Talk:Matter (chemistry)

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Beginning an article on 'matter', from a general chemistry point of view. Anthony.Sebastian 23:01, 10 January 2010 (UTC)

Thing

As for me, the "thing" section is a too long digression from chemistry. Surely the natural language cannot support a "mathematics-like" tree of definitions (see for instance Theory (mathematics)#Defined or undefined), but this is not a matter of "Matter"... Boris Tsirelson 20:03, 13 November 2010 (UTC)

Hi, Boris. Terrific article you directed me to. I keyed on:

"In the axiomatic approach, notions are a tower of defined notions, grounded on the basis of more fundamental notions called undefined primitives. If all defined notions are forgotten they surely can be restored from the undefined primitives. The undefined primitives are sparse and simple, not to be forgotten...The lack of definition of a primitive notion does not mean lack of any information about this notion. Axioms provide such information, to be used in proofs. Informal (intuitive) understanding of a primitive notion is communicated in a natural language. This information cannot be used in proofs, but is instrumental when guessing what to prove, how to prove, how to apply proved theorems and, last but not least, what to postulate by axioms."

As I see it, semantic and the undefined primitives correspond quite well. And, yes, natural language it appears can support a "tree of definitions", grounded on about 60 semantic primitives. It would be interesting to learn about the cognitive origins of mathematical axioms and semantic primes. See Semantic primes, especially the references cited. The semanticists cited give many examples of words defined solely in terms of the semantic primitives.

As for the 'Thing' section, I'm struck by how commonly chemists use 'thing' in defining matter, always taking 'thing' as an undefined primitive. I feel the section is not so much a digression from chemistry as laying a foundation for understanding how chemists perhaps non-consciously define matter, the central concern of chemistry. I will give this more thought, in view of your calling my attention to the undefined primitives of mathematics. Anthony.Sebastian 00:36, 14 November 2010 (UTC)

Hi Antony. I have read "Semantic primes" with a keen interest. This is a good example of the interdisciplinary exchange stimulated by CZ. I also inserted a link to "Semantic primes" into "Theory". However, I am skeptical about a mathematics-like backbone of natural language(s). It seems to me that the transition from the primitive notions to a "derived" notion involves some amount of the same non-verbal understanding that is the source of the primitives. Thus, "derived" notions are only partly derived, and partly primitive. (Well, some notions are 99% derived and only 1% primitive; but some are 70% derived, I guess.) You see (from my experiment with Google...) that the notion "line", when defined by a non-mathematician, is far from 100% derived. Boris Tsirelson 07:57, 14 November 2010 (UTC)

P.S. Hope your "terrific" means more "marvelous" than "terrifying" :-) Boris Tsirelson 08:02, 14 November 2010 (UTC)

Anthony, I have to side with Boris' comment at the begin of this section. A user who wants to learn of the chemist's notion of matter will not be interested in a (phislosophical, semantical) discussion of "thing", or -- I want to add -- in the physicist's notion of mass. Moreover, it will not help him to understand chemistry, rather puzzle him. --Peter Schmitt 12:00, 14 November 2010 (UTC)

Peter, regarding 'mass', I confess I wrote the way I did primarily as a learning exercise for myself, trying to explain to myself in a pedagogically clear way the concept(s) of mass. Basically I wrote it to learn, and, after much editing to render the concept as clear to myself as I could, I thought others struggling with the concept might find it rewarding. CZ's article, Mass I found hard to follow—my deficiency, not the article's. But I take your point. I will give it a careful look and consider abbreviating it, perhaps moving the longer version for the Addendum subpage for those who might want a fuller explanation.

Regarding your argument that a "user who wants to learn of the chemist's notion of matter will not be interested in a (phislosophical, semantical) discussion of "thing"", I would try to argue that a user who wants to know the chemist's notion of matter must know that the meaning of 'matter' rests on a word/concept that humans universally come learn as a semantic primitive, a word/concept indefinable non-circularly in other words, regardless of what language they speak and think in. Matter for chemists is any thing that occupies space and has mass. So then, that begs the question, what does the chemist mean by 'thing'? Why, things are what matter makes up, of course. Then what does the chemist mean by 'matter', the perceptive but confused reader asks? What answer should we give?

We have to build on a solid foundation. The meaning of every word/concept rests on the foundation of socioculturally-based intuitive non-verbal knowledge of the meaning of a small number, about 60, of primitive words/concepts. 'Matter' rests on 'thing', I should like to argue, and only because you know 'thing' without having to define it, can you truly understand the chemist's notion of matter. Of course everyone knows what things are, so they can readily understand matter as any thing with the properties we assert, but does everyone know that they now understand matter as any thing with those asserted properties because they intuitively know what things are? Voltaire, I believe, would ask for a definition of terms, and we would have to tell him that he knows what chose means, or if he speaks to us in German, Sache. (Please forgive me; sometimes I do go on.) Anthony.Sebastian 04:33, 15 November 2010 (UTC)

I doubt that philosophical digressions are very helpful in deciding what is Matter and what is not. Better, let us inform the reader (and decide to ourselves) some boundary cases: (a) electromagnetic radiation (for instance, just Sun light), is it Matter? (b) neutrinos (for instance, just Sun neutrinos), are they Matter? (c) Plasma, is it Matter? Boris Tsirelson 06:57, 15 November 2010 (UTC)

[unindent] Good idea, boundaries, Boris. Photons, zero rest mass. Lots of photochemistry, impacts on matter. Neutrinos, matter for sure, mass a tiny fraction of electron mass, exact value unknown. Relation of neutrinos to chemistry? One might disturb a chemical reaction every bazillion years. Don't know about plasma; need to study more. Your thoughts? BTW: what counts as a philosophical digression. Scientists don't digress when they must do philosophy of science. Only scientists qualified to do philosophy of science, according to Hawking and Mlodinow, then only when necessary. We're scientists, aren't we? Article not about Matter, about Matter (chemistry). Anthony.Sebastian 08:15, 15 November 2010 (UTC)

Zero rest mass, or very small rest mass (it was even doubt in physics whether it is zero or not), is it really important for chemistry? And why only the rest mass counts? "photochemistry, impacts on matter" — ah, in fact you (subconsciously?) treat light as not a matter!

