Gravity at very large distance

  • Context: Graduate 
  • Thread starter Thread starter Dreads
  • Start date Start date
  • Tags Tags
    Gravity
Click For Summary

Discussion Overview

The discussion revolves around the nature of gravity at very large distances, particularly in the context of quantum mechanics and general relativity. Participants explore whether gravity can be considered zero at extreme distances and how this relates to the interactions between particles such as electrons and photons.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • One participant questions if gravity at very large distances can be considered zero, proposing a formula that includes a constant to account for this threshold.
  • Another participant calculates the gravitational force between two electrons 13.5 billion light years apart, suggesting that the force is negligible and questioning the relevance of such measurements due to quantum mechanics.
  • A different viewpoint introduces the concept of entanglement, asserting that gravity is universal and may have implications for entangled particles.
  • Another participant discusses the deformation of space-time caused by massive bodies, noting that while large bodies affect gravity over vast distances, atomic particles interact primarily at short ranges.

Areas of Agreement / Disagreement

Participants express differing views on the nature of gravity at large distances, with no consensus reached on whether gravity can be considered zero or how it operates at such scales. The discussion remains unresolved with multiple competing perspectives.

Contextual Notes

Participants highlight limitations in measuring gravitational effects at extreme distances, particularly in relation to quantum mechanics and the assumptions involved in their calculations.

Dreads
Messages
69
Reaction score
0
Is gravity at very large distances zero?

ie g = (k(m1 m2)/r^2) - k1 (you can also use the relativity formule for gravity here if you want)where k1 is some constant that makes gravity zero when (k(m1 m2)/r^2) reaches some threshold value

so if I had and electron 10^6 billion light years from another electron (ie the opposite ends of the universe or the furtherest distance possible (you choose)).

Now let's assume electron 1 is doing work, through gravity, on electron 2. I was wondering would the energy associated with the work electron 1 does on electron 2 be smaller than the smallest indivisibe unit of energy, which I think is planks constant?. Of course this assumes energy is quantised.

If you assume 2 photons can have a gravitational effect on each other then you can replace electron 1 and 2 with photon 1 and 2 at opposite ends of the universe.
 
Physics news on Phys.org
Using the inverse square law on 2 electrons 13.5 billion light years apart you get a force of 3.4x10-123N. I guess this would make the question pointless because by trying to measure the force QM laws would change your results any way. There isn't much point thinking about gravity in that way.
 
Those electrons would be via entangled, and gravity is universal.
 
Gravity depends of space-time deformation. If you have large size bodies having reasonnable mass, they will deform space - time on large distances but deformations will be low. For atomic particles, deformations are extremely important but they act on short distances. Consequently, interactions between atomic particles only exist at small scales and interactions btween planets and stars exist on large scales. For black holes, you are in the case of strong deformations with large bodies. Then their influence govern universe expansion... and it accelerate ! interesting isn't it ?
 

Similar threads

  • · Replies 67 ·
3
Replies
67
Views
6K
  • · Replies 46 ·
2
Replies
46
Views
4K
  • · Replies 21 ·
Replies
21
Views
2K
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 5 ·
Replies
5
Views
3K
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 23 ·
Replies
23
Views
3K
  • · Replies 4 ·
Replies
4
Views
3K
  • · Replies 11 ·
Replies
11
Views
2K