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Plans To Peer At A Black Hole's Event Horizon
mattorb writes: "From the press release: "Scientists have designed and succesfully tested a new type of X-ray telescope that, when fully developed and placed in orbit, may capture the first images of a black hole and resolve images of nearby stars as clearly as we can see our own Sun today. The report is published in the Sept. 14 issue of Nature."
Go here for more information on the project, which is known as the Micro Arcsecond X-ray Imaging Mission. Note that the proposed MAXIM mission would launch after 2010."
I may be wrong (so all those astophys grads can correct me if they want) but I don't think Hawking radiation works quite like that.
What happens is you have virtual partical pairs (a partical and anti-partical) which blip into existence and then anialate soon after. They have very short lives. However, if a pair form on the event horizon, one half gets drawn into the hole while the other gains the same (but opposite) energy and is ejected out into space.
That was how I understood it, but if I'm talking out of my 'black hole' feel free to correct me.
By the way, always try to reference quotes where the origin isn't obvious, couldn't find your quote on the MAXIM website so I presume you got it from somewhere else.
Paul Leader
I don't know how relevant this is, but we just had an article (too lazy to link, sorry) about how the speed of light barrier was broken (by light, ironically). If this is true, doesn't it shoot many physics theories down the drain? And if so, how would if affect this one?
You mean this article? It wasn't really light travelling faster than light at all, merely an effect due to the fact that the pulse of light has a leading edge which travels ahead of it. When this leading edge hit the target, the entire pulse was recreated and transmitted from the other side of the caesium target.
Whilst it looked like the speed of light barrier was broken, it wasn't really, it was just a cunning effect. Whether this effect could be used to transmit information faster than light is unknown - it depends on whether this leading edge can hold information or not.
As for tachyons, well they always travel faster than light and indeed speed up as they lose energy - a tachyon with zero energy would travel at infinite speed!
When a star collapses the matter begins to implode upon a point, eventually crossing the point where the escape velocity becomes greater than the speed of light and a black hole is formed. The edge of this black hole is what we call the event horizon - anything passing within the event horizon cannot ever escape. The simple solution is described by the Schwartzchild metric.
The matter however is still collapsing to a point at the centre of the black hole. According to general relativity there is nothing to stop this collapse and we end up with a point of infinite density and zero volume - a singularity.
However when you come to rotating black holes (described by the Kerr metric) there are differences. The angular momentum of a collapsing star is conserved, and this causes the black hole's event horizon to bulge out along the equitorial plane, much like the Earth has a slight bulge around its equator. Indeed, the central singularity itself forms a torus rather than a point when the black hole is rotating.
As angular momentum is increased this bulge gets bigger and the polar size of the event horizon shrinks, until eventually you are left without an event horizon at all, but just a torus-shaped singularity, which is said to be "naked".
Of course, whether a naked singularity can ever exist is an open question. There is something called the "Cosmic Censorship Principle" which states that the laws of physics will never allow a naked singularity to form, but the final answer is "we don't know".
Also of interest is that since the naked singularity would be in the shape of a torus you could theoretically pass through the centre of the torus and find yourself somewhere completely different, possibly even in another universe!
For a fairly technical intro to black holes and singularities, see this article at suite101.