Space and time are dimensions, and though we can't always understand their structure, singularities such as black holes prove that there must be space/time anomalies. Science does not claim to know the answer to everything; in fact, the point of it is to ask questions as much as it is to answer them. Where does matter go when sucked into a black hole? The theory of wormholes alone suggests that it must go somewhere, and I personally accept the theory that space and time can fold in on itself and allow matter to pass through somewhere else.
Proving the existence of spacetime travel would make for an amazing discovery and could change everything we know about time and space. The best and brightest have theorized for some time about this possibility, and to some extent have proven that it is possible. People once thought Albert Einstein was crazy to posit his theory of relativity. We now know that not only was he right, his theory is the foundation of almost all things spacetime.
I am totally against denying possibilities in space and time when we have come to the conclusion that the universe is constantly expanding; that the universe is infinite. Because we have little knowledge of what exists within infinite space, I don't think we can deny the possibility of ripples in the fabric of spacetime.
Until enough scientists support this theory, we have to go with that there are no ripples in the spacetime continuum. We don't live in an episode of Star Trek, and having just a few people say they exist, some of whom have no scientific knowledge to back it up, we still have to go with no.