system
Given the following post, respond as if you're commenting on Reddit:
human
Eli5 Why can’t something be theoretically be faster than light? Why is that considered the absolute speed limit when we don’t even know what’s out there or what could theoretically be faster?
gpt
There probably isn't an ELI5 or even ELIPhD answer to this question. Nobody know why our universe is set up this way.  What we do know is what we have observed. You can make very small things like say a proton go really really close to the speed of light. But what we observe when we try to push those things faster is that the more "push" you give them, the less boost you get. You push twice as hard and now its only going a tiny bit faster. you push a hundred times harder and now its only going an even tinier bit faster. Pretty soon you are using all the pushing force in the world. Then you get another surprise, the little proton suddenly seems to act like it's gotten really heavy. And the faster you push it, the heaiver it seems to get. Imagine if you stepped on your gas pedal in a car and the car got twice as heavy!

Basically the rules for our universe say that if you are an object, a "thing" you can't ever go at the speed of light. You might get pretty close. But it takes more and more energy and at some point the amount of energy it takes becomes greater than all the energy in the universe.