It may be that in quantum reality radioactive decay may be perfectly regular and predictable (maybe all such events are even simultaneous.) In mathematics it is easy to create a function with a regular input but a seemingly random output. — EnPassant

I'm not sure what you mean by everything happening simultaneous. If such were the case there would be no cause and effect?

In mathematics it is easy to create a function with a regular input but a seemingly random output. — EnPassant

Yes, hidden variables theories are when things are determined by features we can't observe, represented by variables that we don't know anything about and functions that transform those inputs into outputs; but since we don't know the inputs we can only evaluate the probability space of the outputs -- which happen to be worked out to exactly the same predictions as quantum physics currently provides without the hidden variables.

I'm not sure what you mean by everything happening simultaneous. If such were the case there would be no cause and effect? — boethius

Well, that was a throwaway comment. What I mean is anything could be the case for all we know.

Here is where my thoughts have led.

Space is two things. It is an ontological reality and a geometric reality. Ontologically space is there. It is not nothingness, it is a substance. But space as geometry seems to be more accessible to science.

Can it be that ontological space can simultaneously manifest more than one geometry or spacetime? It seems to me that quantum spacetime and classical spacetime (ie the macroscopic 4D world) exist simultaneously in the same ontological space. The spacetime that particles live in seems to be some kind of exotic N-dimensional geometry that is not classical.

I think it was Bohr that said it is meaningless to talk about where a particles is, outside measurement by a device in classical spacetime. In this respect 'where' means a position is classical spacetime. Apparently it is nowhere in classical spacetime at all, it is in quantum spacetime (geometrically speaking).

We don't see particles, we only see trace effects. A spot on a photographic plate is a trace effect, not a particle! What is important here is to see the both the detection apparatus and the trace effect are macroscopic, classical objects; they both exist in classical spacetime. This means that the trace effect is necessarily a classical object, obviously located in classical spacetime. But where is the particle before/after detection? Nowhere. Nowhere in classical spacetime that is. This is why Bohr says it is meaningless to say where it is. It is 'elsewhere'.

If there is a light source at A and a photographic plate at B and a photon is detected it is natural to assume that the photon travelled in a straight line from A to B. But, strictly speaking, all we can say is that the photon left a trace effect at A and a trace effect at B.
But these trace effects are classical objects and a straight line joining them is also a line drawn in classical spacetime.

If the photon is not really travelling in a straight line (because it is not even in classical spacetime) the straight line must be seen as an artefact of the experimental apparatus itself. This is because the whole experiment is taking place on 'this side' of the interface between these two spacetimes. Consequently any relationship between trace effects must be in terms of a classical 4-D geometry. That is, the positions of particles (in reality trace effects) is imposed on the situation because the experimental apparatus, being a classical object in classical spacetime, can do nothing else but force things into a classical geometry.

Well, that was a throwaway comment. What I mean is anything could be the case for all we know. — EnPassant

Yes, I agree, Kant's noumena, the thing in itself, could be anything.

When I mention we may have a revolution in physics that may change completely our concepts of time and objects ... likely we will still be wondering about the noumena.

Space is two things. It is an ontological reality and a geometric reality. Ontologically space is there. It is not nothingness, it is a substance. But space as geometry seems to be more accessible to science. — EnPassant

Yes, one way to put this distinction into relief, is that we could conceptualize living in a world that has no regular clocks or rulers. We could perceive and do things but could not make any geometry, as we currently understand it.

We don't see particles, we only see trace effects. A spot on a photographic plate is a trace effect, not a particle! What is important here is to see the both the detection apparatus and the trace effect are macroscopic, classical objects; they both exist in classical spacetime. This means that the trace effect is necessarily a classical object, obviously located in classical spacetime. But where is the particle before/after detection? Nowhere. Nowhere in classical spacetime that is. This is why Bohr says it is meaningless to say where it is. It is 'elsewhere'. — EnPassant

I am also partial to reducing to Borhs view, in terms of what we are really justified (at the moment) of taking.

It's not a popular view in "physics discussions", but that's because it doesn't give many ideas; visualizing different interpretations is generally more fruitful, but when physicists ask after a bunch of talk of "what are the observables and what are the operators" I generally take this to imply at the end of the day we need to get back to Borh's view to see what's, if anything, has been accomplished.

However, there is an alternative view, I believe most associated with Dirac, which is the goal is to build a physics theory that describes the quantum realm, describes our apparatus that probes the quantum realm and describes ourselves and to fully get rid of the "classical apparatus of the eye, computer screens and detectors". From what I can tell, this view is gaining a lot of popularity. As far as I know there's no epistemological basis to reject this view, just that it hasn't succeeded yet. Though my feeling is that someone with enough skill and knowledge could still make a very robust defense of Bohrism.

If there is a light source at A and a photographic plate at B and a photon is detected it is natural to assume that the photon traveled in a straight line from A to B. But, strictly speaking, all we can say is that the photon left a trace effect at A and a trace effect at B. — EnPassant

The core of quantum theory is that we cannot "see particles" like we can see large objects; all the math just transforms initial conditions to observables that experiments can probe. Particles are also not really assumed in quantum physics, they are just an analogy for quantized field vibrations, and quantized fields are basically just an analogy for abstract mathematics (abstract spaces that contain all the variables and operators that convert the variables a probabilistic prediction of what a given probe of the system will find) that tie the initial conditions to observables.

Because this is the view and we never actually see what's "happening in the middle", we only ever observe on the sides of quantum phenomena, things have been recently reduced even further to the surface area around our system, such as a particle accelerator (where the detectors are essentially infinity away compared to the size of a quark which is being probed), black wholes (where information must be somehow "on" the event horizon), as well as the entire universe, where in each case we observables are tied together and we can forget about there even being a middle, what is referred to as "the bulk" -- we live in and perceive the bulk, but it seems we don't need it to do physics ... maybe.

