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My dad's an aeronautical engineer. The other day, I visited a pub with him. A friend of his introduced him to someone who told us he was an electrical engineer. My dad replied with what I presume was an allusion to an engineering joke, "Electrical eh. Do you guys even believe in electrons?" The electrical engineer replied with what I presume is the standard reply to that question, "They tell me they exist, but I've never seen one before."

After, I asked him what he meant by "believe in electrons", and he told me that we can't, (or, at least, couldn't when he was at school), look at electrons (which, makes sense), so we've had to infer their existence from observed effects.

I think it's true that, according to an accurate simplified account of physics, for every effect, an instance of some kind of force caused it. (Correct me if I'm wrong.)

If that's true; and if, from the effects of electrons, we inferred every fact we know about electrons, then every fact we know about electrons is a fact we know about the forces of electrons.

However, seeing (and, at bottom, sensing, by any means) consists in an effect caused by a force.

Considering that, it seems to me that we could conceive of any kind of matter, from quarks to bricks, as a set of forces that influence some particular points in space at particular times.

Is there any reason that we can't, or shouldn't, think of matter this way?

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    $\begingroup$ In a certain sense, I suppose the answer is yes. Entities interact and it is their interactions that define them. $\endgroup$ – Alfred Centauri Mar 12 '15 at 23:07
  • $\begingroup$ I posted an answer below but how about this: I could ask you, using e = mc^2 , that all matter is energy and how is energy described in terms of forces? Maybe you could post this as another question later. By definition, Energy is the ability to do work, and work is force by distance. So again we have forces involved in the description of energy/matter. $\endgroup$ – user74893 Mar 12 '15 at 23:58
  • $\begingroup$ Does every material thing just consist in forces? not being pedantic, but would it be a good idea to revise the heading of your question to "of" not "in"? $\endgroup$ – user74893 Mar 13 '15 at 0:08
  • $\begingroup$ @sofia my apologies, but just can't resist (because I don't know enough myself yet,) are you giving an informal description of non-locality?) regards and thanks $\endgroup$ – user74893 Mar 13 '15 at 0:21
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    $\begingroup$ @Hal my apologies for that, I had never come across that particular useage before. I thought the question was excellent, causing me to think more carefully about our process of description regards and thanks $\endgroup$ – user74893 Mar 13 '15 at 2:53
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There is an example in which it is not clear which forces act there, but I am not sure if you learnt of such things. I'll try to make it simple.

In the quantum physics we know to prepare sets of particles in what is called entanglements. Such an example is the so-called singlet of polarization of photons. Polarization is how oscillates the electric field in the photon. We use to pass photons through some devices named polarizers, which check the direction of the electric field. These devices have an orientation in space, and the photon either passes through the polarizer, or not.

In short, assume that we have two labs A and B, in each one there is a polarizer, and each one of the photons flies toward such a lab. Assume that in the lab A the experimenter orientates the polarizer in some direction, picked by him arbitrarily. Assume that in the lab B the experimenter orientates the polarizer by chance in the same direction. Then, what happens is that in the lab A the photon passes the polarizer, so does the photon in the lab B. But if in the lab A the photon doesn't pass, neither does the photon in the lab B. And the labs are far from one another?

Which force acts between the two photons so as to correlate their actions? If one photon behaved in a certain way, passed or not the polarizer, how does it influence the other photon to behave the same way? We don't know. And take into account that by the time the two photons leave the source, the experimenters in the two places, may not have even decided in which directions to orientate the polarizers.

In the classical physics, it seems that every influence goes through some force(s). Only in QM we don't exactly understand.

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If you ask me , what IS an electron, I don't know. Some people might say, without being allowed to describe its properties, it's a meaningless question. My answer would be always to describe it in terms of it's properties, i.e as you say, by means of its forces. So, yes, I would agree with you, if all matter is made up of elementary partices and we can only describe them in terms of their properties, this (to me) leads indirectly to describing all matter in terms of forces.

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Einstein was quoted as saying 'You know, it would be sufficient to really understand the electron'. We understand the electron, but we do not really understand it. The intrinsic spin, the magnetic dipole moment and the relation to the positron are not really in full grasp. We are lucky that nature does not play dice- again by Einstein, and this is how we get our knowledge.. we make thousands of experiments and observe the outcome giving the same results then we conclude that that observable is a property of the thing we are observing. This is about the best we can do now and in any future time it appears so far. Of course as you concluded, we need an effect on our measuring instruments (our eyes or ears for example) in order to tell that something exists- albeit indirectly sometimes.

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