Fractals:
Here is another example of how to model the "clumping" of reality that contradicts our sensual model of "particles." Is our Big Bang a particle? Is an electron? They are material entities in the general sense, but their "Base Reality" nature does not follow the intuition we have built up about what ordinary objects are.
Fractals mathematically perform the type of clumping at different scales that physical materials do, but fractals also are infinite: you can zoom out and zoom in forever and it never ends.
Proving the Relativistic Energy-Momentum relation, the hard way and the easier way.
This adds the proof for the relativistic mass effects from motion, proving that gravity causes it.