A model of what makes up the physical world

[lightarrow]

It depends. If you mean, what does physics say are the closest things to "fundamentals" that we currently understand, I would say it's spacetime and the fundamental fields and interactions given in the Standard Model of particle physics

..and the elementary particles, isnt'it?
About the simmetries from which conservation laws are derived (and so the important quantities as energy, momentum, etc) you have already included them writing "in the Standard Model"?

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[PeterDonis]

and the elementary particles, isnt'it?

"Elementary particles" are particular states of the underlying quantum fields. That's why I said "fields" instead of "particles"; others might have said "the fundamental particles and interactions in the Standard Model", but I think "fields" is a better term since there are quantum field states that do not have a particle interpretation.

 

[PeterDonis]

About the simmetries from which conservation laws are derived (and so the important quantities as energy, momentum, etc) you have already included them writing "in the Standard Model"?

Yes. The Standard Model includes a specification of its gauge group, which tells you the internal symmetries, and being a quantum field theory it's Lorentz invariant, which tells you the spacetime symmetries.

 

[lightarrow]

Yes. The Standard Model includes a specification of its gauge group, which tells you the internal symmetries, and being a quantum field theory it's Lorentz invariant, which tells you the spacetime symmetries.

I also reply to your other previous answer to me in this post: so to start from these "building blocks of physics" we must already have a lot of physics
So the "simple" task of the OP it's not simple at all... after all. Probably physics have to be continuosly "discovered" as we teach it.

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[PeterDonis]

so to start from these "building blocks of physics" we must already have a lot of physics

Yes. And for that reason I agree with a comment made earlier in this thread (post #17 by @Mister T ) that it's better to start with specifics and gradually work up to generalities. Starting with generalities that have no grounding in the student's prior knowledge just makes physics look confusing and daunting.

 

[Dale]

although it is more like a circular list rather than a mind map showing any meaningful relationships between the areas of study.

My experience with mind maps is very much along the lines of a circular hierarchical list without meaningful relationships.

But my question is what are the fundamental building blocks of the universe put forward in this foundation science?

Currently I would say spacetime and fields. However, for a physics class it might be more useful to break down physics rather than the universe. Then you might break it into theories and experiments, or maybe theories, models, and experiments.

 

[jedishrfu]

Having read through this extensive discussion, I have a few things to say that can help.

1) The YouTube channel: Domain of Science has an excellent Map of Physics that is hard to beat and perhaps would give students that sense of understanding that you are trying to bring to your class something you might use as a starting point and elaborate more on:



2) Most textbooks and places like Khan Academy follow a prescribed path through physics that mirrors in some ways the map in #1. Your students will look to these sources in order make sense of what they are learning so we don't want to add unnecessary levels of abstraction on top of it.

For non Calculus students there's this online resource:

https://openstax.org/details/books/college-physics

and for students versed in Calculus there's this resource:

https://openstax.org/details/books/university-physics-volume-1

Another resource is Ben Crowell's excellent books:

http://www.lightandmatter.com/

My suggestion is to incorporate references to these books for your students use doing it for each topic you cover.

3) As a physics major in high school and college, I was caught in the web of trying to resolve the physics popularizations of the day with all the magic and mystery presented with what I was actually learning. It caused me great confusion. The refrain from my teachers was always go back to the math, the math describes the physics accurately in ways the popularized conceptual ideas can't.

@phinds always brings this up in his posts about the balloon analogy of the universe or the rubber sheet description of how gravity works in relatvity. They get an idea across but you then have to drop the analogy before it derails your thinking ie don't read too much into the analogy go back to the math.

4) Have you ever taken math classes where the prof starts at a very general conceptual and abstract approach and its only in the closing days of the class that you discover how everything really fits together in a practical sense? I hated those classes, I would panic and question why I was learning something I didn't understand.

Your students won't have that confidence to stay the course and will panic because high schoolers are worried about their grade point averages and getting into the college of their dreams. So as teachers we don't want to use them as a testbed of new bold conceptual ideas when the focus of the course is to teach them physics as precisely as we can.

Your students will also panic over formulas to be remembered and when they are applied. Many will try to pick the formula needed based solely on the constraints and forget about the added clues found in the geometry and symmetry of the problem because that's what worked in other courses. I have x and y and this formula uses x and y so now I can find z... but wait now what? Typically when doing a force diagram, I would forget to add a force like tension and consequently got stuck.

