Number theory and algebraic geometry were developed for their own sake (i.e. "it is cool"), but later people found practical applications in cryptography.
So "useful math must be motivated by practice" is empirically false
> So "useful math must be motivated by practice" is empirically false
That was not the claim. The claim is that useful physics originates in measurements.
> So "useful math must be motivated by practice" is empirically false
That was not the claim. The claim is that useful physics originates in measurements.