Philosophy
The Hard Problem of Consciousness and Explanatory Gaps
Quick fact
Philosopher David Chalmers coined the term 'hard problem' in 1994, but as early as 1874, William James noted that 'the passage from the physical to the mental' is a 'chasm' that science has not crossed.
Why this is interesting
You have a vivid inner world—colors, tastes, pains—but how does mere brain activity turn into that private, felt experience? Why isn't it all just dark and silent inside?