2 large objects of equal mass, Will they move each other?

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Discussion Overview

The discussion revolves around a thought experiment involving two large planets of equal mass, specifically whether they will move towards each other due to gravitational attraction when initially at rest and separated by a significant distance. The scope includes theoretical considerations of gravitational forces and analogies to other physical systems.

Discussion Character

  • Exploratory
  • Conceptual clarification

Main Points Raised

  • Some participants assert that the planets will start moving towards each other due to gravitational attraction, referencing Newton's law of motion and general relativity.
  • One participant draws an analogy between the scenario and two objects of equal mass connected by a spring, suggesting a similar dynamic at play.
  • A participant encourages looking into the concept of "center of mass" as relevant to the discussion.

Areas of Agreement / Disagreement

There is a general agreement among participants that the planets will move towards each other due to gravitational attraction, though the depth of understanding and implications of this movement are not fully explored.

Contextual Notes

The discussion does not address potential complexities such as the effects of other forces or the implications of their motion over time, nor does it delve into the mathematical details of gravitational interaction.

RobertSpencer
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Suppose there are 2 planets the size (diameter) of Jupiter. Both have the exact same mass. They are separated by a distance of about 10 times the diameter of the planet. They are both at rest. Now, will they start moving towards each other or stay in the same place?

This is a sort of thought experiment. So, you can imagine they have no initial velocity and are in rest with respect to each other and that there are no other big objects nearby.
 
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They will start moving towards each other due to gravitational attraction, as described by Newton's law of motion and by general relativity.
 
Yes, of course.
 
Moderator's note: Thread level changed to "B".
 
RobertSpencer said:
Suppose there are 2 planets the size (diameter) of Jupiter. Both have the exact same mass. They are separated by a distance of about 10 times the diameter of the planet. They are both at rest. Now, will they start moving towards each other or stay in the same place?

This is a sort of thought experiment. So, you can imagine they have no initial velocity and are in rest with respect to each other and that there are no other big objects nearby.

This is no different than two objects of the same mass connected to each other via a spring. If you are familiar with that, then the scenario you described is analogous.

BTW, this is a good point for you to look up the concept of "center of mass".

Zz.
 
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