So, when we say that an object traveling at c must have "0 length," because of the equation we use to calculate length contractions (the Lorentz factor), I think that we must be going wrong somewhere with our theories, because it's incoherent to have an existent with 0 length.

And then I wonder to what extent we really know that the Lorentz factor gives accurate answers for anything in the first place. But unfortunately I don't know enough about how we supposedly know this to critique the methodology. I'd have to research that.

When first encountering relativity and quantum, these sorts of puzzles proliferate.

To make a long story short, there is not really any solution to them, which is why the motto of modern physics is "shut up and calculate". However, at the same time, to excuse the pun, of course someone trained in these sciences does understand something of what these puzzles are and that there is no contradictions or paradoxes of the kind you describe.

It's not exactly true to say the photon does not experience "time" in the metaphysical sense. If time is change, the photon's "wave function" changes over "our time"; so this evolving wave function can be viewed as a metaphysical time. What the photon doesn't experience is classical time, or functional time which is the time that we live in. Likewise, it's a misleading shorthand to say fundamental particles "don't exist" between observations, but rather more accurate to say they don't exist in any classical sense.

We only observe classical time and classical particles, and nature has given us zero clue as to what things are really like behind our observations. For instance, we can easily assume from a metaphysical standpoint that there is some "substance" to a particle and some "mechanism" that causes it to appear on one part of the screen rather than another at each observation, but nature forces us to rule out any "substance" or "mechanism" that makes any sense to us.

To answer more directly your pondering, what "classical time" means is a series of regular events. Einsteins simple clock he used to build relativity and general relativity is two mirrors with light bouncing back and forth, let's say at 1 second per bounce. Let's now consider these mirrors at some speed away from us; now the light must bounce at an angle and travel more distance between each bounce to "keep pace" with the mirrors. Since light travels at the same speed to all observers (just take this as experimental fact for now), then from an observer travelling with the mirrors the light is simply going straight back and forth at 1 second per bounce; but from our perspective the light is going more distance at the same speed and so takes more than 1 second per bounce, therefore we see time for the fast mirrors pass more slowly than our own time (any repeating event, i.e. clock, we will see happening slower than the same setup up kept with us). Of course, an observer travelling with the mirrors can consider themselves at "true rest" and us travelling at a speed and comes to the same conclusion with the rolls reversed. In this setup since we are travelling away from each other, we never meet and who is "really at true rest" cannot be resolved. In order to meet, acceleration of at least one party is needed, which is like being in a gravitational field where clocks run more slowly for same reason that again light must travel a greater distance in a gravitational or experiencing acceleration, but this time the parties can meet and see that less time really did pass for the party that underwent more acceleration.

So the above is a "functional" view of time, based on light bouncing around and "ticking" regular events. So, let's now replace the mirrors with light and imagine that 2 light beams can bounce a third light beam between them. That light doesn't do this doesn't actually matter because all three beams must be going in parallel to "keep pace" with the clock, and so they never converge and never bounce, no ticks in this setup are ever recorded. From this, it is too far a jump to say the universe must therefore be a single point. First for a technical point that it's only 1 dimension that gets contracted, leaving 2 dimensions for all information to be represented in. Second, because our "classical time" is made up of events of fundamental particles. We cannot conclude that classical time is the "only time", and why would we? Fundamental particles must somehow go from one event to another between events, there's simply by definition no "classical time" available for this more fundamental time.

Light travels at the speed light obviously, but what's special about this speed is that it's the speed of causation, nothing happening at A can cause anything at B faster than this speed. What limits a particles speed is mass, and so any mass-less particle goes as fast as it can and delivers it's cause from A to B at the speed of causation. If the speed of causation was infinite, everything would happen simultaneously and classical time would not exist.

With this concept of speed of causation we can now more clearly see that anything going at this speed cannot experience any internal events, no clock can tick for it. But it's also true that our whole concept of experience relies on internal events, within a clock or our brain etc. and so there's no experience at all. A photon travelling between events does record any information and has no perspective as we understand it. So it's not accurate to say "it's clock is stuck at the time of the cosmic microwave background" but rather that the photon "has no clock at all", and so any questions about the photon's clock are simply functionally meaningless: there is no clock you can build that travels with the photon and no experiment you can perform that measures this unconstructed clock, so all questions about time for the photon are not well constructed questions.

We can accelerate things close the the speed of causation, but can never reach this speed and anything even ever so slightly slower can experience time and internal events and has a clock and there's no problem.

From our perspective as observers, if there were a “clock” on board a photon, it would appear to be entirely stopped to us. — Devans99

A photon is essentially an observation, and can only happen once. It is not possible to observe "the same photon"* twice, so it is not possible to observe whether any aspect of the photon "is changing". Hence the idea of a clock appearing to be stopped is invalid because, to appear stopped, at least two observations are needed.

*The scare quotes are there because even the expression 'the same photon' is of dubious validity. Ditto for "is changing".

I think that we must be going wrong somewhere with our theories, because it's incoherent to have an existent with 0 length. — Terrapin Station

As per my previous post, we cannot measure the 'length' of a photon, because that would require two or more measurements - one at each 'end'.

Note also that SR doesn't say an object moving fast relative to an observer 'has a shorter length'. It says the observer will measure the length as being short. Since length measurement is impossible for a photon, that concept does not apply.

I think that we must be going wrong somewhere with our theories, because it's incoherent to have an existent with 0 length. — Terrapin Station

To add to what Andrewk says about this, we can have a 2 dimensional space, it's no incoherent. Indeed, since 3 dimensional information can be recorded on a hologram, it's possible to consider physical systems existing on a "holographic" "true substance" and work out all the math and predictions we "think we experience" in 3 dimensions in 2 dimension. So (on top of being able to make coherent 2 dimensional spaces with working physics; such as a 2D computer game) we can even build a symmetric 2 dimensional universe that expresses a 3rd dimension implicitly. So contracting length to 0 does not create any fundamental problem.

It's not exactly true to say the photon does not experience "time" in the metaphysical sense. If time is change, the photon's "wave function" changes over "our time"; so this evolving wave function can be viewed as a metaphysical time. — boethius

The wave function could change but that is only our estimation of where the photon is; it is not the actual particle. Maybe the photon remains unchanged whilst its wave function evolves? That would fit in better with the photon experiencing no time?

Also it's clear that wave function changes in our time but does it in the photon's time?

Fundamental particles must somehow go from one event to another between events, there's simply by definition no "classical time" available for this more fundamental time. — boethius

So change is possible outside of "classical time"? The photon experiences no time yet goes from existent to non-existent in no time. Seems to indicate change.

This "more fundamental time"... would causation still apply to things in it?

With this concept of speed of causation we can now more clearly see that anything going at this speed cannot experience any internal events, no clock can tick for it — boethius

So things travelling at the speed of light are beyond causation? This is what I'd expect for something that was beyond time.

So it's not accurate to say "it's clock is stuck at the time of the cosmic microwave background" but rather that the photon "has no clock at all", and so any questions about the photon's clock are simply functionally meaningless: — boethius

We know that for something travelling at close to the speed of light, their clock runs slower and slower. It's not too much of a jump from that to fitting a clock to a photon for a thought experiment.

How can we have a two-dimensional space? — Terrapin Station

Dimension just mean how many coordinates are required to define a point in space; in our physics that really means an event in space as Andrewk points out. So you can simply define a physics system with 2 dimensions. A classical system is easy to visualize as it's like most 2D computer games: objects move around in 2 dimensions and interact based on rules.

Of course, we can't actually build a physical 2 dimensional system in our world (when described as 3 dimensions and not a hologram), as our world has 3 dimensions so there will always be interactions along the 3rd dimension even if we try to reduce those interactions by doing experiments on a surface. In certain particle physics contexts, due to the length contraction, certain problems can "drop" the 3rd dimension as it becomes negligible, but it is still there, so this isn't a good example.

