Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The perception of objects

  1. Jul 24, 2007 #1
    What is an object (I will use the term here to signify a coalition of matter and energy)? It seems that most do not contemplate the question; the understanding of what an object is, for most, is subconscious and never comes to the forefront of their minds. A child will point out at an object without the slightest doubt crossing his mind. This having been said, having asked myself the question I found that the definition of what an object is subject to change due to the relativity of things. An object, so do I conclude, is the perception of a foreground on a background; binary logic, if you will. A celestial body is really the perception of a background, empty space, and a foreground, matter and energy. We either perceive existence or nonexistence, 1 or 0.

    Keeping all this in mind, the basis of this logic lies in our senses. We cannot define the background nor the foreground without their use. All information we can gather about the universe has to have an element pertaining to one of our senses. Is it not, then, right to assert that the perception of objects is relative? If we were all crippled from one of our current senses, would every object that we now define as so remain an object? This raises a further question: might an ultimate understanding of the ways of the universe be impossible because science is confined within the framework of our senses?
    Last edited: Jul 24, 2007
  2. jcsd
  3. Jul 24, 2007 #2
    There is a very nice book, "The Evidence of the Senses" by the philosopher David Kelly, 1988, Louisiana State University Press. I think you will find much in common with your thinking in this book.
  4. Jul 27, 2007 #3
    Kant, amongst others, discussed objects in terms of the 'thing-in-itself'. Basically one type of object, for Kant, is the 'unknowable' things that exist and cause our perceptions. Direct knowledge of these 'things' however is impossible, due to the limits of our ability to interact with them, the limits of our human perception. In philosophy this is generally referred to as 'ontology' which is the study of being, or that which exists.

    You could also say that we always 'percieve' the 1, on this basis. Even when we see empty space, it is 'something' to our minds. Here you have switched from a discussion of what is generally referred to as 'objects', to objects of perception. Kant and others talk about this in terms of what is called phenomenology, or peceived things.

    This is why physics and math stump most people. We, our senses, evolved based on a very specific level of interaction with the world. Hard, soft, sharp, hot, bright, dim, etc... Our recent development of higher intelligence has opened up a world of 'internal' perception, that is still quite foreign to us, and that in turn showed us that our 'level' is not the only one that we can interact with. The microscopic and the cosmic levels being the most obvious examples, are quite alien to our evolved senses. Which makes making sense of things on those levels very difficult.

    I would say that this is so, however, I'd question your need for some sort of 'ultimate' anything. Even mathematics is only an abstraction of reality. Its not the thing in itself, but a description. And yet, it can be quite handy, just like our sense of smell when there is a gas leak. If something is described well enough that it allows us to manipulate and do what we want/need with it, then knowing the 'thing in itself' is unnecessary.
    Last edited: Jul 27, 2007
  5. Jul 27, 2007 #4
    Rade, thanks for the recommendation, I'll be sure to examine that book. JoeDawg, you make very interesting points. Could you orient me towards the writings of Kant that your making allusion to?
  6. Jul 27, 2007 #5
    I'm not a huge fan of Kant, mostly because I don't agree with him on a number of things. However, Kant's "Critique of Pure Reason" is really required reading for any serious student of philosophy, not just for the ideas in it, but because so many modern philosophers reference it, either to agree or disagree with him on this or that.

    I'd recommend reading and researching these... and in this order.

    Rene Descartes' "Meditations on First Philosophy"
    David Hume's "An Enquiry Concerning Human Understanding"
    Immanuel Kant's "Critique of Pure Reason"
    Friedrich Nietzsche's "Twilight of the Idols"

    Be aware though that this is not 'easy reading', people spend years studying this stuff, so you might want to read an overview or introduction to their philosophy before you actually start reading the texts. Even check out wikipedia or an encyclopedia of philosophy in order to get your bearings.

  7. Jul 28, 2007 #6
    Some languages do not have the verb "to be", and do not think in terms of objects. Instead, they view reality as a process of constant change where everything is in the process of becoming something else. This is more consistent with modern physics than the concept of objects.

    As physicists like to say, "If it has no properties it does not exist". However, in the case of particles that are also waves the definition of properties becomes somewhat obscured. Therefore about all we can say is objects have demonstrable properties.
  8. Jul 28, 2007 #7


    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor

    Er.. you have somehow misinterpreted the meaning of the word "property" in physics. Having parameters like "wavelength", "charge", "mass", "spin", etc.. are all properties. It has nothing to do with wave or particles. A wave also have properties (i.e. wavelength, amplitude, frequency, velocity, etc). There's nothing "obscure" about these properties.

  9. Jul 28, 2007 #8
    Having both properties at once is what is obscure. Something being both localized and nonlocal at the same time is a paradox which, by definition, is about as obscure as anything ever gets.
  10. Jul 29, 2007 #9


    User Avatar
    Science Advisor
    Gold Member

    In science, the universe has three properties - matter, energy and location. The first two properties are generally not in dispute.
    Last edited: Jul 29, 2007
  11. Jul 29, 2007 #10


    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor

    It doesn't. The "wave-particle" duality is simply an explanation to laymen about the behavior of quantum particles. In QM, there are no duality. All you need to do to confirm this is to open a QM textbook, and you'll never find any formulation of a particle being described by some "particle" equation in one instant, and in the next instant, we switch gears and describe it using some "wave" description. Such a thing doesn't occur in QM. It does, however, occur when we try to describe these things to the general public in terms of what the general public can understand, which are "wavelike" and "particlelike" properties.

    [See, for example, one of the FAQ in the General Physics forum on the issue of wave-particle duality of light


    So no, it isn't obscure. It may be obscure to you, but it isn't obscure as far as how these things are described in physics. As always, one needs to go directly to the source (in this case, actual QM formulation of these things) and not simply rely on popular science description of these things in order to draw a conclusion based on accurate facts.

