This page is for discussion related to the development and improvement of the Physics article. As a result of a noticeable decrease in quality of the article it was decided to create a dedicated sub page where the entire contents could be reviewed and improved without the problems of working on a 'live' page which suffers from constant flux. Other editors have suggested that I act as a form of a secretary. The purpose of this is to add a structure to the process, setting up points for discussion, allowing discussion to take place, calling for consensus after an appropriate amount of time, helping to negotiate and reach consensus, then setting up another point for discussion. Editors who want to join this process are more than welcome - the more people we have involved in the process the more valuable the outcome.
The plan is for each area of the article to be discussed in turn. Once all areas have been discussed, and before the contents are copied across to the main article, a specific amount of time can be set by for A.O.B. to allow past decisions & consensus positions to be reviewed if editors feel strongly about something (and feel it wasn't given fair hearing the first time around - or if the editor wasn't around for the specific discussion the first time around).
Once the final version is completed then it can be copied across to the main article. At that point it can then be freely edited, and the wiki process will take over on this work. The quality may well decrease again, but at least there will be a consensus version to compare with, and editors can at that point bring discussion on the main talk page as to whether the changes are better than what was decided upon here, or worse. Hopefully the majority of the work done on this project will remain intact, but obviously the final version produced here should not be permanently held in place irrespective of changes made by other editors
The Key Points
To ensure that development progresses in an orderly manner there are a few key points that must be kept in mind:
Consensus is the key rule by which this process lives on. Only through this method will we arrive at a result which is going to stand up to the test and scrutiny of time. Give and take is required by all.
Editing of the WIP article itself should not take place until the specific change has been agreed upon by consensus on this page.
Discussion should generally be held within the boundaries of the current designated area. For example, if the "Future directions" section is currently being discussed then posting a lot of views on the "History of Physics" section - unless relevant to the "future directions" - is discouraged. The AOB time at the end of the process can be used bring up matters that have already been discussed.
Above and beyond Civility, a friendly and co-operative environment is encouraged. Ultimately we are all here voluntarily, and all just to try and construct a HQ encyclopedia - if folks start getting worked up then we just need to chillout. A negative environment is neither as constructive nor all that nice a place to work as a positive and friendly one. The use of smilies is encouraged. !
The Definition - between 50 & 150/200 words long. This is the first text read by the majority of people reaching the article page. What should we be aiming to say? - what should we aim not to say? - from those two points we can work out what we are going to say. SFC939410:40, 28 September 2006 (UTC)[reply]
Actually what we want, I suppose, is to define the lead paragraphs. They will of course include, but are not restricted to, a definition of physics --MichaelMaggs12:08, 28 September 2006 (UTC)[reply]
Everybody hopefully. First should come a definition that is easy to understand, and then one that is more rigorous. Krea18:36, 28 September 2006 (UTC)[reply]
No suggestions yet. This is proving difficult. How about looking at the text that's used on the current Physics page, and saying what we think is wrong with it. That might give us some pointers. The current text is:
φύσις (phúsis), "nature" and φυσική (phusiké), "knowledge of nature"), the most fundamental physical science, is concerned with the underlying principles of the natural world. Consequently, physics deals with the elementary constituents of the Universe — that is, all classes of matter and energy — and their interactions, as well as the analysis of systems which are best understood in terms of these fundamental principles. --MichaelMaggs14:43, 29 September 2006 (UTC)[reply]
Oooh, that's just asking for it!
What does "most fundamental physical science" mean? For one thing, taking the population as a whole, the word "fundamental" can be quite subjective. I think we should try to use as basic a set of concepts as possible, like talking about physics in terms of knowledge (which is itself a tricky subject).
The word "underlying" is making an implicit assumption about nature itself: that its laws are hidden from us. Now, for all we know, there is no evidence to suggest that this is the way it had to be and, conversely, no evidence for the contrary. We must ask ourselves if it is reasonable to assume a universe to exist in which this were not true. Therefore, is it reasonable to conclude that this statement is an observation of nature itself and thus should not be included in the definition?
I'm not sure that, "physics deals with the elementary constituents of the Universe," is a consequence of physics being "...concerned with the underlying principles of the natural world."
I could continue, but these complaints suffice to outline the point that I would like to make: I think that we must strive to formulate a definition that is as fundamental as possible. In other words, a definition that makes the least amount of assumptions about nature. For the sake of creating a constructive discussion, let me introduce the following definition of physics:
Physics is the body of statements that assert the manner in which nature truly behaves.
Now, I ask you: are you happy with this definition? I imagine that you will not be, but why? Is this not the most general definition we can make? Krea17:05, 29 September 2006 (UTC)[reply]
What 'the' body of statements is should be clarified. But I don't agree with the definition's perspective. Science is more than the product. Science is a certain method of study, and physics is a science concerned with a certain topic (matter and energy). "Physics is the science concerned with the discovery and understanding of the true and fundamental laws which govern matter [and energy]" is my suggestion. Directly after this, we should elaborate on the constraints (how it's different from other sciences - chemistry is about atoms, aren't they the same then? if we understand matter, we'll be able to know how people work too, right?) "Physics differs from... in that...", "While other sciences...". Then, on the variety of what physics encompasses: "The motion of galaxies and composition of atoms, gravity, light, and the nature of time and space are all in the domain of physics". The second paragraph could offer a brief history covering the most important achievements and some of the most important research going on today. –MT08:16, 2 October 2006 (UTC)[reply]
I prefer "Physics is the study of (or maybe "search for") the mechanisms and behavior of the natural world." for an introductory sentence. Saying anything about fundamentals and how true something is somewhat conceited and not entirely accurate - in my experience, physics appears to be more of an attempt to quantify/predict how something will act, and from there the understanding of the laws governing those actions is derived. Since physical scientists have produced a number of theories in the past which were wrong and/or incomplete (for a variety of reasons, not always their fault), saying that physics is the "true" form of the art isn't exactly accurate. There's also an old joke about fundamental science I'm not going to repeat here, but saying physics is "fundamental" (while a decent descriptor IMO) is a nebulous and ultimately POV way of putting physicists on a pedestal over other scientists. As far as the intended age thing goes, I would venture any pre-college grad (training in physics, not in general) - it's unlikely anyone with a physics degree would just up and read the "physics" Wiki article and expect it to contain something at their level. — Preceding unsigned comment added by Virogtheconq (talk • contribs)
So how about the following operational definition of physics. It shows that we must search and do other work to understand the world, that our understanding does not come for free; that the more we know, the more we can hope to understand, and vice versa. --Ancheta Wis23:21, 3 October 2006 (UTC)[reply]
I disagree with these definitions. Physics doesn't search for behaviour, it tries to determine and understand what causes the observed behaviour. In my definition, "Physics is the science concerned with the discovery and understanding of the true and fundamental laws which govern matter [and energy]" "true" is perhaps redundant with "science", but fundamental is the proper word. We're not implying that physics is fundamental, we're implying that physics attempts to discover those underlying, fundamental laws from which emerge all of the complexity (and complex laws) around us. It's an important thing to note. I can think of no way to express that that isn't tinged with an implication that other matter/energy laws are based on physics - which is a sure truth, they are. If we had a way to state this without the implication, then great, but an accurate description should not be sacrificed for the sake of soothing other scientists because the occasional reader doesn't quite understand the difference between "fundamental" and "important". Note that I'm not at all a physicist - this isn't bias speaking. –MT00:40, 4 October 2006 (UTC)[reply]
Welcome to the discussion M, especially since you can give a non-physicist's point of view, which is very welcome. Now, the fact that you are not a physicist is clear (it was definately clear when you mentioned it!) because your definition refers specifically to "matter and energy". In my opinion, these concepts should not be contained in the definition because it is no way known whether they are fundamental to the existence of physics. The definition should be as general as we can make it. Thus, intead of talking about searching for the behaviour of this or that, we should just say that we are searching for the behaviour of something, anything, which we do not wish to specify. When you say, "Physics doesn't search for behaviour, it tries to determine and understand what causes the observed behaviour," the thing that "causes behaviour" is itself behaviour! Furthermore, Let me expain why I don't agree with your definition:
Physics is the science concerned with the discovery and understanding of the true and fundamental laws which govern matter [and energy]."
Physics is indeed a science. But did it have to be? What do I mean? Well, what is science? Answer: A science is an application of the scientific method. So what? Well, to be a science, the thing itself must not be known - we have to make observations about it. Now, suppose that we already knew the laws of nature - there is no known reason why this should not be possible. Thus, if we did have this knowledge, physics would no longer be a science. Thus, the statement that physics is a science is not as general as it may be. The observation that physics is indeed a science is a particular of our universe (as far as anybody knows).
I've already mentioned that we should remove the words "matter" and "energy" from the definition, and replace them with unspecified entities under the generic name "nature", or something similar.
Thus, what are we left with?
Physics is the science concerned with the discovery and understanding of the fundamental laws which govern matter [and energy]nature."
Which is esentially what I first suggested. So, let me state it again (with some suggested changes):
Physics is the body of, or method of obtaining, statements that assert the manner in which nature truly behaves.
Krea - I rather fear that in your eagerness to be as general as possible you are in danger of losing most if not all readers in metaphysical or philosophical niceties. You question, for example, whether physics has to be a science, and argue that in a hypothetical world in which we knew all the answers physics would no longer be such. You may be right, but in our own world we don't and it most certainly is. Since there's no question about it, I can't see any reason not to describe physics as a science.
We should, in my view, be quite comfortable in using the terms matter and energy. They are both commonly-understood expressions which help the uninitiated reader get an immediate sense of what this thing called physics is all about. Although there's no formally-agreed definition of physics, any more than there is of most sciences, I'd be willing to bet that the majority of physicists would use one or both of those terms if asked to describe physics in a nutshell. And how physicists describe their own field is most definitely of relevance. It goes without saying that non-physicists are most welcome here, and have already contributed significantly to the discussion, but it's hard to accept the implication in an earlier statement (not one of yours) that
that a physicist's viewpoint would show 'bias'. Without the input of physicists an article entitled "Physics" is likely to be a poor thing indeed. We need both views.
You have suggested that the initial sentence of the lead para should read "Physics is the body of, or method of obtaining, statements that assert the manner in which nature truly behaves". But by avoiding words such as matter and energy, which are specific to physics, your definition covers almost any type of scientific reasearch. Research into the mating habits of King Penguins, for example, would seem a good example of "research into the manner in which nature truly behaves".
I suggest something along the following lines. As we are meant to be discussing all the lead paragraphs, not just the first sentence, I have made a proposal for the entire thing: --MichaelMaggs12:26, 10 October 2006 (UTC)[reply]
Krea, I enjoy the correctness of your definition, but I disagree with it. This section 16 of The Elements of Style presents my case. This isn't simply a manner of artistic style, but one of comprehension. "Science", "laws", and "matter and energy" are clearly understood by readers; what exactly is meant by "statements that assert the manner[…]" and "nature" is not so readily understood. The full coverage that your definition attempts to make is best reserved for the body of the article, or better yet, the reader's own common sense and experience. –MT21:06, 10 October 2006 (UTC)[reply]
Oddly enough, the fact that you "enjoy the correctness of [my] definition" brings to me more pleasure than the fact that you "...disagree with it" brings me distress! I agree that it's a little dictionary-esque in style, but it's not completely beyond the realms of comprehension is it? I don't mind having a definition that the non-physicist will understand (in fact, I think this is absolutely necessary), but I would also like to have one that is pedantically "rigorous" and "correct". I don't like MichaelMaggs' definition in its current form because parts of it are plain wrong and misleading, and it includes no acknowledgment of this. Prime example: "Physics is the branch of science concerned with the properties of matter and energy, and the relationships between them." Now, this is wrong: what about the Lagrangian? Properties of the Lagrangian of a system also constitute physics; but the Lagrangian falls under neither the topics of matter nor energy. It is also misleading: energy and matter are not concepts of physics more fundamental than any others as one may be led to think. My point is that it is irresponsible to only include a lay definition or to leave it to "...the reader's own common sense and experience." The article has a duty to appeal to all readers. Therefore to omit my definition is as bad as having it as the only one. What do you say to including both? Krea22:14, 10 October 2006 (UTC)[reply]
It's comprehensible, but my objection is that the definition shouldn't worry too much about being perfect. "Matter and energy" seems to be the best we have, without a paragraph-long elaboration, and without a general word like "nature" (the laws of nature may refer to just about anything natural). I like "matter" because it's bland. You can't mistake it for the study of penguins and other complex things that incidentally are made of matter. Yes, some physics isn't concerned directly with matter, but that detail should probably be pointed out in the body. I think that it harms us to think of it as a definition. Instead we should think of it as an introduction. Sketch the outline, and then fill in the details with the rest of the article. –MT23:02, 10 October 2006 (UTC)[reply]
"...the definition shouldn't worry too much about being perfect"!!! That's a horrible thing for any mathematical physicist to have to read. What you said you want is just personal opinion - I imagine that aiming for a definition that is not as good as we can make it will annoy a lot of people here. Ok, let's stop and take things in. You want comprehensibilty, right? I want rigour. Why not have both? Definitions need to be placed in the definitions section, nowhere else. All we say is: "physics, in lay terms, is the study of matter + energy..." or whatever. Then we say that, "A more rigourous definition of physics, however, is..." What's wrong with that? Krea12:57, 11 October 2006 (UTC)[reply]
To begin with, I agree that matter and energy should not be mentioned specifically by themselves. What about space/time? What is special about matter? To destingush it from other sciences it needs something like fundemental or underlying or mathematical. David R. Ingham00:15, 15 October 2006 (UTC)[reply]
"Physics is the most basic of all the sciences. Within it, the basic laws of natural forces, such as gravity, are formed; as well, the interaction between inanimate objects is observed. Specifically, the interactions between matter, energy, and time are concerned." It's a start. However, I do agree that a general definition should be given. After all, it is only the introduction. Yet, physics is rather hard to define. :( Jerr23:42, 16 October 2006 (UTC)[reply]
Proposal for lead paragraphs
Physics is the branch of science concerned with the properties of matter and energy, and the relationships between them. It seeks to understand and describe the physical properties of the universe at the most fundamental level possible, normally by way of mathematical modelling of the behaviour of physical systems. Physics is accordingly closely allied to mathematics, which provides the logical framework in which these descriptions can be precisely formulated. More generally, the aim is to go beyond simply describing physical phenomena mathematically, but rather to construct mathematical models or theories which can also make predictions about the way in which a physical system is expected to behave in certain defined circumstances. These predictions can then be experimentally tested to support or refute the theory.
Some of the mathematical theories of physics are believed to be common to all physical systems. These are often referred to as the laws of physics, although the word 'law' is a misnomer since even a law of physics could, in principle, be disproved by experiment. Others theories are more limited in that they describe the behaviour of specific physical systems only, or are applicable only within a defined range.
Physics research is divided into two main branches, namely experimental physics and theoretical physics. Experimental physics focuses mainly on empirical research, and on the creation and testing of theories against practical experiment. Theoretical physics is more closely allied to mathematics, and involves creating and working through the mathematical implications of systems of physical theories, even where experimental evidence of their validity may not be immediately available. Most theoretical physicists work on aspects of particle physics and allied fields.
