Applied mathematicians do it by computer simulation. Applied mathematicians do it with a real world model. AI researchers do it heuristically when principled techniques fail. Astrophysicists Astrophysicists do it in the dark. Astrophysicists do it with telescopes.
Astrophysicists do it with large objects.
Banach spacers do it completely. Bayesians Bayesians do it with improper priors. Bayesians do it conditionally. Cantor Cantor did it until he was crazy. Catastrophe theorists do it falling off part of a sheet.