Correction on Physical vs NonPhysical Interaction and follow up on Mobius strip

I experiments some more by inserting a linked Physical prim (made of 2 linked components) into a Non-physical peg attached to the non-physical structure of the buildilng. I found I was able to get the 2 objects to interact, with the Physical object obeying physical laws. So, there is no logical problem with interacting physical and non-physical prims (I just had not been able to insert the peg into the hole in the physical object before...I failed to position things correctly so the physical and non-physical were touching. But as long as the objects do not touch, one can be inserted into the other all right. Still, the question of whether one wants to keep Physical vs. Nonphysical prims separate is an important one, I think. it could be that construction is faster and everything is more stable if one combines both physical and non-physical. However, constructing a purely physical world may be more like the real world than constructing a world that is a combination of the two...or maybe not?...I am not sure... this really goes beyond my mathematical and philosophical abilities.

In terms of the Mobius strip, I was able to make one, but I am not sure if the circle is really closed or not. I took a copy of it, in my inventory.