Something I've wondered about the can portal loop, since that was in an atmosphere it would quickly reach terminal velocity, but what if it were in a vacuum? Would it continuously accelerate to and past the speed of light? Of course if there were a coil around the cylinder that would cause drag and reach a terminal velocity also, but something i've wondered since I have not the mathematical prowess to figure out myself.,(reply>), +Steven Davidson We aren’t cheating nearly hard enough. The gravity would make it keep going faster and faster. At some point (exactly when depends on your measurement techniques), you would notice that Newton’s laws don’t apply precisely. This is when you are going at relativistic velocities. At this point you will see that acceleration as measured by an outside observer is very slightly decreasing: you aren’t actually speeding up as much as you had been before, despite the gravity being the same. As you approach c, you gain velocity only very slowly, and you will never actually get to the speed of light.<br><br>Depending on how you look at it, this can be because f=ma is an approximation, or mass changes, or your definition of acceleration changes. All ways of talking about it would give the same results, but some would make the calculation easier or harder.,(reply>), +Steven Davidson  We aren't cheating the rule that information has a max speed. You would need an infinit time for the energy to build up to the speed of light. You would get closer and closer as time went on, but an infinit amount of time simply doesn't exist.,(reply>), Yeah but we are cheating in this case.