Physics - Description is description

[Omega0]

Hi, I am graduated physicist, working in a company and additionally giving lectures in a university. Just about my background, so I think I know what I am talking about if I say: Physics explains exactly nothing. It just describes the nature but it does not explain anything. This is basically the definition of physics but I think this is not stressed enough nowadays.
As a nice example: In the university in my hometown Prof. Dr. Christoph Strunk is teaching about experimental physics in the field of superconductivity and nano structures. He wrote a remarkable book about thermodynamics. In the beginning of the book he is writing something like (no citation, a german book): If you asking yourself what entropy is... just accept it to be something which is there. Did you ever ask yourself what momentum is? If you think about the formula p=m*v then this is a formla but there is no meaning behind it. So why seems to be something like entropy that different?
Think about Feynman who said something like: Forget about to understand quantum physics, it is just there!

My "problem" is that I from time to time run into situations where I am speaking to educated people who believe that physics is sort of a basic explanation of the entire world. In those situations I try sort of grounding them but this seems to work not always.
So, what is your trick to convince them that they are wrong - or do you believe that physics is the truth?

 

[S.G. Janssens]

This is an epistemological question. The answer depends on what you mean by knowledge and understanding, and even between closely related disciplines such as physics and mathematics this meaning can be very different. So, I am afraid it will be quite hard to have a sensible discussion, unless one is well-versed in epistemology. (I am not.)

 

[Omega0]

This is an epistemological question. The answer depends on what you mean by knowledge and understanding,

Okay, does physics describe nature or is physics truth in itself, meaning: physics is nature?
I have no clue what epistemological questions are and I am sure my students don't know this either.
I think I know the answer - because this is the definition of physics - see Wikipedia or where ever: "Physics is one of the most fundamental scientific disciplines, and its main goal is to understand how the universe behaves".
How it behaves, yes - why it is - no. Why it is how it is - no.
Pretty simple.

 

[russ_watters]

Physics explains exactly nothing...

So, what is your trick to convince them that they are wrong - or do you believe that physics is the truth?

These statements are not identical opposites and not necessarily mutually exclusive.

Also, this question depends very much on what you definition of "explain" (and "truth") is. Here at PF we tend to say that physics describes the world around us, but doesn't tell us why it works the way it does.

Okay, does physics describe nature or is physics truth in itself, meaning: physics is nature?
I have no clue what epistemological questions are and I am sure my students don't know this either.
I think I know the answer - because this is the definition of physics - see Wikipedia or where ever: "Physics is one of the most fundamental scientific disciplines, and its main goal is to understand how the universe behaves".
How it behaves, yes - why it is - no. Why it is how it is - no.
Pretty simple.

It concerns me that you might be "poisoning the well" with your students, by harping on a vague philosophical discomfort you have, that you don't even fully understand yourself, that has little or nothing to do with what you are trying to teach them.

 

[romsofia]

There is no trick. Physics is the art of noticing something, questioning how it occurs and how to predicate its future interactions. So yes, it is a basic explanation of the universe because the universe is just a bunch of interactions...? An explanation doesn't have to be why something occurs.

 

[Omega0]

Here at PF we tend to say that physics describes the world around us, but doesn't tell us why it works the way it does.

Exactly this is what I am talking about.

It concerns me that you might be "poisoning the well" with your students, by harping on a vague philosophical discomfort you have

Okay, I have no clue what you are teaching but your concerns might be a nice laughter.

that you don't even fully understand yourself

Okay, you are not a physicist, damn, you are funny!

 

[russ_watters]

Okay, I have no clue what you are teaching but your concerns might be a nice laughter.

You said:

I have no clue what epistemological questions are ...

So clearly you are struggling to understand what is bothering you. And you said:

...and I am sure my students don't know this either.

Which means you intend to (or already do) share your discomfort with your students. Am I not correct?

Okay, you are not a physicist, damn, you are funny!

I don't find this funny at all. I find it concerning (and additionally concerning that you don't take your own concern seriously!). Not the philosophical conundrum itself, which really shouldn't be an issue, but the idea that you might be teaching it to your students.

I'll try to be more clear/direct: most physicist do not have this concern you have. That should tell you that there is something wrong in how you think about physics/science. And you should not be teaching that to your students.

 

[Omega0]

Which means you intend to (or already do) share your discomfort with your students. Am I not correct?
I don't find this funny at all. I find it concerning ... but the idea that you might be teaching it to your students.

