Considering the fact that SS and Galactus are short of being devine beings because of the power cosmic, I'm not sure how it could be explained without getting somewhat "deep" and philisophical...but I'll take a shot:
Something, comprised partially of, and yet more powerful than time and space itself; transcending the physical in all states and forms. Energy, in its most primordial form, that state in the beginning before there was any and all. A force that can only truly be harnessed by either those whom share a kindred with it from conception to birth or those imbued with it and reborn (the additional "cosmic awareness" that comes with being imbued with the Power Cosmic requires a mental upgrade, for lack of a better term. No mere being could tap the Power Cosmic, but if one could and did through some means such as an earth born device (see Secret Wars, M: UA), both body and mind would be overwhelmed by the stresses the Power Cosmic would slowly and inevitably place on such a frail form. Indeed madness and death would be inevitable.); for one cannot harness the Power Cosmic as a mortal vessel of flesh and bone, less they be torn asunder by the ever flowing, unceasing infernal energies that are the Power Cosmic...
More than likely there will be some enormous display of power by the SS (as if the ability to fly in and out of earth's atmosphere at will without a ship isn't demonstration enough) where he blows something up.
t: