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What is matter?

  1. Nov 21, 2011 #1
    About 40 years ago when I was 15 my science teacher would occasionally collar me in the hallway and bellow, "What is matter".

    Now, I have a pretty good laypersons grasp of atomic structure and particle physics, yet when I ponder the question, I find I still cannot really answer the question in any meaningful way, and I suspect that neither can anyone else. Prove me wrong.

    What I mean is that when the lay person thinks of atoms they imagine some tiny little hard round billiard ball like object because matter seems to be made of solid stuff. But the cognoscenti understand that it is merely electric repulsion and the exclusion principle which gives an appearance of solidity.

    Yet still there is this stuff all around me and the question remains, what precisely is it. The protons seem to be where all the real action is with regards to mass, but even mass is a bit mysterious, apparently no one really knows what mass is other than the effect it has.

    And the proton is really just a trio of quarks which are confined in a tiny space. And the quarks themselves do not have much mass, and 'stuff' doesn't seem to be 'mass', so matter isn't really mass. So we are back to 'what is matter'. Well what is a quark, is it anything other than it's effect on the universe. It can be measured, sure, but what precisely is it.

    I've heard particles described as nothing more than a disturbance in a field, a field of what? Is the field then matter? Heisenberg wanted to do away completely with any notion of trying to visualise particles. So is matter just a mathematical concept?

    It seems that if it's not a hard little ball of something then it's just some sort of a concept in someone's mind, but if that is the case what is all this stuff I see around me? That's not a concept, or is it.

    So this is where I now am, 40 years later still wondering about the question, 'what is matter'.
  2. jcsd
  3. Nov 21, 2011 #2

    Simon Bridge

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    You are pretty much correct - what you call matter so far tends to depend on how you look at it. It is what you get when you have a very short wavelength wave-packet - for example. Remember that matter and energy are the same thing - so you can equally ask " what is energy?"

    But if you think about it - it is really hard just to phrase the question in any sensible way.

    There are a bunch of theories about it.
    Basically matter is that stuff that has mass and volume ... mainly it is the mass that is the problem. The current favored theory involves the Higgs boson - a kind of symmetrical thing where mass gives rise to itself. This is why there is all this interest in finding the thing.

    Note: technically everything is a concept in someone's mind. This is a position called phenominalism. Scientists work from a position of empirical realism - usually.

    There is an old refrain:
    What is matter? Never mind.
    But what is mind? Doesn't matter.
  4. Nov 21, 2011 #3
    Hi, I suppose that question is better discussed in the realm of psychology. What is this "what is"? In fact what are we exactly looking for, when we ask this type of question? Let me draw an analogy, (who is that person?). Here we are looking for an answer to match something already known to our mind; for example "He is the head of such office." I have not been told much if I don't have the image of a "head" or an "office" in my mind. The same goes for "what". If you reduce the nature of an object to something tangible, you are, in fact, looking for the corresponding prototype (image) of it, you have in your mind. And you cannot go further than that, because that just doesn't make sense. You might be able to see a wooden cube in the shape of the atoms that make up the cube, but still, you are trying to make an image of it which you already have in your mind. You can translate "what is it made up of?" into "which one of the concepts that I have already known is the basic constituent of it?" Matter is one of the basic concepts of our mind: hardly reducible to anything more tangible.
  5. Nov 21, 2011 #4
    Same with everything is physics. And, knowing the effect it has is pretty much just as good as knowing what it is. You might say: it is what it does.
  6. Nov 21, 2011 #5


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    Wise words. Worth repeating.

    We have a lot of questions here about whether things are "real". Especially things like electrons. "If, whenever we touch a wooden table, we are only touching the EM repulsive field, is anything really real?" "If an electron is a fuzzy ball of force, is it real?" etc.
  7. Nov 21, 2011 #6


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    Matter is consists of two fundamental particles; quarks and leptons. Quarks are afflicted with severe separation anxiety, hence, are always found in multiples, never alone. They are the building blocks for baryons and mesons. Leptons have no constituent particles. They include the electron, muon, tau and 3 flavors of neutrinos.
  8. Nov 22, 2011 #7
    I think questions like this may result from being told field lines "aren't real". If field lines "aren't real" can the fields themselves be called real? I've mentioned field lines and flux lines here sometimes only to have people jump down my throat and say not to take those lines seriously because they "aren't real". One guy said "A magnetic field is just a series of measurements." Which is kind of a pointless thing to say, because so is a brick. In science, everything is handled as a series of measurements. That fact says nothing about their reality. You set people up for a lot of cognitive dissonance when you introduce a concept while simultaneously asserting it doesn't represent anything real.
  9. Nov 22, 2011 #8


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    The most common definition is that matter is something which has mass and occupies volume. In the standard model this translates into matter is something composed of fermions.

