What is the last question science will answer?

By this I mean, what are the "hardest" questions?

We're trying to figure out gravity and stuff but still have absolutely no idea how organisms can be sentient, conscious beings with an "observer" inside of them who actually sees these signals instead of just being a p-zombie.

I think consciousness will be the last scientific problem, and it will ALWAYS be unsolved because of the philosophical reasons we can question our own sanity and such