This morning at the crack of dawn, I find myself sitting at my PC, ruminating over coffee about language, of all things. More specifically, as of late I’ve been wrestling with the problems I have been having with the language used in quantum physics and how a few simple words cannot only impede a good understanding of what is intended, but how those words can be so damn misleading, sending you off on a tangent, more and more distant from what is a correct understanding.
First, let me dissuade you from any thoughts you may have about my study of quantum physics. I am not a physicist. I don’t play one on TV. I don’t do the math. Period. I’m just a guy with a passion for philosophy and science. A hobbyist.
What I do instead is attempt to learn about the concepts of quantum mechanics. Remarkably, physics is an area where one can study and learn about the many fascinating concepts being taught, discussed, and debated regarding science focused on understanding reality itself. Even physicists agree that this is possible.
The math, of course, is required for anyone who wants to “prove” one thing or another scientifically, but math is not required to get a basic understanding of the concepts being proposed or discussed by physics. This is a wonderful thing! And it is made even more wonderful since we live in an age where we are blessed with certain scientists and philosophers who are great at explaining difficult ideas to mathematically challenged people like me.
I’m not interested in proving any theories. I won’t live long enough to learn the math required to do such a thing. Instead, I seek out trusted scientists espousing one theory or another, and the scientists who oppose those ideas. Along the way, I try to apply common sense and sometimes, even intuition, before drawing any conclusions. My only purpose is to find some answers to life’s biggest questions: What does it mean to be human? How is it that we exist? How did the universe come to be? What is consciousness? What is reality? What is time? You know, the easy stuff.
Anyone can study physics. Anyone can learn the concepts without the math. What is required is just a small matter of time, as it definitely takes time to understand just what the hell physicists are talking about. In trying to understand the concepts I have found myself following various threads of meaning regarding specific words, which invariably turn out to be incorrect. Grrr! It’s irritating.
This brings me to the problem puzzling me this morning, the problem of language within physics. Some of the concepts regarding fundamental physics are difficult enough without using words that can mean very different things to different people. And as you might think, explaining physics requires a lot of words. Yet, knowing what scientists mean by their words is not always clear-cut.
For example, take the paragraph I just wrote above this one. I used a word I don’t even think about anymore: “fundamental.” You can’t escape this word in physics. But what is meant by it? Most would say that “fundamental” means essential, perhaps primary in importance. One wouldn’t be necessarily wrong thinking this, but they would miss the import of what physicists really mean by the term.
To scientists, “fundamental” means not just essential, but also refers to something basic, something that is no longer reducible to anything else, something that cannot be broken down into any smaller components. This means much more than mere essential. This term also reveals the rather ancient philosophical method scientists use today for doing much of their research. This method is called appropriately, “reductionism.”
For example, in physics they refer to things called fundamental particles.
Yes, fundamental particles can be called essential particles, but what they really mean is that a fundamental particle cannot be broken down into any smaller particles. You’ve no doubt, heard of quarks and photons, and maybe even leptons and gluons. These are some of the fundamental particles in what scientists call the Standard Model of particle physics.
There is a great anecdote attributed to philosopher Bertrand Russell that captures the concept of reductionism. I’ll share it, as I think it is loosely related to what I’m writing about and I think it is rather illuminating.
Reportedly, Russell was giving a lecture on astronomy. He was explaining how the Earth orbits around the sun. A woman in the audience raised her hand with more of a statement than a question. She said that this talk of orbiting couldn’t be since the Earth is actually supported on the back of a giant turtle! When Russell asked the woman the logical question, “Well, what is supporting the turtle?” She replied, “It’s turtles all the way down!” Thus, you see, scientists are always on a turtle hunt, trying to find the final turtle.
You may hear scientists talk also about fundamental theories. A fundamental theory is one that cannot be derived from any other theory and provides the most basic, comprehensive explanation for a particular domain of physics. In this context, both quantum physics and quantum mechanics[i] are considered fundamental because they describe the behavior of matter and energy at the most basic level. As far as we currently know, neither can be derived from a more fundamental theory.
