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A Recipe For Black Holes
hozzies writes: "This article at Space.com explains why black holes are "relatively nearby in cosmic terms... [but] don't seem to be eating much these days." This phenomenon has fascinated both scientists and the general public since it was first theorized. It explains a big chunk of the early universe—that is, if we can every prove they exist in the first place."
One of the problems with many studies of Black Holes is that nobody really knows what to look for. Despite many attempts, nobody has actually detected the only definitive proof of a Black Hole, Hawking Radiation.
Many things in space emit X-Rays and Gamma Rays. Some are even "brighter" than Black Holes. There have even been a few events comparable in energy to the Big Bang itself. Also, the requirements for a Black Hole to form are somewhat extreme. You need to -start- with a star of greater mass than Chandrasaker Limit, which is about 3 solar masses. Following the death of the star, the gravitational attraction has to overwhelm everything else. ie: A star that gets ripped to shreds by a nearby massive object is unlikely to form a Black Hole.
Hawking Radiation is radiation which results from virtual particles on, or just outside, the Event Horizon splitting up. This causes the Black Hole to "radiate". This "radiation" will, in theory, eventually cause Black Holes to evaporate. (This is a requirement of Quantum Mechanics, which prohibits any point in space from having no entropy.)
Until this radiation is detected, most suspected Black Holes are just that - suspected, not determined. Now, there are a few objects that can reasonably be assumed to be Black Holes, simply because it is possible to show that there is a massive, dark object being orbited by a star that is being literally vaccuumed out of space. There isn't much room for doubt, in such cases.
But they seem to be finding Black Holes everywhere. If you count all the "missing mass", Black Holes, and other alleged particles, you'll probably end up with 900% of the mass of the Universe. Ummm.... sorry to break it to you astronomer guys, but 100% is the limit. :)
It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)
The problem with spacetime extrapolations like black holes, wormholes, etc... is that the physicists who come up with those theories have no clue as to the actual physical mechanisms that give rise to the phenomenon we abstractly refer to as spacetime curvature. They just know that things fall at a certain rate near massive bodies and that clocks slow down in a gravitational field. From that limited understanding, they feel they are knowledgeable enough to extrapolate all sorts of cockamamie and unfalsifiable theories that are only fit for star-trek episodes.
Kip "Wormhole" Thorne, Stephen Hawking & co claim that, according to their understanding of spacetime and relativity, it is possible to travel in time in principle. The amazing truth is that nothing can move in spacetime, by definition! Spacetime is frozen from the infinite past to the infinite future. So much so in fact that Sir Karl Popper compared Einstein's spacetime to "Parmenides' block universe" in which nothing ever changes. This says a lot about their supposed undertanding of spacetime, IMO. Time travel is pure crackpottery. If you are gullible enough to swallow physics from people who treat time travel as a worthy subject of physics, I've got a bridge to sell you.
every [sic] prove they exist in the first place.
For something to be provable in science it must be testable everywhere. Black holes, _by definition_ devour all light [information] that crosses the event horizon, and anything outside the event horizon isn't part of a black hole. Black hole can never be "proved" in the traditional sense, but that doesn't stop people from accepting that the overwhelming amount of circumstancial evidense, none of the info proves black holes, but the only thing that could do all of the proof is black hole [the proofs i'm talking about, are the light curvature around them, x-ray jet streams, and other random stuff like that.
Only dead fish swim with the stream...
Ingredients: One supermassive star.
Instructions: Bring star to critical mass over a period of fifty thousand years. When the star begins to expand, add 200 billion billion tons of mass to augment its collapse.
The star should collapse in upon itself within the next ten to twenty thousand years. Test for event horizon by placing a small mid-sequence star nearby and observing the accretion disk.
Serves as many people as you can fit in it.
Honorary Member of Jackie Chan's Kung Fu Process Servers
Neutrino mass at google.
On a side note I think I first read about it in scientific american. As some of the dates will tell you this isn't a new development, so I don't know the issue. Maybe this was it. A neutrino, or at least 1 flavor, tips the scales at a svelt .1 eV. I should figure out how many eV's I wiegh in at....or maybe I should have some more ice cream.