The wave function could change but that is only our estimation of where the photon is; it is not the actual particle. Maybe the photon remains unchanged whilst its wave function evolves? That would fit in better with the photon experiencing no time? — Devans99

That's my point, the particle does not exist in a classical sense between events; we are still free however to suppose there is some substance and some non-classical time to it's existence. The interpretation that the wave function is only probabilistic prediction of "where the particle actually is" does not stand up to scrutiny; all local variable theories have essentially been ruled out, so the "particle", insofar as we're still calling it a particle, does actually somehow exist in some sense everywhere it's possible to observe, we simply cannot make any description of it's "true substance" beyond this "existing in some sense at all the points it can be observe". If we interpret time as evolution of a system, what I called metaphysical time (as there's no experiment that is not functional "classical time" of clocks), this wave function experiences this sort of metaphysical time (doing these calculations to predict things has no physical interpretation; but we are free to suppose it might); the only reason to have such a definition of time is simply to remind ourselves that there could be a reality beyond our functional time experiments that we are unable to access (at least for now); for instance, there could be a mechanism that determines where events actually occur (selecting where in the probability space to actually show up); it's not metaphysically ruled out, but we have no way to ask this question in the sense of experiment (again, for now; that things could change with some revolution in physics, is the practical reason to remind ourselves of functional definitions of things may not be the true definition).

Dimension just mean how many coordinates are required to define a point in space; in our physics that really means an event in space as Andrewk points out. So you can simply define a physics system with 2 dimensions. A classical system is easy to visualize as it's like most 2D computer games: objects move around in 2 dimensions and interact based on rules. — boethius

That you can define something in some way does not at all imply that the objective thing has those characteristics, does it?

Two dimensions isn't really possible. It's just an idea we have.

all local variable theories have essentially been ruled out — boethius

Hidden non-local variable theories are still in the running though?

Two dimensions isn't really possible. It's just an idea we have. — Terrapin Station

It's entirely possible our world's true substance is a 2 dimensional hologram.

It's also entirely possible a 2D world really does exist somewhere out in the wider existence beyond what we can observe.

We couldn't build a true 2D physical system, nor can we build other universes of any dimension. But to say something doesn't make any sense, especially in a philosophy forum, is usually interpreted as some internal conflict in the idea itself, not that we simply can't build it. Also, it doesn't create a conflict to make a frame of reference arbitrarily close to the speed of light where the contraction is so great that it's dimension can be ignored, it doesn't approach non-sense to do so but is a physics trick called "boosting" that helps calculate certain problems.

Hidden non-local variable theories are still in the running though? — Devans99

Yes, this is what I mean when I say "some mechanism that determines where a particle actually appears", such a mechanism could be a hidden non-local variable theory or something totally different (maybe there is some deeper level that radically overturns our current quantum understanding, just as quantum radically overturned our classical understanding). A revolution in physics could lead to our understanding of functional "clock time" as emerging from some more fundamental time, that in turn could still be far from "true time". My use of the term "meta-physical" time basically refers to the fact we can always posit that something more is going on beyond whatever our current physical understanding of time is; i.e. today we are free to question whether there is a "time" beyond the closest clock ticks we can measure; and there are people working on theories where our functional time is an emergent property of something more fundamental; though it's very unclear if, even in principle, such theories could even have any physical meaning other than clever mathematics that happens to give right answer (predictions to experiments), just as building a mathematical framework based on holographic math doesn't imply the answers it gives is actually of a holographic system, it's just one mathematical path to the right answer (just as neither wave-mechanics nor matrix-mechanics has any preferred interpretive value beyond generating the right answers).

Also, to be clear, it's likewise possible to argue that functional time equals true time.

For instance, there is a position in the metaphysics of physics where the observation of particles is truly spontaneous, there is no mechanism of any kind but truly pure random occurrence manifesting with any particular observation; conforming to statistical rules but with absolutely "nothing happening in between" that determines if a particle is observed right or left, spin up or spin down. Although this seems difficult to accept, it seems equally difficult (to me at least) how to reject this view without a infinite regress of mechanism for the mechanism for the mechanism.

It's entirely possible our world's true substance is a 2 dimensional hologram. — boethius

Oy vey. Say what? Why would you believe something like that?

Oy vey. Say what? Why would you believe something like that? — Terrapin Station

It's possible because it can be mathematically consistent.

