Compute on all points in geometry nodes

I try (for a while now) to make a gravitation simulation with geometry nodes. The computation is not complex, and I get something that is almost OK.

The problem is that it seems that it's not possible to make a computation from the entire points. We only can get the "nearest" point position.

So, the simulation works only partially, the gravitation is applied for all points with its neighbor, but it should be computed with all the others points.

I provide the example blend file.

https://drive.google.com/file/d/19iRfLL1_WBIOQFTdYoSAAh9RkzFrNNlT/view?usp=sharing