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Tidal forces around BH

  1. Apr 12, 2009 #1
    Please confirm, I am not sure.

    Outside the horizon, object is torn apart in vertical direction but is squezzed in a horizontal.
    Inside the horizon, object is still torn apart in a 'vertical' direction, and in in the horizontal direction too
  2. jcsd
  3. Apr 13, 2009 #2
    The object is stretched in the radial direction and squashed in the horizontal direction (sometimes reffered to as 'http://en.wikipedia.org/wiki/Spaghetiffication" [Broken]' or 'the toothpaste effect'). Measuring the rate of contraction in the horizontal is one way a free-falling observer might be able to measure r-values once inside a static black hole (see page B-8 in 'Exploring Black Holes' by Taylor and Wheeler).

    Regarding tidal forces inside black holes-
    http://io.uwinnipeg.ca/~vincent/4500.6-001/Cosmology/Tidal_Forces_%20In_%20A_%20Black_%20Hole.htm [Broken]
    Last edited by a moderator: May 4, 2017
  4. Apr 13, 2009 #3
    I believe your link is still about the outside region.
    Singularity in the non-rotating black hole is spacelike for a free falling obser4ver, it is not the point.

    I am an amateur, so I check the pictures:
    http://www.phy.syr.edu/courses/modules/LIGHTCONE/pics/bh3.gif [Broken]

    Approaching the singularity, lightcones become sharper and sharper. So any close objects will sooner or later lose connection to each other. The lightcones which become narrower and narrower is exactly the BIG RIP metrics. So tidal forces are ripping all apart in ALL directions.
    Last edited by a moderator: May 4, 2017
  5. Apr 13, 2009 #4
    The equation for tidal forces remains unchanged inside and outside the event horizon.

    Click on the link below (which leads to a draft copy of the second edition of EBH available online), then on 'InsideBH090308v1.pdf' which will open a new window, go to page 7 and you'll see an explanation regarding how distances compact for free-falling objects in the horizontal direction within the event horizon and how this can be used to measure the r-coordinate-


    Better still, I recommend you buy the book as it should answer most of your questions.
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