    Besides, even if something has those characteristics, this qualifies as the PROPERTY of that object. So it is also wrong to say that such an object has no property.

    Last edited: Jul 29, 2007
  12. Aug 1, 2007 #11
    Would it be wrong to say then that x particle only has y property in the presense of an observer? The observer in this case would be like a catalyst for said property. I'm thinking of when a wave function collapses, but I'm not an expert in these things.
  13. Aug 18, 2007 #12
    IMO everything we know and think are based on the properties or things we have seen.
    An apple is round, green, sour, it has a size and so forth.
    None of these things are unique to the apple, and from a certain perspective , even when combined, they do not make an apple.

    An object will always be the sum of its properties, but to humans who have a brain, an object is a whole.
    When you try to describe an object you will always be using properties that all objects have, and these properties are imo the key issue to what consciousness and the brain is capable of.
    I don't want to stray too off topic, but the brain has a very unique way of collecting stimuli and ordering it into objects that make sense.
    But on the other end we can say that the ocean will aways ripple when you throw a rock into it, so the rock and the ocean (and some of its properties like weight, size, material etc) does exist as a whole even with noone perceiving it.

    Hope I understood you correctly.
  14. Aug 19, 2007 #13
    Do not confuse the map with the territory. The mathematics of quantum mechanics are merely a useful description of the reality we observe. In this case, I was referring to the metaphysics that these mathematics imply. If you don't believe quantum mechanics implies serious paradoxes I suggest you check out the Stanford library. Furthermore, I am proud to say that I stand in the company of such greats as Einstein who used the term wave/particle duality not only to explain quantum mechanics to lay people, but also to have discussions with his peers.

  15. Aug 19, 2007 #14


    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor

    But I think you are the one confusing the map with the territory. QM first and foremost is the mathematical formulation. The interpretation is what comes later, and that is what is at issue, even with Einstein!

    And I would also suggest that you go beyond what Einstein has said, because Einstein did not live to see the EPR-type experiments being verified, nor did he live to see all the various other Schrodinger Cat-type experiments being performed and verified.

    The problem with QM has always been that people do not understand and studied the mathematical formalism of it, but still wish to discuss it based only on the philosophical understanding of it. This is similar to discussing the shape of an object simply based on looking at its shadow, and arguing about the apparent paradox of it simply because one is looking at the shadow from different angles, all without actually looking at the actual object itself. In QM, the actual object is the mathematical formalism, which has been shown to work and which has zero dispute even among people who disagree with its interpretation or completeness.

    So really, if you truly think that there is a wave-particle duality in QM, all you need to do is point out to me exactly where we teach that in an undergraduate QM class. Pick up Griffith's QM text, for example, and show me exactly where there is such a thing as a "wave-particle" duality. I'm sure you'll understand why I would not base the actual content of QM from a philosophy paper or discussion. I'd rather look at the object rather than rely on people discussing about the shadow.

  16. Aug 19, 2007 #15


    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor

    I'm not sure if that is necessary the case all the time. For example, we can describe a system by either writing down its Hamiltonian, or solving for its wavefunction. Technically, the wavefunction contains all of the ingredients necessary to describe the system. If you make a measurement, the wavefunction will tell you what you will get, or can get.

    Now one might be tempted to say "Yes, but it is a description on what you will get UPON measurement". So while that may be true, it isn't that simple because in QM, there is such a thing as a "non-commuting observable". A position and momentum observable, for example, are non-commuting observable with respect to each other. If you measure position, the momentum still remains undetermined. This is the source of the uncertainty principle. What this means is that the wavefunction can still remain "uncollapse" for that property even after another property has been measured. Such non-collapsed can, in fact, produce a measured effect which becomes part of the property of the system. In Chemistry, we observe this via the existence of bonding-antibonding bonds. In fact, chemistry is full of quantum mechanical manifestation. Yet, all of these are due to observables that remain uncollapsed and are part of their properties.

    To make a long story short, no, I would not consider a property to only be associated with the presence of an observer.

  17. Aug 19, 2007 #16
    you ask what an object is then define it. Usually in phil. an object is anything that can have properties

    this limits objects to perception, not physical entities that they correspond to. If you use this definition when me and you look at the same table we experience different objects…

    If you are using sense here how I think you are this is false

    I disagree with this too. The existence of at least one entity for example doesn't depend on your senses.
  18. Aug 19, 2007 #17
    Russell’s A critique of philosophy discusses almost his exact ideas too.
  19. Aug 19, 2007 #18
    OK ZZ, I took up your challenge.

    page 374, footnote 1. Enjoy :)
  20. Aug 19, 2007 #19
    also 7th line, page 113 in Principles of Quantum Mechanics, second edition, R. Shankar.
  21. Aug 20, 2007 #20
    Being a physical science, quantum mechanics is first and foremost what we observe. There are more than one mathematical interpretation of what we observe, some of which have different strengths and weaknesses.

    Secondly, I only gave Einstein as an example, there do exist others. Likewise, the epr and other experiments have yet to resolve the particle/wave duality. If someone had resolved this issue it would be the biggest news since Newton's Principia.

    Sigh.... and the problem with physicists who should know better is that they keep arguing philosophical points when it is obvious they know little about philosophy!

    Words only have demonstrable meaning according to their function in a given context. When you start talking about the metaphysics of quantum mechanics you are squarely into philosophical territory. No doubt a book on the mathematics of modern standard theory for budding physicists does not go into the metaphysics behind the subject. Physics is not philosophy.

    Again, mathematics is just another language. Show me the evidence, not more words.
    Last edited: Aug 20, 2007
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook