 
 <prompt> Which word fit mean the solution to the equations of the theory? Given the previous question, write a context wey contain the answer. E fit be 1 - 20 sentences. Context: <response>: ```In quantum mechanics and quantum field theory, dem define vacuum as di state (wey be di solution to di equations of di theory) wey get di lowest possible energy (di ground state of di Hilbert space). For quantum electrodynamics, dis vacuum dey refer to as 'QED vacuum' to separate am from di vacuum of quantum chromodynamics, wey dem dey call QCD vacuum. QED vacuum na state wey no get matter particles (wey be why dem call am so), and also no photons. As we don talk before, e dey impossible to achieve dis state experimentally. (Even if every matter particle fit somehow comot from one volume, e go still dey impossible to eliminate all di blackbody photons.) Nonetheless, e dey provide one good model for realizable vacuum, and e dey agree with plenty experimental observations as we go talk next.``` 