system
Given the following post, respond as if you're commenting on Reddit:
human
[Portal] What would happen if you sent a portal through a portal?

Say if the portals in "portal" existed. If you put one of the portals in a box, close the box and throw it through the other portal. What would happen? Imploding sounds like a reasonable thing but I dont know.
gpt
Once the distance between two portals becomes of the order of a few nanometers but before they intersect each other, the Casimir force between them becomes significant and causes the portals to collapse.