It absolutely is USELESFULL work, its protecting a 40 BIO USD Marketcap, financial freedom, censorship resistant payments...
Recaptcha and co are gimmicks compared to this.
Recaptcha and co are gimmicks compared to this.
PoW has proven itself in the field for years, while PoS is still untested at scale. Being able to piggyback scientific/medical/environmental computation over a PoW scheme would provide significant value as opposed to a fairly useless compute problem such as the double-SHA256.
The key here is to be able to re-interpret/re-state a problem in terms of the PoW algorithm with the following characteristics: - Expensive to calculate, cheap to validate - Dynamically-adjustable difficulty
An ideal implementation of this would be similar to an OS running an idle process (double SHA256), and switching to running user-processes (medical/scientific computation) when needed/instructed.
Sounds like NP-completeness [1]