Comments | gustavolacerda: my compiled rants against physicists

gustavolacerda

my compiled rants against physicists

Feb 17, 2006 19:15

My compiled rants against physicists. In response to like-minded quale, I wrote the following:

quale wrote: I dropped out of being a physics major because everyone was just dogmatically accepting the notion of entropy as the "log of the number of states" and didn't want to question what the hell that really meant.

Me too! Not just they way they gloss over ( Read more... )

physics, education, phil/sci

Comments 29

pbrane February 17 2006, 19:21:38 UTC

You do realize that you look at physics the way a mathematician does, not a physicist, right? Physicists *do* physics - that's how they eventually get understanding, by doing it enough times in different ways that they start to get a handle on making inductive leaps accurately. It is *not* a deductive science ( ... )

quale February 17 2006, 21:32:17 UTC

First of all what we are really discussing here is physics education. Physics like every other subject has real dogma and blind spots but that is a subject for another discussion.

The key word here is Understanding. If what you are trying to produce is a prediction machine then yes the way physicists teach is good. In fact I would be inclined to agree that for the vast majority of physicists, i.e., experimentalists this is the best way to educate them (though like many subjects it still hasn't properly included computers in an educational setting for evaluating horrible integrals and other things). At least about general physics rather than their area of specialization. This method of teaching guarantees that everyone can accurately perform pragmatic calculations and come up with results. What it is not good at doing is creating understanding.

There is a very serious difference between the two and before you say it much of physics intuition is not understanding but rather just a sense of what is likely to happen because you ( ... )

quale February 17 2006, 21:38:18 UTC

Yes what is interesting about my theoritician friends supporting my point is that the more experimentally inclined people in physics don't seem to support my point ( ... )

spoonless February 18 2006, 06:05:55 UTC

It is *not* a deductive science.

What's a "deductive science"? Are there any examples?

.... one last thing pbrane February 17 2006, 19:22:20 UTC

I should finish by noting that as far as I know, very rarely has axiomitization led to advancement in physics. Internal *mathematical* consistency, yes (general relativity, quantum field theory and renormalization, string theory, etc...), but there we typically *don't* worry about understanding what the consistency requirements "mean" to advance the field. Maybe long after, people wonder, but I can't recall cases where such wondering lead to actual advancement of the field (but I could be wrong, of course. Probably gravitational physics was advanced by people coming to really get how the equivalence principle changed the way we look at local/global quantities).

Re: .... one last thing quale February 17 2006, 21:43:22 UTC

I think the equivalence principle is the perfect example of what I am talking about. Formal mathematical axiomitization, while nice, isn't required for understanding and really is something best left to mathematical physicists to come brush up. However, the difference between understanding and just calculating (even with intuition) is perfectly exemplified by the equivalence principle ( ... )

spoonless February 17 2006, 19:56:46 UTC

Not just they way they gloss over entropy, but also where the Schroedinger equation comes from, etc., and the way they avoid thinking about paradoxes

Okay, there are several things wrong with this comment. First of all, the primary reason why everything is glossed over in undergraduate physics classes is because the students are not experienced enough in the subject to be able to understand such things at the outset. This is the reason the Schroedinger equation is not explained further. It would not be possible to give the students a derivation of it or an explanation of what it means, unless they had far more background. The entropy issue is maybe a little different, because the foundations of statistical mechanics are a bit clouded even for experienced physicists. But the way physics is done and thought about by physicists is very different from how it's taught to undergrads. Undergraduates are deliberately given the most dumbed-down superficial version of everything as is possible, because most would get bored and quit if ( ... )

quale February 17 2006, 21:57:57 UTC

Yes, I think this is preciscely a difference between theoriticians and experimentalists. Experimentalists need to be able to quickly intuit/approximate what actually happens in the world and don't need a firm grasp on *why* some theory follows from general principles. Even many 'theoriticians' who are not (is it phenomenologists...or whatever the word for people who work on the very basic laws) often only need this level of understanding. Hence, physics education (rightly) focuses on meeting the needs of the masses and teaching problem solving not theoretical understanding. Personally I would prefer if they would just seperate these groups into theoretical and experimental tracks but I imagine there would be a sociological problem with this approach (everyone would want to show how big their dick was by going the theoretical route). Anyway I was the source of the original quote and I simply had no interest in figuring out what happened in actual real world situations, I only wanted to know why things were true. Once I discovered ( ... )

spoonless February 18 2006, 06:08:47 UTC

I heard a philosopher give a very good explanation of what 'entropy' is just a week or so ago, you just need to be willing to give up the notion that there is obe quantity called entropy. Instead there is entropy relative to a certain set of properties, e.g., entropy relative to pressure, volume, and type of moleculte (e.g. have a semi-permeable membrance to distingush). This seems like a clear case of dogma/preffered intuition winning out over explanation.

I'm as clueless as pbrane here as to what you guys are calling dogma. The definition of entropy is the log of the multiplicity. Calling that dogma is like saying that mathematicians dogmatically assert that a point is a zero dimensional object. I don't understand what the philosopher is saying here.

quale February 18 2006, 06:50:37 UTC

First of all when mathematicians call a point a zero dimensional object this is more descriptive than any formal claim. In pretty much every really formal treatment of geometry/analysis you start with a set with certain structure on it where every element of that set is a point. You do not define a point to be a zero-dimensional object ( ... )

Thread 16

smandal February 18 2006, 01:24:41 UTC

I reject the dichotomy between intuiting the behavior of physical system and understanding *why* things work. Yes, any monkey can predict the behavior of a system if given all the relevant information and if fed all the available laws -- recursive axiomitization. However, it takes a deep understanding of the principles to really intuit how things will happen.

All the best experimentalists I know would put most theorists to shame in their grasp of the principles.

Of course, physicists are not in the business of applying axioms -- w're in the business of showing their incompleteness. This is yet more intuitive.

I was taught this way as an undergrad, though anything that would require too strong/long a technical digression to elucidate was left for grad school.

quale February 19 2006, 05:13:03 UTC

Whether or not they went hand in hand *for you* is a different quesiton but surely you aren't denying that there are people who can get very good at predicting what is a reasonable and unreasonable result in relativity just by applying the Lorentz transformation in many many problems without really understanding how it comes from the equivalence principle ( ... )

smandal February 19 2006, 06:16:17 UTC

I'm a theorist, and I think we're largely useless :)

The problem is that we cannot contextualize -- we can say that this mathematical technique will yield these results, or that if we devise a certain situation, we know which techniques to apply and what motions will lead to reasonable results. However, I think it's an important skill to be able intuit what is reasonable at all in a situation that is not well understood. Building a picture by teasing apart the threads, to paraphrase Feynman. This requires a deep understanding of the physical principles around which to orient one's thinking, and in the special moment guess how the principles may be wrong. Experimentalists are in this frame of mind more often, IMHO, because they deal with tangible issues on a day-to-day basis in getting their stuff to work.

quale March 12 2006, 21:58:56 UTC

Been awhile but maybe you are still listening ( ... )

Thread 5

quale February 19 2006, 05:24:59 UTC

As I've sorta said in my comments elsewhere I am extremely sympathetic to your position. Hell, it's why i dropped out of physics ( ... )