Over three centuries after Isaac Newton formulated the laws of motion and universal gravitation, this paper demonstrates that additional fundamental implications of Newton’s concept of inertia remain to be explored. By re-examining inertia and its intrinsic relation to energy, gravity, motion and heat, a unity model is proposed. Matter is shown to express its natural inertia through two fundamental, intrinsic forces: inertia-at-rest (𝐼𝑟), a pulling force driven by sharing-energy (𝐸𝑠), and inertia-in-motion (𝐼𝑚), a pushing force driven by excess-energy (𝐸𝑒). Under this unity model, gravity (F) and weight (W) are recognised as direct expressions of inertia-at-rest (𝑊 = 𝐹 = 𝐼𝑟), which draws particles together to form hierarchical, nested structures termed unities, ranging from base particle groups and atoms to planets, stars, and galaxies. Conversely, when acted upon by a sufficient external pushing force (𝐼𝑚 ≥ 𝐼𝑟), a unity member is displaced into a free particle. Heat is redefined as the pushing force (𝐼𝑚) of free particles, and radiation is generalised as heat transfer through successive particle collisions until 𝐸𝑒 is dissipated and the particle rejoins a unity. Based on these principles, electric charge and electricity are redefined as electronic heat, electric generators are recognised as electric transferors, magnetic and electromagnetic fields are shown to be electronic fields of circling electron unities, and their heat transfers cause electronism, including the motor effect. A quantum is redefined as a free particle. The base particles and the unity model are proposed to replace the elementary particles and the standard model. Because matter organises and moves relative to its respective unity centre, reference frames and relativistic dependencies are nullified. Ultimately, the universe is shown to evolve through repeated cycles of unity formation, heat transfer via free particles, and reintegration. Time is proposed as the evolution process of the universe, arising from the cumulative changes of matter from the Big Bang, hence, can only move forward, not qualifying as a dimension. Space is wherever matter exists and moves, as three-dimensional as matter. Therefore, time and space are properties of matter, not physical entities, negating the currently defined space-time.