I have written a lot about energy, but I’ve put off introducing the most important type of energy again and again. It’s the most important, because it is this type of energy that is responsible for all the structure in the universe, from galaxy clusters down to protons and everything in between. It is the most challenging to write about because it is not particularly intuitive. All the types of energy we intuitively understand, such as the energy of motion, are positive, but this type of energy, crucially, can be negative. On this website I’ll call it “interaction energy” (not the technical term, but my own, chosen to avoid misconceptions that might otherwise arise) because it is associated with the interactions among fields — including their little ripples that we call “particles”. If you’ve taken physics you’ve heard of “potential” energy; what you learned within that concept is a subset of what is included under interaction energy.
I’ve been wanting to address this for a while, because many of you have asked penetrating and central questions about the basic structure of matter, such as:
- Why is the neutron stable inside of atomic nuclei, given that on its own it is unstable?
- Why is the proton arguably heavier than the quarks and gluons that make it up?
And there are other equally important questions that no readers have yet stumbled upon but that I ought to address. Before I can answer any of those questions, however, I have to first describe interaction energy and the role that it plays in structure.
So — without further ado, here’s the article. This was an especially hard article to write and it may well be confusing in places — so I very much welcome your feedback, in order that I can try to make it clearer, if necessary, in later versions.