There are inertial reference frames and accelerated reference frames, and the laws of physics change depending on the frame through which you're observing them. The universe when viewed through an inertial frame won't let you go faster than light, but the very same universe when viewed through an accelerated frame will. Physics typically treats inertial frames as the default frames, thereby marginalizing accelerated frames. Meanwhile, with the exception of skydivers and astronauts, humans spend 99.999% of their lives in a genuine accelerated reference frame. So what would happen if we formulated the laws of physics as experienced through an accelerated frame instead of an inertial one? Imagine the Einstein of an alternate timeline. His life is identical to our Einstein's save one respect: he formulated his theory from the pov of an accelerated frame. What would his theory look like? We know, for example, that at 1g of acceleration you would reach the neighborhood of the speed of light in about a year, but (provided you had enough fuel) you would not suddenly stop accelerating. From the crew's reference frames, they would blow right past the speed of light. In 30 some years, they could cross a distance that takes 2,000,000 years for light to cross. So we know that this theory wouldn't regard 186,000 miles per second as a speed limit. What else would this alternate Einstein say?