wait so then why can information not travel faster than the speed of light, which is a value that depends upon time existing - you can't measure signals/informa

wait so then why can information not travel faster than the speed of light, which is a value that depends upon time existing - you can't measure signals/information propagation at faster than c; c is in the form of dx/dt, even if you do that trick where you just set c=1, right?; ..is there no dt?