Originally Posted by

**tomjin2000**
But I still think the gravity between 2 objects can be affected by other objects.

As I know, Mr Newton didn't tell us the mechanism of Gravity. Can he really give us a valid equation to calculate gravity.

Well, it wasn't an "assumption", it was based on observation and has been confirmed by all observations since. Do you have a reason or evidence for suggesting that "the gravity between 2 objects can be affected by other objects"?

Of course, there are people who have looked at extensions to the model. Einstein, obviously, quite successfully. But also:

Milgrom, less successfully, with MOND.

Bekenstein's tensor–vector–scalar gravity.

Buchdahl's f(R) gravity.

Moffat's nonsymmetric gravitation.

Moffat's scalar–tensor–vector gravity

Sanders' bi-scalar tensor vector gravity

And several others. None of them are without problems.