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Question on how stars are located

  1. Apr 4, 2012 #1
    Just a thought - does the universe have the equal of a refractive index so to speak, to measure where stars are, due to gravity curving spacetime.

  2. jcsd
  3. Apr 4, 2012 #2
    Oh and why can't we see the things trapped inside a black hole?
  4. Apr 4, 2012 #3
    Jesus, ofcourse its cause the light can't even escape. So it can't reach us. Duh
  5. Apr 4, 2012 #4
    because there's no way for light to escape from the event horizon of a black hole. Light goes in, does not come out, therefore we don't see anything.
  6. Apr 4, 2012 #5
    I heard that at the bottom of the black hole there is only light, what would the light look like? Would it just be like light say from a bulb?
  7. Apr 4, 2012 #6
    I'm pretty sure it's impossible for us to say anything about the insides of a black hole since it is impossible for information to go between there and here. Our physics probably does not work beyond the event horizon therefore we can't do anything but speculate.
  8. Apr 4, 2012 #7
    Wow, so if it was not impossible, we could theoretically need a whole new set of laws of physics. Thats crazy. So even information cannot escape? What would you define as information?
  9. Apr 4, 2012 #8
    well you know that an object is moving because you can see it moving over time, the light travels from it to your eyes and you see that it moves. If something was in a black hole and doing stuff, there would be no way to know it was doing those things because no light could get out of the black hole.
  10. Apr 4, 2012 #9


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    A few things here. First, to answer your question, according to my understanding the refractive index of interstellar space is NOT equal. The gas and dust affects the light as it travels. One of the consequences of this is that certain frequencies of EM radiation from pulsars and other events arrive at different times, requiring us to account for this when measuring these events. For simple pictures the effect isn't that severe. Our current instruments are limited more by diffraction than by the interstellar medium. What this means is that we still have plenty of ways to go before our telescopes are so big that the ISM becomes a major factor.

    As for black holes, our current laws work fine until they get near the inside of the black hole near the center, where the math starts to produce infinities and nonsense. This area is called the "singularity". By information we mean things like the charge of infalling particles or other properties.
  11. Apr 6, 2012 #10
    Thanks, you've cleared up quite a few things there.
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