The pork chop solution

  1. Chronos

    Chronos 10,053
    Science Advisor
    Gold Member

    I was BBQ-ing yesterday. I ate eight pork chops [they were small] and lapsed into a sated, torpid slumber. Suddenly, I was a lonely asteroid drifting in deep space, with nothing but diffuse filaments of primordial hydrogen and helium molecules to keep me company [I was recoil kicked out of my mother galaxy about 8 Gy ago.]. It suddenly occured to me I was being gently pulled in all directions by the gravity of the near infinite number of massive bodies isotropically surrounding me in the universe. Were it not not for the attractive properties of my own feeble mass, I would be stretching... Any thoughts?
     
  2. jcsd
  3. tony873004

    tony873004 1,584
    Science Advisor
    Gold Member

    I imagine 2 things would hold you together. The strength of your body and the very weak gravitational force created by your mass should each be sufficient to prevent the very weak cumulative tidal forces from pulling you apart.
     
  4. Chronos

    Chronos 10,053
    Science Advisor
    Gold Member

    Agreed, but what if I'm empty space devoid of any appreciable resistance to this force?
     
  5. wolram

    wolram 3,770
    Gold Member

    Good question, gravity gravitates, i guess the only thing keeping you from "imploding" is the hubble.
     
  6. pervect

    pervect 8,009
    Staff Emeritus
    Science Advisor

    In newtonian theory, there is no force anywyere inside a sphere of uniform matter. So you wouldn't be pulled apart.

    In GR things get a lot more complicated, and the previous statement is not necessarily true. From some other threads, including one overly long thread about threads :-), you should only get pulled apart if the deceleration parameter q of the universe is less than zero, i.e. if the universal expansion is acclerating. (This happens only when there is a cosmological constant). Otherwise you will only experience compressive forces.

    There isn't any good way of illustrating this without some nasty tensor algebra, though. If anyone wants to see the nasty tensor algebra, I can provde links where this has been previously discussed, and the numbers for our current universe (which does have a cosmological constant) have been calculated.
     
Know someone interested in this topic? Share a link to this question via email, Google+, Twitter, or Facebook

Have something to add?