Using Effective Language

Physicists like to use silly names for things, but sometimes it’s best to just use an everyday word. It can trigger useful intuitions, and it makes remembering concepts easier. What gets confusing, though, is when the everyday word you use has a meaning that’s not quite the same as the colloquial one.

“Realism” is a pretty classic example, where Bell’s elegant use of the term in quantum mechanics doesn’t quite match its common usage, leading to inevitable confusion whenever it’s brought up. “Theory” is such a useful word that multiple branches of science use it…with different meanings! In both cases, the naive meaning of the word is the basis of how it gets used scientifically…just not the full story.

There are two things to be wary of here. First, those of us who communicate science must be sure to point out when a word we use doesn’t match its everyday meaning, to guide readers’ intuitions away from first impressions to understand how the term is used in our field. Second, as a reader, you need to be on the look-out for hidden technical terms, especially when you’re reading technical work.

I remember making a particularly silly mistake along these lines. It was early on in grad school, back when I knew almost nothing about quantum field theory. One of our classes was a seminar, structured so that each student would give a talk on some topic that could be understood by the whole group. Unfortunately, some grad students with deeper backgrounds in theoretical physics hadn’t quite gotten the memo.

It was a particular phrase that set me off: “This theory isn’t an effective theory”.

My immediate response was to raise my hand. “What’s wrong with it? What about this theory makes it ineffective?”

The presenter boggled for a moment before responding. “Well, it’s complete up to high energies…it has no ultraviolet divergences…”

“Then shouldn’t that make it even more effective?”

After a bit more of this back-and-forth, we finally cleared things up. As it turns out, “effective field theory” is a technical term! An “effective field theory” is only “effectively” true, describing physics at low energies but not at high energies. As you can see, the word “effective” here is definitely pulling its weight, helping to make the concept understandable…but if you don’t recognize it as a technical term and interpret it literally, you’re going to leave everyone confused!

Over time, I’ve gotten better at identifying when something is a technical term. It really is a skill you can learn: there are different tones people use when speaking, different cadences when writing, a sense of uneasiness that can clue you in to a word being used in something other than its literal sense. Without that skill, you end up worried about mathematicians’ motives for their evil schemes. With it, you’re one step closer to what may be the most important skill in science: the ability to recognize something you don’t know yet.

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15 thoughts on “Using Effective Language

  1. Lubos Motl

    Tetragraviton, I don’t think that every effective theory is “obliged” to have UV divergences. The effective theory is whatever you get that describes phenomena up to some scale. When the result – like QCD – happens to make consistent predictions at higher energies as well, good for you (the actual truth about these higher energies in Nature may either be the same or something else). What would be your alternative? Would you say that in such cases, the effective theory doesn’t exist?

    Also, I don’t see why the usage of overlapping words should require more disclaimers than the usage of completely new words. If one doesn’t explain every word, then the listener who doesn’t know the jargon may end up thinking that sentences about theory, effective, or realism mean something else than they do. But if you use totally new words, the uninformed listener will also think that the sentence with selectrons etc. means something else than it does – he will incorrectly think that the sentence is incomprehensible gibberish. 😉

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    1. 4gravitonsandagradstudent Post author

      I don’t think that every effective theory is obliged to have UV divergences either, which is why I didn’t state anything to that effect in my post. I did say that my hazy recollection of another grad student’s attempt to explain effective field theory involved mentioning UV divergences, but that should hardly be taken as physical canon. 😉

      I don’t think it necessarily requires more disclaimers, but I do think that often people mistakenly give it fewer. We get so used to an “everyday” technical term that we forget that it is, in fact, a technical term. Also, I think there is a place for putting in terms without full explanations: sometimes it’s best to simply indicate that there is a word for something and move on, if it isn’t the central point of the piece. Doing that with words with everyday meanings requires a bit of extra discretion.

