The ring is not touching the thing passing through it to impart any forces. The object passing through carries only what energy it takes with it.
Then where does the energy to displace the air on the blue side of the portal coming from?
The ring is not touching the thing passing through it to impart any forces. The object passing through carries only what energy it takes with it.
Then where does the energy to displace the air on the blue side of the portal coming from?