It's possible because it can be mathematically consistent. — boethius

Why would you believe that things we can construct via mathematics might correspond to objective reality?

Constructing things with mathematics is simply playing a kind of game of sorts. You might as well think that the world might really be identical to Candyland.

Why would you believe that things we can construct via mathematics might correspond to objective reality? — Terrapin Station

You quote me saying 2 dimensional universe is possible, asking why I "would you believe something like that", I responded why I think it's possible. No where do I say I believe it is the case. I already qualified my use of possible as being internally consistent, not "buildable" and certainly I do not equate possibility with what is true. The context of my assertion is responding to the claim that removing length makes no sense; i.e. results in some internally contradictory scenario, to which I am pointing out that a 2D universe is not contradictory in itself.

Maybe the universe really is 2 dimensional, in the most naive form, but I have just been under the illusion it is 3 dimensional. I cannot dismiss the idea I live in a 2 dimensional world because it makes not sense, I must appeal to my experience and use induction to be highly confident the world of my everyday experience has 3 dimensions.

And once I am confident my everyday experience is 3 dimensional, there remains the possibility that reasoning and more subtle experiment convinces me the world really is 2 dimensional but stores 3 information that I experience as 3 dimension through something exactly like or similar to a hologram.

Whether the "true substance" of the universe is holographic is another question as different is the question whether it is a good pathway to make a better mathematical description of a theory uniting relativity and quantum mechanics (regardless of how we want to interpret what the math really represents, other than correct predictions).

The problems a holographic universe would solve, and why experts are working on the idea, is 2 essential ones.

The first problem is that the only arbitrarily precise measurements we can make are from an arbitrarily far distance, and in such a description we are completely free to then claim that the measurements at this arbitrary distance (what we actually observe) are what actually exists (strict functional approach to physics where we only view experimental results themselves as existing and any object we imagine to exist for ease of calculation is exactly that mathematical mirage you refer to, and there is strictly zero basic to assume that math represents anything beyond the correct answers it gives, which in this scenario measurements at an arbitrary distance); this arbitrary distance we can then view as "at the same distance" for all the measurements we make and this then forms a 2 dimensional surface upon which all our measurements exist (a particle accelerator detector is an example of trying to approach this method, and although the LHC detectors don't seem big compared to the size of the universe, they are immense compared to the size of quarks and other subatomic particles they study). Therefore, if our most accurate approach to modeling the physical universe actually takes place on a surface, then the 3rd dimension that we imagine constitutes the things "inside" our observation shell we can simply dismiss. So, from this perspective, the 3rd dimension of space is simply superfluous to the true (i.e. most accurate) description of nature we can make. Just as developing relativity required abandoning the assumption that time was universal (ticked at the same rate wherever you are) and our quantum theory required abandoning the assumption particles have a precise position and momentum -- in other words just as relativity and quantum required abandoning our expectations of how the universe works based on ever day experience, where time does really does seem universal and constant for everyone and everything we can hold and toss in our hand really does seem to be really there at a well defined position and momentum -- maybe the next revolution in physics requires us to abandon the idea the universe has 3 spatial dimensions even if our everyday experience really strongly suggests space has 3 dimensions (of course, such a theory would still explain why we experience 3 dimensions, just as relativity explains why time seems pretty constant and quantum explains why big objects seem pretty discrete and determined in position and momentum).

The other reason, which is beyond simply a minimalist strict experimental functional approach which has helped us in the past, is that quantum systems seem to have a "non-local" communication within them (which just means things happening faster than the causal speed limit I've already referred to). Though we can't exploit non-local communication within quantum systems to actually pass information around at faster than light-speed, it's difficult (and most experts agree is impossible now) to explain the result of certain quantum experiments that have things happening at a distance (and then those results brought together at equal or slower than the causal speed limit to analyse them) without non-local information transfer within the quantum system. One property real physical holograms have (not 3d illusions based on parallax but real holograms), is that information is stored on them non-locally. If you cut a hologram in half, unlike a normal photograph, you get two smaller copies of the whole hologram each with less resolution. So, if the "true substance" within which quantum phenomena is really happening is holographic, then the information of the universe is stored non-locally and there's no puzzle about quantum systems seeming to communicate non-locally; this non-local information holding "holographic substance" has rules that give rise to our rules of accessible information never travelling faster than our observable causation limit, but quantum systems use the non-local aspect to resolve the results of experiments.

