Tuesday, March 22, 2016

Simple Physics?

I'm all for explaining things in simple terms that the general public can understand. I do that frequently, especially when I'm doing an outreach project or hosting visitors to the facility.

So when I read a review of this book, Thing Explainer: Complicated Stuff In Simple Words by Randall Munroe, it sounds like something that can be recommended to a lot of people who are curious about how various things around them work.

However, this author, and the reviewer of this book, fall into the same cliche trap that is one of my pet peeve.

There’s a nice quote attributed to the physicist Ernest Rutherford (or is it Einstein?): “If you can’t explain your physics to a barmaid, it is probably not very good physics.” There are variations of the theme, such as, “You do not really understand something unless you can explain it to your grandmother”. In essence, keep it as simple as possible.

I had already addressed the fallacy of this statement (and yes, I am challenging Rutherford or Einstein if they actually said such a silly thing). I have plenty of evidence to point to the contrary. I wish people who keep repeating this would actually read my counter point, but hey, what are the odds?



noddeat said...

However, inability to explain anything in simplistic form can be an indicator that this person doesn't fully understand what they're talking about. I think, that was the point in the original citation (whoever said that).

Of course, that doesn't deny the fact that there are a lot of experts who are bad explainers. But there are fewer such experts than poor scientists who cover their lack of knowledge with jargon buzzwords.

ZapperZ said...

A doesn't automatically imply B. Dirac was AWFUL at explaining things (read his biography). Yet, would anyone want to claim that Dirac doesn't understand QM?

As I've stated, being able to understand something, and having the skill and ability to explain it, is NOT mutually inclusive! I have been taught by many prominent physicists while in school, and half of them I consider to be mediocre to poor teachers. So knowledge is not commensurate with teaching ability or explaining ability.

But the issue here is that NO ONE, at least I haven't read any, has challenged this prevailing notion as stated in these throw-away quotes. Everyone seems to accept it as FACT. I disagree and I have evidence that points the flaw to these claims. People who make such claims need to be told that they are perpetuating a statement that has CONTRADICTORY evidence! There are people who are good at explaining things, and there are people who are poor at explaining things. The correlation between that and knowledge of the subject matter has NOT been established by any means!

Intelligent and rational people should know better than perpetuating such fallacy.


Douglas Natelson said...

I'm still waiting for someone to explain the spin-statistics theorem on the level that a first-year undergrad can understand it.

Eric VolkerLindell said...

I think it was Julian Barbour ("The End of Time") who said most seemingly esoteric concepts from physics and mathematics are capable of being explained in simple and intuitive terms. Examples (from me):

Quantum discreteness and quantum waves .. like the wave pattern of a vibrating drum, which can only assume discrete forms -- eg, half moves up while other half moves down; 1st and 3rd quadrant move up while 2nd & 4th move down; &c ..

I just heard an explanation of Godel's theorem, in general, systems-theoretic terms. A system cannot completely describe itself, requiring some referent from outside for a complete description. This is true, for example, of a book -- you cannot find out from the book how to read it. To read a book, you must refer to a source outside of it. (off-topic -- this is the problem with DNA -- the instructions for reading and interpreting it are in the DNA; a minor crisis for origin-of-life theorists.)

I have found this to be true of the CPT theorom, FTC theorem, & a lotta other things. I think it depends more on the explainer than the explained. Feynman was a master of this.

That's my two cents, anyway.

Eric Lindell

GDL said...

I'm going to push back and defend the statement.

Dirac (for example) may not have been very good at explaining physics to ordinary people, but that doesn't mean he was incapable of it. The point is whether he knew the subject well enough to clearly trace everything back to fundamental (and easy-to-understand) postulates. In Dirac's case, I believe he did understand this logic chain; it's just that he was (apparently) not very good at explaining the logic trail. But, if he were willing to put in enough time and effort, I have to believe he was capable of it.

I've known many people who have a hard time putting themselves in the position of someone who is unfamiliar with physics. It takes effort, and some people just don't feel like the effort is worth it ("if you can't keep up, it's your problem, not mine"). But that doesn't mean that the statement by Randall Munroe (or Rutherford, or Einstein, or whoever) isn't correct.

On a related note, one of my favorite quotes attributed (or misattributed - I never actually checked) to Einstein is something along the lines of "Everything should be made as simple as possible, but no simpler."

ZapperZ said...

