Everything is interacting.
People are interacting with their cars and cats and jeejahs, with the woods, with each other. Mosquitoes are interacting with dragonflies. Blue jays with sunflower seeds. Roots with soils. Sunlight with raindrops. Moons with planets, planets with stars, stars with galaxies, and galaxies with more galaxies. The whole thing is interactively expanding. And underneath it, molecules of water made of hydrogen atoms are interacting with oxygen atoms.
Inside a hydrogen atom is the interaction of a proton and an electron, which are not objects, exactly, but behaviors of energy that are bound together by another behavior of energy called a gluon, which carries the binding force of the interaction. The interactions between protons, electrons, gluons, quarks (up, down and strange) and a galactic array of other particles behave according to general patterns which are not completely understood, though well enough to disclose and predict incredible things and to have a name: the Standard Model of subatomic physics.
One of the incredible things described in the Standard Model is that subatomic particles appear and disappear. Where they go and where they come from, no one knows, though of course there are theories, some involving other dimensions and such. Fundamental particles can decay, which means they transform from one kind of particle into others. Unstable atomic nucleuses, like in uranium, decay into particles collectively called radioactivity which is so energetic it can kill you if you spend too much time in its vicinity. Radioactive elements are unusual in our world, though.
But in addition to decaying, subatomic particles can also annihilate each other. This happens because most particles have an opposite, or antiparticle. The antiparticle of an electron is an antielectron, or positron, meaning it has the same mass as an electron but instead of the electron’s negative charge, the antielectron has a positive electrical charge. When an electron knocks into a positron, they annihilate each other and generate a tremendous, orgasmic amount of energy. (Quick note on how much energy: Matter is a form of energy, shown in the equation e = mc2; in other words, the amount of energy (e) contained in a piece of matter equals the mass (m) of the piece times the speed of light (c) (186,000 miles per second), squared. Huge. The amount of energy in your fingertip is awesomely huge.) The annihilated electron and proton can turn into a photon of light and a couple of different quarks, which can then produce a couple of different mesons.
No one knows why matter and antimatter, as the antiparticles are collectively called, should necessarily exist in this offsetting way. It is only known that behaviors of energy in the subatomic world are successfully explained by this offset, that is, they can be predicted with mathematical equations and verified in photographs.
Particles interact in four different ways, known as the four fundamental forces or four interactions: gravitational, electromagnetic, strong and weak. Force carrier particles such as photons, bosons and gluons (and possibly gravitons) somehow transfer or carry the forces between particles.
The strong interaction is the binding force among quarks and gluons. The weak interaction governs certain kinds of changes, or instabilities, in particles. The electromagnetic force is the interaction due to electric charge and is responsible for light. The gravitational force is the interaction of particles due to their mass.
We notice two forces here in our version of the world. One is gravitation, which holds us and the moon to the Earth, and the Earth to the sun, the sun to the stars, and galaxies to galaxies. The other is electromagnetism, some of which we see: Light is electromagnetic energy. Meanwhile, subatomic particles are continually changing and swirling, popping into and out of existence, knocking into each other, annihilating each other and producing more particles, always keeping a virtually perfect balance of energy in the universe.
It’s happening in the photon flows from your computer screen. It’s happening in the air and in the light streaming through copper-colored beech leaves. Inside your brain while you read and in your transparent eyeball. When you meet a friend at the lake. Every time you open your mouth, up against a wall, and when your fingers work guitar strings. In the image of yourself in your mind. When pictures trigger memories of delight and torture. A blue moon May. Where do memories go, and where do they come from? It’s happening in your DNA.
All the time, electrons and positrons are knocking into each other and producing mesons, galaxies are colliding and producing more galaxies. Asteroids knock into planets and disappear into moons. People knock into people, annihilate each other and produce more people and memories and music, one song unfolding uncannily into another: My meson Jack one day from out of nowhere started playing note for note on his guitar a melody I created one summer 10 whole years before he was born, toyed with for a few weeks and then forgot until that moment 28 years, one return of Saturn, later. Where did that melody go, and where did it come from? People, songs and planets appearing, disappearing and reappearing in other forms, sent from who knows where to who knows elsewhere.
What is happening here, there and everywhere with all this knocking together and up? The physicists think space and time itself is made of interaction. The whole universe is a stupendous ecology of energy, a great music of the particles.