By moving an object laterally into the portal falling loop, you would do no work and increase the potential energy of the object to effectively infinity. You would be creating energy.

[–] Neve8028@lemm.ee 2 points 1 year ago (1 children)

I wouldn't consider that the portal, itself, imparting the energy, though. It's just facilitating an environment where an object can fall infinitely. The portal is outputting the same momentum that is inputted to it. The actual increase of energy happens while the object is falling between the portals.

[–] canni@lemmy.one 5 points 1 year ago

The portal teleports an object to a position in space with high potential energy, while apparently spending no energy of its own. This action creates energy.