GDL: you need to read the link at the end of this blog post that I linked to my earlier entry on this topic. Specifically, I wrote:

"Most of us who have been in physics for any considerable period of time have met people who we KNOW for a fact to be experts in certain areas, and yet, they suck at explaining what they do to us, much less, to someone who isn't familiar with the subject matter. This may happen for a variety of reasons: (i) lack of pedagogical skills (ii) laziness in figuring out how to present something at the level that the audience can understand (iii) or simply a complete ignorance of the fact that the audience is clueless to what he/she is saying. Being able to present something in understandable form is not a skill that comes with knowledge. It requires quite a bit of thought, a consideration to the level of knowledge of the audience, and a lot of consideration on how to present something that is in touch with what the audience already know. This takes effort, and this is something not everyone realizes. Thus, you get brilliant scientists who could have a lot of trouble explaining something that a grandmother can understand. It has no reflection on his knowledge of the subject matter."

In other words, there are MANY reasons why someone didn't convey a piece of information effectively, including laziness! None of these reflects the level of knowledge that person has. Dirac may not put in much effort in trying to make himself clear, but that's the POINT!


noddeat said...

One should differentiate between "A. was awful at explaining things because they didn't understand them good enough" and "A. was awful at explaining things because they didn't want to put an effort/were lazy/didn't care".

Of course, Dirac was the second case. Other things equal, a more qualified person is more capable of explaining things than a less qualified one. Other things however are never equal, that's true.

ZapperZ said...

Certainly, but the whole premise of the "If you can't explain to your Grandmother...." is based SOLELY on the fact that the person can't explain the concept in an understandable way, and therefore, it automatically implies that he/she doesn't understand the subject matter.

I just posted the issue of Bill Nye tripping over himself in explaining quantum entanglement. So this is the case where the bad explanation was due to lack of knowledge. But I've just proven that this isn't true in all cases. In fact, as I've said, half of my physics professors while I was in college sucked at teaching!

Having a pedagogical skill isn't commensurate with knowledge of a subject matter. The former is often a skill that scientists are not taught. That's why we subject our students to public presentations, etc.. so that they and hone their skills as a presenter. You are not borned with such skills, you acquire them. And many still struggle with it.


Peter Morgan said...

I have lots of trouble understanding understanding. Many things I understand quite well, sometimes I understand them well enough that I can even engineer things with them, yet, as they say, the better I understand something the more I realize that there are many open questions in my understanding and even what some of them are. So, I would say that the self-reflective investigator never understands anything and certainly would never claim to understand anything without reservation. The simpler the statement, often the longer and more elaborate the reservations. "Quantum theory is true", for example, might sometimes be better said as "quantum theory can describe this list of experiments to this degree of accuracy: ...".

Equally, explanation is never finished. I take an explanation to be an attempt to communicate an understanding, so it can only be as good as the understanding, but a good explanation also takes into account, as a minimum, the presenter's understanding of what common misunderstandings there are, of how those misunderstandings arise in different types of people, and of who the audience is.

GDL said...

I think I understand what you were claiming (I actually did read the link), but I still believe the "if you can't explain it to your grandmother..." claim has merit.

I believe people use the claim as a convenient shorthand for "you should be able to start from a set of basic postulates, which are assumed to be conceptually simple and generally accepted, and use a clear chain of easily understandable logic without gaps to derive whatever principle or conclusion you're talking about. If you can't, you don't really understand it." In practice, of course, it might take decades to go through that logic chain, but it should be possible in principle if not in fact.

To really explain physics clearly to a barmaid/grandmother/5th grader requires than just knowledge, of course (that's your point). Nevertheless, the knowledge is a necessary precondition. I think that's the point of people who make that claim. Perhaps they just don't make it clearly enough, and need to work on a better explanation that can be understood by a grandmother.

ZapperZ said...

I disagree.

First of all, that person must make an effort to KNOW WHAT IS THE "SET OF BASIC POSTULATES ... CONCEPTUALLY SIMPLE AND GENERALLY ACCEPTED..." for THAT person that he/she is explaining to. I can explain a lot of things from First Principles of quantum mechanics, but it doesn't make it any more understandable than a bunch of gibberish to a layman.

A person must not only be able to explain things simply, he/she must also put some effort into understanding the level of knowledge of the receiver. This takes effort and not many people are willing to do that. In other words, you have to explain things at the level that your grandmother can understand, and you need to first know what that is!

Feymann's Lecture series books are outstandingly good. But it is NOT a good book to learn from if you have no knowledge of physics. It is very difficult to follow pedagogically, because it assumed a certain sophistication of knowledge. That book certainly can't be used by your grandmother to learn physics. It can't even be used by a typical first-year undergraduate! So does this mean Feynmann doesn't understand physics?

The skill at presenting something is NOT a valid indicator of the knowledge of that person. Period. A does not automatically imply B. It is a matter of simple logic.