And finally your TA explains that what you're getting is normal, and that's how science works -- you don't get the exact values like you do in the highschool textbooks. What you get instead are values, and you have to be HONEST about recording EVERYTHING that is relevant, even if it goes AGAINST your expectations. After a while, you understand this: http://www.youtube.com/watch?v=serTNuuKA… And you realize that what you did instead, with the crappy experimental uncertainty you didn't manage to get much better, is that instead of "proving" that the acceleration of gravity on Earth is 9.8 m/s^2, you've instead shown that it's not wrong.
And this happens also in other stuff, such as when you're trying to find out what is the geometry of space, and you're trying to find out whether it's curved or flat. http://www.astro.ucla.edu/~wright/DL-vs-…
How one could make such an assumption as light being the cosmological speed limit,
How can you assume that electrons can only orbit around atomic nuclei in discrete orbits and cannot occupy any space they want? http://en.wikipedia.org/wiki/Bohr_model
Again, as Feynman was describing: "First, you guess it. Then, you compute the consequences of your guess, see what it would imply. And then you compare the consequences of your guess with experience."
When Max Planck proposed the quantization of the electromagnetic field in a blackbody "oven", it was out of trying every idea. He *knew* that the energy couldn't be infinite -- that would make no sense. So he had to find a way that the sum of the energy densities would give a finite sum, and he tried the idea of discrete levels, and it worked -- it gave a finite result.
In the end, it only matter whether it WORKS. If it's not wrong, then it MIGHT be right.