[dekken_]

You can say what you like. Science is not about certainties. You can only control experiments to a particular degree and have no control of confounding factors which might interfere with your experiments. Do you really want to compare the totality of all universal processes to such trivial examples? I find it absurd.

[kergonath]

You did not qualify the complexity below which it is acceptable to be certain of something so this is unlikely to be productive. You said that certainty was impossible and I gave you examples of certain things. Besides, both a ball and a glass of water are insanely complex systems. I am not sure we have the same definition of science, to be honest.