Aether

Aether is, according to the Aetheric Wind Model, a substance which fills up the majority of the universe and causes Universal Acceleration.

Physics
It is made of a mixture of Hydrogen (H) and Helium (He). Aether was formed before the Big Bang, when all matter and energy in the Universe was crushed together in the same particle with near infinite heat and pressure. It is of a state of matter unreachable by man. It, like gas, is very fluid, and is so spread out that not even London Dispersal Forces (van der Waals Forces) affect it. As such, it retains energy indefinitely. It is also what warms the Earth and causes the lava under the crust.