 

[kith]

what is physics the study of exactly? I feel I might have a better chance of making a mind map if I had this I am looking for a reliable comprehensive and meaningful definition of physics?

I don't think that the approach of having a visual representation of the most important physical concepts and their interconnections first and filling it with life later works. It doesn't work for you right now and it won't work for your students.

These visualizations are always personal because everybody understands physics in their own way. If you aren't able to come up with a visualization which is satisfying to yourself, this probably means that you haven't understood the concepts well enough. So if you want to find a satisfying visualization, you need to dig deeper into the concepts.

I really don't think that there's a way of skipping this by simply taking the opinion of others about how a good visualization should look like. At least for me, it takes a lot of work to integrate big ideas into my thinking. Taking a visualization serious which doesn't reflect my own understanding tempts me to fool myself into thinking that I have understood the concepts while I may have only names.

As for the teaching, I think you shouldn't aim for finding the "correct" way to connect the names but for bringing the concepts alive for your students and have them draw their own connections afterwards.

 

[pkc111]

Thank you to all those who made constructive suggestions about the model..I have learned so much!

 

[pkc111]

Ok so I have really got a headache trying to make all the things fit together as I first envisaged and as posters have pointed out its probably too big a job to attempt. I have decided to aim for a simple classical physics view of the universe and a modern view of the universe separately...as they really are fundamentally different paradigms I now realize probably never meant to be put together.
The course I high school course I teach is primarily classical physics, so that the view where I would like to put the more detail in a map. Of course my students do some relativity and some quantum physics but not enough to justify getting carried away with the mind map.I really like this image from jedishrfu

which to me shows "big ideas and discoveries in classical, relativity and quantum physics"
and I like the image from Berkeman which to me shows the "current fields of study of physicists"
However I would still like to have something that attempts to map the fundamentals of what physicists think the universe is made up of so here is round 2...any comments welcome.

 

[Dale]

Ok so I have really got a headache trying to make all the things fit together as I first envisaged and as posters have pointed out its probably too big a job to attempt. I have decided to aim for a simple classical physics view of the universe and a modern view of the universe separately...as they really are fundamentally different paradigms I now realize probably never meant to be put together.
The course I high school course I teach is primarily classical physics, so that the view where I would like to put the more detail in a map. Of course my students do some relativity and some quantum physics but not enough to justify getting carried away with the mind map.I really like this image from jedishrfu View attachment 225883 which to me shows "big ideas and discoveries in classical, relativity and quantum physics"
and I like the image from Berkeman which to me shows the "current fields of study of physicists"
However I would still like to have something that attempts to map the fundamentals of what physicists think the universe is made up of so here is round 2...any comments welcome.
View attachment 225884

This is better. I would get rid of aether, otherwise you would need to include all of the discarded concepts.

 

[Vanadium 50]

Or phlogiston or caloric...

I think many people overestimate the time that classical physics favored the aether theory. ("Light is a wave and the aether is the medium that supports this wave") Yes, the idea goes back to Newton, but Newton favored the corpuscular theory of light. The wave theory wasn't cemented into the consciousness of the field until at least 1820 with the Poisson spot, and it wasn't until the decade after that that any attempts to quantify the properties of the aether were made. None of those attempts were really successful until Maxwell in 1867, which wasn't confirmed until "Hertzian waves" were discovered in 1887. That was the same year as Michelson-Morley.

Essentially, the moment you had a clear, complete and testable theory, it was known to be in trouble.

 

[Mister T]

I have decided to aim for a simple classical physics view of the universe and a modern view of the universe separately...as they really are fundamentally different paradigms

You will learn a lot constructing and refining your map. If you are a conscientious teacher you will test your students over what you ask them to learn, otherwise they will learn that they don't need to learn your map. And if you get them to understand your map you will have wasted valuable time and effort getting them to understand physics.

Your idea of a map may be a good thing for the end of the class, but it is blunder to start with it.

 

[Dale]

And if you get them to understand your map you will have wasted valuable time and effort getting them to understand physics.

I am not so sure it is wasteful. Although if I were doing it I would make a hierarchical list of theories and the assumptions that lead from one to the other. I.e. start with the standard model, neglect non EM interactions to get QED, take the classical limit to get Maxwell’s equations, branch off to circuit theory and optics each with their assumptions, etc. Then when students asked a question that was out of scope I would just indicate where it fit.

