Causality, Action-at-distance and Force in contemporary physics

[Psyduck]

I don't take this question to be a scientific one, but a philosophical one.

Can someone explain me from scratch (introducing each non-trivial concept) what the contemporary views on causality are.

In particular, so far as I understand it, a field (say, gravitational field) is only a mathematical object, in the sense that it is a function F that assigns to each point in space and time (x,y,z,t) some scalar/quantity or vector. This must be contrasted with a physical object, or a metaphysical thing that is the "condition of possibility" of mediation of information throughout the medium. Not sure how something having that nature would look like. Even if it were to have some kind of material status, it certainly would have an awkward ontological nature. For if one posits something that "mediates" between entities/things, this can (by an easy regressus argument) itself not be another entity/thing.

Related to my question: what are contemporary views on empty space? What is there "between" two different objects. What separates them? There must something metaphysical (or if you don't like the word "meta," say: pre-physical) that causes the separation and individuation of physical object X and object Y because else everything would dissolve in an undifferentiated plenum of pure Oneness.

 

[rangrz]

With quantum field theories, while yes just like classical fields on paper in terms of defining a scalar/vector/tensor for all points in a space mathematically, the physical nature of it is more apparent. It's a sea of intermediate vector bosons that interact with other things and exert an effect on them as appropriate. This can be, and is confirmed empirically. I.e. Casimir effect, tracks left in bubble chambers, the birefringence observed in "free" space around Magnetars, etc.

 

[Psyduck]

It's a sea of intermediate vector bosons that interact with other things and exert an effect on them as appropriate.

I still don't understand.

But do you see my problem?

What is "between" objects...? There is must be some "mediating thing" such that object X and object Y can "know" about each other via this medium, and feel or exert influence on each other.

To take a metaphor. Before two people can speak to each other they need to have a common "sound-medium" in which sounds can be uttered and heard. Only by virtue of such a medium can person X and person Y talk. It is useful to to distinguish in this metaphor the following elements: 1° the two people, 2° the words they utter, and 3° the sound-medium that mediates the words uttered between them and "connects" the two persons.

Likewise, in physics, there must a "mediating field" in which objects X and objects Y can "talk physics" and "ex-change in-form-ation," i.e. exert some force (active) and feel force (passive). Only by virtue of such a medium (say, gravitational field) can object X (say, for simplicity, the sun) and object Y (say, the earth) inter-act and can gravitational force be felt by, and exterted on, each of them. This event must be the "condition of possibility" of the empirical phenomena (i.e. the motion of the planet one sees).

 

[Foreigner]

^ Events are all triggered by physical means. Affecting something at a distance is due to a cascade reaction of many physical events interacting, if we're talking about physical consequences.

 

[rangrz]

I still don't understand.

For the three forces treated by quantum field theory, there is no medium as such. It's particles moving though the vacuum and interacting with each other. Electromagnetic force is mediated by photons, the weak nuclear force is carried by W and Z bosons, the strong nuclear force is carried by gluons and mesons, the mesons themselves exchange gluons with hadrons, and inside mesons and hadrons, the quarks exchange gluons.

Handwave it as being akin to a free for all game of dodge ball, with everyone throwing balls at each other and only when/if the ball hits you does it affect you.

Gravitation can't be understood like this yet/we have not observed a graviton and based on current theoretical predictions we'd need to use a detector the size of Jupiter orbiting a neutron star at about the same distance as the Earth-Moon system to detect a graviton every 10 days. so, for now it seems like we're probably not going to be able to confirm or falsify any of these conjectures, but ya never know...

 

[ebola?]

What is "between" objects...? There is must be some "mediating thing" such that object X and object Y can "know" about each other via this medium, and feel or exert influence on each other.

Particularly from within a framework where particles may be described so similarly whether they are the bearers of force (as particles 'exchanged' by other particles) or objects exerting force on other objects, I'm not so sure what we can press this matter fruitfully. I'm guessing that the goal isn't to draw up an infinite regress of 'mediating phenomena' between other mediating phenomena, so at some point, we're going to have to accept a certain ontological gap. This type of move might be inherent with ontologies that conceptualize object and action in this fashion.

ebola