The Pork Chop Solution: Pondering My Place in Space

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SUMMARY

The discussion centers on the implications of gravitational forces in the universe, particularly in relation to personal identity and existence as metaphorically represented by a drifting asteroid. Participants agree that while Newtonian physics suggests no internal forces act within a uniform sphere, General Relativity complicates this view, indicating that gravitational effects depend on the universe's expansion rate. The deceleration parameter (q) plays a crucial role, with implications for whether one experiences compressive or tensile forces based on the presence of a cosmological constant.

PREREQUISITES
  • Understanding of Newtonian physics and gravitational forces
  • Familiarity with General Relativity (GR) concepts
  • Knowledge of cosmological constants and their implications
  • Basic grasp of tensor algebra for advanced discussions
NEXT STEPS
  • Research the implications of the deceleration parameter (q) in cosmology
  • Study the role of the cosmological constant in the universe's expansion
  • Explore tensor algebra and its applications in General Relativity
  • Examine the differences between Newtonian gravity and General Relativity
USEFUL FOR

Astronomers, physicists, and anyone interested in the interplay between gravity and cosmic expansion, as well as those exploring philosophical implications of existence in the universe.

Chronos
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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 occurred 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?
 
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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.
 
Agreed, but what if I'm empty space devoid of any appreciable resistance to this force?
 
Chronos said:
Agreed, but what if I'm empty space devoid of any appreciable resistance to this force?
Good question, gravity gravitates, i guess the only thing keeping you from "imploding" is the hubble.
 
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.
 

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