>>12608229Portals definitely need to apply force, at least insofar as the concept makes sense in weird portal physics. Think of it this way. Portals can change the direction of velocity, so they must somehow apply acceleration (dv/dt), and F=ma, so...
In fact when you think about portals and forces you end up with more weird stuff. Like say you put a concrete barrier in front of the orange portal, then something has to stop the piston from going down, so the portal actually needs to be able to apply force to the piston as well.