Okay, I see, you have the big picture I haven't. I promise, I will carefully check and afterwards share your deep knowledge with my students. To let it be part of my lectures could you please answer (for example):

- classical mechanics: why does momentum exist?
- quantum mechanics: why does it exist at all?
- electrodynamics: why are there fields?

Feynman said something nice about electromagnetic fields when he was asked which picture he has in mind to describe it. He said something like: Well, I usually use the picture which fits best in the given situation (vectors or whatever). One of the rare physicists who believed that physics describes the nature, nothing more.

 

[Omega0]

Physics is the art of noticing something, questioning how it occurs and how to predicate its future interactions.

Which is measurement, theory and prediction, right?

So yes, it is a basic explanation of the universe because the universe is just a bunch of interactions...? An explanation doesn't have to be why something occurs.

Okay, I am not an english native speaker so it may be that we mean the same but talk different. For me an explanation is answering the "why" question. Everthing else is a picture which might be even super elegant, which might even allow to predict new effects or explain known effects easier/better.
I am absolutely stunned that here is a discussion at all but just one example:
Newton had a theory describing how mass might be related to forces. Awesome discovery, there is something called "mass" which resists if a "force" is trying to pull or push it and now comes the miracle: The mass involved in gravity and the mass which resists if you try to change its momentum seem to be the same!
This is just a tiny example showing that the physicists (at least me) have no clue why this is the case. I can measure it, but that's it.
For me, this isn't sort of a problem. It is just there. It does not demotivate me to think about natures laws.

 

[PeroK]

To let it be part of my lectures could you please answer (for example):

- classical mechanics: why does momentum exist?
- quantum mechanics: why does it exist at all?
- electrodynamics: why are there fields?

For what it's worth, I would say:

Momentum is a useful concept and a useful number that you can calculate. If you ask "why is momentum conserved?", then - in classical mechanics and in SR - it's effectively a postulate, supported by experimental evidence.

More fundamentally, you could attribute conservation of momentum to the homogeneity of space (via Noether's Theorem). Then the question becomes "why is space homogeneous?".

Quantum mechanics is a human invention, designed to predict the behaviour of nature at the most fundamental level. Why nature behaves quantum mechanically can't be answered by quantum mechanics.

More fundamentally, I know there are theories that tie QM to information theory in ways that partially explain "why nature chooses QM". But, again, the fundamentals of these theories become the unanswerable questions.

Electromagnetic fields are, again, a very useful concept that can be used to model electromagnetic behaviour.

 

[Omega0]

Momentum is a useful concept and a useful number that you can calculate. If you ask "why is momentum conserved?"

No I do not. I love Hamiltonian mechanics which is useful but unfortunately explains nothing in a deeper sense.

Then the question becomes "why is space homogeneous?".

You got it. There is no need for it. The theory itself relies on propostions.

Why nature behaves quantum mechanically can't be answered by quantum mechanics.

Yes, but this is valid for any level of physics. Physics does not explain itself.

But, again, the fundamentals of these theories become the unanswerable questions.

For me it appears to be sort of absurd to even discuss about this. This is physics.

Electromagnetic fields are, again, a very useful concept that can be used to model electromagnetic behaviour.

Yes, a nice picture. I like the vector picture which helped me a lot with general relativity.

 

[ZapperZ]

Hi, I am graduated physicist, working in a company and additionally giving lectures in a university. Just about my background, so I think I know what I am talking about if I say: Physics explains exactly nothing. It just describes the nature but it does not explain anything. This is basically the definition of physics but I think this is not stressed enough nowadays.
As a nice example: In the university in my hometown Prof. Dr. Christoph Strunk is teaching about experimental physics in the field of superconductivity and nano structures. He wrote a remarkable book about thermodynamics. In the beginning of the book he is writing something like (no citation, a german book): If you asking yourself what entropy is... just accept it to be something which is there. Did you ever ask yourself what momentum is? If you think about the formula p=m*v then this is a formla but there is no meaning behind it. So why seems to be something like entropy that different?
Think about Feynman who said something like: Forget about to understand quantum physics, it is just there!

My "problem" is that I from time to time run into situations where I am speaking to educated people who believe that physics is sort of a basic explanation of the entire world. In those situations I try sort of grounding them but this seems to work not always.
So, what is your trick to convince them that they are wrong - or do you believe that physics is the truth?

