Black Hole Observed by X-Ray Satellite 143
eldavojohn writes "Scientists at JAXA and NASA used the Japanese Suzaku satellite to collect data and observations at a distance nearer to a black hole than we've ever been. From the article: 'The observations include clocking the speed of a black hole's spin rate and measuring the angle at which matter pours into the void, as well as evidence for a wall of X-ray light pulled back and flattened by gravity. The findings rely on a special feature in the light emitted close to the black hole, called the "broad iron K line," once doubted by some scientists because of poor resolution in earlier observations, now unambiguously revealed as a true measure of a black hole's crushing gravitational force.' Suzaku also has been providing images and data of super novas and their activities. It's always nice to see national space agencies working together, it almost gives me hope that the world might one day be united in space exploration."
Getting closer.... (Score:3, Interesting)
Re:Serious Question (Score:2, Interesting)
Broad iron K line (Score:2, Interesting)
Re:Serious Question (Score:3, Interesting)
'No space between the smallest particles' is basically what a neutron star is. It's essentially a mass of neutrons edge to edge, held up by the quantum-mechanical requirement - the exclusion principle - that no two particles can occupy the same quantum state.
However, there's a limit to this state. In general relativity, mass isn't the only thing that produces gravity: pressure does too. Pile on extra mass to a neutron star and its gravity increases - and so does the internal pressure. The upshot is that the pressure approaches infinity at about five solar masses; the neutron star can only collapse (the actual limit may be much lower, last I heard it wasn't precisely known).
Thus if general relativity is correct there's nothing that can prevent the total collapse of a five-solar-mass neutron star. Propose a force that can resist it, and it can only do it by upping the pressure still further, and hence the gravity it must oppose... The star collapses to zero volume and infinite density, the notorious singularity hidden inside the event horizon.
All that said, though, it's probable that the star does not reach zero volume. General relativity is known to be unreliable on the very small scale of quantum mechanics, and quantum mechanics is known to be unreliable where very large masses are concerned, so the applicable physics when you compact five solar masses to a volume smaller than an atom is anybody's guess...
Common Misconceptions about a Black Hole (Score:2, Interesting)
So why do black holes emit X-rays and Hawking radiation or why do they emit stuff at all?
The black holes don't emit anything per se. However, as particles close to the event horizon are accelerated more and more by the gravitational pull of a black hole, THEY can emit radiation. An illustrative model is a star/black hole binary system in which gases from the star are being pulled in to the black hole, thus emitting X-rays as they are accelerated.
Hawking radiation is also not really emitted from the black hole itself. Theory goes quantum fluctuations occur so close to the event horizon that one particle gets sucked in while the other escapes: imagine a positron-electron pair appearing right on the cusp of an event horizon. Let's say the positron disappears into the black hole while the electron escapes out into the universe. From our perspective, the electron will have been "emitted" from the black hole. The energy required for this is also taken from the black hole as the positron (think of it as negative energy) will go into the black hole and take that much energy away from it.
Re:Serious Question (Score:5, Interesting)
Electrons, neutrons, and so on don't really exist as volumes, but rather as forces. Think about a balloon filled with air; it takes up space, but the only reason it does is because of the pressure of the air inside pushes out on the surface.
Now, if you squeeze the balloon, it'll shrink. The more you squeeze, the smaller it gets. If you could squeeze as hard as you please, you can continue to shrink the balloon smaller and smaller.
Particles are like that. Gravity is unique in that it's a force that can get infinitely strong, so it can overcome any other force, and squeeze everything together down to an arbitrarily small point.
Interestingly, from the perspective of a star collapsing into a black hole, it never actually quite makes it, as time slows down as gravity becomes stronger. It's like Zeno's paradox: If you try to go from point A to point B, crossing half the distance each time, do you ever get there? Intuitively, you'd think no, but if you take an infinite number of steps, yes.
In other words, black holes, from the perspective of the black hole, take forever to collapse down to a singularity. However, from our perspective outside the black hole, the singularity forms essentially instanteously, as our subjective time speeds up relative to the black hole's subjective time.
(As a side note, we don't have a theory of quantum gravity, so we don't actually know what the absolute center of a black hole is like, but we do understand the physics up to and past the event horizon, all the way to the singularity, all of which is just subject to general relativity. All the effects with astronomical significance occur outside the event horizon, as information that goes past there is effectively meaningless.)
Re:Whiney Liberal Comment (Score:3, Interesting)
More bullshit whiney rhetoric from the left.
What in that sentence gave you the impression that the author even supports high taxation of the rich to fund comprehensive public services, let alone workers' control of the means of production?
At any rate, you seem to have overlooked the word 'always' in the sentence, which strongly implies the existence of other cases of international cooperation in space. Such cooperation is always nice to see. Or perhaps you think it's a bad idea?
Re:Serious Question (Score:1, Interesting)
Re:Question about black holes (Score:3, Interesting)
The basic principle is that things are spinning. In the case of a galaxy, the whole thing would originally have formed from a collapsing gas cloud. This cloud would have had some small overall spin, which would be magnified during collapse by conservation of angular momentum (try it yourself: hold a brick in each hand, spin around and around as fast as you can with your arms outstretched, then quickly pull in your arms and hold the bricks to your chest...) So you've now got a smaller ball of gas which is spinning quite fast. Now it should be obvious how it flattens out: the spin stretches it at the equator, gravity collapses it at the poles, and before long you've got a disc.
As for black holes, that's spin again, but it works a little differently. Black holes are so powerful that they drag space itself around with them, and infalling matter really has no choice but to fall in line over the equator...