what's the exact definition of "matter"

[gib65]

I'm having this debate on another forum. I'm trying to argue that the atom is the fundamental building block of matter, and therefore when you break an atom down into its particles, what you get is not necessarily matter. Take hydrogen for example: when you break hydrogen down, each atom becomes an electron and a proton. At the macroscopic level, electrons are seen as electricity, and protons are seen as proton beams (or some kind of proton plasma). In either case, what you have is not matter.

 

However, the person I'm debating with defines matter as "that which has mass and occupies space". He goes on to say:

 

"Matter is the substance of which a physical object is composed. In physics, it is everything that is constituted of elementary fermions. All gauge bosons (of which the photon is one), which mediate the four fundamental forces, are thus not considered matter, even though they certainly have energy and some also mass."

 

So this sounds like the technical definition that physics gives it (but I'm not sure - he might be pulling this out of his ***).

 

What's the consensus on this within the scientific community? Are electrons and protons examples of fermions or bosons? If a fundamental particle is considered matter by the standard definition that physics gives it, does this mean that we aught to think of it as some kind of hard, solid ball?

[timo]

"Matter is the substance of which a physical object is composed. In physics, it is everything that is constituted of elementary fermions. All gauge bosons (of which the photon is one), which mediate the four fundamental forces, are thus not considered matter, even though they certainly have energy and some also mass."

That would pretty much fit my usage of the term, although I´ve never bothered about a strict definition. The elementary fermions are the quarks (up,down,strange,charm,top,bottom) and the leptons (electron, tau, myon and their respective neutrinos).

 

Are electrons and protons examples of fermions or bosons?

Fermion, actually. But notice that protons are no elementary fermions since they consist of quarks and gluons (and would still be matter by above definition).

 

If a fundamental particle is considered matter by the standard definition that physics gives it, does this mean that we aught to think of it as some kind of hard, solid ball?

Might depend on the framework you´re working in and what you´re currently calculating. For the framework of the standard model where the definition of the elementary particles stems from the answer is no.

[KaiduOrkhon]

Not large on the fermions, bosons, gluons, tachyeons, musons or leprechauns, etceterayeons, Copenhagen entanglement, foam, dark matter, slits, shotgun pellets, blitz, waves, staves and perhaps too many pinkly smoking barrels of philological raves. I'm sure these emergences of energy need nomenclature; just not so sure about the flocking flippancy.

 

The most enduring definition known to these old fashioned parameters is:

 

"Matter is that which occupies three or more dimensions of space-time; disallows the simultaneous occupation of it's space by any 'thing' else, and, opposes a resistance to non uniform motion" - meaning, if it's matter, it's gotta have negative and positive inertia.

 

Not sure, but it sounds like in your concept of matter stops being that once it's no longer an element, and after it's reduced to what elements are made up of, which is of course, sub-atomic, so called 'particles'.. 'So called', because until further notice, all the particle slingers are projecting is charges of electricity having no distinct boundaries. Electrons, protons, and even neutrons - all charges, positive, negative or neutral.

 

The billiard ball concept is rotated completely off the slate as far as I know.

The 'charge of electricity' fulfills the above definition, even when it's an electron or proton. I dunno about the rest of that stuff. The electrical charge is without a discontinuous surface defining it's seperation from surrounding space. The surfaceless charge just gets more dense as you approach it's center. Short of fission, it doesn't look like the center of any of the sub-atomic particles is getting reached, if it's getting got to at all. It looks like the center of a sub atomic charge is as challenging to reach, as is the outside parameters of the macrocosmic universe (Is finite <in space>, but unbounded <in time> - Einstein) Fission after all being the 'splitting of atoms', not necessarily the splitting of subatomic particles. Then you got Planck's constant h - photons.

It sounds like, so far, distinguishing matter from mass. I always gathered they were inseperable.

Hope this helps some. Interesting - thought provoking -interrogatory.

Think I'll just listen as more cogent information may be (ahem) fielded here, before the next atomic or sub atomic inning. A TOTAL FIELD THEORY guy, here.

- That Rascal Poof, Aka Kaiduorkhon

"If it moves, it is." - Einstein

('There is no space empty of field' - Ibid)

[Locrian]

I'd have to agree with you Gib65, while at the same time using his definition of matter. To me, two particles that have mass but are best described by wavefunctions don't "occupy space" in the traditional sense. They don't have positions, they have probability distributions that describes the chance of them being measured somewhere.

 

I see matter as emerging from the condensation of multiple particles. It may still only be made up of fermions, but, in short, the whole is more (or at least different) than the sum of its parts.

[Severian]

It is a matter (no pun intended) of definition. We call certain fundamental particles 'matter' and others not. As Atheist said the fundamental quarks and leptons are the matter while the gauge bosons were not.

 

Historically this came about because the photon is its own antiparticle, so when you have a reaction like [math]\gamma \to e^+e^-[/math] this definition of matter allows us to say that 'matter is conserved'. It would be better to say 'fermion number is conserved'.

 

This historic reasoning breaks down though as we include more forces. The gluon is the strong force analogue to the photon, but since the gluon has color it is not its own antiparticle (a [math]R\bar G[/math] gluon is not the same as a [math]\bar R G[/math] one). Nevertheless we still regard it as not-matter to allow us to say 'matter' and 'anti-matter' rather than 'fermion' and 'anti-fermion'.

[Locrian]

It is a matter (no pun intended) of definition.

 

This is undoubtedly true! Of course I don't think it helps much, because now we can just ask the question - which definition makes the most sense?

 

If you asked someone for water you wouldn't accept steam. Despite the fact that they have the same constituents, they have different properties and the fact that they are interchangable doesn't relieve us from having different names for each.

 

Physicists who deal with subatomic particles on a regular basis may find the term "fermion" and "matter" pretty close to interchangable, but for most people, including many physicists, subatomic particles simply lack the characteristics we generally associate with matter. It is still my opinion that if we want to be clear with what we mean, matter refers to something more than the parts it is made of.

[Severian]

In that case you need to ask someone who is not a particle physicist. Atheist and I both are, so we will give you the particle physicist answer.

[swansont]

I'd have to agree with you Gib65' date=' while at the same time using his definition of matter. To me, two particles that have mass but are best described by wavefunctions don't "occupy space" in the traditional sense. They don't have positions, they have probability distributions that describes the chance of them being measured somewhere.

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That's true of all particles, though. Atoms and molecules have been made to interfere, so there really isn't any doubt that they are described by a wave function.