Well-put. There is much to say of its merits, but I won't focus there as it won't get us far. Some things are best left unsaid. I'll edit it, revert, link the diff, and elaborate. Here's the diff. As expected, I still prefer my own definition. Properties and relationships are best summarized as laws. Note that while things that we think are laws may be disproven and therefore not laws, there are genuine laws that exist. I don't like the personification in "it seeks to". The note on the definition of "laws" may be out of place. If the distinction between classical and modern is no longer important, then perhaps it shouldn't be mentioned, and in its place describe the various sub-fields. –MT21:59, 10 October 2006 (UTC)[reply]
IMO, the distinction should still be mentioned for historical purposes - since it was an important distinction in the past and many articles may refer to it, it belongs somewhere in the opening statements. I still think the word "characterize" (or some reasonable facsimile thereof) needs to be in the first or second sentence, since that's ultimately what most physicists (indeed, most scientists) do. Finding the fundamental reasons for why things happens is all well and good, but even if a theory is wrong, it (can) provide a good mathematical model characterizing an interaction without ever explaining why it's so. I also disagree with the inclusion of "matter" and "energy" in the first sentence; it may sound a little too mumbo-jumbo-y to a casual reader and implies something related to QM, GR or ST (which obviously isn't true, but still...). Simply saying "the natural world" is far clearer and more general - technically everything revolves around the study of matter and energy, but most fields aren't concerned with the details of matter and energy in the implied sense. — Preceding unsigned comment added by Virogtheconq (talk • contribs)
In that case I agree on keeping the distinction. I'm a casual reader (layman in physics), and "matter and energy" is pretty clear to me. "Nature" on the other hand is absolutely ambiguous. All science concerns itself with the natural world. Physics distinguishes itself by focusing on ... well, plain old matter and energy. Those small and universal things that make up the bigger things. –MT00:03, 11 October 2006 (UTC)[reply]
Yes, striving for a general definition will indeed take you down philosophical and metaphysical roads! That's not altogether a bad thing though. I agree that my definition is one extreme; thus, we should have many definitions: one for everyday use, one general, one specific, etc. You have struck at the heart of the issue when you say that there is no formally-agreed definition: many people define what physics is and its bounds of working validity subjectively. In fact, you may argue that the mating habits of King Penguins is indeed physics! So, let's sort out each of these definitions in turn. I would like to keep the general definition of physics for the sake of pedantry and the "rigourous way". I would also add the "particular definition" - i.e. the one that says, "yes, physics is actually a science". In fact, I only gave you half of my definition: I was going to add the latter half later on (since nobody uses a practical definition that speaks of the true laws of nature - these are not known!). So, lets first decide the type of definitions. I suggest:
Lay, easily understood definition - for the casual reader to have a general understanding of the topic.
General definition - one that is "rigourous".
Specific, or particular definition - a more useful, working definition than the general one.
We can discuss your suggested lead paragraph in more detail bit-by-bit once we have a clearer direction of where we are going.
Krea17:12, 10 October 2006 (UTC)[reply]
I've tried to pull the threads together, so far as I can, and I set out a revised proposal below. We ought I think to keep in these lead paragraphs the distinction between modern and classical physics, as they are common categories that readers will have often come across. The paragraph on laws is, I think, important to keep here as a lot of readers may well have heard the term law of physics with no understanding of what it means. I agree with M on using the terms matter and energy. For the reasons I've already stated the alternative 'Nature' or 'Natural World' are too broad as they don't in any way limit our understanding of what physics actually is (which we could perhaps think of a 'what physicists actually do'); they don't study King Penguins!
Physics is the science concerned with the properties of matter and energy, and the relationships between them. Physicists seek to characterize and describe the physical properties of the universe at the most fundamental level, normally by way of mathematical modelling of the behaviour of physical systems. Physics is therefore closely related to mathematics, which is the logical framework that allows for the precise formulation of these descriptions. The aim, however, is to go beyond describing physical phenomena, and to construct mathematical models or theories which can also predict how a physical system will behave. These predictions can then be tested experimentally to support or refute the theory.
Some theories are of such significance that they are referred to as the laws of physics. Typically, these are physical principles that are believed to be common to all physical systems, or at least are of very general applicability. Some principles, such as Newton's laws of motion, are still generally called "laws" even though they are now known not to be of such universal applicability as was once thought. The word 'law' is a misnomer since even a law of physics could, in principle, be disproved by experiment. Other theories are more limited: they describe the behaviour of specific physical systems only, or are applicable only under certain circumstances.
Physics research is divided into two main branches: experimental physics and theoretical physics. Experimental physics focuses mainly on empirical research, and on the development and testing of theories against practical experiment. Theoretical physics is more closely related to mathematics, and involves generating and working through the mathematical implications of systems of physical theories, even where experimental evidence of their validity may not be immediately available. Most theoretical physicists work on aspects of particle physics and related fields.
I really like the preceding paragraphs by MichaelMaggs. Here are a few comments:
I think it's important to say (near the comment on the more limited theories) that one of the major goals of physics is universal applicability, i.e., progress is made when you expand the range of validity of a single, unified understanding.
I wasn't aware that solid state physics and condensed matter physics were separate regimes. I think solid state is a subset of condensed matter but I'm not an expert in that area.
It might be dangerous to say that most theoretical physicists work on aspects of particle physics without backing it up with a demographic citation. There are a fair number of theorists in condensed matter, too, although they don't get as much press as the string theorists. I was going to suggest mentioning phenomenology here too, but decided against it since it's a bit too specific for an intro (and I think the theory/phenomenology/experiment distinction is mainly limited to particle physics). HEL13:04, 11 October 2006 (UTC)[reply]
Excuse me. MichaelMaggs, could we kindly stop and take everything in for a moment. We have 2 different viewpoints on the definition. You have objected that my definition is too general (I agree with that), whereas I object that yours is too narrow and specific. What is wrong with including both? Why not say, "physics is the study of this or that...", and then say, "we can have a more general definition of physics that says..."? Is it that you don't agree that my definition is useful (because it is too general)? I agree that it is not useful, but I still believe it should be at least stated because it is the only definition that is always true. I think the mathematically and philosophically minded members of this discussion would appreciate that. Thus, can we stop for a moment and outline what the structure of this section should be. Neither you and M, nor I should continue without a clarification of the issues at hand. Krea13:29, 11 October 2006 (UTC)[reply]
Hi Krea. Yes, I'm more than happy to continue the discussions, but I must confess to having real problems understanding the thinking behind your definition. It seems to me - please correct me if I'm misinterpreting - that you are arguing that your definition is correct because it is broad enough to encompass all of physics. It is extremely broad, true, but to my way of thinking a definition should so far as is possible cover only the subject being defined, nothing more. To the extent that your definition covers things (such a biology) that cannot on any reasonable use of the word be considered to fall withing the scope of physics, it is wrong. You have agreed that your definition is in any event not useful, and I don't understand the argument that Wikipedia would be improved by having non-useful definitions added to it. --MichaelMaggs13:55, 11 October 2006 (UTC)[reply]
Thanks for clarifying what is troubling you. You're partly correct, but you seem to have also partly misinterpreted my meaning. It's quite subtle, and it would be better if I could explain this in person, rather than through words, but I'll give it a go. Definitions, in a sense, can't be "correct" - they're definitions! All they can hope to be are consistent, and useful. When I formulated that definition, I didn't think: "in order to ensure that I encompass physics in my definition, I'll make it really general so that nobody could possibly argue that it is wrong". What I did was this: I just made any consistent definition of physics (not something contradictory), and then asked myself: is it useful to us in some way? My general definition is not useful in a practical sense, but I still argue that it is useful because it is required for aesthetic purposes (sorry for not saying this before, and so contradicting what I did say before). Let me explain.
When I formulate definitions, I would like them to be independent of the thing that they try to describe. For example, if we define physics as the study of particles (for example), then the definition is based on things that physics itself identified! That's a bit silly because, in a sense, it is circular: physics defined particles, and particles now define physics. This requirement is, of course, one of personal "aesthetics" (i.e., what makes a good definition?) - but many theorists, mathematical theorists and philosophers prefer things this way.
Many people, myself included, search for such definitions that satisfy this "aesthetic" property. The problem is that this also make the definition very general. Specifically, if we wish to keep this aesthetic quality, we must admit that everything is physics! Thats not too unreasonable: penguins are physical objects and they do interact via the laws of physics, so, in a way, they could be thought of as being under the bounds of physics (ignoring issues of consciousness - don't ask!).
Thus, you have to ask yourself what's more important, a defintion that correlates with what you feel physics is (and that means not including penguins!), or one that is "aesthetically nice". That's my only justification for including this definition: just because it has some favourable properties.
So, it's not completely useless, it's just not very practical. Thus, I would like to have both: one that gives you a feel for the subject (but has some undesirable properties), and one that is "nice" and "rigourous" (but not very practical, and gives you no everyday sense of the subject). If I haven't convinced you of the desirable properties of my general definition, please permit me to try harder! Krea15:49, 11 October 2006 (UTC)[reply]
I must confess I'm not a philosopher, but a practical physicist. While I understand the desirability of having non-circular definitions, we do need something that make sense to the average reader, and which tells him or her something useful about the subject under discussion. On your own admission your wording implies that everything is physics, and furthermore that it gives you no everyday sense of the subject. The concept of "aesthetics", in the sense in which you use it, would need a lengthy exegesis which even if it were helpful would not, I feel, fit into this article. For that reason I'm against having two definitions. Also, as M has pointed out, it harms us to think of the first sentence as a definition in the strict sense. We should view it as a practical description of the remit of the subject.--MichaelMaggs17:53, 11 October 2006 (UTC)[reply]
It need not be too lengthy. Of course, it should not be the first thing the reader reads! But I still think it should be there somewhere. Let me just say for the record that I don't like the idea of saying that the lead section be short: it needs to be a big as it needs to be. It must, however, be readable and well structured. Also, definitions on physics are personal - there is no written formal definition, and this should be said.
