Re: Just a new thought
Posted: Wed Jul 18, 2007 11:11 pm
you guys are mixing up three or four different things in astronomy...
the "light we see is teh gases on the edge of the event horizion of the black hole being superheated as tehy are sucked in" has little to do with our galaxy. while there is what is called a "complex radio source" at the center of the galaxy, it is nowhere near as powerful as what are called AGNs (active galactic nuclei). in some galaxies, so much matter is falling into the black hole in the middle with such speed that a MASSIVE amount of radiation is emitted. this simply is not the case for the milky way.
right now the best hypothesis states that there is likely a supermassive black hole at the extreme center of our galaxy, just as there is likely a black hole at the center of every galaxy. what I was taking issue with is the fact that in the drawing above, a significant number of the stars in the galaxy are ignored.
also, are you talking about human life? perhaps you could make the argument that humans wouldn't fare too well VERY CLOSE to the black hole, but that doesn't write off the possibility of life all together. we don't even know how to define life on OUR planet, much less for the whole galaxy.
not to mention the fact, as was pointed out a few posts up, that 343 said the effective range was 3 radii.
edit: what i think some of you are referring to is something called the "galactic habitable zone". ignoring the fact that this is a highly controversial concept to begin with (mostly because we have no idea what are the absolute minimum requirements for life), the zone has only a little to with radiation. the zone has more to do with the distribution of heavy elements, which are required for life on EARTH (so we assume they are required for life in general). in fact, the closer a star is to the center of a galaxy, the higher the concentration of heavy elements (due to the life-cycles of stars, etc).
while the concept states that we must be relatively far from the center of the galaxy due to radiation, the radiation is not entirely from the black hole. it is also from supernova, which i study at school, which go off in a given galaxy of our size about once or twice a century (we haven't had one go off in the milky way since 1604, and trust me, if one went off, you'd see it). anyway, it is silly to say that life can't exist in the center of the galaxy, we can't say that for sure.
the "light we see is teh gases on the edge of the event horizion of the black hole being superheated as tehy are sucked in" has little to do with our galaxy. while there is what is called a "complex radio source" at the center of the galaxy, it is nowhere near as powerful as what are called AGNs (active galactic nuclei). in some galaxies, so much matter is falling into the black hole in the middle with such speed that a MASSIVE amount of radiation is emitted. this simply is not the case for the milky way.
right now the best hypothesis states that there is likely a supermassive black hole at the extreme center of our galaxy, just as there is likely a black hole at the center of every galaxy. what I was taking issue with is the fact that in the drawing above, a significant number of the stars in the galaxy are ignored.
also, are you talking about human life? perhaps you could make the argument that humans wouldn't fare too well VERY CLOSE to the black hole, but that doesn't write off the possibility of life all together. we don't even know how to define life on OUR planet, much less for the whole galaxy.
not to mention the fact, as was pointed out a few posts up, that 343 said the effective range was 3 radii.
edit: what i think some of you are referring to is something called the "galactic habitable zone". ignoring the fact that this is a highly controversial concept to begin with (mostly because we have no idea what are the absolute minimum requirements for life), the zone has only a little to with radiation. the zone has more to do with the distribution of heavy elements, which are required for life on EARTH (so we assume they are required for life in general). in fact, the closer a star is to the center of a galaxy, the higher the concentration of heavy elements (due to the life-cycles of stars, etc).
while the concept states that we must be relatively far from the center of the galaxy due to radiation, the radiation is not entirely from the black hole. it is also from supernova, which i study at school, which go off in a given galaxy of our size about once or twice a century (we haven't had one go off in the milky way since 1604, and trust me, if one went off, you'd see it). anyway, it is silly to say that life can't exist in the center of the galaxy, we can't say that for sure.