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      1. Lubos Motl

        Maybe I am making a logical mistake or misreading something. But you wrote that you asked what makes the theory “ineffective” and the presenter answered “Well, it’s complete up to high energies…it has no ultraviolet divergences…” which you seemed to endorsed but I don’t think that this is what makes a theory “ineffective”. 😉 What makes it ineffective – well, more than effective – is that it is actually to be a correct description of the system of interest at arbitrarily high energies.

        Good point that people are incorrectly fooled into thinking that a technical word needs less explanations just because it sounds and spells the same as a non-technical word 🙂 which is how I would articulate the problem.

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        1. 4gravitonsandagradstudent Post author

          I suspect this is a language barrier issue. In English internet-writing, ellipses in quotes often indicate haziness or confusion on the part of the person speaking. I would generally expect readers to view the text as endorsed, but not the quote. That said, if anyone in the actual target audience (people who don’t know this stuff already 😉 ) was confused I can certainly edit to make things clearer.

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              1. Lubos Motl

                LOL, JollyJoker, so that’s even juicier. Are you serious or is it some elaborate joke? So ellipses in English mean hesitation and therefore at least partial disapproval? Indeed, I was assuming that in every language, like in Czech, ellipses are symbols to shorten the quote when the original text was too long and most of it was either irrelevant or redundant for the topic being discussed here.

                I am surely using quotes in this neutral way, with absolutely no universal bias, all the time. Sometimes I agree with the quotes, sometimes I don’t, sometimes I partly do. Doesn’t it lead to any misunderstandings in my text?

                And what about colons in English? Do they mean that the writer promises to donate a villa in Hollywood to the reader? 😉

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                1. JollyJoker

                  http://www.thepunctuationguide.com/ellipses.html

                  “In informal writing, an ellipsis can be used to represent a trailing off of thought.

                  If only she had . . . Oh, it doesn’t matter now.

                  An ellipsis can also indicate hesitation, though in this case the punctuation is more accurately described as suspension points.

                  I wasn’t really . . . well, what I mean . . . see, the thing is . . . I didn’t mean it.”

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                2. 4gravitonsandagradstudent Post author

                  I’ll add that usually, it’s pretty clear in which sense ellipses are being used. Quotes that are merely abbreviated generally explicitly say who they are quoting, usually in such a way that the full quote can be checked by a skeptical reader. Quotes which use ellipses to indicate hesitation are more often used in personal contexts, where it’s more relevant to convey tone and the original statement is harder/impossible to check.

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                  1. Lubos Motl

                    Oh I see, so the width of spaces in between the three dots also matters. Is there something I don’t know about the hidden meaning of colons, semicolons, or other things? 😉

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  2. Wyrd Smythe

    Philosophy to me was an unexpected minefield that way. Philosophers use lots of ordinary terms (like “know”) that have precisely defined (and sometimes unexpected) meanings in the field.

    Ya gotta learn the jargon; that’s all there is to it.

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  3. ohwilleke

    There are times when I wonder if physicists are too timid about creating new technical words for concepts that don’t correspond to common experience – like someone creating a new brand name for a product using a meaningless invented word. For example, give thanks that someone stole the word “quark” rather than calling those particles “semi-protons” or “uber-atoms” or some such.

    For example, I have serious doubts about whether was wise to use the term “color” to describe the different varieties of QCD charge. I am inclined to think that this false friend (as one calls them in foreign language instruction) has done more harm than good. It is particularly problematic because there is another property of particles in the Standard Model (the wave length/frequency of a photon) which does correspond to the common English language meaning of the word which is not called “color” in technical discussions. Perhaps, the word “scent” or “gender” or “axis” could have been used instead.

    “Effective theory” isn’t too bad, because the sense of the word “effective” as “provisional” or “have a certain practical effect” is one of the senses of the word in the non-technical sense in the English languages, in addition to the sense of the word as “functional” or “producing results”.

    Also, while I’m ranting about names in physics, I think it would be delightful of the historic names of the various hadrons (especially light mesons and quarkonia) were replaced by a completely systemic set of names that naturally correspond to their structure.

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