Of course the yellow/orange portal carries momentum. That's why it should be B.
Its just a hole though. If you have a tennis racket with no strings and swing it over something stationary the object doesnt move
With the tennis racket analogy both portals would be moving. In the thought experiment from the image just one is moving, resulting in an unaccounted for momentum, unless the people shoot out the blue portal
Of course the yellow/orange portal carries momentum. That's why it should be B.
Its just a hole though. If you have a tennis racket with no strings and swing it over something stationary the object doesnt move
With the tennis racket analogy both portals would be moving. In the thought experiment from the image just one is moving, resulting in an unaccounted for momentum, unless the people shoot out the blue portal