Open problems
Cosmology
1. Why the present value of the cosmological constant is so extremely low?
Formulation of the problem
Related posts: Disorder on the landscape, Anderson loclization on the landscape, WMAP 5 year
2. Why did dark energy start to drive the Universe’s expansion only recently?
3. What is dark matter?
4. What is the origin of ultra high energy cosmic rays?
5. How to understand probabilities in eternal inflation?
Astrophysics
1. How to explain galaxy formation of gaseous galaxies?
2. What is the origin of forbidden velocity wings?
Field theory
1. How to explain confinement of quarks?
Formulation of the problem
Related posts: Chaos in YM and confinement
2. Mass scale in the Yang-Mills QFTs
3. Chiral symmetry breaking in YM QFTs
4. Heirarchy problem: why electroweak scale is so much smaller than the Planckian scale?
5. Where are instantons in non-equilibrium QFT?
String theory/Gravity
1. How to rigorously proove AdS/CFT correspondence?
2. How to formulate string theory on a time-dependent background?
3. How to formulate string theory on dS space? If there a field theory dual to the string theory on dS, what is this dual theory?
4. Thermodynamic origin of classical gravity
Condensed matter
1. 3D Ising model
2. Fractional quantum Hall effect and origin of the state with filling factor 
.
[Formulation of the problem] [Related posts]
Turbulence/hydrodynamics
1. Finite-time singularities in 3D Euler equation
2. Existence and uniqueness of solutions of the Navier-Stokes equations
