Gravity Part 1
Consider an apple hanging from its stem. Gravity is acting on it. What is gravity? You can find out more as you read, especially if you follow this to the end. In the meantime, we ask: what is gravity doing? Gravity is ACTING on the apple and FORCING it to "want" to act a certain way. I put "want" in quotation marks because the apple does not really "want" anything. It has no consciousness. I mean only that because of the interaction between the apple and the gravitational field, the apple is being forced to behave in a certain way, but right now, it can't, because its attachment to the stem is holding it back.
The Dirac Equation is Relativistically Invariant.
Proof attached.
Proving the Relativistic Energy-Momentum relation, the hard way and the easier way.