The energy of the universe (as contained within the elements) is declining as it ages, some of which is being stored as potential energy by converting to mass within the existing elements and the rest to an entropy that heats the elemental mass:
E (energy) <===> m (mass) or E ----> ɛ (entropy - heat and temperature).
Energy and mass can neither be created nor destroyed but are interconvertible. The flow of heat is from warmer to cooler and irreversible. In an open system, heat flows toward the empty space of the colder universe. Heat, unable to reverse flow, indicates it is not reverting to energy but causing the entropy of the universe to increase. The temperature of the universe (~2.7 Kelvin) appears low because space is expanding much faster than the heat produced by the stars and elsewhere. Space is the container of entropy. Time is non-linear when space is expanding.
On Earth, the declining energy of eight elements (O, Fe, Si, Mg, S, Al, Ni and Ca) as exemplified by their ionization properties, is responsible for accumulating sufficient mass to double Earth's radius at least twice in the past billion years. Before that time, the energy converting to entropy from the same elements internally heated a near absolute zero planet for several billion years, cooling to a core, mantle, and crust. Afterwards, it provided sufficient heat to maintain a temperate environment to support life while exponentially growing to its present size. Ionization is responsible for oxygen becoming water and doubling in volume several times to incrementally fill the expanding ocean beds shown on the NOAA map, Age of the Ocean Floors.
Ionization is presented as a feasible mechanism for expanding and heating Earth and the other planets in the universe.