--Jimmy has fancy plans; and pants to match.
Minture black holes have odd properties. Thanks to virtual particles and the immutable laws of thermodynamics, black holes radiate energy. A breeze of virtually virtual (but not quite) particles. This is of course at the expense of their own mass. That's certainly not news, not even in the discussion of this article. However, the odd part is a small black hole is more likely to capture only one of the particles than is a larger black hole (which will likely capture both). So much so, in fact, that a black hole with the mass of a mountain and the size of a proton would make a very impressive explosive. (E=mc^2 where m is the mass of a mountain, tends to be a fairly substantial number) For comparison, a larger black hole, say of about 3 solar masses, might take 10^60 years to waste away. (I would check my guesstimations, but it turns out I'm fantastically lazy.) But aside from thowing off a pretty decent storm of random particles, a black hole, even with the measily mass of a mountain, would affect the matter around it. Sure on the small scale electrons wouldn't really care about the gravity, but on the larger scale that gravity could be pretty significant. Then black holes can have charge, so when it eats an electron, it then attracts a positively charge particle due to the charge etc. (I would also guess that a black hole would never acquire color charge as the other of the color charge pair would certainly be swallowed as well) But this doesn't really matter, because all the micro black holes have long since gasped their last. I for one don't see us making any black holes with any sort of real life span within the next few millenia. (I'm usually hesitent to prognosticate more than three millenia in advance.) Anyhoo I feel quite comfortable packing this in the same box with Schroedinger's Cat, Parallel Worlds, and other thought experiments. But who knows, with a quantum theory of gravity, they might suddenly become very interesting to think about, and worthy of dusting off.
--Jimmy has fancy plans; and pants to match.
Black holes are pretty well accepted to exist, in a multitude of flavors I might add. There is a wealth of evidence from many sources that pretty well prove it. If the author means proof in the sence of walking up to the edge and tossing a star in, well grow up. Abstraction isn't a four letter word. I can't see an atom with the naked eye either, but their existance is quite certain from infered information. Sure, this information is pretty direct. But Rutherford's inferance of nuclei at the center of atoms in a sheet of gold is about the level of proof we've got for black holes. What are they like at the singularity? Well that's the realm of science yet to be invented. I think there's a place for scepticism, but this isn't it. Couldn't time be better spent disproving moon landings? For love of god, Hawking already paid off that bet. Black Holes are real, because you can't return a subscription to Penthouse.
--Jimmy has fancy plans; and pants to match.
Actually fairly recently both measurements of space-time dragging effectsas well as the accretion disk around several black holes. Plus the BH at the center of our galaxy has recently been pinpointed by observing several start orbiting around it waiting to be gobbled up. This pretty much makes them an observational reality
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You can find the articles here:
http://web.mit.edu/newsoffice/nr/1997/blackhole
and here:
http://cfa-www.harvard.edu/blackhole/release.ht
and here:
http://www.space.com/scienceastronomy/astronomy
----- In Your Cubicle No One Can Hear You Scream...
Now, I think science is good, and I think teaching children is good, and I think this article is good for that, sure. Anyone really expecting it to be anything more than that, though, is just plain deluded. I mean, c'mon, you can't possibly write a serious article about the current thinking on black holes without using the words "accretion disk," "Cherenkov radiation," or "spacetime curvature."
In short, there's nothing there that's not available in a children's book of 25 years ago. I could probably, with a little effort, even dig up the children's book I read all of that in about 25 years ago.
-- Robert Bunn, gun-toting neo-Nazi anarchist redneck freak
As long as massisive black holes are on the table, I was wondering about the other end of the scale.
A long time ago I picked up a book that listed among some theoritical objects in space, the object that stood out in my mind was the idea of a miniture black hole. This would be a black hole that lost a majority all its mass do to energy given out by spin or some other force and flying through space, it would have nothing gobble up to help increase its size. It listed some intersting properties if I remember correctly, like the ability to fly through matter supposidly without effecting it. Its been a very long time since I read about them and I was wondering if anybody intersted in black holes has heard anything about them.
Thanks!
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