Um, I believe I saw something similar to this posted on Slashdot or somewhere else in the recent past. It had to do with the German law that the/. post mentioned. Appartently, in Germany, they put a tax on media like this because it is LEGAL to make as many copies as you want of music or other content. Basically copyright as we know it in the US just doesn't exist over there, or it is in a much weaker form. The tax, as I understand it, is meant to compensate artists IN LEIU of copyright protection.
-white dwarf
For everything that you ever wanted to know about X-ray novae, and a sketch of the evolution of the Disk Instability Model (DIM), go
here. Its a technical journal article, but it has a very nice introduction that is almost understandable by someone who is unfamiliar with the field.
Also, because I am strangely compelled to come to the defense of the/. submitter, I think he might have been thinking of white dwarf novae, which fall under the category 'cataclysmic variables', when he was talking about fusion as the source for these x-ray novae. In cataclismic binaries, fusion is the main source of energy. The surface of the white dwarf builds up hydrogen quiescently until it reaches a breaking point, and then the whole thing ignites fusion at once, and goes off like a giant nuclear bomb.
-white dwarf
The problem with that is that the ISS and Mir are in very different orbits. I forget which is which, but I read somewhere that one is in an orbit that is inclined 30-something degrees to the equator, while the other is 50-something degrees. It would be excedingly difficult to send the shuttle up to one of the stations, and then shift its orbit so that it could link up with Mir. The shuttle and the stations are moving so fast up there, that the change in momentum required would almost warrant a whole extra rocket-full of fuel. Its a nice idea, but it just couldn't be done, unless you wanted to incur the cost of sending an empty space shuttle directly up to Mir, just for the purpose of dismantling it and bringing it down.
Under the broadest theoretical models, this is possible. The universe could have an overall curvature, so that light emitted at one end of the universe would travel in a very large circle. To understand this, you can think about the two-dimensional analogue: a 2-d world existing on the surface of a sphere; the geometry of the universe would be non-Euclidean. (ie, if you draw a triangle on the surface of the sphere, the 3 angles would add up to more than 180 degrees).
There are two problems with this, however. (One is more trivial than the other.) First, if the circumference of this sphere is larger than (speed of light)*(age of universe), then we would not be seeing echos of our own galaxy, since the light wouldn't have had time yet to make an entire loop around the universe.
Secondly, and most importantly, all of our current experimental evidence seems to rule out the possibility of a curved universe. By studying the Cosmic Microwave Background (CMB), (as well as using other methods) astronomers can determine all sorts of things about the large scale structure and nature of the universe. Most recent observations point toward a universe that is "flat", rather than curved. One of these recent results came from the Boomerang team, which I believe was reported by/. a few months ago. So basically, the normal, euclidean geometry that we love so much really is correct. Two beams of light that are emitted parallel to each other will stay parallel.
So, to sum up, while it is theoretically possible that the universe is curved and not infinite, fewer and fewer scientists acually believe it anymore.
Slashdot Mirror
Um, I believe I saw something similar to this posted on Slashdot or somewhere else in the recent past. It had to do with the German law that the /. post mentioned. Appartently, in Germany, they put a tax on media like this because it is LEGAL to make as many copies as you want of music or other content. Basically copyright as we know it in the US just doesn't exist over there, or it is in a much weaker form. The tax, as I understand it, is meant to compensate artists IN LEIU of copyright protection.
-white dwarf
For everything that you ever wanted to know about X-ray novae, and a sketch of the evolution of the Disk Instability Model (DIM), go here. Its a technical journal article, but it has a very nice introduction that is almost understandable by someone who is unfamiliar with the field.
/. submitter, I think he might have been thinking of white dwarf novae, which fall under the category 'cataclysmic variables', when he was talking about fusion as the source for these x-ray novae. In cataclismic binaries, fusion is the main source of energy. The surface of the white dwarf builds up hydrogen quiescently until it reaches a breaking point, and then the whole thing ignites fusion at once, and goes off like a giant nuclear bomb.
-white dwarf
Also, because I am strangely compelled to come to the defense of the
The problem with that is that the ISS and Mir are in very different orbits. I forget which is which, but I read somewhere that one is in an orbit that is inclined 30-something degrees to the equator, while the other is 50-something degrees. It would be excedingly difficult to send the shuttle up to one of the stations, and then shift its orbit so that it could link up with Mir. The shuttle and the stations are moving so fast up there, that the change in momentum required would almost warrant a whole extra rocket-full of fuel. Its a nice idea, but it just couldn't be done, unless you wanted to incur the cost of sending an empty space shuttle directly up to Mir, just for the purpose of dismantling it and bringing it down.
Under the broadest theoretical models, this is possible. The universe could have an overall curvature, so that light emitted at one end of the universe would travel in a very large circle. To understand this, you can think about the two-dimensional analogue: a 2-d world existing on the surface of a sphere; the geometry of the universe would be non-Euclidean. (ie, if you draw a triangle on the surface of the sphere, the 3 angles would add up to more than 180 degrees). There are two problems with this, however. (One is more trivial than the other.) First, if the circumference of this sphere is larger than (speed of light)*(age of universe), then we would not be seeing echos of our own galaxy, since the light wouldn't have had time yet to make an entire loop around the universe. Secondly, and most importantly, all of our current experimental evidence seems to rule out the possibility of a curved universe. By studying the Cosmic Microwave Background (CMB), (as well as using other methods) astronomers can determine all sorts of things about the large scale structure and nature of the universe. Most recent observations point toward a universe that is "flat", rather than curved. One of these recent results came from the Boomerang team, which I believe was reported by /. a few months ago. So basically, the normal, euclidean geometry that we love so much really is correct. Two beams of light that are emitted parallel to each other will stay parallel.
So, to sum up, while it is theoretically possible that the universe is curved and not infinite, fewer and fewer scientists acually believe it anymore.