Page 3 of 3 FirstFirst 123
Results 21 to 30 of 30

Thread: Black Hole Question

  1. Top | #21
    Super Moderator
    Join Date
    Sep 2000
    Location
    Nevada
    Posts
    27,603
    Archived
    96,752
    Total Posts
    124,355
    Rep Power
    100
    Quote Originally Posted by bilby View Post
    Quote Originally Posted by Lion IRC View Post





    Ceases to exist?
    If somebody walks behind a wall so that you can no longer see them, have they ceased to exist?

    If you turn the lights out in a deep slate mine, so no photons bounce off your hands, have your hands ceased to exist?
    No, because there's still some light. It was a lava tube rather than a slate mine but I've had the experience--it feels really strange, but there were a few very faint points of light emitted by inhabitants.

  2. Top | #22
    Super Moderator
    Join Date
    Sep 2000
    Location
    Nevada
    Posts
    27,603
    Archived
    96,752
    Total Posts
    124,355
    Rep Power
    100
    Quote Originally Posted by bilby View Post
    He is only immortal in its mass 3 and 4 isotopes. The longest lived unstable He isotope has a half life of about 800ms (6He).
    You're assuming the proton doesn't decay.

  3. Top | #23
    Fair dinkum thinkum bilby's Avatar
    Join Date
    Mar 2007
    Location
    The Sunshine State: The one with Crocs, not Gators
    Posts
    22,759
    Archived
    10,477
    Total Posts
    33,236
    Rep Power
    87
    Quote Originally Posted by Loren Pechtel View Post
    Quote Originally Posted by bilby View Post
    He is only immortal in its mass 3 and 4 isotopes. The longest lived unstable He isotope has a half life of about 800ms (6He).
    You're assuming the proton doesn't decay.
    Well, given long enough, probably nothing is stable.

  4. Top | #24
    Fair dinkum thinkum bilby's Avatar
    Join Date
    Mar 2007
    Location
    The Sunshine State: The one with Crocs, not Gators
    Posts
    22,759
    Archived
    10,477
    Total Posts
    33,236
    Rep Power
    87
    Quote Originally Posted by Loren Pechtel View Post
    Quote Originally Posted by bilby View Post
    Quote Originally Posted by Lion IRC View Post





    Ceases to exist?
    If somebody walks behind a wall so that you can no longer see them, have they ceased to exist?

    If you turn the lights out in a deep slate mine, so no photons bounce off your hands, have your hands ceased to exist?
    No, because there's still some light. It was a lava tube rather than a slate mine but I've had the experience--it feels really strange, but there were a few very faint points of light emitted by inhabitants.
    There's no visible light at all in a deep slate mine without illuminating sources. The operative word is 'deep' - in an accessible lava tube I would expect you to still be close enough to the outside world to get some ambient light.

    There are, perhaps unsurprisingly, visual hallucinations of various kinds even in the complete absence of photons in the visible range. The brain really HATES to interpret retinal input as zero. And even in the complete absence of light, retinal cells and optic nerves will occasionally fire.

  5. Top | #25
    Super Moderator
    Join Date
    Sep 2000
    Location
    Nevada
    Posts
    27,603
    Archived
    96,752
    Total Posts
    124,355
    Rep Power
    100
    Quote Originally Posted by bilby View Post
    Quote Originally Posted by Loren Pechtel View Post

    No, because there's still some light. It was a lava tube rather than a slate mine but I've had the experience--it feels really strange, but there were a few very faint points of light emitted by inhabitants.
    There's no visible light at all in a deep slate mine without illuminating sources. The operative word is 'deep' - in an accessible lava tube I would expect you to still be close enough to the outside world to get some ambient light.

    There are, perhaps unsurprisingly, visual hallucinations of various kinds even in the complete absence of photons in the visible range. The brain really HATES to interpret retinal input as zero. And even in the complete absence of light, retinal cells and optic nerves will occasionally fire.
    It was long enough with enough turns that no ambient light got in.

    I also feel there were some dots that glowed as a reaction from our lights, but this was so long ago I'm not completely certain of what the lights were, only that they did exist.

