Prologue
Chapter 1:

Light Chapter 2:

Potential Energy Chapter 3:

E=mc^{2}
Chapter 4:

Exchange Rates Chapter 5:

Clock-Rate Chapter 6:

Gradients, Motion, and Acceleration Chapter 7:

Gravity and Light Epilogue

Light Chapter 2:

Potential Energy Chapter 3:

E=mc

Exchange Rates Chapter 5:

Clock-Rate Chapter 6:

Gradients, Motion, and Acceleration Chapter 7:

Gravity and Light Epilogue

There’s no Such Thing as Gravity:

The World Just Sucks!

A slightly different approach to general relativity

for high school physics students

By Mark Sowers

Potential Energy

Let’s say you have a really strong arm and are able to throw
a 1kg rock from the ground, up through a window on the 7^{th} floor of
a building (about 74 feet up). You give it the energy it needs to reach that
height (about 220 joules of kinetic energy in the form of vertical motion[1]).

There is a law of physics called the conservation of energy. It states that energy never just disappears. Energy is always there in one form or another. As that rock rises, it slows down. Its kinetic energy is converted into potential energy. And when it reaches 74 feet, all its kinetic energy is gone. Those 220 joules are now entirely in the form of potential energy.

Potential energy isn’t a very satisfying concept to most
physics students. Potential energy is the amount of energy that an object *would*
have *if* it were to fall from a given height. If our rock falls 74
feet, it would reach the ground with 220 joules of kinetic energy. But where
did this energy come from? Does the force of gravity somehow transfer energy
from the Earth into this rock? If so, does that mean that the Earth now has 220
joules less energy than it did before?

It depends on how you look at it. One way of looking at it says that the Earth does indeed have 220 joules less energy than before the rock fell. And while valid (meaning all the math works out), explaining how this happens starts to involve gravitational force-carrying particles (called gravitons) and becomes much more complicated than the scope of this paper.

Another way of looking at it says that the energy is somehow ‘stored’ in the rock, and is ‘released’ when it falls. But that leaves the question of just how that energy is stored, and how does it know to release when the rock is falling? It is this approach that I will focus on. To answer these questions we need to know something about energy itself. And when it comes to energy, there is one equation that says it all.

[1] Given the
equation for potential energy (U) as
U=mgh we find that 1kg(m) times 9.8m/s^{2}(g) times 22.5m(h) gives us about
220 joules.