I would really like to look back on this when it is finished and be really pround of it: to think, "you won't find anything better than that on the internet", instead of thinking that it was compromised. Come on! Let's not take the easy route. Let's at least give it a go. Let's give it the "all out" treatment! What about this:
Start the article off really slowly - easy ideas, commonly understood phrases.
Then say that there is no formal definition: that many people have their own definitions of what physics is...
and then introduce some definitions that are more "desirable" in some ways.
If we can keep it well structured, it should be fine. I don't think we need to write essays: we can just say that the first definition is circular, and that avoiding this leads to this definition, and then point out some of the objections of this definition. Viola. That's not too bad is it? If it becomes long and difficult to follow, then I agree that the article would be better off without it, but I really don't think it will become so. What do you say? Besides, I can't let you experimentalists get the only say!! Krea22:48, 11 October 2006 (UTC)[reply]
Putting my replies down here since I can't arse myself to properly find where they need to go.... Certainly the first sentence isn't the end-all be-all of a definition of the subject, but given as its the first thing the reader is going to see it will have the most impact. Given that we seem to be having difficulties agreeing on a definition, perhaps that ought to be addressed instead: something along the lines of how broad a field it is, and then trying to establish some definitions. I still object to the use of "matter and energy" as it implies something about the majority of subfields which really isn't true: in my experience, saying "matter and energy" to most average people will immediately provoke a comment about QM, ST or (more rarely these days) GR, which is really just a tiny fraction of the total population of physicists (though the only ones worth a darn to the media, apparently). Maybe I'm just splitting hairs, but that's what my experience has been, and I think it does the article a disservice to (unintentionally) lean it towards a particular field. Virogtheconq00:54, 12 October 2006 (UTC)[reply]
"Physics is the science concerned with the properties of matter and energy, and the relationships between them." might also be stated
I dunno, it hard to write a good sentence. I also don't like the link to "on the nature of things", its too specific for the general definition. linas04:40, 12 October 2006 (UTC)[reply]
Whoooah guys, calm down! We've got to sort out what we want to do first. There's this whole issues of multiple definitions. I'd personally like to say that lots of definitions are possible, each with their own merits and shortcomings. So far, there are 2: a simple one, and one that I suggested (it's somewhere above). I doubt anybody objects to the "simple definition", but does anybody else object to the one I suggested? Plus, does anybody want to add another defintion with reasons on why it is useful? Krea11:46, 12 October 2006 (UTC)[reply]
Just to add my two cents: I prefer MichaelMaggs's lead-in above,
Physics is the branch of science concerned with the properties of matter and energy, and the relationships between them. It seeks to understand and describe the physical properties of the universe at the most fundamental level possible, normally by way of mathematical modelling of the behaviour of physical systems. (etc)
I have no problem with "matter and energy" in the first sentence; to me it seems to fit everything from fluid dynamics to vibrational solids to particle physics, but then I'm a particle person so I might not be hearing it the way others would. Virgotheconq, do you have another suggestion? The second sentence together with the first adds a lot of solidity and really clarifies the definition, in my opinion.
Krea's proposed definition (copied from above; please let me know if I didn't find the right one you were referring to!):
Physics is the body of, or method of obtaining, statements that assert the manner in which nature truly behaves.
I am not as happy with it because to me it feels kind of vague. Could we cut out the words "assert", "manner", and "truly"? Isn't this statement, rewritten in plain English, just Physics is the set of statements about the way nature behaves, and the method for finding them out? But this applies to all of science, and then we run into the problem of penguins. We may like to say "everything is physics", but everything is not physics. We can talk about the linkages, like biophysics etc, but that's the application of physics to biological systems, not fundamental physics research. (Oh, and I'm a theorist. :) HEL12:26, 12 October 2006 (UTC)[reply]
I think I'm going to second this opinion. The intro suggested by MichaelMaggs is clear and to the point, and I believe that most physicists would identify with studying "the properties of matter and energy". A more general definition runs the risk of being too vague, and anyway: "the properties of matter and energy" should be general enough for anyone! O. Prytz13:10, 12 October 2006 (UTC)[reply]
Having just endorsed it, I have to say I have a bit of a problem with physical properties of the universe. If I were studying, say, high-Tc superconductivity (an unsolved problem in theoretical physics!), that phrase wouldn't really cover me. How about universe and its contents? (Or maybe, physical world or material world?) I want to avoid using the word nature here, because while a physicist would probably say high-Tc superconductors were part of nature, a layperson wouldn't, because they are man-made. HEL13:23, 12 October 2006 (UTC)[reply]
Okay, these suggestions are missing the point a little: I'm not looking for opinions on whether you like it or not. I argue that it is a useful definition (although, not in a practical sense - which is what has been already mentioned), and I want to know whether people disagree with this or not. Also, just a few remarks: the word truly is required because this leads to distinctions about the fact that we do not know the true laws of nature; the rest are, yes, probably superfluous. Furthermore, you cannot say, "but everything is not physics," because the truth of that statement depends upon your definition, which is what we are arguing for in the first place! It's like saying your definition is not true, because my definition says so!
Again, forget the specific content, all I want to know is if you agree to the idea behind this definition or not. Specifically, this definition tries to define physics independently of the objects that it itself defines - in effect, avoiding a circular definition. Having clear and understandable definitions is all good and well, but does not one of you also want a more "solid" definition? Krea13:31, 12 October 2006 (UTC)[reply]
Krea, I appreciate your persistance, but I don't think I do want another definition which is more 'solid' (or 'aesthetic') according to the meanings that you're applying to those words. Any definition, however 'aesthetic', which implies that everything is physics, and which gives you no everyday sense of the subject is sufficiently content-free, in my view, to be excluded from this article. You have already argued long and hard on the main Physics talk page for your proposals from March to July 2006 and I'm afraid I'm no more convinced than were the other editors there. --MichaelMaggs16:22, 12 October 2006 (UTC)[reply]
I'm aware of how hard I tried this summer, but I still cannot believe anybody would want to settle for such a sub-standard definition. And make no mistake, it is sub-standard; useful for the public undoubtably, but nevertheless a poor definition. I hoped that it could be supplemented with something more "solid", but alas, those who don't think "mathematically" seem to have the majority. So be it. Krea16:43, 12 October 2006 (UTC)[reply]
Very few would understand a rigorous definition. Rigorous definitions exist, but are not mainstream physics. The positivists have some definitions, but no one pays attention. That has got to be significant. Possibly because no physical predictions have come out of these efforts? So no one pays attention? --Ancheta Wis17:21, 12 October 2006 (UTC)[reply]
The world of language is, sadly, not as precise as the world of physics. You have not, and I suspect won't be able to, provide a definition of physics that is a) complete b) comprehensible c) short and well-formed. When you use the word "nature", you lose comprehension: penguins too are part of nature. Continue proposing, of course, if you wish. Just be attentive to what you lose when you gain. I think that the best way to handle it is to make it comprehensible, short, and well formed. Completeness down to detail can be left to the rest of the article. –MT08:55, 13 October 2006 (UTC)[reply]
"...and the relationships between them" seems like a waste alongside of "the properties of". Readers can guess that we're not excluding relationships. Do physicists sharply distinguish 'properties' and 'relationships'? I would use the word "behaviour" to cover all that, myself. "Concerned with the properties of matter and energy" is redundant to "concerned with matter and energy". Readers will know that it's the properties, or the behaviour, or the inter-relationships even if you omit those words. The real issue, if there is one, is what the form of the concern is not stated. That it's scientifically concerned with matter/energy is good, but perhaps being explicit about understanding/discovering/characterizing is better. "Universal" was brought up, which is a better word than "fundamental", for reasons more than political correctness. With this in mind, the definition:
Physics is the science concerned with the properties of matter and energy, and the relationships between them.
