Nothing can go faster than the speed of light. It would require infinite energy for anything with mass to attain the speed of light, and FTL travel in any form creates unresolvable paradoxes. That’s the simple answer, anyway.
Nothing stuck on our brane can exceed light’s limit as we see it. Change the temporal coordinates and it is a completely different reality, and I’m wondering how we are going to discern when/if we’ve tapped something over into those different temporal coordinates. THAT is what I wanted to write and ask Lisa, but I haven’t an address.