 

[sophiecentaur]

I am not so sure it is wasteful.

It would depend on which of the class of students we're discussing. I can see it as in fact being a soft option for many students who would see a conversation about the map as far preferable to solving questions from the book or learning a few useful formulae. Those students who have the motivation to do the 'official' parts of the course, read, learn and solve the problems independently will find it enriches their experience of Physics. But they would probably do well if they were just given a book and an exam deadline - with the occasional tutorial with a teacher. That's the way many University courses are structured and the students will have been selected from amongst the ranks of the OP's High School cohort.
I repeat the point I have often made that most school students are unbelievably literal in the way they receive what they're told in class. They want facts and lists of definitions and can easily become confused when called upon the 'think'. The Philosophy of the subject they are learning can easily serve to confuse and demotivate them.

 

[pkc111]

One need I have for a simple mind map showing the fundamentals, is when a student asks (as happened last year) , what is momentum. My response was mass x velocity. The student's response was "yes, but what is it really?".
This was after they had developed some really nice understandings of matter and energy and the differences between them, we had understood motion well in terms of its descriptors of speed, velocity, acceleration and up to that point physics made sense to them. Thats where I got stumped..I didnt have a nice description of what it was that had meaning to the students and related it to the real world. I told them it is "an indicator of the difficulty to stop of an object, but really kinetic energy is a better indicator of it". I could see it wasnt really a satisfactory answer to the student.
In hindsight I felt I really needed a map, and be able to point to a box of these less tangible physics words and say they belong here in the world of " mathematical constructs" so don't worry too much about their meaning or relationship to the world just at the moment... just use it and be thankful that it is conserved in collisions.. so you can solve some of these great problems!
I don't want a map for students to recite and learn and spend hours in talking about it, I want it to show what can be "understood" easily..in terms of some specific simple relationships.. and also list those which don't really have a place that is easy to see, and really don't need to be understood beyond a mathematical formula for the syllabus at this point in time...and the real value of it is in its usefulness rather than its meaning.
I want a map to smooth the journey for the students so they don't get caught up with concepts they don't feel they understand and therefore worry they are missing something in the course (and feel reassured that many other scientists don't fully understand the concept either). But for this concepts for which there is some sort of classical model for understanding (mass, energy, space, time, force, fields) I want to be able to have one...at least in my own mind.

 

[PeterDonis]

a student asks (as happened last year) , what is momentum. My response was mass x velocity. The student's response was "yes, but what is it really?".

There are two ways of handling this. One would be to disuss the relationship between momentum and space translation symmetry, given by Noether's Theorem, which is more generalizable than mass x velocity. (For one thing, momentum = mass x velocity is no longer true in relativity.)

The other, which you'll eventually be forced to in any case, is that we don't know what momentum "really" is; we don't know what energy "really" is; we don't know what mass "really" is; etc. All we know is that we observe certain law-like regularities in the way the world works, and these things like "momentum", "energy", "mass", etc. appear in the mathematical models we construct to describe these law-like regularities and make predictions using them. If the student wants more than that, they need to look elsewhere than science class; as Indiana Jones told his students, "if it's Truth you're interested in, Dr. Tyree's philosophy class is right down the hall."

 

[Mark44]

The other, which you'll eventually be forced to in any case, is that we don't know what momentum "really" is; we don't know what energy "really" is; we don't know what mass "really" is; etc.

This put me in mind of one of the Feynman Youtube videos, on magnets, and why they repel each other, but more about how difficult "why" questions are in physics.

 

[sophiecentaur]

I don't want a map for students to recite and learn and spend hours in talking about it,

An admirable sentiment. But what audience are you actually going to present this map to? I am in UK and the school divisions are slightly different. I have read that High School is for students from 14 to 18. In the UK, 'secondary' is from 11 to 16 and then there is a two year '6th Form' which is aimed at preparing for University Education. The Physics Syllabus (called a specification, these days, I think) is chock full of stuff that they need to learn and they are as grateful as hell if you can give them a practical way through. A concept map of the Hyperphysics kind is something that's very tangible and it's at a low philosophical level but highly applicable for them. It shows them categories of study and it's a 2D tick box for them to see their progress. I know it has its shortcomings but, if you want all students to have some idea about what a map is all about then they all have a chance with it.
Bottom line is that most of the comments people have made in this thread are way above the heads of the majority of School age students in respect of words and concepts. The map classifications that have been discussed are suitable for adult retrospection and they are not for finding your way through for the first time.
Dealing with the "what is x, really" question is a separate problem.

