For a good while now I’ve been researching in an attempt to explain the causes of one of the four main fundamental forces of the universe, the electromagnetic force. This particular force is responsible for holding atoms together, repulsive and attractive properties in certain elements and materials, and is responsible for chemical reactions. (That grade school project you did back in the day where you put baking soda and vinegar in the paper mache volcano and made one heck of a mess, that’s the electromagnetic force.) We’ve all seen in school the project where you place a magnet in the middle of a pile of iron shavings to see a pattern form, but what causes this? I looked into this particular branch of physics and I wish to consolidate in my own words what I’ve found in my research and attempt to explain what causes this force. Surprisingly there is a good theory called Quantum Electrodynamics that explains with great accuracy what causes magnetism, but it’s not a complete explanation, and I wish to summarize conceptually in this article what our current understanding is when it comes magnetism (and without a bunch of math, because I like to go beyond just the numbers and paint a picture of what happens on a visual level.)
Magnetism is a very strong force. The electromagnetic force is as abundant as gravity, although it’s significantly stronger than gravity. (Think of a magnet being able to pick a nail up off a desk and hold it against itself without allowing it to fall.) Magnetism itself is believed to be caused by any and all charged particles, such as protons and electrons. The charged particles give rise to what are known as “Virtual Photons.” Virtual photons are implied photons that are believed to exist, but have such a short lifespan that if a virtual photon were to be measured, it would in fact be a regular photon because anything living long enough to be measured could never be a virtual photon and could only be a regular photon. In essence there currently exists no way to directly confirm the existence of virtual photons but their inclusion into Quantum Electrodynamics gives us great accuracy in explaining what causes magnetic forces.
Virtual photons if they exist would have to be massless and travel at the speed of light, just like regular photons. In other words they would have no rest mass, which means they would have an infinite range just like gravity and regular photons. (They can travel at the speed of light through the universe.) These virtual photons are given off by electrons for example, and an electron will give off a virtual photon to be absorbed by another electron, and depending on the spin of the electrons in question the virtual photon can either cause a repelling or attracting “force,” and from there we get the force of magnetism. The virtual photons transmit this force through momentum, which can be either positive or negative. It’s important to keep in mind that this momentum occurs in a time that is measured as a constant, meaning the time is not variable when measuring this momentum. The virtual particle’s momentum isn’t like the momentum of ordinary matter.
Regularly particles do not have a negative momentum but virtual photons can have a momentum that can numerically negative, meaning that the particles actually are travelling backwards in time. So when you’re picking that nail up off the desk with the magnet, you’re essentially using reverse time to get it done. (The truth is stranger than fiction, but it’s cool isn’t it?) When this negative momentum gets absorbed by the receiving particle it has an attractive effect, pulling that nail off the desk. (The receiving particle actually moves towards the photon as its negative energy causes it to have an opposite reaction to a photon with positive momentum, every action has a reaction and a negative momentum produces an opposite reaction than one would expect from a positive momentum, try and think of it that way.) If a virtual photon has a positive momentum it will move forward through time like normal particles and causes a repelling force when absorbing by the receiving particle. Think of two people tossing playing catch with a baseball. The ball has a positive momentum and when you catch the ball the force pushes your hand back. Imagine that ball having a negative momentum and when you toss that ball it pulls your hand towards the ball instead of pushing it away. The ball is traveling back in time and causes the opposite reaction that you’d expect. It’s weird but that’s what you have to imagine when you think about this force.
Overall the virtual photon explanation has been widely accepted by physicists because it fits in so well with the overall theory of quantum electrodynamics. In other words it does a very good job of explaining what goes on in magnetism without upsetting any other established theories. So far this theory about magnetism has been shown to be true through mathematics, but in my opinion it is a very preliminary explanation. It’s a very good explanation with a lot of potential, but until we can verify the existence of virtual particles in a physical way there exists the possibility that another theory will come to fruition and upset everything about magnetism. We still don’t know exactly how the virtual photons are being generated and that is something that will have to be explained through further mathematical exploration of this concept. The numbers are great and all but it’ll always be a theory until it’s proven beyond the shadow of any doubt. We live in an exciting time in physics where we can deduce the reasons behind certain invisible forces and I look forward to seeing where the electromagnetic force theory takes itself in the years to come.