What are unsolved problems in physics?

Question

What are unsolved problems in physics?

Answer 1

I think an honest physicist would tell you that all of our present theories are just our best educated guesses.

Answer 2

Unifying the four natural forces.

Proving the existence of Dark Matter.

Proving the existence of Dark Energy.

Answer 3

There are always things we haven't figured out yet, but unsolved problems in physics aren't like unsolved problems in math - we might have mathematical solutions for them, but if we haven't tested those solutions, then they aren't considered valid yet.  So you can't really solve them sitting around at home with a pen and paper.

The biggest one currently is how to make quantum mechanics and general relativity agree with each other on common scales - they both work very well on their own scales, but not together.  String theory can solve this problem, but again, we need to test it - and we will, in the LHC.  For more ideas, try asking this again on one of the physics-oriented forms, like physicsforums or advancedphysicsforum.

Answer 4

Provide your criteria, or I could give you 6.02 x 10²³ answers

Answer 5

Why we have to study it in high school. =| seriously.

Sure mass and Weight and stuff are practical. But Vectors, Diodes, Torque? Blah.