I don't dispute that Relativity makes sense from the perspective that it solves certain problems and is observable to some degree. But then, the rules that were used to fix observable problems when the planets were presumed to be on spheres centered on the Earth and atoms were presumed to be solid structures also worked (as long as you accepted that physical laws weren't constant).
Einstein wasn't completely happy with Relativity, and I've got a gut feeling that there is a simpler solution that does not require special rules.
I won't pretend to be well schooled in Relativity, but I'm just applying the same principle that has worked so well in all other puzzle solving, i.e. "First eliminate the impossible." I well accept that time can be different for two different observers, if molecular activity determines our perception of time and approaching C affects molecular activity. But I fail to see the limiting factor of exceeding C for a single observer.
I realize this makes me a rube, but I don't pretend to see the Emperor's clothes (even if they really do exist).
Well, I’m not an expert either. But I have read John Wheeler’s Gravitation book, and I understand enough differential geometry to get though most of it.
You might not like this argument, and I bet there are better ones, but relativity is a very simple elegant model that predicted many things before they could be verified, or before anyone even thought to see them. One prediction is that if you take two synchronized atomic clocks, put one on the roof of a skyscraper and one in the basement, the one in the basement will run slower because it’s closer to the Earth’s gravitation. Well, sure enough, after a year, the basement clock was a few microseconds slower. So they swapped the clocks, and after another year, the two clocks were synchronized again—at least within the error of atomic accuracy.
GPS is so incredibly accurate because the position calculations take the actual speed of the satellites into consideration when measuring time. Clocks that move run slower.
Relativity explains why these observations exist via geometry. The geometry will not allow things that move slower than the speed of light to surpass the speed of light. Also interesting, it will not allow things that move faster than the speed of light to move slower.
Ultimately, of you want to go faster than the speed of light, you have to accelerate. This requires applying a force. That force has to move in the opposite direction faster than you want to go. Notice, I said force, and not any particular mass. Yes, big planets can accelerate slow probes. This is why jets that go 600 MPH expel exhaust faster than 600 MPH. Since we know of no force that goes faster than light, we have nothing to use to accelerate us faster than light.