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  1.  
    Oh, I see what you're getting it. Quite so. But the integral only takes account of the weight above your head - not the mutual gravitational attraction of the stuff over your head with the stuff beneath your feet.
    • CommentAuthorAsterix
    • CommentTimeSep 10th 2019 edited
     
    When you're in the center of the earth, gravitational attraction from all directions is the same.
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      CommentAuthorAngus
    • CommentTimeSep 10th 2019 edited
     
    The net attraction arises only from the mass beneath your feet - the rest cancels out. The net pressure on an element otoh provides an upward force sufficient to hold up the stuff above it.
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      CommentAuthoralsetalokin
    • CommentTimeSep 10th 2019 edited
     
    So. Imagine a tube or tunnel on an exact diameter of this spherical Earth. The tunnel goes all the way through from one side, through the center, to the other side in a straight line. You drop a Tesla Model X into the tunnel at one end. What happens to it?

    I mean, like, it obviously drops and accelerates on the way down... but the accelerating force decreases and drops to zero at the exact center and becomes a decelerating force that gets stronger and stronger as the vehicle passes the center and climbs upwards. Will the silly thing wind up oscillating and finally coming to rest at the exact center? What a ride -- in free fall the whole time too.
    • CommentAuthorAsterix
    • CommentTimeSep 10th 2019
     
    Posted By: AngusThe net attraction arises only from the mass beneath your feet - the rest cancels out. The net pressure on an element otoh provides an upward force sufficient to hold up the stuff above it.


    The observer is not part of the equation. There is no "up" or "down'" masses on either side of the center attract each other with equal gravitational force. The observer can mass zero and will still be compressed by the gravitational forces acting on the exterior.
  2.  
    Consider the pressure gradient as you descend towards the centre (suppose the planet to be modelled by an incompresssible sphere filled with incompressible fluid). As you approach the centre, the gradient levels off to zero. It's maximum up at the surface.
  3.  
    Posted By: alsetalokinI mean, like,
    Solve the differential equation and find out!
    •  
      CommentAuthorAngus
    • CommentTimeSep 10th 2019
     
    Posted By: Asterix
    Posted By: AngusThe net attraction arises only from the mass beneath your feet - the rest cancels out. The net pressure on an element otoh provides an upward force sufficient to hold up the stuff above it.


    The observer is not part of the equation. There is no "up" or "down'" masses on either side of the center attract each other with equal gravitational force. The observer can mass zero and will still be compressed by the gravitational forces acting on the exterior.


    Of course he's not. I was just being homey. I remember solving this one fifty years ago in a calculus class and it has failed to amaze me ever since.
    • CommentAuthorAsterix
    • CommentTimeSep 10th 2019
     
    Or to view it most simply, any object is collapsing on itself because of gravitational forces. The forces are greatest at the center of the object.
  4.  
    I sure wish that applied to my housemate. Rather, the inverse seems to be the case. She is expanding outward, and soon will be very nearly spherical, with just the occasional protuberance sticking out to manipulate the fork and spoon.
  5.  
    When they explode they can leave a nasty stain
  6.  
    Who needs shows like The Expanse when we have this?
    https://www.youtube.com/watch?v=u7LMlr9cWO4
  7.  
    A Tour Of The Lagrange Points. Part 3 - Trojans and Space Colonies at L4/L5
    https://www.youtube.com/watch?v=t3JfHp9ls8M
    ASTROD sounds very cool indeed
    •  
      CommentAuthoraber0der
    • CommentTimeSep 12th 2019
     
  8.  
    Reminds me of a girl I knew in high school....
  9.  
  10.  
    Boy, are you out of date!

    But yeah, that was the best vid on Hoppy. Because engineer.
    •  
      CommentAuthorgoatcheez
    • CommentTimeSep 13th 2019
     
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      CommentAuthoraber0der
    • CommentTimeSep 13th 2019
     
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      CommentAuthorAngus
    • CommentTimeSep 13th 2019
     
    Is it a Ukrainian discovery or a Russian discovery?