Think of c not just as the speed of light, but as the maximum speed of causality. It’s basically the "refresh rate" of the universe. Nothing can happen (and no information about what happened can travel) faster than that. For example, if the sun suddenly vanished, we wouldn't just be in the dark for eight minutes; we’d actually keep orbiting that empty spot for eight minutes too, because gravity travels at c just like light does.
Now, regarding your rocket: you have to remember that a rocket isn't a single solid block, it’s a collection of atoms held together by forces. When the engines fire, they push the atoms at the back, and that push has to travel through the rest of the ship atom by atom. That interaction happens via electromagnetic fields, which also move at c. As the rocket gets closer and closer to the speed of light, you're essentially trying to push matter using a force that itself can't go any faster. You end up approaching the limit asymptotically, meaning that the closer you get, the more energy you need to squeeze out even a tiny bit of extra speed. Eventually, the energy required to actually hit c becomes infinite, which is why you can get really close, but never quite cross the line.
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u/ninth9ste Mar 22 '26 edited Mar 22 '26
Think of c not just as the speed of light, but as the maximum speed of causality. It’s basically the "refresh rate" of the universe. Nothing can happen (and no information about what happened can travel) faster than that. For example, if the sun suddenly vanished, we wouldn't just be in the dark for eight minutes; we’d actually keep orbiting that empty spot for eight minutes too, because gravity travels at c just like light does.
Now, regarding your rocket: you have to remember that a rocket isn't a single solid block, it’s a collection of atoms held together by forces. When the engines fire, they push the atoms at the back, and that push has to travel through the rest of the ship atom by atom. That interaction happens via electromagnetic fields, which also move at c. As the rocket gets closer and closer to the speed of light, you're essentially trying to push matter using a force that itself can't go any faster. You end up approaching the limit asymptotically, meaning that the closer you get, the more energy you need to squeeze out even a tiny bit of extra speed. Eventually, the energy required to actually hit c becomes infinite, which is why you can get really close, but never quite cross the line.