With all of the discoveries and all the progress that has been made and advanced scientific tools at their disposal, physicists have yet to find answers to many of the most prominent questions that pertain to our physical universe.

We looked at 18 of the most compelling enigmas to see more precisely what we know and do not know about our universe. Far from being exhaustive, this list is a representative sample of the major issues facing physics today–and we’d love your input to help round out this list.

Among these questions, which may sound esoteric, there may be those that we will never be able to resolve.

But we’ll let you make that distinction.

With any further ado, here are 10 unanswered physics questions we still need help figuring out.