Of course, even if the holographic principle does play a central roll in our next physical theories, that doesn't imply it wins the "true substance" argument or even that such an argument can ever be won. Maybe out next, next physical theory will describe a 2 dimensional holographic surface within a 3 dimensional space and that parts of the the surface can interact with other parts through the 3rd dimension of this space, which appears to us like energy disappearing and reemerging through a 4th spacial dimension in our experiments (in more naive, less accurate description that don't take into account things are really a holographic spherical surface within a larger higher dimensional spherical space).

You quote me saying 2 dimensional universe is possible, asking why I "would you believe something like that", I responded why I think it's possible. No where do I say I believe it is the case. I already qualified my use of possible as being internally consistent, not "buildable" and certainly I do not equate possibility with what is true. The context of my assertion is responding to the claim that removing length makes no sense; i.e. results in some internally contradictory scenario, to which I am pointing out that a 2D universe is not contradictory in itself. — boethius

I was saying it makes no sense as something that could actually exist, not as an abstract construction.

Hi Devans,

I had this same thought regarding the timelessness of photons a few days ago.

Imagine a pair of entangled photons/ particles emitted in the early universe. One photon makes its way over billions of years through the entire universe to land at a detector at present day Earth. Its spin is then measured and so the spin of the entangled particle is then known.

However the entangled photon could have interacted with a particle billions of years in our past, or even billions of years (or more) into our future. Yet these two events happened simultaneously as viewed from the photons' entangled states.

A conclusion I could infer is that the whole universe is predetermined, macrospic time is therefore merely an illusion. It might be true to say that the whole universe lived out its entire existence instaneously through quantum intereractions. We are now merely witnessing the realtime effects of all these interactions play out...

I was saying it makes no sense as something that could actually exist, not as an abstract construction. — Terrapin Station

I've already presented several arguments that a 2D universe could actually exit.

First, there could be another universe that actually exists detached from our own.

Second, our universe could be actually a 2D hologram.

Third, we could actually be in a 2D universe in the straight-forward sense, but have both mistakenly interpreted our experience as 3 dimensional. I.e. we must verify with our experience the dimensions of the universe, we cannot reason that it's impossible there's a 2D universe out there and rule that out a priori.

Do you see faults with the above arguments?

If you're using the term "non-sense" to mean "not a sensible interpretation of our experience in our own particular universe", then yes, I'd agree that 3 dimensions is a good conclusion to draw from our experience. But there's a difference between "not sensible in itself" and "not a sensible conclusion from our day-to-day experience".

Your original argument was that length contraction to zero at the speed of light made a non-sensible interpretation of the world and therefore there's some sort of problem. My points above are that the conclusion does not follow, nonsense is not the result of length contraction to a 2D description of reality (it's completely acceptable in our theories and is sometimes done on purpose to simplify certain calculations).

299792458 metres per second is the speed of light. If you had a distance of 2 light years (thats a distance not a time period) it would take 2 years for a photon to travel that. What you are touching on is special relativity and some other things. Yes a clock that approaches the speed C will tell time much slower than a clock moving on the earth (the earth is moving). This has been proven on airplanes that move faster than clocks on earth (in proportion of course). A photon does not move instantaneously but just fairly fast as far as i can tell. Ofcourse i'm sure you've heard that nothing can travel faster than C but i guess some scientists say that isn't true.

It seems the photon moves at the speed of light from our perspective but from the photon's perspective, it is covering no distance in no time to get anywhere so I'm not sure the notion of speed applies (speed = distance / time and time is zero so speed is undefined from the photon's perspective).

i see what your saying. When matter and energy comes to a standstill who knows what that is like. i used to be a bad wrestler in high school and when you are on your back and there are 20 seconds left on the clock those 20 seconds feel like 10 minutes.