 

[PeterDonis]

Moderator's note: two off topic posts have been deleted. Please keep the discussion on topic.

 

[pkc111]

The other, which you'll eventually be forced to in any case, is that we don't know what momentum "really" is; we don't know what energy "really" is; we don't know what mass "really" is; etc. All we know is that we observe certain law-like regularities in the way the world works, and these things like "momentum", "energy", "mass", etc. appear in the mathematical models we construct to describe these law-like regularities and make predictions using them. If the student wants more than that, they need to look elsewhere than science class; as Indiana Jones told his students, "if it's Truth you're interested in, Dr. Tyree's philosophy class is right down the hall."

Yes I like this approach of being clear about what science is and what it is not...which reminds me that I should try to prepare students minds for Physics before I teach it... manage expectations so to speak. I think I need to let them know that mathematics is a valid language, just as valid as words, and it is sometimes the only accurate way we have to describe a concept. In some ways as Feynman says in the magnetism video it would be cheating the student to try and explain some concepts in any other way.
There is a subject called Theory of Knowledge in the IB program which has a resource which may give me a good basis to do that I feel (see below).

 

[Dale]

My response was mass x velocity. The student's response was "yes, but what is it really?".

I would strongly recommend to never ever engage in such a question. Simply repeat the definition. The definition is the answer to the question “what is it” and it is also the answer to the question “what is it really” and the question “what is it really actually truly”.

Alternatively, you can restate the definition and then say something like “but what you should be asking is why is it useful”

 

[sophiecentaur]

I would strongly recommend to never ever engage in such a question. Simply repeat the definition. The definition is the answer to the question “what is it” and it is also the answer to the question “what is it really” and the question “what is it really actually truly”.
Alternatively, you can restate the definition and then say something like “but what you should be asking is why is it useful”

Non - Scientists are the ones who tend to justify the "why' question. Getting across the idea to students that Physics only tries to make working models of the World can relieve the stress they can feel about not 'understanding things fully'. They have to learn that Science does not work on Axioms, like Maths does. We are aiming at a set of theories that are mutually self consistent, rather than any ultimate truth.

 

[pkc111]

so from a classical physics point of view if we decide to relegate momentum to only being talked about as concept or mathematical construct rather than some sort of thing like matter or energy, then is it valid to ever describe momentum as being "transferred" during a collision?

 

[weirdoguy]

if we decide to relegate momentum to only being talked about as concept or mathematical construct rather than some sort of thing like matter or energy

Energy is a property of matter/fields and a mathematical construct the same way momentum is.

 

[Dale]

We are aiming at a set of theories that are mutually self consistent, rather than any ultimate truth

Self consistent and consistent with experimental evidence.

 

[Dale]

if we decide to relegate momentum to only being talked about as concept or mathematical construct rather than some sort of thing like matter or energy

I would not do that at all! Momentum is on the exact same footing as energy. Neither is a “thing”.

 

[Vanadium 50]

To build on Dale's point (and "what is it really?" has the inevitable follow-up, "yeah but what is it really really?") Which is the better answer?

"Momentum is a quantity that was discovered to be useful".
"Momentum is here on the map, next to Ohio"

 

[pkc111]

I would not do that at all! Momentum is on the exact same footing as energy. Neither is a “thing”.

Ok so I am guessing you would not describe momentum or energy as being "transferred" ...in the everyday meaning of the word? I mean concepts don't usually "transfer' right?
Btw I only want to understand the classical model of the world first. As I hope it is has definitions and descriptions that are going to be consistent and create some sort of model that hangs together.
so are you describing momentum and energy on the same footing... as only mathematical constructs ...the way that classical physicists would have thought of them?

 

[Dale]

Ok so I am guessing you would not describe momentum or energy as being "transferred" ...in the everyday meaning of the word? I mean concepts don't usually "transfer' right?

