There is an approachable explanation in [1], chapter 16 ("Duration-bandwidth relationships and the uncertainty principle"), that says that the product of rise-time and bandwidth of a signal must be greater than some minimum.
[1] Siebert, W. M. (1986). Circuits, Signals, and Systems. McGraw-Hill.
The analogy speaks to the number of paths that need be considered so that, later, we can find the overall shortest path (there are likely other intermediate places that we're also evaluating, along with Toronto). Once we know the shortest path from Waterloo to Toronto, that's the only one we need to consider (on that segment) from then on.
I model systems that naturally have block diagrams (modulators, phase locked loops, power amplifiers, channels...). I came to an object oriented approach relatively late, but I would not go back. I don't know about general software, but for simulating physical systems it seems ideal.
Cool. I confess I don't have this 100% straight, but it must be related to the CRB for range estimation. For time (equivalent to range) tau, [2, example 3.13] gives it as var(tau) > 1/(Eb/N0 * MSB), where MSB is the mean-square bandwidth of the pulse.
[2] Fundamentals of Statistical Signal Processing, Volume 1: Estimation Theory.
Here is another [1]--perhaps not to everyone's taste, but it was influential for me. In particular, the first words of the preface: "The underlying spirit of this treatment of the theory of matrices is that of a concept and its representation."