However the entangled photon could have interacted with a particle billions of years in our past, or even billions of years (or more) into our future. Yet these two events happened simultaneously as viewed from the photons' entangled states. — Jonmel

There is no functional definition of time from the photon's entangled state. No clock can be built to tell us this event happened simultaneously; we can only make a clock that records the time of experiments; so in this case when the two particles were observed (which due to relativity has no absolute definition of simultaneous already), and from there we can note a correlation between the results of experiments of the entangled particles. However, it's not meaningful to say that the photon's experienced the observation of the entangled variable at the same time; photon's do not experience anything at all and have no perspective and no functional time (no clocks) ever tick for any photon.

Your argument could be reformulated without functional time, with a context of some form of meta-physical time. I'm not sure how that would be done, but it's important to have clearly in mind what observable time is in these sorts of arguments.

A conclusion I could infer is that the whole universe is predetermined, macrospic time is therefore merely an illusion. It might be true to say that the whole universe lived out its entire existence instaneously through quantum intereractions. We are now merely witnessing the realtime effects of all these interactions play out... — Jonmel

It's not clear to me how your inference works. Entangled observations still happen at moments in time (in whatever frame of reference you want to choose), and what makes entangled observations strange (in most interpretations of what is going on) is precisely that they are not determined, an observation does not reveal a correlation that was already present (hidden local variable) but brings into existence the observation and correlation (a non-local link between the observations). However, there is nothing instantaneous between the event that created the entangled pair and the time one or both are observed. Likewise, the speed of causality is not violated as we cannot use what appears to us as instant communication between the entangled particles to communicate any information at faster than light speed, we can only bring results of experiments together at sub-light speeds and note interesting correlations between the results.

Quantum phenomena remain bound by the speed of causation, so it's not clear how an inference would be made that all events happened instantly.

Time does not pass in the frame of reference of a photon, but what is really going on is that the speed of light is not an admissible frame of reference. The speed of light remains the speed of light in all reference frames, and a light beam world line (in a sub-light speed reference frame) cannot be transformed to be at rest. What "from the perspective of" means, in a physical sense, is that the thing in question is considered at rest and everything moving relative to it. This transformation of the coordinates everything is following can be done for all sub-light-speed particles and observers, and the paths of everything else relative to the thing we're now considering at rest worked out. However, no matter how much we try to transform the path of a light-beam to be at rest it can never be done, light just stays at light-speed. So, there's simply no sensible formulation of the "frame of reference" of a light speed observer: it's impossible to have such a frame of reference in our physics. The point is, arguments are not sensible from a non-sensible frame of reference (i.e. "what light experiences" or "from the perspective of a photon" etc.).

Of course, there's plenty of theories, both predating and postdating quantum mechanics, that the universe is pre-determined and both the past, present and future already exist and experience is an illusion.

There is no functional definition of time from the photon's entangled state. No clock can be built to tell us this event happened simultaneously; we can only make a clock that records the time of experiments; so in this case when the two particles were observed (which due to relativity has no absolute definition of simultaneous already), and from there we can note a correlation between the results of experiments of the entangled particles. — boethius

Hi Boethius,

Thanks for this, maybe we need to define (or take as assumption) that the functional definition of time for an entangled state, or indeed that of a waveform, is zero or instantaneous. This could offer insight into quantum phenomena such as observed in the Delayed Choice Quantum Eraser experiment - https://en.wikipedia.org/wiki/Delayed-choice_quantum_eraser - where the choice to measure the interference of an entangled photon is made after its pair has already hit a detector.

Conventionally time is measured as progressing steadily forwards in a local frame, relativity then accurately describes different references frames. However, as you note, it is not possible to define two events as occurring simultaneously under this framework - an observer will perceive the timing of events dependent on his location.

An old analogy is for an observer moving away from a clock tower at the speed of light. He will always 'see' the same time, hence for a photon time is not progressing in the conventional sense. If an entangled pair of photons exist in a state of zero time then they would indeed be able to exhibit interference, or have opposite spin, when detected at any locations across the universe. These detections can then be assumed to be simultaneous under relativity so that the frame of reference for the entangled state would be precisely midway between the two observations. Could this explain quantum paradox?

