It is all about information ..
Mainly (i believe) there is no definite way to tell if a certain info is true or not.
Over time, we have found ways that we have agreed that everything that applies on it is true.
Some of those include Logic, on which Mathematics are based (somehow).
Therefore scientists believe that whatever has been derived using Mathematics will and Logic (in the right way) will be true.
It is hard to find flaws or errors in things that have been based on Logic and/or Math, but it is not impossible, it is possible that someday someone will find something wrong in either the original data that has been used to derive a certain theoretical limit, or something wrong in the use of Math/Logic in it.
Otherwise, every other impossibility is just people that are too lazy to work to make something possible.