Calculus and analysis are the base of modern mathematics. When we see maths in physics we find many demonstration using calculus but without the necessity rigoriste, for exemple in classical mechanics or analytic mechanics many demonstration using calculus without check limits or continuity of objects. They use tiny objects. I'm learning calculus and analytic mechanics however i'm starting to think mechanics and more widely physics aren't rigorous. I heard to speak about no-standard analysis but I don't know if it can say that physics are rigorous.