Redefining Gravity reconsiders the current definition of gravity. Newton defined gravity as a fundamental force in physics. Einstein defined space-time as the special observer's reference frame. Their path is curved by only a gravitational field. There is no force of gravity between this observer and other bodies. Their path is not affected by electromagnetic forces. Physics has replaced the force of gravity with space-time. Einstein assumed gravity had a velocity of c, which is wrong. This mistake lead to its false waves. Gravity is instantaneous, as demonstrated by all bodies in the solar system orbiting around the system's center of gravity. Newton defined the force of gravity but Newton did not define its mechanism. That enabled Einstein to propose space-time with no force. However, a mechanism for the force of gravity is possible. Physics has evolved assuming space-time is correct, resulting in mistakes. Space-time neglected electromagnetic forces so cosmology neglected them also. After redefining Newton's force, the misapplications of space-time must be reconsidered. Among the book's topics are the atomic model and the fundamental particles, the author's mechanism for particle pair production, Author's description of a neutron's behavior in the atomic mass defect, velocity of light and matter, the author's mechanism for Newton's force of gravity, Kepler's Laws of motion, the author's revision to Kepler's third law, gravitational lensing and waves, dark matter (included to explain why it does not exist but there is much real matter), black holes, neutron stars. The conclusions here affect our understanding of this fundamental force and how it is being applied in both physics and astrophysics. This book is the fourth in a series about cosmology by the author. It follows:1) Observing Our Universe, which explained mistakes with the Doppler effect so red shifts resulted in wrong velocities, and there is no expansion. Gravitational waves don't exist. The author made confirmed predictions of the supposed waves in late 2019. LIGO detects a terrestrial source. Both relativity and its space-time do not perform as claimed in cosmology, because we observing the universe from Earth. 2) Cosmology Transition, which explained the transition required in cosmology to fix the mistakes which followed those with red shifts, relativity, and others. The transition includes the author's quasar model. 3) Cosmology Connections continues the transition for cosmology with further observations of the solar system and beyond, including nebulae, supernovae, galaxies and clusters, and also the importance of plasma, electric currents and magnetic fields. Each book in the series of 4 has its theme and can be read individually. None of the earlier 3 are required before reading this fourth, unless their more thorough explanation of certain issues in cosmology is desired. This book is mainly about physics, even down to the subatomic level. Redefining Gravity offers a new definition of gravity because relativity ruined gravity, thereby confusing cosmology to over-emphasize gravity, when it neglected the other forces. This neglect directly lead to dark matter. In conjunction with the earlier books, after abandoning relativity, cosmology should grasp the balance of the 3 fundamental forces, electric magnetic and gravity. Nearly all the universe is plasma so all forces are relevant.