system
Given the following post, respond as if you're commenting on Reddit:
human
Eli5: What is physically stopping something from going faster than light?

Please note: Not what's the math proof, I mean what is physically preventing it?

I struggle to accept that light speed is a universal speed limit. Though I agree its  the fastest we can perceive, but that's because we can only measure what we have instruments to measure with, and if those instruments are limited by the speed of data/electricity of course they cant detect anything faster... doesnt mean thing can't achieve it though, just that we can't perceive it at that speed. 

Let's say you are a IFO(as in an imaginary flying object) in a frictionless vacuum with all the space to accelerate in. Your fuel is with you, not getting left behind or about to be outran, you start accelating... You continue to accelerate to a fraction below light speed until you hit light speed... and vanish from perception because we humans need light and/or electric machines to confirm reality with I guess.... 

But the IFO still exists, it's just "now" where we cant see it because by the time we look its already moved. Sensors will think it was never there if it outran the sensor ability... this isnt time travel. It's not outrunning time it just outrunning our ability to see it where it was. It IS invisible yes, so long as it keeps moving, but it's not in another time... 

The best explanations I can ever find is that going faster than light making it go back in time.... this just seems wrong.
gpt
So way down here at non-relativistic speeds we look at F=ma and think if we double the force we are going to double the acceleration, and if we do this enough we will eventually go faster than 300k km/s.  This makes sense to us, it's very intuitive, and it fits with our day to day relative of how the world works.  It's also wrong (ok, not really wrong, more imprecise, or limited in its extent).

Relativity changed our understanding of how the universe works, and it turns out it's a much weirder place than we are used to.  It turns out there is this universal constant called c.  Now we first learned about it from the point of view of it being the speed of light, but that's not really what it is.  c is the conversion factor between time and space in our universe.  So it turns out that if you double the force you don't exactly double the acceleration.  At low speeds it's very close to double, but as you get closer to c it takes more and more energy to move faster.  When you get very close to c the amount of energy needed gets closer to infinity.  Since we don't have infinite energy, we can't ever get to c, we can only get closer and closer.

This has nothing to do with our perception.  We can mathematically calculate relativistic speeds, we can measure objects moving at those speeds, and we can prove to ourselves that Einstein was right.