Good point, and a point which all scientists assume. That's why replication of results is so important in the scientific method. In all probability everything man conceives is not infallible, including the concept of God, a notion of a creator and intelligent design.
Where is all of the universe? In your head.
I hear you on this. The point is that "experiments" as we design them are limited. As a physician, I know that many "clinically proven" therapies are worthless. Everyone who actually cares for people knows that this is true. The scientific method is the best we have, and it is a tool that we are obliged to use. No reproducible experiments can prove that life evolved in the absence of a Creator. That it may have, is highly counter intuitive and mathematically unlikely. Nevertheless, it is certainly possible.