# Friedmann Expansion

I have a strange question that I can visualize but not find anything to really answer my query.

The Newtonian law states that something in motion tends to remain in motion. We all know about Friedmann expansion and more accurately (maybe) an acceleration phase to boot.

It is possible that as gravity weakens, spacetime can expand in an exponential way? I can see straight away this particular question would rely on a ''force applied'' to a universe, often translated as the cosmological constant which is seen to drive a continuous acceleration.

Is it possible there is some unseen connection with the weakening of gravity that may result in the acceleration of a universe?

I should mention, a recent study I read just the other day, seems to calculate the early universe expanding at a slower rate than the late epoch, which is in disagreement with standard interpretation. Anyway, my guess is that it is not as simple as gravity weakening giving rise to an acceleration, but I am curious as to what others may think.

• That seems to be an interesting idea. When you talk about the weakening of gravity, are you thinking perhaps of something like Brans-Dicke theory? en.wikipedia.org/wiki/Brans-Dicke_theory – Filipe Miguel Mar 31 '19 at 14:40
• I suppose a varying constant $G$ would explain the variation of gravity over time. But my question is more to do with how spacetime appears to be accelerating, I wonder about drawing synonymous relationships with parameters that seem to be changing, like gravity, in the sense that gravitational binding is weakening as it expands. – Gareth Meredith Mar 31 '19 at 14:44
• I am not sure I understand your question, but if there is no mechanism that intensifies the weakening of gravity, the exponential expansion we observe is not possible, i.e. the fact that the distance between things is getting larger weakening gravity is not enough to explain the rate of expansion we observe – Filipe Miguel Mar 31 '19 at 14:51
• It might make sense in the reference of a recent study presuming the early universe expanded slower than we have in standard cosmology. The gravitational interaction was very strong during the initial stages, the only thing I can draw when making the relationship to gravity, is that gravity has to get weaker as more degrees of freedom enter the picture. – Gareth Meredith Mar 31 '19 at 14:53
• That seems accurate – Filipe Miguel Apr 1 '19 at 12:05