*takes coffee break* you know, people have told me it would be cool if they could measure their IRL proof-of-work and convert it into a digital proof. Imagine having some unforgeable digital record of a workout or some other activity that is meaningful to you. AFAIK it isn't possible without some new incredible technology probably involving nanomachines, so it can't be done with full veracity, but it also might not make sense to do in the first place. When you move a muscle, the proof of work is the movement of the muscle (which also happens to result in growth). When you dig a hole, the proof of work is the hole. The unique and interesting thing about digital proof of work is that it is abstract. When you hash, the proof of work is just a number with no inherent meaning. But if you apply conditions to that number, it suddenly has a powerful connection to the real world. Trying to capture physical work like exercise and turning it into a verifiable receipt is an exciting concept, but it's kinda like a double-spend; the work went toward something physical, so it shouldn't also be replicable as a digital receipt. The abstract nature of digital proof of work is its own unique strength that sets it apart from physical proof of work. In fact, digital proof of work has the asymmetric advantage in that it can be represented in the physical world (by writing numbers on paper, for instance), while physical proof of work cannot be captured in the digital world (at least not in a full comprehensive manner; lesser means of capture might include a photograph, but that doesn't provide the verifiability of a hash). physical proof of work: energy => physical change digital proof of work: energy => number This is what I think about when I'm doing sit ups.