  10. Nov 22, 2011 #9
    Posts like 6 and 8 capture the best we have. And that doesn't refute your premise.

    When one considers observational results such as the double slit experiment we begin
    to see that in many respects the quantum world, the world of the small, is 'illogical' based on macroscopic world perceptions. Even the 'craziest' aspects of quantum theory, like entanglement [ "spooky action at a distance" ] have been experimentally verified to the satisfaction of most physiscts

    But other things are equally "illusory" ..Is spacetime "something"? Is it continuous or
    discrete? How can the speed of light be fixed while space and time are NOT? And the worst question of all "Is that REAL."
  11. Nov 22, 2011 #10
    I don't like to accept statements like that because it takes science off the hook.

    For example I just completed successful cataract operations on both eyes. The effects of cataracts can been seen (cloudy lenses) and deterioriaitng vision. Science has developed artificial lenses to replace them, anesthetic drops to prevent pain during surgery, antiseptic eyedrops to combat infections and steroid drops to reduce the chances of inflamation during healing and even the ultasonic medial equipment used to shatter the old lense into tiny pieces for easy removal before placing the implants. Even the image magnification equipment and TV monitor which enables the surgeon to see what he is doing.

    NONE OF THIS IS AS GOOD AS KNOWING 'WHAT IT IS'.... Nobody knows the cause and therefore nobody knows how to prevent cataracts....

    I just glad we have learned as much as we have. Alzheimer's patients are not so lucky.
    Last edited: Nov 22, 2011
  12. Nov 22, 2011 #11
    I'm sorry about your cataracts, of course, and the frustration you must feel.

    What I was addressing in my post is the cognitive dissonance a particular kind of question creates. The OP has been stuck in this cognitive dissonance for years, apparently. The parameters of the question his teacher kept asking were incredibly vague but the question was pounded in to him as if there was a specific sort of meta answer he should seek. What in hell was that teacher really asking for? Would posts 6 and 8 have satisfied him? I don't think so.

    My answer is the best answer in the context of the Opening Post because, yes, it lets science off the hook, the hook of having to be "meaningful" in some philosophical/ontological way. Physics isn't directly looking for what things are, it studies what things do. Definitions of terms are often mere stipulations to help get traction in analyzing things. Definitions allow everyone to remain on the same page.

    My answer does not let medical science off the hook for not having discovered the cause of cataracts. To the extent knowing the cause may lead to prevention those researchers are still very much on the hook of finding out what it is. (With the caveat, though, that knowing the cause might not lead to being able to prevent them.)
  13. Nov 22, 2011 #12


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    I think it does refute the premise that we don't know what matter is. When you ask the question "what is X", the answer is known as the definition of X. That is, in fact, the whole point of having definitions. So the question "what is matter" is fully and completely answered by providing the definition of matter.

    There are many terms which do not have a scientific definition, but "matter" is not one of them.
    Last edited: Nov 22, 2011
  14. Nov 22, 2011 #13


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    Nothing is matter. What is matter with you?
  15. Nov 22, 2011 #14

    Simon Bridge

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    We do have to be careful about the distinction between something we made up as an aid to computation and something that exists in nature.

    You cannot observe field lines. They are not something that you measure. They are an imaginary guide to something you can measure.

    Where it gets vague is when the imaginary aide to our computations turn out to be real measurable objects ... eg. in the sum over many paths (Feynman integral) for reflection of photons at a surface works even though we know the photons do not bounce off a smooth "surface" ... and, the paths for which the angle of incidence is not equal to the angle of reflection can easily be demonstrated to actually contribute to the resulting reflection. This despite that even Feynman describes this process as a rule to get a prediction, making no claims about the "reality" of the picture it paints.

