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This question is actually related to my earlier question ("what is motion"). The fact that objects move a lot in the universe and that the universe is expanding, can imply that gravity is a repulsive force that increases with distance.. so the farthest objects repel us more.

This can still explain several existing observations, e.g., why does the apple fall?

Motion is the result of such repulsion. Two objects unlucky enough not to be moving relative to each other get squished due to the repulsion of the rest of the universe around them. The earth repels the apple less than the stars so it is pushed towards the earth.

Furthermore, it can explain the expanding universe without the need for dark energy.

This could be demonstrated in a thought experiment. If we take a lot of same-charge particles (with small mass) such as electrons and lock them in a large box at a low enough temperature. The mutual repulsion of the particles may cause similar motion as if due to gravitational attraction.

Another experiment would be to measure the slight changes in our weight during day and night when the sun and earth align (if their masses are large enough to detect the feeble change in repulsion).

[EDIT: the question in the original form may not have been clear. It is "can we model".. with a yes/no answer and why (not). If downvoting, please justify.

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If the stars push the apple to the Earth, wouldn't the stars on the other side of the Earth push it back up with an equal force? Or maybe you're a flat-Earthist? – Pete Jackson Aug 5 '11 at 21:52

5 Answers

up vote 6 down vote accepted

Show me a distribution of remote mass that would provide the behavior we see for both

  • Jupiter in orbit around the sun
  • the many moons in orbit around Jupiter

which both appear to be $1/r^2$ forces.

Now try to generalize to support all the moons and planets in the solar system. You can't do it because the system is highly over-constrained.

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This article might help: metaresearch.org/cosmology/gravity/… – Glen Little Jan 11 at 18:18

Yes, the force that causes the expansion of the Universe is repulsive. No, this force is not gravity. It is the fifth force.

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Interestingly, this theory has been proposed earlier (Le Sage theory). According to wikipedia, mainstream scientists discount this theory for lack of experimental evidence. So this answers the question.

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Suggestion to the answer(v1): If you mention the words Le Sage theory explicitly in the answer, then it would become a searchable keyword for future visitors to find this post. – Qmechanic Jan 11 at 18:31

There is definitely a strong history of "repulsive" gravity... often called "pushing gravity". You can read about it in the book: Pushing Gravity.

For a recent proponent of the concept, the late Tom Van Flandern collected lots of pieces of the theory and made a number of predictions based on the ideas.

You can read more about his work here: Gravity

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I would assume the expanding of the universe is perhaps due to the fact that systems with relatively equal gravitational densities repel each other rather than attract. The theory that gravity causes dents in space can model the idea of repulsion. So perhaps there can be a gravitational model for repulsion; however I don't think it could be modeled in your sense. The universe is expanding due to ultimately the infinite increase of entropy which can be seen as dark matter of similar gravitational density repulsion.

Mind you, I have no real evidence for the stuff I wrote, this is all speculation. Good luck in finding your answer.

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