What would happen if you could create or destroy energy?

Question: What would happen if you could create or destroy energy?
- Keywords:
  create,
  destroy,
  energy
Asked by to Hannah, James, Meggi, Olivia, Oli, Paul, Saiful on 3 Jan 2017. This question was also asked by .
- Meggi answered on 3 Jan 2017:
  
  Phew, I can only make a humble guess… So you mean, what happens if we make energy out of nothing or we transform energy into nothing?
  
  First we would need to define nothing, I am not sure there already.
  
  I guess this would be very powerful. Nature seeks for the equilibrium and playing with forms of energy like this, should therefore shift something far away from equilibrium.

Question: What would happen if you could create or destroy energy?