Slashdot Mirror
More Blackholes Discovered...
Lispy writes "Space.com has this story about the surprising finding of missing blackholes. There might be up to five times more blackholes in space than previously estimated.
"The European Southern Observatory in Munich, Germany reports that the black holes were all in "active" galaxies, meaning they were actively consuming large quantities of galactic matter.""
Although some say that these black holes account for the "missing matter" that is needed for the universe to gravitationally collapse upon itself some hundreds of billions of years in the future, current analysis shows that the mass of all black holes are less than one trillionth of the mass of the universe.
Even if there are a thousand more times the number of black holes out there, it still won't account for the so-called "missing mass".
Of course, there could be many million times more black holes out there. Or some other large masses that we have yet to find. In any case, this 2-to-5 times the number of black holes isn't the (possible) mass we're looking for.
As far as we know, black holes result from the collapse of a star. They don't just "appear" for no reason. The new ones discovered were obscured by their accretion disks and the torus of gas and matter surrounding them.
:)
That's like saying what if dead bodies suddenly started appearing everywhere - without there having been live people first. Corpses don't just "appear" out of nowhere, they have to be made
-- You are in a maze of little, twisty passages, all different... --
Um, antimatter doen't gravitationally repel. Maybe that's why you put the word in quotes? Anyway, the acceleration of the universe is already explained by the gravitational repulsion of dark energy.
Incidentally, theory does not predict that galaxies should be expanding. It predicts that distant galaxies should stay the same size (being gravitationally bound), but should expand away from each other, which they are.
Occam's Razor
"Occam's razor is a logical principle attributed to the mediaeval philosopher William of Occam (or Ockham). The principle states that one should not make more assumptions than the minimum needed. This principle is often called the principle of parsimony. It underlies all scientific modelling and theory building. It admonishes us to choose from a set of otherwise equivalent models of a given phenomenon the simplest one. In any given model, Occam's razor helps us to "shave off" those concepts, variables or constructs that are not really needed to explain the phenomenon. By doing that, developing the model will become much easier, and there is less chance of introducing inconsistencies, ambiguities and redundancies."
Don't make things more difficult then they have to be. Black holes are the simplest explanation. Anti-matter and anti-gravity is a more complex explanation than what is possibly needed.
"There is a way that seems right to a man, but its end is the way of death." Proverbs 16:25 (NKJV)
RTFA:
The idea of a black hole 'sucking' things in is wrong. If our own sun was to turn into a black hole, the planets wouldn't suddenly get ripped out of their orbits and inexorably dragged (kicking and screaming) into it. Black holes, like all other massive accreting objects, have to wait for stuff to come their way. At the center of a galaxy, where matter is denser (more stars, more gas), things around the black hole can get involved in a massive traffic jam. The losers are sent by collisions or gravitational interactions on orbits straight towards the hole. Eventually the hole eats so much of the traffic that there's no longer a traffic jam. The objects orbiting around it don't interact with each other enough to get sent towards the hole, and the hole is now on a strict diet. This is the state of our own Milky Way. If our galaxy were to collide with another, a density wave of stars and gas might get sent towards the black hole, and it would start to eat again. So, yes, there are active and passive black holes.
"I'm so moist I'm sticking to the leather." -Kermit the Frog on The Late Late Show
What the other guy said. I believe they also emit various sorts of radiation.
Some other neat stuff: near black holes, there are pairs of little particles popping into existence, smashing into each other, and annihilating each other. If this happens at just the right point at the event horizon, the particles fail to annihilate each other -- one falls in, and the other goes shooting out into the universe.
If you look at the behaviour of some stars you can see that they are orbiting something massive. If its really massive and you can't see it, its probably a black hole. If an object is massive enough, and its not keeping itself spread out because of heat (like a star that has run out of fuel) it will inevitably collapse into a black hole. You can measure the size of some objects by how rapidly they flicker. If things change in a matter of hours, then the effect can be no larger that that number of light-hours across. If you also know the mass of the object (by how fast things orbit round it) you can calculate a minimum density. In many cases this works out at black hole density.
this is all just to outline
the real question. would i every reach the event
horizon, befor the univers came to an end?
Yes. You are only frozen at the event horizon from the point of view of someone distant from the black hole. Also, you are only frozen there for a short while in practice. The light by which they could see you would be red shifted by gravity until pretty soon you are invisible.
From your point of view, you fall in in finite time.
Remember, relativity does not guarantee synchronicity. A black hole produces the ultimate split in synchroncity: From the point of view of an outsider, you don't fall in. From your point of view, you do. The paradox is resolved because even for the outsider, you become invisible and undetectable except as a mass increase in the black hole.
Whoops, whack my third paragraph. Wikipedia says it all better and probably more accurately.
This is yet another example of a non-story story. 99.9% of all astronomers would have told you before this story that these active galaxies had big black holes. We would have also pointed to other results (from Hubble) from the last 5 years or so that have clearly indicated that essentially ALL massive galaxies -- active or not -- harbor black holes in their cores about 1/1000 as massive as the bulge component of the host galaxy. I've been saying this to my classes and in seminars for years. I'm not saying this isn't a nice project, seeing the waste heat from the active core, but it's a confirmation not a "discovery of new black holes." Sheesh.
Professor of Astronomy, Author of Spider Star & Star Dragon (Tor)