Problems that only humans will ever be able to solve With the increasing complexity of reCAPTCHA, I wondered about the existence of some problem, that only a human will ever be able to solve (or that AI won't be able to solve as long as it doesn't reproduce exactly the human brain).

For instance, the distorted text used to be only possible to solve by humans. Although...


  The computer now got the [distorted text] test right 99.8%, even in the most challenging situations.


It seems also obvious that the distorted text can't be used for real human detection anymore. 

I'd also like to know whether an algorithm can be employed for the creation of such a problem (as for the distorted text), or if the originality of a human brain is necessarily needed.
Informally, AI-complete problems are the most difficult problems for an AI. The concept is not mathematically defined yet, as e.g. NP-complete problems. However, intuitively, these are the problems that require a human-level or general intelligence to be solved.

Real natural language understanding is believed to be an AI-complete problem (this is also discussed in the paper Making AI Meaningful Again by Jobst Landgrebe and Barry Smith, 2019). There are a lot more AI-complete problems. For example, problems that involve emotions.