cool off till nothing is left but a random particle floating here and there).
Black holes are fascinating objects and there is much more weirdness surrounding them. I know this primer is old-hat to many on this board but it seemed as if tsukinotenshi could use a quick run-down. Take this to your science teacher and tell him (or her) to try reading a little more about what they are teaching otherwise what they are doing is not teaching but spreading misinformation.
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