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    18 Jan '13 16:29
    We are told this happens,especially when galaxies collide.If an outside observer perceives time progressivly slowing for something falling into a Black Hole, then what will an outside observer see when two Black Holes come togeather?
  2. Standard memberfinnegan
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    18 Jan '13 23:05
    Originally posted by OdBod
    We are told this happens,especially when galaxies collide.If an outside observer perceives time progressivly slowing for something falling into a Black Hole, then what will an outside observer see when two Black Holes come togeather?
    Two black holes coming together is what they will see.

    Time and space inside each black hole may be distorted, but outside of their edges, here in the good old cosmos, things are not distorted
  3. Joined
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    19 Jan '13 01:25
    Originally posted by finnegan
    Two black holes coming together is what they will see.

    Time and space inside each black hole may be distorted, but outside of their edges, here in the good old cosmos, things are not distorted
    I thought that outside observable time changes near any large gravatational body,this being the case the effect would be progresive and large long before the edges came into contact.
  4. Subscribersonhouse
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    19 Jan '13 22:07
    Originally posted by OdBod
    I thought that outside observable time changes near any large gravatational body,this being the case the effect would be progresive and large long before the edges came into contact.
    We don't really know what goes on inside a black hole and may never do so since its like a roach hotel, you check in but you can't check out. So two black holes collapsing on themselves would have effects internally we cannot access so can only theorize about. For instance, if black holes are as some theories go, a door that converts the mass inside to energy and then starts up another universe, a daughter universe then two black holes colliding might have really strange implications for each daughter universe, since if they each one have generated a daughter universe, there could be some kind of double 'explosion' ripping into those daughter universes.
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    19 Jan '13 22:28
    Originally posted by sonhouse
    We don't really know what goes on inside a black hole and may never do so since its like a roach hotel, you check in but you can't check out. So two black holes collapsing on themselves would have effects internally we cannot access so can only theorize about. For instance, if black holes are as some theories go, a door that converts the mass inside to ener ...[text shortened]... verse, there could be some kind of double 'explosion' ripping into those daughter universes.
    Thanks for your input but was thinking more in terms of what an external observer would see as the two edges or event horizons came together given that from his perspective time slows and virtually stops at that point.You see where I'm going with this, will an external observer ever be able to witness such an event? Any thoughts on this?
  6. Standard memberapathist
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    21 Jan '13 10:55
    I think they just, you know, make a bigger black hole.
  7. Subscribersonhouse
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    21 Jan '13 11:531 edit
    Originally posted by apathist
    I think they just, you know, make a bigger black hole.
    Yeah but there would be several things happen for sure. Any matter in the vicinity would flare up converted by E=MC^2 into mostly gamma radiation (which would be invisible but if you were close that would be the last thing you would 'see'😉
    and a spike of gravitational radiation that might produce the first hit from the various gravity wave detectors around the world, like LIGO:

    http://en.wikipedia.org/wiki/LIGO
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    21 Jan '13 22:22
    Originally posted by sonhouse
    Yeah but there would be several things happen for sure. Any matter in the vicinity would flare up converted by E=MC^2 into mostly gamma radiation (which would be invisible but if you were close that would be the last thing you would 'see'😉
    and a spike of gravitational radiation that might produce the first hit from the various gravity wave detectors around the world, like LIGO:

    http://en.wikipedia.org/wiki/LIGO
    I wonder if the time dilation question at the point of impact will have consequences for E=MC^2 as there is a time element within the equation?
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    22 Jan '13 04:24
    Originally posted by OdBod
    We are told this happens,especially when galaxies collide.If an outside observer perceives time progressivly slowing for something falling into a Black Hole, then what will an outside observer see when two Black Holes come togeather?
    probably wouldn't see anything more than possibly the light from stars behind them bending in toward them with exception of light passing between them going straight if the event horizons are not quite together yet.
  10. Subscribersonhouse
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    22 Jan '13 11:312 edits
    Originally posted by OdBod
    I wonder if the time dilation question at the point of impact will have consequences for E=MC^2 as there is a time element within the equation?
    Time dilation would not effect us, from our POV the collision would take place at full speed. Inside, if you had an observer inside, it would be another story, time slowing down in an extreme bending of space that is the gravitation there leading to the thing never completing in the lifetime of the observer. Time only slows down inside a gravity well, for instance, atomic clocks are already accurate enough to tell the difference in the flow of time of two atomic clocks, one one meter higher than the other, the upper one ticking away slightly faster, so flatter space=faster time flow
    bent space=slower time flow.