Really, I think, chemistry is about chemical reactions (rather than a much wider class of physical interactions). A chemical reaction can be only between atoms and/or molecules. Many other things (!) can influence. For example, the temperature; but of course it is not a matter. A light can influence; but does it mean that it is a matter? The same for neutrino (though of course its influence is extremely small, at least on the Earth).

Thus maybe it is better to say that for chemistry matter is atoms and molecules (including ions, of course) with a reservation that the physical notion of matter is wider, and that any physical-but-not-chemical matter can influence chemical reactions, but not participate in them; and physical conditions, being surely not any matter, also can influence. Boris Tsirelson 08:31, 15 November 2010 (UTC)

About the light... not really relevant, just by the way... I recall something interesting and not widely known: the light has a rest mass!! Surely you can find a lot of quotes saying the opposite. However I did read somewhere (in a physical paper) that in quantum electrodynamics, a photon is always accompanied by a cloud of virtual particles, mostly electrons and positrons (but do not take these words literally: words never describe correctly quantum effects, only formulas can), which is a very-very small but nonzero addition to its mass; and for that reason the speed of light in vacuum is not c, it is less (by a very-very small amount). True, c is mostly called "the speed of light in vacuum", but this is a bit incorrect; c is rather the constant that appears in Lorentz transformations, and the upper limit to the speed of any signaling. Boris Tsirelson 09:12, 15 November 2010 (UTC)

Boris and Peter: I abbreviated the sections 'Thing' and 'Mass' in the Main Article, moving deleted text to a footnote for the former section, to the Addendum subage for the latter. Thanks for your interest and input. I would hope those changes remove your objections about distracting readers with, arguably, content that would not interest them. If you are right, the reader can bypass that information in their out-of-the-way new homes, but if some readers have less satiable curiousity, they can still access the information they need. Anthony.Sebastian 17:53, 15 November 2010 (UTC)

I see; it is better than before. Boris Tsirelson 20:43, 15 November 2010 (UTC)

Do photons have mass?

Boris: Some interesting links, made my head swim:

• What is the mass of a photon?.

• Does the photon have mass?.

• Photon mass.

• Proton-Mass Bound Destroyed by Vortices. | The possibility of a nonzero photon mass remains one of the most important issues in physics, as it would shed light on fundamental questions such as charge conservation, charge quantization, the possibility of charged black holes and magnetic monopoles, etc.

• the "Mass" of the Photon.

Anthony.Sebastian 03:36, 16 November 2010 (UTC)

Well, this is an interesting... what? physics, not chemistry.

Fortunately or unfortunately, I am not a chemist, nor a physicist; thus I am not entitled to draw the border between chemistry and physics. However, all this exchange about mass only convinces me that the problem, what is mass, and what has mass, is deeply physical, far not chemical. The same can be said about the problem, what is space and what does it mean, to occupy space. And therefore the definition that says "occupies space and has mass", be it apt or not, is anyway inappropriate for chemistry. For "matter (physics)" — maybe; for "matter (chemistry)" — not at all.

Naively or not, I still believe that chemistry is about regrouping atoms in molecules. Thus, atoms and molecules are directly relevant; and everything else is indirectly relevant as far as it influences the process of regrouping atoms in molecules. Accordingly, the relevance of the photon mass (if any) to chemistry is as small as this very mass is. The relevance of space occupation is also tiny.

Boris Tsirelson 17:58, 16 November 2010 (UTC)

Ah, Boris, now you philosophize. I can assure of one fact, from the practicing and teaching chemists' point of view, matter is anything that occupies space (has extension, or volume), as conventionally understood (derived from the SI base unit, the metre), and has mass (SI base unit, kilogram). What you say, "...chemistry is about is about regrouping of atoms in molecules", is certainly correct, as stated, but that is not all it's about.

Regarding, "...the relevance of the photon mass (if any) to chemistry is as small as this very mass is", I would not want to dispute, and our article Matter (chemistry) makes no point about photons, and as far as my thinking goes in contributing to the article, I hadn't given much thought to photons until you raised the issue. Nevertheless, photons do play a prominent role in chemistry, where the dividing line between chemistry and physics becomes a merging lane, as in, for example, photosynthesis.

Anyway, we have come a long way from the interesting issue of mathematical and semantic primitives. Here's a question: can you teach/explain/learn/invent mathematics without natural language meaningful words? —Anthony.Sebastian 02:23, 17 November 2010 (UTC)

But you already know my answer: "Informal (intuitive) understanding of a primitive notion is communicated in a natural language. This information cannot be used in proofs, but is instrumental when guessing what to prove, how to prove, how to apply proved theorems and, last but not least, what to postulate by axioms." And moreover, early stages of explaining math to children always involve non-verbal communication, too. Boris Tsirelson 07:04, 17 November 2010 (UTC)

An example of a "being" that learns math with no natural language can be found in Proof assistant#A robot as a student. And indeed, this "being" is very dull!

But if we discuss something not related to "matter (chemistry)" then we'd better move to another place. Boris Tsirelson 09:15, 17 November 2010 (UTC)