We don't understand dark matter, don't understand black holes due to not understanding physics in that realm (no unified theory), don't know how to interpret quantum theory. We know that entangled quantum particles act in synchrony over arbitrary distance without any signal between them being transmitted at all ... there's a lot we don't know (including not knowing the full extent of what it is that we don't know).
Even if did know it all, what if the thing traveling has a lifetime of millions or years, or in an AI, maybe traveling at near light speed?
Science simply is not in the business of saying what is impossible - it is in the business of predicting what happens in an experiment where we have an adequate theory. When the prediction is wrong you revise the theory.