Overhertz wrote:"So if it is possible for the player to stay center of their newton world, I'd love to know how to do this with newton without causing problems concerning the physics reactions

I told you, in the server you need to have a physical absulte adress whith is the absolete position of teh player in the universe.
The server know that lcation calculated the relative locations of the player on the client. all of the client neigborgh are update by the server.
But like I say if you make the client to be teh center of the world, tnan teh selrve will have to do lot and lot of updates.
it is better to have aisland size and the 8 possible island neiborgh (in 2d) or 27 neigborg (in 3d) and update when bodies cosses those boudaries.
This is a thecnique that operating system uses to mapping diffrent prosses in the same memory, also the x87 segment architectecture implemented for years.
in both cases they use a granulatity, beacuse otherwise the virtual memory manager will kill the system doing update each time avery time an item move.
each client will have in own owner that can move locally insidde its works, and upadte only wen it cross it word size,
plsue teh immidatye nighbod island tha ge update win vistors form adjacen isalen enetr and exit that world.
it should be strighfporqred to ge it going.
that way and add and removing obvjects can happen at much lower rate, give teh engine the chaneg to maintain contact perssitance and onley update with position update are made.
I do no see any problem with doin that.