Are empty orbitals degenerate?
My chemistry teacher Mr Ong Chiau Jin answers: 


  Why are all the orbitals that have the same principal number in
  Hydrogen degenerate?
  
  In hydrogen, all orbitals with the same principal quantum number 'n'
  (1,2,3...) are degenerate, regardless of the orbital angular momentum
  quantum number 'l' (0,1...n-1 or s,p,d,). However, in atoms with more
  than one electron, orbitals with different values of l for a given
  value for n are not degenerate. Why is this? Surely the radial
  distribution functions are similar for hydrogen (in that there's still
  penetration of orbitals and so on). Or is it that orbitals with
  different values of l are degenerate for a value of n greater than
  would be occupied in that particular atom's ground state?
  
  The answer is right there in your question. It's only the interaction
  of multiple electrons in an atom like He, Li, Be, etc. that makes the
  different angular momenta wave functions differ in energy. Consider
  this. For the one electron system, why should a p or d orbital differ
  in energy from an s? What makes them differ? In the multi-electron
  case, the p orbitals have different spatial extent, different angular
  components, so the electron density caused by an electron in that
  orbital will interact differently with the other electrons. In other
  words, you need to have more than one electron for the "shape" of the
  p and d and f orbitals to matter to the other electrons. In the H
  atom, there's only one electron, so there's no electron-electron
  repulsion to differentiate the s, p, and d orbitals.


This may not be the perfect answer but it does capture the essence of the perfect answer, which is the idea of multi-electron interactions. Hope this helps.