Physics is the science concerned with the discovery and understanding of the universal laws which govern matter and energy.
I have the following bracketted commentary on the rest:
Physicists[worthy of linking] seek to characterize and describe the physical properties of the universe at the most fundamental level[this is all just a rehash of the above paragraph], normally by way of mathematical modelling of the behaviour of physical systems. Physics is therefore closely related to mathematics, which is the logical framework that allows for the precise formulation of these descriptions[we already state that physicists formulate/characterize/describe by way of this logical framework; this is redundant]. The aim, however, is to go beyond describing physical phenomena, and to construct mathematical models or theories which can also predict how a physical system will behave. These predictions can then be tested experimentally to support or refute the theory[or should we stick to falsifiability?].
One important thing to keep in mind is that this article is not within the domain of physics, though it's about physics. Words like "nature" and "characterize" don't have the same rigid and useful meanings. –MT08:55, 13 October 2006 (UTC)[reply]
Sorry to respond so late, but my Internet connection only works about once a day for a variable amount of time, so I'm a little behind on the discussion.
I have no problem with "matter and energy" in the first sentence; to me it seems to fit everything from fluid dynamics to vibrational solids to particle physics, but then I'm a particle person so I might not be hearing it the way others would. Virgotheconq, do you have another suggestion? The second sentence together with the first adds a lot of solidity and really clarifies the definition, in my opinion. - Matter and energy are fine in a technical sense (ultimately every subfield uses energy to try to characterize matter behavior), but again, my concern is the general connotation of the terms. The casual reader coming to this specific article is influence by what those two words mean in the mass media, which is mostly modern physics: most of the people I went through undergrad with are far from those fields (as a clarifier, I come from an astrophysics, not cosmology, background, though only at the undergraduate level - I've since migrated to astronautics). While "matter and energy" may be the tools we use to characterize the behavior of whatever it is we're studying, it's not the ultimate purpose of the study in and of itself (with a few exceptions, of course).
I personally think "nature" and "characterize" are just fine. For the former term, HEL has an arguable point, but physics encompasses so many fields (geo, bio, chem, materials, etc.) that there's no way to capture them all without using some catchall, sorta indefinite term like that. For the latter term, I think characterization both within the physics domain and outside is rather cut and dry: I would argue the entire purpose of most sciences in general is to find a way to describe (characterize) phenomena we see around us (primarily; finding the root causes would be a close second). Mathematical characterization is still characterization, and ultimately mathematical models still can qualitatively characterize what is happening.
That being said, my estimation is that a more general, simple sentence (not even definition) needs to be used to open the article to describe how wonderfully varied/encompassing "physics" is (that variance probably being the cause of our disagreement), and as such cannot be fully articulated simply. I can give it a stab later today or tomorrow working off MichaelMagg's architecture (I generally like his opening but for the semantic arguments I've been making), but don't expect anything until tomorrow at the earliest. Virogtheconq14:38, 13 October 2006 (UTC)[reply]
Again I stress that "nature" is not the right word. The things that physicists study are at the root of everything, yes, but 'everything' is not what they study. Ask the average person "which science studies nature?" - my bet is that they'll reply with "biology" or "zoology". Using that sort of definition will unnecessarily and disproportionally blur the edges of what physics is. –MT20:38, 13 October 2006 (UTC)[reply]
Before we let the King Penguin thread die, it is pertinent to note that according to the laws of physics, all of nature should be subject to the laws of physics. Thus living organisms are subject to gravitation, etc. --Ancheta Wis21:58, 13 October 2006 (UTC)[reply]
You say that a system fundamentally operating under the laws of physics falls under physics - this is wrong. Maybe when we have computers that can, using a complete theory of everything, model, say... quasi-infinite environmental factors operating on a quasi-infinite set of penguins to determine average results, then we'll be able to say that physics covers the "natural world", that really biology and medicine and psychology and even chemistry fall truly and fully under physics. As it is now, physics covers the fundamental laws of the particles that make up the natural world, and has practically nothing to do with complex systems like penguins. Physics covers only one part of the natural world: the fundamental. Matter and energy. –MT04:52, 14 October 2006 (UTC)[reply]
M is quite right. Saying that "penguins are subject to the laws of physics" or, more broadly, "all of nature is subject to the laws of physics" actually tells us nothing about the actual range of scientific enquiry that can be carried out within the science that we call "Physics". Is a study of the mating habits of King Penguins research into Nature? Of course. Is it Physics? Absolutely not. --MichaelMaggs08:36, 14 October 2006 (UTC)[reply]
Allow me a little story: as a result of Operation Paperclip one of my teachers, Kurt Lehovec, formulated the equations behind "The photovoltaic effect", Phys. Rev.74, 463 (1948), #6; also #1, 3 and 5, from some rocks he found, sitting in his desk, at the United States Army Signal Corps in Camp Evans, New Jersey. Being curious, he managed to identify the rock as silicon carbide and published equations relating the emitted light from the rock under the influence of a current, and vice versa. Do you call that physics? I happen to do so. By the above reasoning, Lehovec was engaged in an esoteric form of electronic engineering, and indeed he is one of the founders of the integrated circuit industry. But I call him a physicist. That is not merely my POV; the editors of Physical Review thought so too. Or might the application to electronics be the only thing? No. It was brand-new. That makes it interesting to physics. --Ancheta Wis11:08, 14 October 2006 (UTC)[reply]
Let's call it physics. He was doing physics, and this discovery through physics led to the field of electrical engineering. I don't really see the relevance, so I'll re-iterate. The word "nature" covers penguins, penguins aren't physics, so "nature" is too broad. You seem to say that penguins (and electrical engineering?) are physics. This is wrong. A physicist doesn't care about the penguin and how it behaves, he cares about the stuff that the penguin is made of, and how it behaves. "But the penguin's behaviour is dictated by its molecules" is true, but irrelevant: physics is incapable of predicting anything in terms of relatively massively complex systems like penguins. Or cells. Or (I've heard) even many chemical reactions. –MT12:37, 14 October 2006 (UTC)[reply]
I have no problem in calling that physics. It's a pretty clear investigation into some properties of matter and energy. But how would you deal with my 'mating habits' question?--MichaelMaggs12:46, 14 October 2006 (UTC)[reply]
M, so that we not escalate, I use φυσική (phusiké): the subject of φυσική is matter, energy, etc. But φύσις (phúsis) is governed by fundamental law, to which it is subject (i.e. to which it obeys). Ilya Prigogine (whom I call a physicist) has made a start on your critique of the limitations of physics by introducing the concept of the 'thermodynamic branches' of 'systems far from equilibrium'. I admit, the subject has a ways to go. But it has gone beyond simple systems.
MichaelMaggs, life itself was shown to have a reasonable physical explanation with the discovery of the structure of DNA. One of its discoverers, Francis Crick (whom I call a physicist) cast off much of the essentialist baggage of life force or vis viva etc by requiring only a view of the structure, and nothing else. That was that physicist's POV. And the discovery was made in Lawrence Bragg's lab. Before we proceed, I respect your current precis, and am only worried about the essentialist cast of its first sentence. --Ancheta Wis14:41, 14 October 2006 (UTC)[reply]
I'll add one more thing, and then I'll leave it up to the rest of you guys to sort this out: "all of nature is subject to the laws of physics" actually tells us nothing about the actual range of scientific enquiry that can be carried out within the science that we call "Physics". So what? I'm a stereotypical theorist: I genuinely don't care about the practicality of physics. Having a vague definition that admits all of nature is physics really does not cause me any concern (because ultimately, this is probably true). The fact that the understanding of physics is not yet at this level does not mean that we cannot define physics this way. This view is by no means untypical of many theorists and mathematical physicists. Why, then, should an experimentalist view prevail? Merely because there are more practically-minded people here who don't like that way of thinking. And that is the key word: like. These views are not wrong (they are just definitions after all), they are just being forced out by the majority. Krea10:51, 14 October 2006 (UTC)[reply]
All of nature is not physics. Rather, all of the particles that make up nature are governed by the laws that physics studies. You're confusing component parts (matter and energy) with some whole (earthly biology, medicine, psychological systems, penguins, etc.) Physics studies the component parts, but not the wholes. –MT12:37, 14 October 2006 (UTC)[reply]
Krea, you seem to be using the word "definition" in the mathematical sense (let x=y), in which we can can never be wrong because we are defining things to be some particular way. But what we are discussing here is not a definition in that sense at all, it's a decription of the way in which the word "Physics" is applied in ordinary English usage. We're not addressing how the word might be used when our understanding of the universe reaches some as-yet unknown level: that's an issue for future editors, assuming the encyclopedia is still around then. This is a purely practical issue, and editors who take issue with you need make no apology for being practically-minded people. --MichaelMaggs13:59, 14 October 2006 (UTC)[reply]
Ah, so much has been said about the definition of physics – here, and before this WIP page was set up. Here's what I have to add:
There is no reason to suppose that the term has one single proper definition.