Here's the thing. I truly believe that the world "explain" has the same conundrum and mis-interpretation between scientists (physicists) and the general public as the word "theory".

The criteria that we hold to to say that something explains something is a lot stricter than when the public use that word. Say A hits B on the head. That describes the event. What causes A to hit B on the head is the "explanation" for the event. For the public, that's sufficient of an explanation, in most cases. But this isn't true in physics, for example.

Let's bring out the example of superconductivity. Conventional superconductivity occurs because in some material, there is a formation of condensed pairs that allow for long-range coherence, i.e. as described in the BCS theory. So that is the "explanation" for the occurrence of superconductivity. But physics doesn't stop there. We then look at the foundation of that explanation, i.e. the interaction between the charge carriers and the lattice, and the many-body ground state of the BCS wavefunction, and we get all the way down to the fundamentals of QM, which as we all know, has no "explanation", merely description.

So that leads us to say that physics explains nothing, merely describes things. While this is accurate, it is misleading to the people who are hearing it, because to them, you are saying that there's no explanation for why A hit B! In reality, we do have a reason for why A hit B, but if you look down at a lower and lower level, the impetus that triggered the neurons in A's head which caused an emotional and physical reaction that resulted in A hitting B is also quite quantum mechanical, meaning that we also, at the most fundamental level, has no explanation for it. And this is even more true for "emergent phenomena", where we do not have any physical description of why large-scale phenomena occurred starting with the most basic, few-body interactions.

I always say that we can find an explanation for why things happen in physics, but then we need to find the explanation for the explanation, and then the explanation for that explanation, etc...etc... until, say, we come against one of the fundamental pillars of our universe (C, P, T, symmetries and the conservation laws). Then we have bumped into a wall where all we have are descriptions, because until someone can come up with an explanation on why we have such symmetries and conservation laws, those are the limits of our explanation, and we have arrived at the lowest, most fundamental description of our universe.

Zz.

 

[hagopbul]

Hope that you remember that physics is 300+ years old it is a new science

The question Why in regard for the actions of nature and universe ,Is a good question when we consider a conscious universe but dose nature a conscious thing ? To ask her why and expect an answer

We have a long way to be able to tell ourselves that we know truth , but saying we are trying to find it and we know little about the universe is a good step to find it

We and others use the scientific method to find and understand the universe around us that makes us able to grasp it before anyone else but with that comes the fact that we need to channel that truth to the rest of mankind , to simplify and to teach that is not an easy thing

Trying to consider a branch of science as a holder for the ultimate truth is also exaggeration , as every science is a projection of nature by our minds

Best
Hagop

 

[Omega0]

So that leads us to say that physics explains nothing, merely describes things. While this is accurate, it is misleading to the people who are hearing it, because to them, you are saying that there's no explanation for why A hit B!

Nope, not misleading. If there is state A (for example in thermodynamics) there is very likely a well defined state B which is described in physics, following from A.
Unfortunately, state A needs to be defined and so on.

I always say that we can find an explanation for why things happen in physics, but then we need to find the explanation for the explanation, and then the explanation for that explanation, etc...etc... until, say, we come against one of the fundamental pillars of our universe (C, P, T, symmetries and the conservation laws).

Well, as I said, I may have a very limited english vocabulary, but I don't understand why CPT and conservation laws - and the worse: entropy! are any different from other things in physics we measure and where we have no clue where it comes from...

 

[ZapperZ]

Nope, not misleading.

Please note that I said "misleading" based on what the general public understood!

You need to keep in mind that what you intended to say may not be what the listener actually understood! I've lost count how many times I've personally observed what a scientist said, and intended to communicate, and how DIFFERENT someone who isn't a trained scientist perceived and understood the message (I was involved in a public outreach program). It is why popular news report, written by reporters who have little training in that area, can sometime get the accuracy horribly wrong, even when they get the info directly from the horse's mouth!

So just because you think that you've conveyed something accurately, don't assume that that was exactly the message that the listener understood. Helen Quinn's excellent essay in Physics Today should be a must-read for every scientist intending to communicate to the public.

Zz.

 

[Omega0]

So just because you think that you've conveyed something accurately, don't assume that that was exactly the message that the listener understood. Helen Quinn's excellent essay in Physics Today should be a must-read for every scientist intending to communicate to the public.