    I should amend that to say time also slows down if your velocity increases and that is also easily measured by atomic clocks on board GPS satellites, for instance. So there are two competing forces, more than two but the major ones: up higher time goes faster, slightly, when you are in orbit doing 8 km/second. But doing 8 km/second also causes your flow of time to slow down so it is the difference between the two competing effects that the atomic clock picks up, which sends the proper pulses to earth so your GPS, which has relativistic computational ability, can figure out your location within a few feet. Another competing effect that reduces the accuracy of GPS signals is the slight changes in refractive index of the atmosphere, slightly changing the velocity of radio waves, enough to give a small error in the GPS calculations. I think GPS signals would be more accurate on the moon, for instance, since there is no atmosphere to introduce refractive index effects. How much more I don't know.
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    24 Jan '13 18:55
    Originally posted by sonhouse
    Time dilation would not effect us, from our POV the collision would take place at full speed. Inside, if you had an observer inside, it would be another story, time slowing down in an extreme bending of space that is the gravitation there leading to the thing never completing in the lifetime of the observer. Time only slows down inside a gravity well, for i ...[text shortened]... since there is no atmosphere to introduce refractive index effects. How much more I don't know.
    So, if time slows donw the more space is "bent" then technically earth could be older than the sun?
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    24 Jan '13 19:14
    Originally posted by tomtom232
    So, if time slows donw the more space is "bent" then technically earth could be older than the sun?
    If you mean as measured by a clock on the surface of the sun relative to a clock on the surface of the
    earth then yes...

    If it were not for the fact that the effect is tiny, and the sun formed significantly before the earth did...
    as in millions of years.

    A difference that would utterly swamp any effect of general relativity, even over multi billion year time-scales.
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    24 Jan '13 19:25
    Originally posted by OdBod
    We are told this happens,especially when galaxies collide.If an outside observer perceives time progressivly slowing for something falling into a Black Hole, then what will an outside observer see when two Black Holes come togeather?
    If you were floating in space looking at an object falling into a black hole then you would see the
    object slowing and reddening as it got closer and closer to the event horizon.

    This happens because the closer it gets to the black hole event horizon the more stretched space
    becomes and so the longer it takes for a photon to climb out of the gravity well and reach your eye/camera.

    Light takes longer and longer to escape the combined gravities of the object and the black hole until
    the object reaches the event horizon at which point the light takes infinity time to reach you.

    So you never "see" an object reach or cross the event horizon.



    However for two black holes merging, what you would see is incredibly complicated.

    Space would be incredibly distorted as the two black holes spiral in towards each other leading to all kinds
    of lensing effects and distortions with the event horizons of the black holes wobbling and distorting and
    eventually merging.

    To see what it would look like would require enormous amounts of computing power to simulate.

    However it would definitely not take forever.

    http://www.astro.cardiff.ac.uk/research/gravity/tutorial/?page=4blackholecollisions

    Has a little bit on the topic.
  14. Subscribersonhouse
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    26 Jan '13 13:10
    Originally posted by googlefudge
    If you were floating in space looking at an object falling into a black hole then you would see the
    object slowing and reddening as it got closer and closer to the event horizon.

    This happens because the closer it gets to the black hole event horizon the more stretched space
    becomes and so the longer it takes for a photon to climb out of the gravi ...[text shortened]... f.ac.uk/research/gravity/tutorial/?page=4blackholecollisions

    Has a little bit on the topic.
    We may see such a simulation if we get quantum computers going bigtime. Not sure exactly how much computing power it would take with classical computers but I know they are clocking in at 17 petaflops right now and every year that number gets bigger. So we should start calling it .017 EXAflops which is the next big goal, exaflop computing.
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