The Shorter Oxford English Dictionary (SOED), and its big brother the OED, give two relevant definitions. Here are the two as they occur in SOED:
1 a Hist. Natural science in general, esp. the Aristotelian system of natural science. L15.
b The branch of science that deals with the nature and properties of matter and energy, in so far as they are not dealt with by chemistry or biology; the science whose subject-matter includes mechanics, heat, light and other radiation, sound, electricity, magnetism, and the structure of atoms. Also, the physical properties and phenomena of a thing. E18.
Now, Krea and I are among those who insist on respecting the first of these definitions. Others are vociferous about the second. In fact, I think there is a strong case for respecting both. Historically, physics started out as simply the science of nature. In coming to a broad and robust appreciation of the scope of physics, we should understand it that way. Then, of course, we can point out that in practice the term is used in SOED's second way: as excluding chemistry, biology, and all the other special sciences. There is no conflict here. Compare an uncertainty about the meaning of body. The word is used in two different senses in these two sentences:
His head was severed from his body.
His whole body was sunburned.
In the first case, the head is something separate from the body, yes? In the second case, it is assumed to be included as a part of the body, and we infer that it is sunburned along with the rest of the body. So it is with the word physics: two senses, which we should be able to accommodate easily in our definition. In one sense, physics includes chemistry, biology, and all the other "sciences of nature"; in another, it is all that is left of natural science after you remove the special sciences.
Another analogy, closer to the situation of physics. Consider medicine. It is, roughly, the applied science concerned with the health and disease of the body, yes? So, given that the teeth are a part of the body, medicine should be concerned with the health and disease of teeth, right? Well, yes and no. Conceptually and broadly, dentistry is a part of medicine, and the teeth are one of medicine's concerns. It is valuable to think that way about the scope of medicine, at first. But then, as a practical and historical fact, dentistry and teeth are considered separately.
It is for this sort of reason that I have stressed the need for a historically informed approach to introducing physics, and to reaching a useful definition. My concrete suggestion? Something like this, as my first draft:
Broadly, physics is the science of nature: the science concerned with describing the basic constituents of the natural world, and specifying the laws governing their behaviour, singly and in combination. In most current uses of the term, physics is understood as more limited: there are special sciences (chemistry, biology, psychology, etc.) which are treated as if they were autonomous and not as parts of physics. This exclusion of some complex features of nature is a matter of mere historical fact and mere practical convenience; it does not limit the original scope of physics as the universal science of nature.
That's how I see things, anyway. Such a definition would need further work, of course. But if we are to achieve consensus at all, we must in the end give both senses of the term their due. – Noetica13:30, 14 October 2006 (UTC)[reply]
"Physics" used to mean something different and probably broader, yes. In fact the field as we know it today derived from what used to be called 'Natural Philosophy'. And that's consistent with the first definition in the SOED, which tags that meaning as Hist[orical]. By all means let's cover earlier meanings in the historical part of this article: it's very important. But the lead paragraphs ought to concentrate on the primary meaning of the word to a modern educated reader. Collins English Dictionary gives:
1. The branch of science concerned with the properties of matter and energy and the relationships between them.
2. Physical properties of behaviour: [eg] the physics of the electron
3. Archaic. Natural science or natural philosophy.
Michael, you say: "Physics" used to mean something different and probably broader, yes. But it isn't just a matter of some single meaning that it used to have, and some other objectively discoverable single meaning that it now has. Yes, SOED, OED, and Collins – and other sources too, no doubt – give the "universal" understanding as historical, or somehow not current. That's why we need to respect the more current, more limited, sense. But that's not the end of the story. The sorts of limitations that physics is subject to are a matter of historical accident and practical convenience, just as the limitation of medicine by the excision of dentistry is a matter of historical accident and practical convenience. There is nothing conceptually fundamental or inevitable about either of these excisions – as limiting physics or medicine. In the case of physics, there will be new areas that are excised, no doubt. Since we have to come up with a definition that is robust enough to give what is conceptually important about physics, and what is immune to historical and practical accident, we need to respect the first definition too. If I am making one central claim, it's that. The debate so far has failed to issue in reasons for our disagreements. I urge you and others to consider this pluralist solution. We ought to be concerned with the place occupied by the science of physics in all of human intellectual endeavour (past, present, future, and merely possible), not just with that part of it falling within its scope according to current fashions in demarcations among the sciences. Beyond all that, as far as much current philosophy is concerned, the original sense of the term physics is indeed the best one to take as primary; and philosophy has a strong claim in this domain of definition and settling of concepts. – Noetica14:35, 14 October 2006 (UTC)[reply]
Thank you Noetica!! Physics is more than what we can currently apply it to: it is also an idea, a concept - one to acquire knowledge (of everything). Michael, I wasn't aware that, "...what we are discussing here is not a definition in that sense at all, it's a description of the way in which the word "Physics" is applied in ordinary English usage." Ahh. Then why call it a definition then? Indeed, in this case, "editors who take issue with you need make no apology for being practically-minded people." Also, I know we can never be wrong with definitions - I have said so on several occasions. I'm not particularly pleased about this situation: I thought it was fairly obvious that under the heading "definition", we would be discussing definitions. As Michael has said, I have tried for too long to convince people that this DEFINITION was useful, and if people can't even grasp that it was a definition then why am I bothering? Krea15:44, 14 October 2006 (UTC)[reply]
Krea, Surely it's been the rule since Samuel Johnson that dictionary definitions (which is essentially what we are talking about here) are descriptive not prescriptive? I imagine we can all agree that the dictionary definition (or description) has varied over the years, and that that neeeds to be reflected in the article. But there is simply no way to specify/define a word or a science in the strict mathematical sense without doing violence to the language. In the mathematical or prescriptive sense you can define physics as anything you wish it to be, but that doesn't make it so. All you've done is to re-define one word as another, as per Humpty Dumpty: "When I use a word ... it means just what I choose it to mean - neither more nor less." There is no "real", "truer", "deeper", "more meaningful", "aesthetic" or whatever sense in current English usage than the practical one which is used day by day. If you want to discuss how we should best integrate historic meanings, fine, but failing that it's pretty clear that we're not going to agree on this.--MichaelMaggs18:08, 14 October 2006 (UTC)[reply]
Show me how physics can predict and describe anything useful about a complex system like a penguin, as biology could. Under "nature" fall both complex systems, and constituent parts like matter and energy. Physics studies the latter. How many physicists are attempting to make physics cover the former also? –MT20:24, 14 October 2006 (UTC)[reply]
Clouds, illustrating an atmosphere with a uniform temperature across the sky at a single altitude, but with temperature which varies with altitude. The clouds have condensed from vapor to water droplet at a precise temperature, uniformly, thus causing a flat-bottomed cloud. The air is not mixing at these altitudes, which we see as a straight line, parallel to the horizon. Thus gravitation is influencing the shape of the flat-bottomed clouds. At other locations in the sky, the clouds are subject to turbulence and mixing. The density of the atmosphere also is varying with altitude, causing a continuum of hue, with deeper blue at the zenith and lighter blue at the horizon (obscured by the trees). The blue color of the sky is due to Rayleigh scattering, which also explains the red color of the sunsets (not shown).
