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Quantum particle empirical status

  1. Aug 11, 2008 #1

    I have some basic (naive, ignorant) questions regarding the empirical nature of quantum particles. That is, in what way(s) are quantum particles empirically verifiable?

    To better demonstrate my question, it might be easier to pose it as a hypothetical scenario.

    When I look at my finger with my 'naked eyes', I see a macroscopic object: my finger has a certain spatial location, shape, colour, etc. Now suppose I get hold of a futuristic microscope that enables me to examine macroscopic objects (such as my finger) at microscopic levels. I put my finger under the microscope, tweak the magnification knob, and am able to see some cells. These cells are concrete objects, in that they are directly (via the microscope) observable entities.

    I crank the magnification up again, and am able to see the nucleus of the cell, ribosomes, mitochondria, etc. Again, these parts of the cell are concrete objects, in that they are directly (via the microscope) observable entities.

    Now, if I focus the microscope on, say, the nucleus of the cell, and crank the magnification up, will I eventually be able to see atomic/subatomic particles? Again, the microscope is a hypothetical futuristic device that has infinite magnification.

    Is this last act of magnification utterly nonsensical? Are subatomic particles not concrete, directly observable (via microscopes) entities in the way cells/cell nuclei are?

    If not, in what way are atomic/subatomic particles observable? By inference? I mean here that yes they are actual entities, but only their effects are measurable (we can infer the particles existence due to certain effects it has, and these effects are observable/measurable)? Or are they abstract entities, in the way genes are abstract 'theoretical' entities?

    Cheers for any help.
  2. jcsd
  3. Aug 12, 2008 #2


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    Your microscope will be limited by the uncertainty principle. I would say that subatomic particles are concrete, directly observable entities, but that conclusion depends on the precise meaning of "concrete", "directly", "observable", and "entities".
  4. Aug 12, 2008 #3
    You never really see atoms, you see the photons that bounce off them which are particles themselves. If you could see an atom depsite that, the electrons would look like layers of cloudy shells because they move around the atom at a blinding speed in a random pattern. The nucleas would be an extremely small dot within those shell layers.

    The existance of those particles is known through numerous verifiable experiments, things like nuclear fission and nuclear bombs are very real and weren't discovered by accident but through understanding what atoms are.
  5. Aug 13, 2008 #4
    Okay. That was what I was wondering: the atomic particle's existence is inferred based on the kind of observable effects it has on other observable particles (photons). In other words, the atom itself cannot be seen, but it is known to exist because it has certain observable effects (and it can be affected itself, as you point out below).

    Yes; I wasnt suggesting that atomic/subatomic particles were fiction. I appreciate they can be measured and 'manipulated'. My questions are purely from a (naive) philosopher's perspective.

    Last edited: Aug 13, 2008
  6. Aug 13, 2008 #5
    My definition of 'concrete' would, at least as a starting position, be that of a naive realist: a visual object that can be touched. Of course, I understand that this becomes impractical when we are dealing with microscopic entities. But where subcellular entities can be directly seen (via microscopes) and 'poked and prodded', can the same be said, at least hypothetically, of subatomic particles? Put another way, how are quantum particles 'manipulated' or 'interfered with'?

    By 'directly seen', I mean without any kind of spatial-altering device. The only way I think I can illustrate this is by analogy: seeing a shadow is different to seeing that which casts the shadow. If I could only see the shadow of something, then whilst I directly see the shadow, I do not directly see the thing which is casting the shadow. This is a 'spatial' issue: the shadow exists there, but that which casts the shadow exists over there. Or, a reflection of the moon is in a different place than the moon itself: to directly see the moon would not be to look at the water.

    When I look through the microscope at a cell, the magnified image is still consistent with the cells actual spatial location (I presume!), and so in that sense I am directly seeing the cell. However, if the only means of observing quantum particles necessarily involves representations that are generated via computer monitors and the like, then this would not be seeing the particle's directly (the particle itself is at spatial location 'X', and the observed image that corresponds with the particle is at spatial location 'Y').

  7. Aug 13, 2008 #6
    objective existance imply ditinguishability

    The formulation of quantum theory does not comply with the notion of objective existence of elementary particles. Objective existence independent of observation implies the distinguishability of elementary particles. In other words: If elementary particles have an objective existence independent of observations, then they are distinguishable. Or if elementary particles are indistinguishable then matter cannot have existence independent of our observation.

  8. Aug 13, 2008 #7
    Don't forget about particle accelerators; they "smash" atoms and then are somehow able to observe the ementary particles that go flying off in every direction.
  9. Aug 13, 2008 #8
    There seems, im my view, an unsurmountable boundary between matter and mind. We don't know, if only through logic, whether what we observe are just what they are. We invent concepts to comb our experience. However, the key is whether the system of concepts works to the purpose.

    So, in this sense, it's hard to say the way we see our fingers is essentially different from the way we see atoms. We could touch atoms by, for example STM (scanned tunneling machine). In fact, we could even manipulate these atoms via STM. Obviously, touch is not tantamount to zero separation in physics.

    Why we believe there's a real world? My answer is, our experience and logic are driving us to believe.
  10. Aug 13, 2008 #9
    Re: objective existance imply ditinguishability

    Thanks for the link, Ive dl'd the paper and will read it later. At this point, though, Im not sure what 'objective existence' has to do with my question regarding the empirical nature of particles. I mean, are you arguing some kind of Idealist interpretation here? Im not following your reasoning here, sorry.
  11. Aug 13, 2008 #10
    Yes, its precisely that 'somehow' Im interested in here. If I said to you that brain cells fire and then somehow consciousness is generated, you'd probably be interested in knowing just what that 'somehow' involved beyond brain cells firing. *Im not intending this to become a debate on consciousness.
  12. Aug 13, 2008 #11
    I agree. Your use of 'seems' in your first statement is, I think, due to the concepts you (or we) utilise in understanding and knowing matter and mind. It 'seems' as if there is an insurmountable boundary because thinking about consciousness is an excercise of conceptual reasoning, and our thinking (especially abstract thinking) is limited by the concepts we employ. Of course, this neednt be some sort of absolute 'imprisonment': concepts evolve and develop due to experience, rationalisation, creativity/imagination, and idea sharing (books etc). The 'evidence' for evolution existed long before Darwin was a twinkle in Mitochodrial Eve's eye, but its discovery took someone with the appropriate concepts with which to interpret and understand it accordingly. Historically, many have seen the same 'evidence' as that for God.

    I agree with you here, too. Our everyday concepts have evolved in terms of our everyday world of macroscopic objects. However, I think we need to be careful when applying these concepts in areas where they may be misleading. In the macroscopic world where we spend most (if not all) of our lives, seeing our fingers and touching rocks is (and should remain) a straight forward affair. For sure, I think there must be a continuity here somewhere, between particles and fingers. Personally I dont find literalist 'multi-world' proposals helpful in the slightest: a 'world' of particles, a 'world' of cells, a 'world' of mind, etc.

    I dont think an organism that didnt 'believe there is a real world' couldve survived very long in its 'illusory' world. I admit, this is assuming my conclusion (that the world we experience is real), but when I consider the practical implications of a species of organism that essentially acted as if something like 'The Secret' were true, well, I dont see how that species could survive. Every organism that is driven to believe there is a real world is an organism that will survive because its playing the best odds.
    Last edited: Aug 13, 2008
  13. Aug 13, 2008 #12
    I found this description of atom smashing that's pretty good: http://education.jlab.org/qa/experiment_06.html

    The nucleus of an atom has a force called "nuclear force" holding the nuetrons and protons together in a small bundle, but even though the force that contains them there is very strong its area of influence is very small so if an electron smashed into the nucleus with enough momentum it can push some of the particles far enough away from the bundle to let them escape off into the distance.

    Radioactive materials are ones whos nucleus are so large that the forces holding the bundle together is insufficient, so particles just fall away from it at will. In a fission reaction the particles flying away from one atom actualy run into the nucleus of nearby atoms causing those atoms to in turn lose particles from their nuclues, and every time this happens various amounts of energy and other stuff is released as well. Nuclear bombs work by causing fission to occur very suddenly.
  14. Aug 14, 2008 #13
    Cheers for that. I'll check out the link.
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