Thanks for this, maybe we need to define (or take as assumption) that the functional definition of time for an entangled state, or indeed that of a waveform, is zero or instantaneous. This could offer insight into quantum phenomena such as observed in the Delayed Choice Quantum Eraser experiment - https://en.wikipedia.org/wiki/Delayed-choice_quantum_eraser - where the choice to measure the interference of an entangled photon is made after its pair has already hit a detector. — Jonmel

Yes, I alluded to in an above comment that functional time does not exclude metaphysical definitions of time. For instance, the time between clock ticks (i.e. the shortest and most accurate clock ticks we can make) has no functional definition, but we are free to presume that there is a non-functional time that does pass between clock ticks. Likewise, the "time" used to progress quantum states between observations is not functional (by definition we are not making any observations, about anything including clocks) and again we are free to employ and use a non-functional definition of time to try to understand better what is going on.

You may have noticed that I, and others with training in the math of relativity and quantum, have a strong tendency to avoid any interpretation at all. And, many professionals would hear "metaphysical time" and react immediately that the conversation is meaningless.

However, by trying to understand "what's going on" from different metaphysical points of view (that, should be noted, cannot be eliminated altogether: functional time depends on meta-physical definition and intuition of time to be formulated), in my view is productive way to clarify ideas as well as generate new ideas.

So these conversations I fully endorse, whether between professionals or amateurs.

However, once one understands the math ... it's very hard to actually come up with interpretations or any candidate for "true time" other than "that time in which clocks tick". Quantum and relativity have a way of making any real change to these theories essentially unthinkable, and the theories themselves have a way of making any access to the underlying reality (the "true substance") completely opaque. For instance, questions like "is 4D space-time a single 'material'?" and "what 'decides' any particular quantum observation?" have no sensible answers. Relatively presents space-time as a 4D "object" that is static (yet we experience time) and quantum theory rules out any "hidden local variables" that determine the results of any given experiment in a "sensible way", and yet any particular experiment has a result (we really do experience only one of the probabilities, and yet quantum theory essentially rules out even the possibility in principle of getting any insight ever into what makes a particular experiment spin up or down, the detector activate here or there).

What's even crazier than perfectly sensible questions being eliminated in principle from our theories (unlike in Newtonian physics where universal time goes forward moment by moment and any process will be wholly determined by probing smaller processes that make it up), is that our two theories are not mathematically compatible.

As for the issue at hand, how "entanglement works" again has no sensible approach to answering in quantum theory as it exists today. It simply is what happens, there's no way to explain how it happens. But it is not actually much more bizarre than other quantum things, it's just we've gotten used to each individual experiment being "purely spontaneous" and the uncertainty principle between momentum and position. What's different with entanglement is only that it took more time to rule out completely every local variable possibility.

However, there remains the possibility of a complete revolution in physics as profound a change as classical to quantum. But within the context of the theories as they are today, everything does make a lot of sense. There's not some trivial or obvious nonsense happening with modern physics theories; this is the basic point I'm trying to make in this thread.

Going beyond our current understand is a profoundly difficult and subtle undertaking. A lot of really smart people created our theories, made them work and many of these same people also tried every way they could think of to make it "sensible". Nevertheless, it is a journey I wholeheartedly encourage anyone to join.

I've already presented several arguments that a 2D universe could actually exit. — boethius

But it can't, because the actual world in no way hinges on stuff we just make up in what's essentially a fantastical manner.

You may have noticed that I, and others with training in the math of relativity and quantum, have a strong tendency to avoid any interpretation at all. And, many professionals would hear "metaphysical time" and react immediately that the conversation is meaningless. — boethius

Hi Boethius,

You make some interesting points. I suppose the whole point of philosophising is that one seeks to understand the underlying reality, gain insight or interpretation which could lead to leaps of judgement so that the maths can be developed or experiments can be devised which would prove/ disprove new theories about reality. I feel we're only just beginning to scratch the surface of what science can reveal about this universe. From general and special relativity through to QED, these theories are incredibly accurate and powerful and I'm sure they will be built on in the future. Maybe the whole point is we will never fully understand concepts such as consciousness but I'm certain we will continue to unravel the mysteries about the nature of reality.