For, another theory being worked on today reduces things even further to just "events" that are all discrete and individual are not in a "space" but have a network of relations between them which gives rise to the illusion of space, time, particles, fields etc.

If the photon is not really travelling in a straight line (because it is not even in classical spacetime) the straight line must be seen as an artefact of the experimental apparatus itself. This is because the whole experiment is taking place on 'this side' of the interface between these two spacetimes. Consequently any relationship between trace effects must be in terms of a classical 4-D geometry. That is, the positions of particles (in reality trace effects) is imposed on the situation because the experimental apparatus, being a classical object in classical spacetime, can do nothing else but force things into a classical geometry. — EnPassant

Our apparatus is definitely classical, but it's a fairly radical direction to claim our apparatus imposes anything on the quantum realm ... as this seems to imply the apparatus exists first. To understand the limitations of what we're able to observe doesn't require giving up the assumption that we're made up of smaller things and that smaller things are causing things to happen in our apparatus. So to say our apparatus force things into classical space-time, is extremely ambitious. It's not required to go that far, though I wouldn't say on a philosophy that you can't go that far. The less extreme view is that we just so happen to live on a scale where thermodynamics affects us, we have definite observations, and how this arises from our various many parts is somewhat of a mystery: that entropy was low in the past and that quantum probabilities do resolve into something definite at some point between us and our parts / experiments; are both unresolved mysteries, as far as I know, that give rise, in addition to general relativity and the standard model, to our classical perceptions.

I think it's useful to add to my last comment, of which the theme is to reduce everything to observations and abstract mathematics, that physicists do not generally have the view that we're just noticing patterns from our "head box" and the math gives the right patterns of what to expect but has no meaning, rather they do usually view there is profound building blocks of the universe in the mathematics.

What physicists generally view as "what's really real" are symmetries and symmetry breaking.

If there was no symmetry then nothing would stay the same from time to time or place to place, and there would be no time or space to begin with, and so nothing could have any identity (which we seem to have, so we don't live in a universe with no symmetry) and if symmetry was never broken then everything would be exactly the same everywhere and again there would be no identity apart from the whole (and we seem to be a separate part from everything surrounded by other similar separate parts, and so again we don't live in a fully symmetric universe).

So, although we can't really visualize the "true substance" and there can always be smaller features we can't see at the moment - and may never be able to see - we do know that whatever the true substance is that we live in, it has real properties of symmetry as well breaking of that symmetry; and when we think about what it is to "know a substance" it is to know properties of it, so in this sense we do know something fundamental of the noumena that is beyond simply our observations. What we don't know, for now, is exactly how all the symmetries and symmetry breaking fit completely together (but we do know a surprising amounts).

Our apparatus is definitely classical, but it's a fairly radical direction to claim our apparatus imposes anything on the quantum realm ... as this seems to imply the apparatus exists first. — boethius

What I'm saying is that the geometry is imposed on the trace effects that register on photographic plates etc. It is not the particle that is being observed but the trace effect (eg a spot on a photographic plate). The point is that these trace effects are necessarily classical objects and any geometry that relates them is going to be a classical geometry.

Suppose you have a light source at A and a photographic plate at B with a spot made by a photon. Here are two trace effects with a straight line joining them. It is natural to assume the photon travelled in a straight line between A and B. But since photons exists in some exotic quantum geometry we cannot really say it travelled in a straight line, not least because it does not even live in our classical world.

Where then does the straight line come from? It is an artefact of the experiment itself. The experimental apparatus is a classical object in classical spacetime and likewise with the trace effects that are collected. Given this, the only geometry these trace effects can have is a classical geometry. But this tells us nothing about how the photon travelles from A to B since it is travelling in its own spacetime.

The crux of my idea is that there are two distinct spacetimes (quantum and classical) made manifest by ontological space. These spacetimes exist 'here' in our ontological space but because they are different geometries they are, from a geometric perspective, two different spacetimes.

The trace effects exist at the 'edge' between these two spacetimes, but on the classical side of it. The photon exists on the other side of it. So how can we measure quantum spacetime with classical rulers?

The crux of my idea is that there are two distinct spacetimes (quantum and classical) made manifest by ontological space. These spacetimes exist 'here' in our ontological space but because they are different geometries they are, from a geometric perspective, two different spacetimes. — EnPassant

This idea of interactions between two spacetimes/ dimensions (classical and quantum) must carry some weight. It is the interaction between the continuous classical world and the timeless quantum world that holds reality together, without one or the other substance would dissolve into nothingness.

On the macroscopic scale, what we see and interact with is only a tiny fraction of what lies behind. If you look at a tree, you only see a few of the photons which have recently interacted with the tree. The vast majority of stuff which makes up the tree exists in a seperate quantum dimension which we can only probe into. Yet it is these interactions which holds the substance of the tree together. With small electromagnetic force interactions constantly tugging and pulling through all the branches, the quantum fuzz of the tree is brought into the classical world.

The position that there is not any randomness in a Newtonian sense, is called "hidden variables theories", but you can imagine that there's just small "springs and gear mechanisms" everywhere (that we can't observe) that fully determining how every event turns out; the internal states of these tiny mechanisms are the hidden variables. — boethius

I am not educated in QM or Relativity beyond a smattering of readings of science popularizers, so my question might well be naive. If there were "hidden variables" that determine quantum events, would those hidden variables be self-determined or determined by "something else"? It seems to me that nothing is solved in either alternative, it just pushes the explanation back one step further. And with the alternative that the hidden variables are determined by "something else" an infinite regress seems to threaten.