Gravity
All objects, no matter how large or small, are connected by gravity. In the case of the Earth and objects on it, the force of gravity equates to 9.8 meters per second for a falling object. Gravity is what keeps the planets orbiting the sun and the moon orbiting the Earth. Everything is connected by gravity, but the strength of that connection is dependent on mass and distance.
Aether
Many classic scientists, and some modern, believed in a physical medium that permeated the universe. All objects, from planets to microscopic organisms, passed through this medium when they moved. Brush gave aether the quality of absorbing the kinetic energy of an object. He theorized that when kinetic energy is created, due to forces such as gravity, there should be heat as the energy dissipates or changes. The fact that the force of gravity between planets should incinerate most matter means the aether absorbs this energy.
The Kinetic Theory of Gravitation
The theory dictates that most energy in the aether does not affect matter except for gravity and small amounts of heat. As high frequency energy passes through atoms and collides with the nucleus, it produces a force - gravity. His theory stated that this kinetic theory of gravity is observable between material in the Earth's upper atmosphere and aether waves.
Michelson-Morley Experiment
The Kinetic Theory of Gravity is dependent on whether the universe is covered in the medium called aether, and if it affects matter to create gravity. The Michelson-Morley experiment done in the mid-1800s proved that since the intensity and speed of light did not change, this universal medium cannot exist since it did not affect light in any way. Despite this research, the theory of aether continued to be prevalent well into the 20th century and even today.