Slashdot Mirror
Deep in the Core
meehawl writes "A video of what is currently thought to be the closest star to the supermassive black hole at the centre of our galaxy. The star orbits the black hole in a highly elliptical orbit with a period of 15 years or so, but at its closest approach it swings within 17 light hours of the black hole (around three times the distance between the Sun and Pluto). In the video, you can see the star ricochet past its closest approach to the black hole. This slingshot effect enabled astronomers to further pinpoint the mass of the black hole, which is confidently estimated at 2 million suns or so. The mass observation, coupled with the size constraints observed, indicates the object at the centre of the galaxy is definitely composed of some exotically dense form of matter."
As they note, there remains now the mystery of how they got so much mass to concentrate in one place. Stars don't forget all about conventional orbital dynamics just because they've spotted a black hole somewhere not too far off.
While the idea of black holes, dark matter, etc seems intringing, it is still a lot of theory. It is nice to see that people haven't given up, but that's not to say that this article is just as much speculation as the next.
With that said, wouldn't it be nice to focus all of humanities efforts on answering the questions we don't yet know the answers for ... instead of killing each other? I know that we already have the answer, but 42 only answers the ultimate question, we can't even answer the simple things like "do black holes exist?"
Ignore the "p2p is theft" trolls, they're just uninformed
You'd be surprised how much scientific research is sponsored by DARPA (in the States, of course). While it's likely that this particular piece of research was not, in general DARPA funds a lot more than NSF. In other words, "killing each other", to a certain extent, drives scientific research. "killing each other" gave us the IP stack of protocols, for instance ...
The Raven
The Voyager I is currently at a distance of 95 AU. 122 AU could be the distance from the sun to the heliopause.
Take a look at the original press release, dated 16 October 2002.
The article was published in Nature at the same time, and the video isn't new either.
Remind me why this is going up on Slashdot today?
There is no center of the Universe!
"But if it's expanding, it must be expanding _from_ somewhere, right?"
No, not in any observable way.
The best analogy I've got for this is to think about the surface of a balloon. This surface is a curved, 2-dimensional space--if you were a 2-D inhabitant on the surface, you would not know about its curavture. If you had tiny markers on the balloon, as it inflated they would become more distant from each other. There is no 'center' to your 2-D world, the space between the markers is itself expanding, because your 2-D surface is being expanded into the extra 3rd dimension.
Similarly, there is no center to our 3-D world. It is, in a sense, expanding into a 4th dimension, and the space between galaxies is increasing as a result. This is somewhat of a misnomer ('4th dimension'), but it gets the point across.
The only reason galaxies, planets, etc. (all matter) don't expand along with this is the effect of the elemental forces. Gravity, Electromagnetism, and the Strong Nuclear force all pull stuff together at certain scales, thus clumping matter together depite the expansion of space.
And yes, IAAAP (I Am An AstroPhysicist)...or at least an astrophysicist in training.
Actually, there is some recent debate as to whether or not the milky way galaxie is a spiral galaxie. Some astronomers think it has a different shape, something like a bar if i recall correctly.
It looks like all the observations, measurements, analyses and even the 'press embargo' are over three years old. Are there any updates?
Kevin Fox
17 light hours is roughly 113 AUs, if the star passes that close to the black hole, I wonder if the line of the node of the orbit will precess forward enough to measure due to the frame dragging from the spin of the black hole. That would also help prove it's a black hole. The spin of the black hole should be pretty fast since if formed by capturing matter in orbit. The Einstein "Gravity Probe B" tried to measure the same affect in earth orbit but it's so tiny in the Earth's case, a 2 Million Ms black hole would have a big frame drag effect. I guess it comes down to whether the star gets close enough and long enough to get dragged much. http://einstein.stanford.edu/ Mark
In order for the balloon analogy to be correct, you must take into account that the inhabitants are entirely 2-D. They can only look around on x & y axes. The 'up-down' (or 'centerward-anticenterward') z axis has no meaning to them, just as a fourth axis is mentally and visually inconceivable for us. (Draw x, y, and z axes. Now draw an axis perpendicular to all three...yeah.) They have no ability to look 'through' the balloon, just as we have no ability to look into our '4th axis'.
On the balloon, the 'universe' is an observationally 'flat', 2-D plane...for us, the universe is a 'flat', 3-D space. At long enough measuring distances, you might detect some hints of curvature, such as the angles in a triangle adding to less than 180 degrees. This would indicate the degree of curvature, but again would have no directional significance.
We actually think we know rather well how fast the universe is expanding. It's called the Hubble Constant, and is generally accepted to be 'around' 2/3 * 100km s^-1/Mpc. In other words, objects 1 Megaparsec apart will be moving away from each other at about 66km/s.
Measuring is one thing. Finding a center is another. If you imagine that the universe is actually smaller than the distance light has traveled since its first emission, then when we look out in any direction, we may actually be seeing ourselves (far, far away). How do you place a center of the universe when you can look out and see the back of your own head? Especially when everything is constantly moving.
I'm starting to meander now...time for my hour of sleep before classes. X_x