In the vast realm of science, there's no shame is answering a question with "I don't know." Well, except in a science class when you are tested on things you should have studied. The whole idea of science is to explore those things we don't yet know and we're doing pretty well when we can find any answers at all. But all new discoveries lead to more questions, so it's a never-ending quest to learn all we can about the universe we live in. Vox explores those questions and discoveries in their regular podcast called Unexplainable. While they explain plenty, there are quite a few questions that science has no definitive answer for yet.
These questions range from the cosmic to the mundane to the intriguing. How do we define "life"? Or conversely, how do we define "death"? Every time we think we might have an answer, something happens to bend our definitions out of existence. What effect does weed have on pregnancy? That's a sticky area to research, since both drug laws and child abuse laws keep possible subjects from participating. Are there living microbes on the moon? Astronauts who have been there left their poop behind in bags to save weight on liftoff, but we can't yet get there to check on them. Explore 17 as of yet unanswered questions in science at Vox. Each question is explained in text and also has the relevant podcast attached in case you want to learn more about a specific question.