1. Subscribersonhouse
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    17 Sep '08 20:58
    Originally posted by adam warlock
    One thing though: I forgot that while calculating the radius QM effects are already taken into account, so this gravitational collapse will be even stronger than the degenerate pressure cause by fermions.

    The radius is called Schwarzschild radius and is calculated by r=2Gm/c^2 where the letters have their usual meaning. Just for you to have an ...[text shortened]... mind a person. So say that you weigh 90Kg your Schwarzschild radius will be 1.483173*10^-27m.
    Whats the schwartzy radius of a proton?
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    18 Sep '08 07:03
    Originally posted by sonhouse
    Whats the schwartzy radius of a proton?
    Quite small. 🙂 and unstable.
  3. Standard memberadam warlock
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    18 Sep '08 11:061 edit
    Originally posted by sonhouse
    Whats the schwartzy radius of a proton?
    2.48076*10^-54m. Gulp this number doesn't even make physical sense... 😕
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    18 Sep '08 11:121 edit
    Originally posted by sonhouse
    Whats the schwartzy radius of a proton?
    Another question of the same type:

    If whole of the universe and all its mass were to be a giant black hole, what would the schwartzy radius be?
    Like the radius of a normal galaxy? Bigger? Smaller?
  5. Standard memberadam warlock
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    18 Sep '08 11:151 edit
    Originally posted by FabianFnas
    Another question of the same type:

    If whole of the universe and all its mass were to be a giant black hole, what would the schwartzy radius be?
    Like the radius of a normal galaxy? Bigger? Smaller?
    It's present day radius. 😉
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    18 Sep '08 11:301 edit
    Originally posted by adam warlock
    It's present day radius. 😉
    😵 Does this mean that it is impossible to know wheter or not we already is inside the radius of one gigantic black hole? Is the universe a black hole? Is everything a black whole?
  7. Standard memberadam warlock
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    18 Sep '08 11:42
    Originally posted by FabianFnas
    😵 Does this mean that it is impossible to know wheter or not we already is inside the radius of one gigantic black hole? Is the universe a black hole? Is everything a black whole?
    Actually I'm not that sure I gave you the right answer... 😕

    My fist thought was to do some kind of a very rough estimate of all the mass present and than just use that formula...

    But then it occurred to me what is the definition of a black whole and the whole Universe seems to fit right in. I'm too lazy to check my General Relativity and Cosmology course notes and book but from what I remember I don't see any reason why the whole Universe doesn't fit in the Universe of black hole.

    One way for you to notice that you are indeed in a black whole is for you to watch someone wlak directly into its singularity. Of course you'd have to know were the singularity lies and then convince someone to walk into it. 😵
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    18 Sep '08 11:56
    Originally posted by adam warlock
    Actually I'm not that sure I gave you the right answer... 😕

    My fist thought was to do some kind of a very rough estimate of all the mass present and than just use that formula...

    But then it occurred to me what is the definition of a black whole and the whole Universe seems to fit right in. I'm too lazy to check my General Relativity and Cosmolog ...[text shortened]... you'd have to know were the singularity lies and then convince someone to walk into it. 😵
    Well, my question was not as dumb as it looke at the first glance.

    A black hole and the whole universe has one property in common:
    There is no way out of it. (No this is not a spiritual forum, don't answer it if it's a religious answer).

    One said once, that the radius of a black hole with the mass of the whole universe's is the same as the actual universe radius. I don't know if this is true, I should probably do the calculations myself.

    But can we tell how it 'looks' like inside the swartzy radious of a black hole? Is it like in the normal universe? Is the spatail and temporal distortions be such so a singularity cannot be found? What about time? Etc, etc...

    Do i have the answers? I don't think so... 😞
  9. Standard memberadam warlock
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    18 Sep '08 12:09
    Originally posted by FabianFnas
    Well, my question was not as dumb as it looke at the first glance.

    A black hole and the whole universe has one property in common:
    There is no way out of it. (No this is not a spiritual forum, don't answer it if it's a religious answer).

    One said once, that the radius of a black hole with the mass of the whole universe's is the same as the actual u ...[text shortened]... t be found? What about time? Etc, etc...

    Do i have the answers? I don't think so... 😞
    Well up until near the singularity we have a pretty good idea to what happens to an observer in the context of GR. Neat the singularity things are a little more shaky and some people think we need GR and QM to properly understand what's going on.

    But like I said I don't remember these things very well now. I've been planning a whole re-study of things I've learned and are shaky now for some time. When I finally get to do it I'll take a better look at your question.

    In the mean time would you consider joining Club 39?
  10. Cape Town
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    18 Sep '08 12:49
    Originally posted by FabianFnas
    One said once, that the radius of a black hole with the mass of the whole universe's is the same as the actual universe radius. I don't know if this is true, I should probably do the calculations myself.
    I don't know if the radius of the universe is known.
    However, if it is known, and is within the visible portion of the universe, then we would expect to see certain effects if we were in fact in a black hole. I suspect that there would be a fairly large tendency for all matter to migrate towards the centre, which I don't think has been observed within the observable universe.
    But then we must remember that the universe is also expanding which might counter such an effect.
    It is almost certain that the universe was for a certain period after the big bang within the swartzy radius but since there is no space external to the universe, it probably would not fit the definition of a black hole.
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    18 Sep '08 13:16
    Originally posted by twhitehead
    I don't know if the radius of the universe is known.
    However, if it is known, and is within the visible portion of the universe, then we would expect to see certain effects if we were in fact in a black hole. I suspect that there would be a fairly large tendency for all matter to migrate towards the centre, which I don't think has been observed within th ...[text shortened]... s no space external to the universe, it probably would not fit the definition of a black hole.
    Is it fair to expect the radious of the universe less than the same number of lightyears as the number of years universe is old? This will say a radius no more than 13.7 billion of lightyears, if the age of universe is 13.7 billion of years?

    But I see the appearance of universe as a threedimensional spherical form, as the universe has no centre, nor edge. Exactly as the Earth is a twodimensional spherical surface. No edge, no center.
  12. Standard memberPalynka
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    18 Sep '08 13:30
    Originally posted by FabianFnas
    Exactly as the Earth is a twodimensional spherical surface. No edge, no center.
    Are you really saying the Earth has no center?
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    18 Sep '08 14:08
    Originally posted by Palynka
    Are you really saying the Earth has no center?
    The surface of the earth has no center. If you want to find a center then you have to go deep into a third dimension.
  14. Standard memberPalynka
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    18 Sep '08 14:23
    Originally posted by FabianFnas
    The surface of the earth has no center. If you want to find a center then you have to go deep into a third dimension.
    I knew, I was just being pedantic. 🙂

    On a more serious note, I'm not sure why you think the appearance of the universe would be like that. Since all matter was originated by the Big Bang, in a three dimensional point (so to speak), then why wouldn't the universe have a center?

    For example, when we say the universe is expanding, then surely this implies the existence of a center and an edge, as it requires the universe to be bounded.
  15. Cape Town
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    18 Sep '08 14:31
    Originally posted by FabianFnas
    Is it fair to expect the radious of the universe less than the same number of lightyears as the number of years universe is old? This will say a radius no more than 13.7 billion of lightyears, if the age of universe is 13.7 billion of years?
    No, there is no reason to make that conclusion. The very fabric of space is expanding, so it is in fact possible for objects to travel away from each other faster than light.
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