Microsoft, Google, Facebook, and pretty much every other tech company are investing billions into artificial intelligence, making great strides in building smarter software and hardware.

But in a Reddit AMA (ask me anything) session, Microsoft co-founder and richest man in the world Bill Gates replied to a question about the advancement he most wants to see in his lifetime by indicating that AI can go further still.

"The big milestone is when computers can read and understand information like humans do. There is a lot of work going on in this field - Google, Microsoft, Facebook, academia," writes Gates. "Right now computers don't know how to represent knowledge so they can't read a text book [sic] and pass a test."

While Microsoft itself has built technology that's actually better than a human stenographer at transcribing a natural conversation, it's a lot harder for the machine to parse what's said and take the appropriate action. It's the kind of limit to understanding that owners of the Amazon Echo or Google Home live with every day.

So while the big tech companies are working on ways for computers to glean the correct action from what they're told, Gates is looking forward to the next step after that. Notably, Gates has expressed a lot of interest in the study of education and learning, for humans as well as for machines.

Meanwhile, the Reddit jokesters are out in force: User "PikachuSquarepants" replied to Gates' assertion that a computer couldn't pass a test with "[today I learned] I'm a computer."

Otherwise, Gates says that he's looking forward to more developments in health and vaccine science.

"We need a vaccine for HIV, Malaria and TB and I hope we have them in the next 10-15 years," Gates writes.