Why not? That is the basis for the majority of our monetary system at the present. The funds that my employer transfers are not physical things. Why should only “things” be transferable? I have also transferred knowledge to my students and traits to my children.

so are you describing momentum and energy on the same footing... as only mathematical constructs ...the way that classical physicists would have thought of them?

I wouldn’t describe them that way. I would never say “only mathematical constructs”. It is only your insistence on making this map where you artificially label some terms as parts of the “classical view of the universe” and others as “calculated quantities” that forces such a dichotomous characterization.

Look, this is clearly a doomed venture. Your map is not even helping you understand anything. How will it possibly help your students? At this point all we can do is recommend against it.

 

[pkc111]

Why not? That is the basis for the majority of our monetary system at the present. The funds that my employer transfers are not physical things. Why should only “things” be transferable? I have also transferred knowledge to my students and traits to my children.

Look, this is clearly a doomed venture. Your map is not even helping you understand anything. How will it possibly help your students? At this point all we can do is recommend against it.

To say that the whole universe is just mathematical concepts may be true at a higher level, however it is not the framework of the high school syllabus I teach or the textbooks that students have and it's not an model that allows access to understanding to most 17 year olds.
I also can't see how it was the entire framework of classical physics either which is often described as having a "mechanical universe" paradigm.
I also don't think it's unreasonable, or "doomed", to ask what was the model of the universe ...Definitions of concepts, their nature, and most importantly to me their relationships to each other (hence the aim of a mind map) of mass energy momentum forces fields torque...that was held by the mainstream thinkers around 1900..About their mechanical universe.

 

[Dale]

To say that the whole universe is just mathematical concepts

I wouldn’t say that. I wouldn’t even say that about momentum and energy, let alone the whole universe. This “mathematical concepts” stuff is a product of your map, and one indication why it is a bad idea.

I also don't think it's unreasonable, or "doomed", to ask what was the model of the universe

It is not doomed to ask what is the model of the universe, that is what physics is. What is doomed is your map. It introduces a bunch of classifications that are not part of the model. You are trying to say that these parts of the model are more fundamental or more real than other parts, and the model itself does not make that distinction.

Definitions of concepts, their nature, and most importantly to me their relationships to each other

Then use the hyperphysics site. It does exactly that, complete with text describing many of the relationships.

 

[sophiecentaur]

so from a classical physics point of view if we decide to relegate momentum to only being talked about as concept or mathematical construct rather than some sort of thing like matter or energy, then is it valid to ever describe momentum as being "transferred" during a collision?

Energy is a property of matter/fields and a mathematical construct the same way momentum is.

Both of those posts are factually correct and well written and I agree with them. But seriously, how do they fit in a thread about presenting Physics to a mainstream class of immature students who may not have yet even got the SUVAT equations sorted in their minds?
Many classes will have one or two students who can cope with this sort of thing but they will be future PF stalwarts and they've already got the basics. I think that many of the contributors to this thread have forgotten just how little they had in their heads before they started on their revision for the Physics exams.
I have often told students, unashamedly, that it's a trick that delivers answers. Never had any complaints about that.

 

[Mister T]

I have decided to aim for a simple classical physics view of the universe and a modern view of the universe separately...as they really are fundamentally different paradigms I now realize probably never meant to be put together.

It's a requirement that they fit together. They are not separate, one is a part of the other.

so from a classical physics point of view if we decide to relegate momentum to only being talked about as concept or mathematical construct rather than some sort of thing like matter or energy, then is it valid to ever describe momentum as being "transferred" during a collision?

Momentum and energy are in the same category. They are inventions of the human intellect. Matter is not in that category.

And there is no need to insert the restriction concerning classical physics.

The reason we ask students to learn about momentum or any of the concepts of physics is because we have discovered their utility. That is, they are useful for understanding how Nature behaves. There are lots of other concepts designed to help us understand Nature that we don't ask them to learn because they are not as useful.

 

[pkc111]

So is it accurate for a physicist to describe energy as being "absorbed" by an object? Given that it doesn't exist.
I mean I can go along with the idea of talking about it from a bookeeping sense as being "transferred" as non existent money is "transferred" between bank accounts, is "absorbed" being used in a similar way?
Cos eventually you talk about them literally the same way as you do existent material (which are not concepts) (eg flow,absorbed,transferred), and then at the same time you remember they don't exist..All except matter ...which does exist...is that the idea?