On modified theories of gravity

In summary, there are various theories of gravity that have been modified from the traditional Schwarzschild solution in General Relativity. However, these modifications must still be able to accurately predict phenomena such as light deflection and perihelion shift of Mercury in the solar system. While some modified theories may not have the same Schwarzschild-like solution, they must still account for Newtonian gravity and have similar deviations as General Relativity in weak fields. These theories may differ in their predictions on a galactic scale and in strong fields. A helpful resource for understanding this topic is the book "Was Einstein Right?"
  • #1
xiaomaclever
13
0
I am confused about the modified theories of gravity. We all know there is the Schwarzschild solution for GR. The solution can give right prediction for the solar-system experiments, such as Light deflection, perihelion shift of the Mercury and gravitational time delay. Whether all kinds of modified theories of gravity should have the same Schwarzschild solution, otherwise they will be ruled out by the solar-system experiments. I know some modified theories of gravity don't have the Schwarzschild-like solution for spherically symmetric vacuum spacetime.
 
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  • #2
They all have to give Newtonian gravity and at least the same first order deviation as GR in weak fields (gravitation in the solar system is weak). They might give different results on a galactic scale (very weak fields) and in strong fields.
 
  • #3
A good book on this topic is "Was Einstein Right?"
 

Related to On modified theories of gravity

1. What is modified gravity?

Modified gravity is a theoretical framework that suggests modifications to Einstein's theory of general relativity in order to explain phenomena that cannot be accounted for by traditional gravity models. These modifications are often based on adding new terms or functions to the equations of general relativity.

2. How is modified gravity different from general relativity?

Modified gravity differs from general relativity in that it incorporates additional terms or functions into the equations of general relativity in order to better explain certain phenomena, such as dark matter and dark energy. It also allows for deviations from the predictions of general relativity in certain extreme conditions, such as near black holes.

3. What is the current status of modified gravity theories?

Modified gravity theories are still largely theoretical and have not yet been confirmed through experimental evidence. They are actively studied and researched in order to better understand the behavior of gravity and its effects on the universe.

4. How do modified gravity theories explain dark matter and dark energy?

Modified gravity theories propose that the effects of dark matter and dark energy can be explained by modifying the equations of general relativity. This can include adding new terms to account for the additional gravitational pull of dark matter or modifying the behavior of gravity on large scales to explain the acceleration of the universe's expansion caused by dark energy.

5. What are some potential implications of modified gravity theories?

If modified gravity theories are confirmed, it could have significant implications for our understanding of the universe and the laws of physics. It could also provide a new approach to explaining phenomena that are currently attributed to dark matter and dark energy. Additionally, it could potentially lead to new technologies or applications based on a better understanding of gravity.

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