Take inertial mass and gravitational mass. Experimentally these have found to be identical although there is nothing to indicate mathematically that they need to be. However it seems intuitive to me that they should be the same. An object accelerating through space is equivalent to a large body deforming spacetime. Does this mean that acceleration also causes spacetime to deform?

Liwewise quantum behaviour seems somehow intuitive - we now have a limit to how small particles/ energy can become. Things seem to jump about and exhibit non-local behavior because they are discrete, quantum properties can only be ascertained by disturbing/ interacting with a particle, time as we know it fizzles out into a blur of nothingness.

Mathematically we can make predictions about experiments and know that this form of logic works 'in the real world'. However I believe further that mathematics, logic, and consciousness forms part of the real world, they are intimately connected - mind/ reality are one much like energy/ matter are one. There is no reason to believe that the universe should be understandable, or describable, or even coherent - but mathematics has proven that we can gain insight into the universe we are a part of.

What's even crazier than perfectly sensible questions being eliminated in principle from our theories (unlike in Newtonian physics where universal time goes forward moment by moment and any process will be wholly determined by probing smaller processes that make it up), is that our two theories are not mathematically compatible. — boethius

There is a duality between Relativity and QED where it seems there is an impasse. However we know they are both solid theories, maybe it is impossible to reconcile these two perspectives and progress is to encompass both. Quantum experiments show that two realities exist in confluence - timebound, discrete particles and timeless, non-local wavefunctions.

For instance, there is a position in the metaphysics of physics where the observation of particles is truly spontaneous, there is no mechanism of any kind but truly pure random occurrence manifesting with any particular observation; conforming to statistical rules but with absolutely "nothing happening in between" that determines if a particle is observed right or left, spin up or spin down. Although this seems difficult to accept, it seems equally difficult (to me at least) how to reject this view without a infinite regress of mechanism for the mechanism for the mechanism. — boethius

I agree with your definition of the difference between classical and quantum time (what you seem to call metaphysical time). But if we deem a series of events to be random - like radioactive decay - we should specify by what time line they are random. They are only random according to the classical time line but does that mean they are 'truly' random when measured by quantum time? 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.

I agree with your definition of the difference between classical and quantum time (what you seem to call metaphysical time). — EnPassant

I am not equating classical and metaphysical time. One could do so (that there is a newtonian-like world beneath our ability to observe), but by metaphysical time I mean to refer to any and all definitions that are not observing clock ticks.

But if we deem a series of events to be random - like radioactive decay - we should specify by what time line they are random. — EnPassant

The randomness issue is not directly related to time definitions, but to whether there are hidden features that we can't observe.

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. Actually building such theories is usually highly abstract and don't generally involve tiny springs and gears but deterministic fields or just deterministic abstract variables added to our existing theories: variables we cannot, and can never, observe; they just remain an unknown and the probabilities are built-up out of our lack of knowledge; just like if I shuffle a card deck I can predict a 1 in 52 chance of flipping over any card due to losing track of the variables, but the event is not spontaneous since if we do keep track with a high-speed camera we can work it out, unlike radioactive decay -- current quantum theories, as they are used, simply give us directly the probability curve of radioactive decay or any other event; it is pure spontaneity.

Physicists generally take this pure spontaneity view because there it makes not difference to add variables that have no consequence on the results; so there's no practical reason to think in terms other than pure spontaneity. Of course, not everyone, those working on hidden variable theories have a different view, and I'm sure there's some physicists that don't view hidden variable theories as fruitful to work on, and would bet against them coming up with any new prediction, but do not believe in pure spontaneity from a metaphysical point of view.

And, according to quantum physics things will stay with the pure spontaneity in terms of how predictions are made, but we can't exclude a revolution in physics next year or a thousand years from now that changes this perspective.

The definition of space and time would likely be a central part in any revolution in physics, but not necessarily relating to the spontaneity issue. Quantum gravity would be a revolution in physics, and the main approach for a while was to simply try to fit gravity into our Quantum theory and behave like the other forces (reduce everything to the quantum paradigm and call it a day); it's only the failure to have done so that has led physicists to more radical frameworks, that redefine time and space differently.