M, I admit physicists haven't gotten very far with complex systems. One thing that we do know is that entropy is maximum in an isolated thermodynamic system, and increases. In contrast, Erwin Schrödinger (1887–1961) pointed out that life depends on a "negative entropy flow"[1]. Ilya Prigogine (1917–2003) stated that other thermodynamic systems which, like life, are also far from equilibrium, can also exhibit stable spatio-temporal structures. Soon afterward, the Belousov-Zhabotinsky reactions[2] were reported, which demonstrate oscillating colors in a chemical solution[3]. These nonequilibrium thermodynamic branches reach a bifurcation point, which is unstable, and another thermodynamic branch becomes stable in its stead[4].
The point is that a physicist will have something to add to the mix just from knowledge of general principles [5] (and physical effects[6] ), which I am attempting to demonstrate by the caption in the image (right). Regarding the image, I am meaning to take a picture from the top of the Niagara escarpment, overlooking the Great Lakes, at sunrise. The scene will commonly show a horizontal line at the elevation of the lake, with a horizontal cloudbank of flat-bottomed clouds stretching across the horizon, obscuring the sunrise. Of course, the horizon appears linear in this case because the curvature of earth is not visible at ground level, but gravitation is influencing the entire scene, which my quick picture today also illustrates. --Ancheta Wis21:18, 14 October 2006 (UTC)[reply]
^Cesare Emiliani (1995), The Scientific Companion: Exploring the Physical World with Facts, Figures and Formulas Second edition ISBN 0-471-13324-8
Michael, you write as follows:
There is no "real", "truer", "deeper", "more meaningful", "aesthetic" or whatever sense in current English usage than the practical one which is used day by day.
I disagree. Sure, people use the term physics in an everyday fashion for everyday purposes. Most of most people's everyday purposes are, of course, immediate and practical. One such purpose is to identify physicists, and their concerns, separately from chemists, biologists, planet scientists, with their various concerns. Fine. Same with medicine and dentistry!
But there is indeed a "deeper" meaning for the term physics, and it too is a current sense because it is perennial sense. A dictionary, since it is adapted for everyday purposes, may reasonably give this deeper meaning less prominence. But any respectable encyclopaedia will treat the matter more comprehensively and philosophically. Consider this from the introductory material in Physics in Encarta (though please don't take this as a general endorsement of Encarta). I add emphasis in bold:
II SCOPE OF PHYSICS
Physics is closely related to the other natural sciences and, in a sense, encompasses them. Chemistry, for example, deals with the interaction of atoms to form molecules; much of modern geology is largely a study of the physics of the Earth and is known as geophysics; and astronomy deals with the physics of the stars and outer space. Even living systems are made up of fundamental particles and, as studied in biophysics and biochemistry, they follow the same types of laws as the simpler particles traditionally studied by a physicist.
And further along in the same article:
Even into the 19th century a physicist was often also a mathematician, philosopher, chemist, biologist, or engineer. Today the field has grown to such an extent that with few exceptions modern physicists have to limit their attention to one or two branches of the science. Once the fundamental aspects of a new field are discovered and understood, they become of interest to engineers and other applied scientists. The 19th-century discoveries in electricity and magnetism, for example, are now the province of electrical and communication engineers; the properties of matter discovered at the beginning of the 20th century have been applied in electronics; and the discoveries of nuclear physics, most of them not yet 40 years old, have passed into the hands of nuclear engineers for applications to peaceful or military uses.
Now, the assertion that I mark in bold here is ill-phrased, and there are problems of logic and expression in the whole passage. But the central message is clear: a physicist was a generalist, and physics was all-encompassing; but because the science had grown more complex, with so many powerful discoveries expanding its horizons, it was a practical necessity that parts of it be taken over by various special sciences. This brings about the everyday sense of the term: physics as the "remnant" of fundamental natural science that is left, after those specialist excisions.
That's part of the story. To show another part, let's take chemistry as an example. It might have some notional claim to being the result of the "first cut" applied to the body of physics. But no: it has for historical reasons always developed separately. To speak approximately but with sufficient truth and relevance, it developed not from a Greek source and through a continuous "Western" route, but along a Middle Eastern path. It therefore acquired its own separate baggage of terms, methods, and concepts. Should this accident of circumstance settle how relations between physics and chemistry are best thought about? No! Just about all chemists and physicists acknowledge that the laws discovered in particle physics and quantum physics ultimately and completely determine the truths of chemistry. In an important sense, chemistry is reducible to physics: and, in another equally important sense, this amounts to chemistry being a part of physics, as Encarta (bless it) allows. Britannica, while general stressing the modern "excised" sense of the term physics, also acknowledges this "nesting" of chemistry within physics. I have only an old hardcopy version to hand right now, but it offers this in the article Nature, Philosophy of, in the section headed Philosophy of Physics:
Inasmuch as the binding forces of chemistry can now, at least in principle, be reduced to the well-known laws of physics, or calculated from quantum mechanics,[...], chemistry can henceforth be considered as a part of physics in theory if not in practice.
"At least in principle". That, if it's accepted, is enough to justify our including in our definition the broad, idealised, and robust conception of physics as the general, all-encompassing science of nature – alongside the more restrictive and practical sense, of course. I have seen no good argument here against having both elements in our definition; and it is most unlikely that there will be any consensus until such ecumenism is accepted. – Noetica00:27, 15 October 2006 (UTC)[reply]
Physics includes those aspects of the other sciences and the things they study that are not unique to them and are not philosophy or mathematics. (Statistics seems to be a minor problem here.) How about "The system of underlying principles of the world" This is general and it implies the interconnections that are so hard for beginners to see. David R. Ingham00:47, 15 October 2006 (UTC)[reply]
Physics can't predict and describe anything useful about a complex system like a penguin, as biology could. Yes, principles of physics can be applied by other sciences, just as math can be applied to them. But physics does not encompass the other sciences. Physics is absolutely useless in describing penguin behaviour, and I'm not talking about "gravity pulls the matter that penguins are composed of downwards". That's why we have biology etc., because physics just doesn't cut it when it comes to complex systems. It's as if some of you think that in understanding physics we'll understand everything. That's like saying that if we understand each word that a book uses, we'll understand the book. Science tries to understand nature. Physics tries to understand the fundamental components; things like matter and energy. –MT06:39, 15 October 2006 (UTC)[reply]
M, I will focus on this sentence of yours: Physics can't predict and describe anything useful about a complex system like a penguin, as biology could. You appear not to have absorbed what I have laid out above. That's not too heinous a crime! But I put it to you that what I have said – in detail and at length – opens up a way forward as we strive for a widely acceptable definition. Let me deal with your sentence in the light of the distinction I want to make.
Physics has two senses, I say. Let's call the physics that is all-encompassing broadphysics. Broadphysics includes all of the special sciences: chemistry, biology, planetary science, etc. And let's call the physics that excludes those special sciences narrowphysics. Narrowphysics is the remnant after specialised areas, mostly dealing with large and complex systems, have been cut away. Now, even if you don't like the distinction I make (and which some encyclopedias tentatively make, as we have seen), you will have to admit that it is an intelligible distinction. OK?
Now I ask you: what do you mean by physics in your sentence?
If you mean broadphysics, then the sentence is plainly in error. Broadphysics includes biology; so if biology predicts and describes facts about penguins, so does physics!
If on the other hand you mean narrowphysics, then the sentence is closer to being acceptable. Narrowphysical notions (like momentum, kinetic energy, electric charge, and so on – to restrict ourselves to classical narrowphysics) will have limited application when we try to give an account of penguins. But so what? Narrowphysics is simply the remnant of theory that is left after biology and the other special sciences are removed, and given subject matter, theoretical resources, and methods of their own. We can all agree!
If you mean neither broadphysics nor narrowphysics, please tell us what you do mean.
Narrowphysics is still strongly connected with the special sciences, of course. We can say that these special sciences are reducible to narrowphysics (however hard or impracticable such a reduction might be). Or we can be more modern, and speak of supervenience. The facts and laws of biology supervene of the facts of narrowphysics; that is say, it is impossible for there to be a change or a difference in the biological state of affairs without some change or difference in the narrowphysical state of affairs. – Noetica07:54, 15 October 2006 (UTC)[reply]
Adding to what Noetica has said, we can indeed define physics in two ways. The first way is defining it to be the study of things, and the second as the set of laws of things (where I will leave what these "things" are dependent on how one chooses to make their definitions). I think that there is disagreement between us, M, because you talk of the former, and we of the latter. If we define physics to be the study of things that we, physically, "know well", then it is naturally restricitive (and arbitrarily so) and it is precisely Noetica's "narrowphysics". We can also define physics, however, as the set of laws of all things that we believe will ultimately come under the scope of physics. This is Noetica's "broadphysics". Some of these laws are unknown to us now, but that doesn't stop us making such a definition.
The "penguin definition" (the one I suggested), as I will now call it, was an attempt at a defintion based on the set of laws of "things". I still do not understand either of your, Michael and M, criticisms of it. When you said "penguins are not physics", you were taking the first sense of the word physics (that it is the study of things) from one definition, and applying it to the alternative sense (that it is a set of laws) from an alternative definition. This is obviously wrong to do. Within each definition, the description is sound (and, if I may go further, correlates well with what people think physics is). Start to mix concepts from different definitions, and you will certainly engender a long and pointless debate! I think that this is what has happened - right? Krea13:47, 15 October 2006 (UTC)[reply]
Yes, we are indeed talking about different things, and if we can perhaps all identify what we mean, and agree how to refer to them, we may be able to move forward. Can I tentatively expand on the broadphysics and narrowphysics concepts and include some others that have also been discussed:
1. The study-based definition/decription
the type of scientific investigations that can be carried out, today, under the banner of the science of that name (based on the way in which the word is used in common English parlance, both by Physicsists themselves and by educated non-specialists).
For example: Physics is the science concerned with the discovery and characterization of the universal laws which govern matter and energy.
2. The rules-based definition/decription
The set of physical laws which many (probably most) physicists believe underpins the fundamental workings of the physical universe, knowledge of which is at present very incomplete but which may in the future become better understood, thereby allowing a broader range of phenomena to be mathematically described.
For example: Physics is the set of univeral laws which define, at the most fundamental level possible, the behaviour of the physical universe.
3. The everything definition/decription
The physical universe itself, being subject to those univeral laws.
4. The historical definition/decription
The older sense of Natural Philosophy.
Probably (but please correct me if I'm wrong), 1. is what Noetica refers to as narrowphysics and 2. is what he refers to as broadphysics.
Now, it seems obvious to me (but others clearly disagree) that a science is properly defined by the type of investigation carried out (definition 1). The physical laws (definition 2) are the output of those investigations, while the universe (definition 3) is their subject. The historical definition 4 appears to be non-contentous.
Are we able at least to agree on these four classes, or something along those lines, and that all are worthy of mention in the article? If so then we are moving along, and we simply (ha ha!) need to agree on how best to elucidate these concepts for the reader. --MichaelMaggs15:04, 15 October 2006 (UTC)[reply]
Progress!!!
1. The study-based definition/description
the type of scientific investigations that can be carried out, today, under the banner of the science of that name (based on the way in which the word is used in common English parlance, both by Physicsists themselves and by educated non-specialists).
For example: Physics is the science concerned with the discovery and characterization of the universal laws which govern matter and energy.
2. The rules-based definition/description
The set of physical laws which many (probably most) physicists believe underpins the fundamental workings of the physical universe, knowledge of which is at present very incomplete but which may in the future become better understood, thereby allowing a broader range of phenomena to be mathematically described.
For example: Physics is the set of univeral laws which define, at the most fundamental level possible, the behaviour of the physical universe.
3. The everything definition/description
The physical universe itself, being subject to those univeral laws.
4. The historical definition/description
The older sense of Natural Philosophy.
[Big sigh of relief] Ahh, the sweet taste of progress! Anyway, yes, I think 1 is "narrowphysics" and 2 is "broadphysics" (but we'd have to ask Noetica to be sure!).
You say that, "physics is properly defined as...". Well, I personally think this is just one's own preference. I regard physics as being defined as 2 and that that leads to 1. But, I can certainly see the case for the alternative view: to which concepts we choose to identify the word physics is a reflection of our own character. For example, my mind thinks that 2 is a "better" definition because 2 is more "fundamental". Such arguments are, of course, complete rubbish. I don't want to go down the road of, "this definition is better than that one because...". A discussion of each definitions shortcomings would be nice though (but where to put this?).
I'm happy with ideas behind 1, 2, and 4, but can I check if I understand the meaning of 3? Does it mean to say that, "one definition of physics is the universe itself (and not of its laws)," or that it is, "the set of all laws (as per definition 2) and the universe itself too"? Krea15:52, 15 October 2006 (UTC)[reply]
Definition 3 was my attempt to reflect what you said above, in this quote: Specifically, if we wish to keep this aesthetic quality, we must admit that everything is physics! Thats not too unreasonable: penguins are physical objects and they do interact via the laws of physics, so, in a way, they could be thought of as being under the bounds of physics (ignoring issues of consciousness - don't ask!). But if you actually meant 2, we could simplify things further and get rid of 3.--MichaelMaggs19:40, 15 October 2006 (UTC)[reply]
I propose striking 3 to preserve a distinction between subject and object. --Ancheta Wis20:03, 15 October 2006 (UTC) Note: Dbuckner has just rewritten the article on Definition. There has been progress on several fronts. 20:09, 15 October 2006 (UTC)[reply]
I meant that quote to fall under definition 2. I think that when the time comes to sort out the details of the definitions, definition 2 will implicitly consume the ideas of definition 3. Anyway, I say strike 3 too. Krea21:22, 15 October 2006 (UTC)[reply]
Yes, I'm for the "narrowphysics" definition. What you call "broadphysics", I call "science". A science is not just a body of knowledge. It's a study. And it surely isn't a set of laws, but a description/understanding/way of discovering those laws. Now, even if this article was about a set of as-yet-unknown laws that governed everything at some underlying point, it would still be improper to say that they govern nature, because most people wouldn't understand what that means. "Nature" brings to mind green forests, singing birds, lions tearing apart zebras, and not... what? "everything"? Even "the natural world" is wrong, because it's not like physics exludes the artificial. Perhaps "Physics is the science concerned with the discovery and characterization of the universal laws which govern stuff that isn't made up"? I can agree with that, but I don't quite support making it the definition. –MT22:58, 15 October 2006 (UTC)[reply]
Of course, the word "nature", or whatever else is used, will also need to be defined clearly (hopefully!). Bear in mind that this is not a popularity contest. You say that you, "...don't quite support making it the definition." Why? Just because you don't like it? That's not good enough. Also, it will not be the definition. It will be one particular definition that a significant number of people "like". If you call definition 2 "science" - good for you. What difference does that make? Indeed, since definition 2 essentially says that everything is physics, then all the sciences are really just subsets of physics - and the only science is physics. Remember, I'm not saying that this view is "correct", it's just a definition that some people subscribe too. Essentially, yes, details will need to be sorted out; and, I don't care if you, or anybody else, don't like any particular definition, unfortunately, because that is not sufficient for its removal. Krea13:19, 16 October 2006 (UTC)[reply]
I "dislike" it because it's not good, or wrong. You seem to be accusing me of randomly throwing my whims about - please stop that. I'm offering what I think are very valid arguments to support my case. My reason for not supporting my definition was that "stuff that isn't made up" isn't very eloquent. | All sciences are not subsets of physics. Just because behaviour in a complex system studied by science X is ultimately caused by the interactions of things studied by physics, this does not mean that science X is a subset of physics. But before we get into that, I disagree that this article is about a set of as-yet-unknown laws that govern everything at some underlying point. It's about the study of those laws. Definition 1, not definition 2. | "Nature"'s connotative associations aren't the only problem, so taking a few sentances of the lead to define nature probably isn't a means to consensus. –MT22:15, 16 October 2006 (UTC)[reply]
Sorry. I don't understand what you mean when you say it is "wrong". It's a definition - how can it be wrong (besides contradictions)? Also, you keep saying that all sciences are not subsets of physics. Just so that we are not arguing pointlessly, can you make that statement as pedantic as possible (defining everything and stating all assumptions as best you can). It's late, and I'm pretty tired, but, doesn't "ultimate cause of" mean that things are subsets of physics? Again, reply to this question as pedantically as possible please. Before all of this, however, you want to discuss this "set of laws" thing: ok. Do you mean to say that physics is only a "study of things...", and not a "set of laws..."; or is it this "not-yet-known laws" business that irks you? Krea23:24, 16 October 2006 (UTC)[reply]
!
