The physical laws have to be thoroughly investigated and one might have to take quantum effects into account because of the extreme conditions like high tension and large curvature in the Schwarzschild wormhole. The Viennese physicist Ludwig Flamm [11] was the first to discover that the Schwarzschild solution represented a “handle” or wormhole and that this wormhole also posesses a future and a past horizon as well as being static.

After the Kruskal treatment of the Schwarzschild coordinate Robert W. Fuller and John A. Wheeler mentioned in their paper: That there are alternative routes between two points in a multiply connected space. One may ask, is such a route designed for a material particle or even for a photon. Niels Bohr mentioned in a conversation between him, Fuller and Wheeler in 1958 that there could be some problems
with causality. Later it has appeared that there are several objections against the Schwarzschild wormhole: causality, horizon and the stability.
Morris and Thorne have mentioned two objections against this type of a wormhole if one will use it as an interstellar travel-machine.