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?
Answer
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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