system
Given the following post, respond as if you're commenting on Reddit:
human
[Portal] if I step through a portal and reach a greater height by only stepping forward, from where did I gain the potential energy to fall?

Using portals, it seems that I could create an infinite energy machine by taking objects to higher ground for almost no energy, and then drop them to gain more energy than I started with and violate conservation. By what mechanism does portal technology conserve the total amount of energy in the system?
gpt
When objects pass through the portals event horizon from an area of low energy to an area of high energy a miniscule amount of energy (in the form of heat) is removed from the surrounding atoms. When you travel the other way the extra energy is dissipated into the surrounding atoms. 

This effect propagates at the speed of light and far reaching so it's not observable to the casual user and is difficult to measure for the researchers. Therefore it requires the use of the GLaDOS AI to perform the testing.