I'll agree that this makes it easier. But why? Have you ever, in your life, needed to do this? Do you know anyone who has? Have you heard of anyone who has? Th

I'll agree that this makes it easier. But why? Have you ever, in your life, needed to do this? Do you know anyone who has? Have you heard of anyone who has? This problem sometimes comes up in thought experiments, and sometimes involves convoluted solutions such as bouncing signals off of celestial bodies to produce a time delay. I have never needed to do this. And either way the actual cost for society to do this with blockchains is huge, in energy. You're not paying it, but the cost is there. Or you could just do it the traditional way: Put it on pastebin. Hell, put it on a couple of cloud services, who will likely have logs about upload times. Maybe there are cases, where you want to guard yourself against someone reinventing your industry secret and claiming IP theft saying you copied them. It won't help against a patent lawsuit, I'm pretty sure, since you didn't publish. And publishing is the trade you make with society in order to get monopoly for 18-20 years via a patent. But more importantly: This NEVER needs to be a blockchain. This is not a use for a blockchain. There is nothing chain about it. You just want your blob signed. You could build a service in a weekend that does nothing but sign "I saw the following hash on 2018-05-24: 82390182903120", and run it for no cost (not 0.5% of world electricity). Send your hash to 100 places and boom, done.