What would for an observer be the mass of an isolated wormhole (meaning that there is no gas and no mass of stars around it) if the wormhole mouth opposite to the observer reflects the light of a region from the galaxy it opens into.
Wormholes per definition require negative energy in the form of exotic matter so as to have their mouths open. Would this negative mass be the only mass of the wormhole object or for an observer in the isolated wormhole also include the light reflected of stars and gases visible through the wormhole of another galaxy.
Wormholes connect two systems for only a short time, and collapse when too much time has passed, or too much mass has passed through them. My question would be for wormholes that can have their mouths connected either naturally or artificially for a reasonable length of time.