  6. Top | #26
    Veteran Member
    Join Date
    Feb 2001
    Location
    Birmingham, Alabama
    Posts
    2,113
    Archived
    4,109
    Total Posts
    6,222
    Rep Power
    74
    Quote Originally Posted by Elixir View Post
    Quote Originally Posted by Shadowy Man View Post
    The tidal forces will depend on the mass of the black hole. A supermassive black hole won’t have nearly as large a tidal force as a small one.
    As long as you're falling "straight in" you might survive a while ... but otherwise you'll go into close orbit, accelerate to near lightspeed and become part of the superheated glowing aura around the supermassive black hole where magnetic fields are so strong that the very atoms of your body are ripped into their constituent subatomic particles... fun times!
    I think that’s from the perspective of the observer. The observer will basically see you slowly merge into a glowing aura that surrounds the black hole, but getting redder and dimmer as time goes on. But don’t confuse the singularity with the Schwarzschild radius. You can cross that boundary at any particular speed <c. You will not realize it, unless there’s a firewall of Hawking radiation, which is unknown at this time. You can then orbit the singularity forever. You just can’t leave.

    Wait. Are there other levels to the black hole out of which light can’t leave? Further Schwarschild radii within the hole?

  7. Top | #27
    Veteran Member
    Join Date
    Sep 2004
    Location
    California
    Posts
    3,975
    Archived
    4,797
    Total Posts
    8,772
    Rep Power
    62
    Quote Originally Posted by bilby View Post
    If you turn the lights out in a deep slate mine, so no photons bounce off your hands, have your hands ceased to exist?
    Photons continue to bounce off your hands. There's no escaping blackbody radiation.

  8. Top | #28
    Formerly Joedad
    Join Date
    Mar 2001
    Location
    PA USA
    Posts
    6,271
    Archived
    5,039
    Total Posts
    11,310
    Rep Power
    78
    Quote Originally Posted by Loren Pechtel View Post
    Quote Originally Posted by bilby View Post
    Quote Originally Posted by Loren Pechtel View Post

    No, because there's still some light. It was a lava tube rather than a slate mine but I've had the experience--it feels really strange, but there were a few very faint points of light emitted by inhabitants.
    There's no visible light at all in a deep slate mine without illuminating sources. The operative word is 'deep' - in an accessible lava tube I would expect you to still be close enough to the outside world to get some ambient light.

    There are, perhaps unsurprisingly, visual hallucinations of various kinds even in the complete absence of photons in the visible range. The brain really HATES to interpret retinal input as zero. And even in the complete absence of light, retinal cells and optic nerves will occasionally fire.
    It was long enough with enough turns that no ambient light got in.

    I also feel there were some dots that glowed as a reaction from our lights, but this was so long ago I'm not completely certain of what the lights were, only that they did exist.
    I had a cave experience. There is no visible light. It's all gone. If your hand is a tenth of an inch in front of your eyeball it might as well be on the other side of the moon. You cannot "see" it. It's not like in the movies.

  9. Top | #29
    Super Moderator
    Join Date
    Sep 2000
    Location
    Nevada
    Posts
    27,603
    Archived
    96,752
    Total Posts
    124,355
    Rep Power
    100
    Quote Originally Posted by T.G.G. Moogly View Post
    Quote Originally Posted by Loren Pechtel View Post

    It was long enough with enough turns that no ambient light got in.

    I also feel there were some dots that glowed as a reaction from our lights, but this was so long ago I'm not completely certain of what the lights were, only that they did exist.
    I had a cave experience. There is no visible light. It's all gone. If your hand is a tenth of an inch in front of your eyeball it might as well be on the other side of the moon. You cannot "see" it. It's not like in the movies.
    Yeah, there was no seeing your hands other than by occluding the points of light. They were very, very dim.

  10. Top | #30
    Veteran Member
    Join Date
    Feb 2001
    Location
    Birmingham, Alabama
    Posts
    2,113
    Archived
    4,109
    Total Posts
    6,222
    Rep Power
    74
    I did a lot of caving during college. There is no light at all down there.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •