Degringolade

To clarify this: a proof is a resignation – that the concept of truth does not apply at all.

The reason is that every proof is based on presuppositions, and to get picky about it, an infinite collection of presuppositions.
In physics, if the variable mass “m” has no other properties that make a difference in a calculation, then this is a presupposition. Whether an equation containing “m” is “true” depends on how certain you need to be. At some point in the process of proofing the ‘truth” of the equation in the early 1900s, the presupposition became false.