I hope this linguistic rabbit hole I just dragged you into demonstrates that understanding what physicists mean by the words they use is important. They don’t always mean what you think.
In particular, let me visit another word used by scientists, one that you hear mentioned frequently. It may appear as just a familiar manhole cover, but once you open it and look inside you are drawn quickly down into a labyrinth of meaning, full of twists and turns. The word is: “particle.”
Theoretical physicist, Matt Strassler said, “The problem with explaining physics… is that the first thing that gets in your way is language… and the word ‘particle’ is a particularly problematic one.”[ii]
“Particle” is a common word, is it not? We get it from our English language, but it is also a word in many other languages. As such, it is a word that, unfortunately, carries a lot of baggage. Think about it.
What comes to mind when you hear the word, “particle”? You perhaps thought of a speck of dust floating in the air, or a grain of sand? Maybe a biblical reference popped into your head, as in a “mote in God’s eye”? Something along these lines, right?
From there you may think of a particle as a small thing, shaped like a tiny ball perhaps. This then, is the thought, the picture in my head that I had when I first heard of a fundamental particle. I was aided in thinking of this picture by the fact that numerous graphics depict fundamental particles as tiny balls. Granted these tiny balls are much smaller than I can even conceive of, but that’s what I thought they looked like, even at that scale. I am not the Lone Ranger in this, as many people have the same thoughts when they hear the term. Did you?
These days we might even think about that tiny ball being so small that is becomes just a point, like a dot of ink on paper. You can even hear physicists talk about a “point particle.” I guess this is a way for them to get the concept of “very tiny” across.
So what is an example of a fundamental particle? Well, an electron is a fundamental particle. You’ve heard of electrons, for sure. But, if you really want to understand what an electron does, that image of an electron as a teensy little ball floating in space, will cause problems because that image cannot capture some of the things electrons do.
Physicist Matt Strassler uses the following example to make this point. Take a box and put a particle in it. What have you got? What is that particle doing? You may think of it as a lone particle floating around in the box, where gravity eventually makes it end up at the bottom of the box. If there wasn’t any gravity, it would probably just float around the box. That’s it, right? There’s really not much more one can say about that particle.
Now, put an electron in the box. What happens? Well, what happens is that the electron fills the entire box! Say what? Yep, and that’s not all. It also vibrates while it is there! You have to admit, this is quite different from the idea you had of a particle in a box. It sure was for me, as this was a WTF? moment. Strassler then rightly queries, “Why are scientists calling electrons particles if they can do things like fill an entire box and vibrate, all very different from any idea we have of a particle?”
To answer this, Strassler takes us back to the origin of the word, which involves cathode ray tubes of all things. Now, if you were born after 2000, you probably don’t know what cathode ray tubes are. It’s a glass tube containing a vacuum. Inside is an electron gun that shoots electrons out in a straight line and can make spots appear on a screen. Tubes made of cathode ray emitters were used in early television sets and computer terminals, often called CRTs for obvious reasons. Thus, cathode rays gave us the first manifestation of electrons ever discovered.
At the time cathode rays were first being used, all we knew was that these beams could shoot a narrow beam of stuff at a screen. We didn’t know what that “stuff” was. Eventually, scientists figured out that the beam was actually comprised of lots of tiny objects that were all the same. They all had the same mass and electric charge. So, they decided to give them a name and thus called them “electrons.” Strassler tells us that the scientists, looking at what they had found, decided that if they had a bunch of objects traveling one after another in a beam, they thought they must be a bunch of particles going in a straight line. He concludes, “A reasonable thought.”
In the 19th century, when cathode rays were first used and those little dots were identified as electrons and labeled as such, light was considered to be a continuous electromagnetic wave. As such, there was no discussion of particles when it came to light. But then someone came along to upset this particular apple cart: Albert Einstein. Doh!
