The big O question for computer programming is how efficient a computing device can be in solving a problem, which could be seeking some answer or storing an item.
The state-of-art algorithm is really at O(logN) level. No algorithm is able to achieve efficient level better than O(logN), such as O(constant) or O(1/N). N is the representation of the information space or time.
However, if we look at brain, it is in fact running in the range of O(constant) to O(1/N). It takes human limited time to find a solution in driving a car, packaging a bag or falling into love. The more information a human brain have, the more efficient the brain runs, which is O(1/N).
This puts a doom future for AI of using computer, a O(logN) system, to simulate a O(1/N) system. The reverse is possible. This is why human brain invented computer. We do not have the computer that we need to simulate human brain.
Will quantum computer provide solution to solve problems at O(1/N) efficiency?