Five big philosophical questions:

1. Do we really have free will?
2. Can we know anything at all?
3. Who am “I”?
4. What is death?
5. What would “global justice” look like?

5 Big Unanswered Science Questions:

1. Why does the universe exist?
2. What is a matter made of?
3. How did life originate?
4. How does consciousness emerge from the human brain?
5. Is there intelligent life on other worlds?

The 7 Biggest Unanswered Questions in Physics:

1. What is a matter made of?
2. Why is gravity so weird?
3. Why does time seem to flow only in one direction?
4. Where did all the antimatter go?
5. What happens in the gray zone between solid and liquid?
6. Can we find a unified theory of physics?
7. How did life evolve from nonliving matter?