    I don't think anyone has detected a force-mediator in the act of mediating a force - but the actual particles have been produced in high energy collisions and detected by the interaction they mediate. So are they real?

    You'll notice that terms like "matter" and "reality" tend not to be used much at this end of physics ... they don't seem to be very helpful. We talk about "observable" and "measurable" and so on, instead.

    But just look at this discussion ... this is what I was talking about when I said:
    You'll find as many positions on this as there are philosophies ... suggesting that we are asking the question wrong. In practice everyone ends up working with: something is what it does. Like the guy said.

    I should point out that knowing what cataracts are to the extent of being able to prevent them means knowing what they do to a finer degree than now. You need to know the mechanism for how they form and develop. Because that is also part of what they do.

    And, finally, is a definition the same as knowledge?

    The word "matter" is a handy label for a bunch of phenomena - so we can talk about it - but is naming it the same as knowing what it is?

    Consider - you know my name... but do you know me? Clearly naming me is not the same as knowing me ... but after a while you can get to know me, and you prove this by anticipating my actions under different circumstances - you hear of me doing something surprising and say, "that does not sound like him!" When you can do that confidently then we say that you know me.

    You may not know all about me and will get things wrong occasionally - I may still surprise you. But notice - for all intents and purposes, you can demonstrate you know me only to the extent that you know how I behave. In this sense, I am how I behave.

    I like to think there is more to me than that - but maybe that is just a conceit? Bottom line: it is what I can demonstrate that counts. The other way leads to pseudoscience and woo.

    To be is to do.
    -- Socrates

    To do is to be.
    -- Sartre

    Do be do be do.
    -- Sinatra

    (Naturally someone will disagree - isn't this fun?)
  16. Nov 22, 2011 #15
    You want a "cause." This, to me, implies that you seek a "why" explanation for matter's properties. Such an explanation likely is beyond the realm of empirical science to fully answer.
  17. Nov 22, 2011 #16
    I have always thought of physics as trying to find out, what everything in it self is. While we might never know, we can always get closer and closer to the reality, and how do you even defy reality, what is real. Everything and nothing is real it is only a concept made by humans. Even our dreams could be concidered reality for ****s sake. If something exists it is real period. So we got that clear, matter is REAL, otherwise it wouldn't exist. What matter is is simply energy. Matter/energy is existence.
  18. Nov 22, 2011 #17
    It's all based on the great axiom of life:

    If there is a question a smart person doesn't know the answer to...

    There shall be an answer that cleverly dodges the question.

    *shakes* Looks like: "Ask again later."
  19. Nov 22, 2011 #18
    I don't understand everybody saying we can't know, we can easily find a defenition to what matter in itself is, it is energy, defining energy is a whole other story. Why is everybody here saying stuff like ''we will never know'' ''it is only a concept'' and comparing it to human concepts that only exist in our brain, media. Think about it if you say X is the definition of X and I am my name, You can't say that to real life things. It would be like saying matter is matter, well it is, but it doesn't answer the question. We want to find out what in space-time causes forces and mass, and how it does it. It may seem impossible But if we find the answers to these questions, we will ultimately know the answer. Stop retreating upon human conceptsss you can't compare existence itself to the things it creates.
  20. Nov 22, 2011 #19
    THIS, everybody is answering with questions. That don't even relate.
  21. Nov 22, 2011 #20


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    Jarfi, despite popular media, matter is not energy. Furthermore the OP's question isn't about what our definition of matter is, he is asking a common question that most people don't realize is hard to answer. When I ask you what X is, and you give the definition of X, I can ask "Ok, but what is it really?". Asking what something "really is" isn't a good question. It ignores what we know and asks about things we don't know and may not even be able to know.

    Also, when you look into quantum mechanics and other related theories, we actually don't know what to call matter for sure. We don't even know if we are asking the right questions. Is matter a particle? Is it a wave? Is it both? Is it just energy or a field? What if it's none of the above? Then all our questions were meaningless because they simply weren't asking the right thing. Your statement "If something exists then it is real" ignores the fact that we can't always tell the difference between what exists and an effect that doesn't exist but is the product of something else that actually exists. Of course that entire statement depends highly on what you mean by "existence", which it in itself is far more complicated.
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