Essentially, how do the two forces differ in the way they attract two objects together? I understand that gravity is a relationship between any two objects with mass, and gravity’s “pull” is visualized as an object creating a depression in space; the more massive the object the deeper the depression. But how would you define magnetic force in terms of the relationship between two objects? Is there a comparable way to visualize magnetic force as in the gravity example?
In: Physics
They are almost completely different.
Electromagnetism is a well understood effect of the electromagnetic quantum field. The photon is the quantum force carrier of the field. Quantum electrodynamics fully integrates this quantum representation of the Universe with special relativity.
Gravity is a shape property of space itself, explained by general relativity. A quantum theory of gravity is not yet known, and creating one is an active research element in the physics community today.
You can visualize any field. For magnetism, the common way is to plot field lines. Here’s an example of [Earth’s magnetic field](https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcTCJ8oWbX0Ov-xCR5NJq0AdJIKNMBQB8o11cPMDdpYs_Q&s) on the left side, it’s stable as now, on the right side, it’s in a reversal, which happens every now and then.
Every force has a sort of “Charge”. For gravity, we call that charge “Mass”. In electromagnetism, we call it “Charge”. In the strong force, we call it “Color Charge”.
We don’t really have an understanding of fundamentally what these charges are, we just know that they carry force, and react to other charges.
The intensity of the charges is really what sets them apart.
Electromagnetism is about 10^36 times as strong as gravity. It’s why a simple magnet that fits in the palm of your hand can offset an entire planets worth of gravity. One single pound of pure electromagnetic charge has the same strength as the entire planets worth of gravity.
The thing is, electromagnetism has two poles (positive and negative) which cancel each other out. Gravity has only one pole, and no cancellation happens.
As it happens, the strong force with its color charge has three poles. It’s why we call it “color” charge. Much like we arbitrarily chose “positive” and “negative” to be the two opposing poles of electromagnetism, we chose “red”, “green”, and “blue” to represent the poles of the strong force, as all three together cancel out, similar to how red, green, and blue all add to make pure white.
The strong force is about 100 times as strong as electromagnetism, and is responsible for keeping atoms together.
You can picture magnetism similarly, but it won’t give quite as good an approximation. Remember that the whole ‘depression in a rubber sheet’ thing is just an analogy.
However, magnetism unlike gravity has two different poles. While gravity forms a trough, magnetism forms a peak and trough. Graph these to get an idea of the difference: gravity = -1/(x^2) | magnetism = 10/( (1/x)+x )
Keep in mind that magnetism also only interacts with magnetic things.
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