Einstein essentially said that these ideas are all good, but you can’t explain the photo-electric effect[iii] with them unless… wait for it… light comes in little packets. Einstein called these little packets of joy, “quanta.” This is the birth, Strassler says, of the quantum idea. He goes further and tells us that this is where waves and particles first came into contact and conflict, as ideas.
Let’s not forget that before this, science was a bit simpler. Atoms were particles, or at least, particle-like. Electrons were particles. Light was a wave. Einstein agreed but pointed out that there was something about light that was particle-like. He delivered this idea to his peers in the form of a proposal that would explain an experiment. At the time, this was a big deal and a lot of scientists did not believe him. Their argument for light as a wave was based on the demonstration that light shows interference. This was demonstrated whenever you passed light through two slits or through a diffractor, creating lots of interference patterns. This was acceptable because everyone knew that all waves show interference patterns, even waves of water. Thus, the idea that light was somehow particle-like was not accepted by many.
Don’t forget that Einstein was in his 20’s at the time. Just a kid. And here he is telling established scientists that light was somehow comprised of tiny packets of these quanta. This had to have been met with not just doubt, but derision. The idea made no sense to them. They thought, “What about the interference pattern?”
We now know, of course, that Einstein was right. But all these years later, we are still grappling with the knowledge that he was right. Somehow light can exhibit both interference and particle-like behavior! And we don’t know why! Here, take note of something important in what I just said. I said that light is “particle-like,” not that light is comprised of particles. In other words, light is not made of little dots!
Now it is true that light is actually made of something we call photons, and physicists tend to call photons particles, but photons are only like particles in certain ways. At the same time, photons also have these other features that they share with electrons, which is that if you put photons in a box, they too, will fill the box and they will vibrate. This is, Strasser reminds us, essentially how lasers work.
So here you have it folks. This conflict, born at the beginning of the 20th century, between the words we use, the concepts we use, and the behavior of objects, has caused significant confusion in classrooms and in the books the public reads about physics. I know. I am one of the victims! Strassen goes further and says he thinks it also causes some physicists problems, at least for those who don’t have to deal with these concepts on a regular basis.
But, for those scientists who work in theoretical physics, who have to become experts in something called, quantum field theory (QFT), they cannot be confused about this, because QFT “…is very clear about this.” In QFT, it is not true that electrons are particles of one type and photons are some other thing. Strassler says that in QFT, photons and electrons are “treated on the same footing.” Thus, whatever is true about photons, whatever wave-like property photons have, and whatever particle-like property electrons have, “Well, they both have them.” Doh!
So, welcome to my world this morning, now afternoon! I have been going around in circles about the differences between particles and waves for days. Discovering Matt Strassler and his book, “Waves in an Impossible Sea,” has been a godsend. Yet another great explainer! I can only, in my dreams, try to emulate him.
Strassler’s book is about quantum field theory, which is a subject I just mentioned. I’ll be writing about this soon. If you’re wondering what QFT is all about. I can give you a hint. Remember the lady and the turtles? Well, she was wrong. It’s not turtles. And it’s not particles. It’s fields, all the way down!
[i] Quantum mechanics is a specific branch within quantum physics. It refers to the mathematical framework and set of principles used to explain the behavior of matter and energy at atomic and subatomic scales. It deals with phenomena such as wave-particle duality, the uncertainty principle, and quantum entanglement. It provides the equations and rules, like Schrödinger’s equation, that govern the behavior of quantum systems. Quantum physics is a broader term that encompasses the study of quantum phenomena. It includes quantum mechanics as well as other theories like quantum field theory. It covers all aspects of quantum theory and the study of particles at the quantum level, providing a comprehensive understanding of quantum behavior. It is essentially the field of science that studies quantum mechanics and related theories.
[ii] Youtube video interview, by “Know Time.”
[iii] The photoelectric effect is a phenomenon where electrons are ejected from the surface of a material, typically a metal, when it is exposed to electromagnetic radiation such as light.
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