Does gravity apply at very short distances?

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Discussion Overview

The discussion centers on the behavior of gravity at very short distances, particularly in the context of dense objects such as neutron stars and the implications of different gravitational theories. It explores theoretical frameworks, observational evidence, and the challenges of measuring gravitational effects at small scales.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions whether very dense objects, which are not black holes, still attract each other according to the inverse square law.
  • Another participant notes that both Newtonian gravity and General Relativity are theories that describe predictions rather than definitive behaviors, suggesting that the inverse square law may be incorrect at larger masses.
  • It is mentioned that gravity's effects are significantly weaker than other fundamental forces at small scales, complicating experimental verification.
  • A participant raises the issue of neutron stars, inquiring about the gravitational interactions between neutrons and the potential for measuring density variations within them.
  • Another participant speculates on stellar activities and their effects on gravitational behavior, suggesting that fusion processes may alter the expected inverse square relationship.

Areas of Agreement / Disagreement

Participants express differing views on the applicability of the inverse square law in extreme conditions, and there is no consensus on how gravity behaves at very short distances or in dense environments.

Contextual Notes

Challenges include the difficulty of conducting small-scale gravity experiments due to the dominance of other forces, and the limitations in understanding gravitational interactions in extreme conditions like those found in neutron stars.

Ulysees
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What happens to gravity when something is very very dense but not a black hole?

Do parts of it still attract each other as in less dense objects, ie according to the same inverse square law?
 
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Newtonian gravity (inverse square) and General Relativity (Einstein/Black Hole gravity) are both theories - they don't describe what the world does, but, rather, describe what we think the world will do.

In some sense, the inverse square law is always incorrect. As you deal with more massive objects, the size of the error is larger. There are observable differences in prediction for things like solar system orbital mechanics.

http://en.wikipedia.org/wiki/Tests_of_general_relativity

That said, people don't know how gravity behaves at very short distances. At small scales, the effects of gravity are dwarfed by electromagnetic, strong, and weak forces, so small-scale gravity experiments are very difficult. Predicting and testing the behavior of gravity is an area of active research.
 
What about observations of neutron stars, I understand there's only neutrons in them therefore no E/M interactions. Is there anything that tells us what gravity is like between the neutrons in a neutron star? Maybe the density says something. Is there any way to measure density variation with depth?
 
You want to dabble at stellar activity. SOHO's data is interesting.

Once thought to induce fission, super-mass now thought to induce fusion. But, I'd speculate there are other activities as well.

Somewhere, along the way, instead of tending to stay at rest. A star is born. Then you've got an inundation of all types of momentums, tendency to maintain reactions, and what not.

There's definitely a differencing of the inverse d^2 rule, what with the fusion. Amongst others.
 

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