An outstanding essay, thank you very much! Citation:
"If we set up science as just another belief system, we weaken its authority and dilute the power of our knowledge. " woooww here we are:
"We could, and I think should, excise the word “believe” from our vocabulary when talking about science. "
Great reading! Thanks.
"Without the postulate of the universality and immutability of the laws of nature, I do not even know that the Sun will rise tomorrow morning. Without the validity of that postulate, there would be no point to doing science! "
Yes, so we have postulates... I hope you got me now...

 

[ZapperZ]

Yes, so we have postulates... I hope you got me now...

I'm not sure what to get. Did I indicate anywhere that we do not have "postulates", as if I've never learned things such as Special Relativity?

The fact that we ended up with these fundamental "walls" of basic symmetry principle of our universe that did not come out of something else clearly indicates that there are things we accept in our universe that have no underlying, more fundamental "explanation". That was the whole point of my earlier post, and that even when the public thinks that "A hits B" has a sufficient explanation, in the end, if they dig deeper they way we do in physics, then they too will end up with this wall that has no explanation, only description.

But that's something they need to be informed of. Just saying that physics doesn't explain, only describe, and leaving them under the impression that everything else in their lives DO have proper explanation, will give them that erroneous conclusion. You have to give them context, and ironically, the explanation behind your statement.

Zz.

 

[Omega0]

But that's something they need to be informed of. Just saying that physics doesn't explain, only describe, and leaving them under the impression that everything else in their lives DO have proper explanation, will give them that erroneous conclusion. You have to give them context, and ironically, the explanation behind your statement.

Who said that I am just doing some job in leaving someone under the impression that physics isn't telling an awesome story? If you think about Einstein, he was awesome, closing gaps in the physics in this time. Do you believe Einstein was sort of depressed by not being able to solve the problem of combining quantum theory and GRT? This mind boggling theme exists since a hundred of years. Do you believe that it helps anyone to tell: "hey, this is given by a miraculous god"? It is something we face, nothing more.

 

[ZapperZ]

Who said that I am just doing some job in leaving someone under the impression that physics isn't telling an awesome story? If you think about Einstein, he was awesome, closing gaps in the physics in this time. Do you believe Einstein was sort of depressed by not being able to solve the problem of combining quantum theory and GRT? This mind boggling theme exists since a hundred of years. Do you believe that it helps anyone to tell: "hey, this is given by a miraculous god"? It is something we face, nothing more.

Huh??!

Zz.

 

[Mark44]

From post #6:

Okay, I have no clue what you are teaching but your concerns might be a nice laughter.

Okay, you are not a physicist, damn, you are funny!

Snide and condescending comments are not at all appreciated at this site. Please try to keep your replies more civil.

Here at PF we tend to say that physics describes the world around us, but doesn't tell us why it works the way it does.

Exactly this is what I am talking about.

If you (@Omega0) have not already seen this Feynman clip, you should definitely take a look. It contains Feynman's views on questions about why something happens --

 

[Omega0]

From post #6:
If you (@Omega0) have not already seen this Feynman clip, you should definitely take a look. It contains Feynman's views on questions about why something happens --

Mark, I don't know how to help you further. Yes, I know that video and you might notice that he is speaking about understanding mechanisms in nature using laws which seem to be given by nature.
Nature is doing what nature is doing.
I did not want to attack you, sorry if you feel that way.
The laws of physics do not define why they are.
If you have don't agree please let me know.

 

[davenn]

Mark, I don't know how to help you further.

You don't have to help Mark any further as it is you that doesn't understand.
You should be listening/reading carefully what Mark, Russ and others are telling you
as they have a much better understanding than yourself.

The laws of physics do not define why they are.

that's correct, they don't and they don't intend to. AGAIN ... as others have said
and as Feynman said physics doesn't answer why questions
That doesn't seem to be getting into your understanding
Physics simply describes what is happening

 

[Omega0]

as others have said
and as Feynman said physics doesn't answer why questions
That doesn't seem to be getting into your understanding
Physics simply describes what is happening

To help you a little bit as you seem to be another awesome expert... My question was nothing but - I reformulate: "How do you explain others that physics doesn't answer 'why questions'? How do you react if someone believes that physics is doing that?".
I just wrote it differently. Instead of answering the question I am called a bad teacher or whatever and you super expert believe to have understood that I didn't understood what I even expressed in my question.
The difference to my original question and the reformulated one is that I am not any more interested in an answer from you. Feynman did a pretty good job and I have to admit that I knew the video but forgot it.