johnny tisdale
moving the needle forward

Do we know what electricity is?

March 27, 2021

If you google “do we know what electricity is,” you’ll find that someone asked the following question on Quora :

Why do some people say "We really don't know what electricity is." We have Maxwell's equations and we know that conductors have free electrons in their outer shells. So where does this belief come from?

The first reply:

There are a host of reasons why someone might say “We really don’t know what electricity is.” Some of them are philosophical, some of them are contrarian, some of them are deliberately misleading, and others come from a place of ignorance … Of all theories, none is more fundamental than the modern theory of electricity (QED) and none has shown better agreement between prediction and experiment.

This answer misses the point. When people ask if we really know what electricity is, they are not questioning the predictive power of quantum electrodynamics. It is obvious that scientists and engineers know how electricity works; if they didn’t, we wouldn’t be enjoying the benefits of electricity. But knowing how to manipulate something to achieve desired results is not the same as knowing what it is. The textbook definitions of electricity, being circular, do not satisfy someone seeking to form an understanding of what electricity is.

William Beaty, an electrical engineer, writes:

If we look up "electric charge" in a dictionary, we encounter a problem. The definition of "charge" is circular. What is charge? It's the stuff that causes electrical phenomena. What are electrical phenomena? Those are the things caused by charge! Simple, no? (grin!)

Brian Skinner, a physicist, writes:

If you ask a teacher “what is electricity?”, the standard answer you’ll get is that “electricity is the movement of electrons.” … [One problem with this answer] is that if you’re going to tell someone “electricity is the movement of electrons,” then you should probably tell the person what an electron is. And it turns out that science struggles to give a satisfying answer to even this obvious question.

For any science student at the college level or below, an electron is always drawn as a black dot and we are told that this black dot has a mysterious property called “charge”. The existence of such charged black dots is supposed to be taken as a given, with no explanation as to where they come from or what they’re made of.

If you happen to keep pursuing such questions to the level of graduate coursework in physics, the buck gets passed one level further, and you are told that an electron is actually a kind of excitation or defect in a pervasive, “electron field” that fills all of space. But don’t try to ask “what is this field?” or “what is it made of?”. You are likely to be told that such questions are nonsensical, and the electron field is simply a mathematical object.

So, if you’re keeping score, after just two levels of drilling into the question “what is electricity?” we arrive at the answer “it is a mathematical object.” Only a strange kind of person would consider that to be a satisfying form of understanding.

So what is electricity? My favorite explanation is given by Beaty:

There is a good reason why the definition of "charge" is circular. Like mass, length, and time, Electric Charge is a "fundamental." Many dictionaries say this: "Electric charge: a fundamental property of matter." … The circular definition is hard to avoid because normal definitions are based upon deeper concepts, and when we finally arrive at the deepest concepts of all, we cannot "take them apart" into their fundamental pieces … Electric charge is a component of atoms. In other words, after we have broken an object into molecules, and broken the molecules into atoms, when we break the atoms apart we discover particles of electric charge. Charge is material, it is like atoms but it is one step lower than atoms. Most science textbooks tell us that solid objects are made of atoms. It is also valid to state that solid objects are made of electric charge. Objects are made of equal quantities of positive and negative charge, and objects stay together because of the attraction between the quantities of opposite charge inside them. Chemical bonds are electrical in nature.

I am satisfied when Beaty says that "objects stay together because of the attraction between the quantities of opposite charge inside them." I can think of electricity as the reason my body stays together.

I find it helpful to remember that there are four fundamental interactions in nature (“interactions that do not appear to be reducible to more basic interactions”):

  1. Gravitation
  2. The weak interaction
  3. Electromagnetism
  4. The strong interaction

Reality consists of stuff. Stuff is made up of specific kinds of particles (e.g. electrons) that interact with each other in specific ways (e.g. electromagnetism). To dive any deeper we have to ask: Why is reality structured this way, as opposed to some other way? That is another question altogether!