Reality, No Matter How You Slice It by Ken Wharton
Ken,
I very much enjoyed reading your thoughtful essay. The "Independence Fallacy" can also be examined in terms of quantum information theory (see my essay "A Complex Conjugate Bit and It"). Your all-at-once analysis is supported by Aharonov, Popescu and Tollaksen's time-symmetric formulation of quantum mechanics (Physics Today, November 2010).
You advocate a path integral in standard 4D spacetime approach, rather than "making almost everything interdependent in some strange [QM] configuration space". The problem is that while a static 4D block appears to remove subjectivity, as a God's eye view it is still based on forms created in the mind. The model is epistemic.
On the other hand, if a quantum configuration space is the ontic basis of being, our 4D spacetime collapses to a combinatorial group of symmetries with no unique solution. Perhaps dynamical time evolution is just the difference between the conditional entropy of the local observer (her ignorance) and reciprocal quantum entanglement entropy (the totality of all that is possible).
Best wishes,
Richard Shand
Hi Stuart,
Just because I'm advocating an all-at-once viewpoint doesn't mean I think there is a "formal system that can describe the complete configuration of the universe". In fact, my latest research is based on a framework that explicitly denies that one can deduce the exact configuration of any space-time region, even given the complete boundary conditions. (This is not to say there isn't one particular configuration, it's just that it's not knowable from only the external boundaries.)
As for why the rules that govern our universe happen to be the way they are, that's a good question, but one that's tough to address until we have the correct rules at our disposal! At the end of the day I imagine it will look quite simple and possibly unique, but that day might not happen in our lifetimes...
Best,
Ken
Hi Akinbo,
I'm afraid you still probably won't like my (materialistic) answers to your questions... but here goes.
1) Yes, Yes.
2) Would it have a "beginning"? If you mean a temporal beginning, then I suppose so (although there are interesting cosmologies in which it would not; see Sean Gryb's excellent essay.) But I can tell by your later questions that you also mean a *causal* beginning, that determines the rest of the universe, and this I reject in my all-at-once viewpoint.
3) If it did have a temporal beginning, associated with some cosmological boundary condition at the Big Bang, then while that boundary condition would certainly be an "IT", it would not need to result from anything else. Cosmological boundaries are like ultimate causes. There might be some rule that told us what that boundary might look like, but definitely not a causal rule in that it would have to evolve from something else. The all-at-once view helps with this perspective; if you're in a dynamical view, it may be hard to imagine a free-standing boundary constraint that doesn't evolve from anything else.
4) see 3.
Best,
Ken
Hi Lawrence,
As for whether I'm arguing for local hidden variables depends on exactly what is meant by "local" (see Matt Leifer's comment above). But I certainly do think there's a nice all-at-once definition of locality, as in GR; in that case it's possible to have a "local" ontology and still have crazy features like closed-timelike curves. My hidden variables also have the feature that they are all associated with points on spacetime, and correlations between points can only be enforced by continuous pathways.
I agree with your excellent point about how we're biased to see things as dynamical, but disagree there is necessarily a dynamical version of the all-at-once story I'm trying to tell. For example, the path integral only converges onto the Euler-Lagrange equations in the hbar->0 limit; is there a finite h-bar dynamical version? Well, arguably yes, if all you care about is probabilities, but I'm restricting the path integral further such that there is no dynamical version at all.
For more on this you might review my previous essay, the Universe is Not a Computer.
Cheers,
Ken
Hi Mikalai,
I enjoyed most of that last link you posted; excellent points!
Where I think we differ is that I don't assign any particular foliation as fundamental; time and space are all blended together in an all-at-once viewpoint, so Hamiltonian formulations are not fundamental either (or indeed, even always possible). So the energy x time = action is a bit of a red herring in my book; this is no different from momentum x length = action, and any approach that doesn't treat both of these on the same footing is probably treating time as special in a way that I don't think is justified... at least not in an all-at-once perspective!
Best,
Ken
Hi Jonathan,
I have no real problems with (say) a 5D cosmology, so long as it's analyzed "all-at-once". I don't think it's even coherent to talk about the (time)-evolution of a 4D universe into a 5D universe, because the meta-time that this evolution is happening in is supposed to be part of both the 4D and 5D universe. Maybe this is what you mean by saying a block view is impossible, but I'd go so far as to say *any* view is impossible, unless you assign the meta-time as a sixth dimension (in which case I'd advocate for an all-at-once 6D view).
Of course, there may be surfaces in an all-at-once 5D cosmology that are effectively the 4D universe that we experience, but that doesn't mean one can't take a 5D all-at-once view to describe this as well (which would include a 4D all-at-once view as a subset).
Best,
Ken
Hi Richard,
Thanks for the kind comments. Yes, there are some connections with quantum information theory, although I think the all-at-once view is more difficult to introduce there for a variety of reasons. And there are also connections with Aharonov's two-state formalism, but important differences as well. An all-at-once view of that proposal looks quite strange if you consider A) multiple particles, or B) how things compare on both sides of strong measurements.
I'm not exactly sure what the problem is concerning the mind. While my view is effectively "psi-epistemic" as applied to the standard quantum story, I'm a firm realist about the universe actually being filled with one particular 4D field history. Sure, we humans came up with the idea of physical fields, but that doesn't mean that they can't comprise a realistic ontology.
Best,
Ken
Dear Ken, what an excellent essay, I enjoyed reading it tremendously. Questions: is up is up or down is down? Is down is up and up is down? The Americans tell the Ausies correctly that you are the down-under people, whereas the Ausies retort correcyly we are the up-upper people and you the Americans are the down-under people. Both turn out to be correct from their respective frame of references as the center of their universe. Now back to this essay main point that time is a persistent illusion or is time a persistent real and our perception of no time is a persistent illusion of the illusion of time? Again both are literally correct from their respective frame of reference, however, KQID describes time is NOW in the block Multiverse every absolute digital time T≤ 10^-1000seconds as the Newtonian absolute time. Time is in a perfect symmetry that anything can go backward or forward at will. Every T, time-past-present-future collapse into the NOW and everything is rebooted, refreshed and renewed from Tn to Tn+1 to Tn+2 and so on. All the bugs are fixed and new version of the software Qbit is released Tn+x. No crash. This explains why computer like Multiverse does not crash. KQID: all things are one Qbit computed inside one singularity Qbit Multiverse. This is our block Multiverse all-at-once is a slice of all Minkowski events jump all-at-once according to Feynman's sum-over-histories to the next one and to the next one as you said like a movie running at ≥ 10^1000 frames/s, just like a movie of 120 minutes or two hours or 1/12th of day; hence we have Newtonian duration. This objective slice of our 3D Multiverse, not subjective slice as you pointed out is not possible. We do have as I called it KQID relativity ψτ(iLx,y,z, Lm) with its flexible c-timerod that gives length its length. When the c-timerod contracts its length contracts. At velocity at 0.6c, the time contracts KQID τ=(1-v^2/c^2)t=o.8t and the length = 0.8L. In short, KQID argues our Existence both absolute digital all-at-once: time disappears and relative Multiverse: time reemerges. This way KQID brings back our sanity, we can normally view the world as it is or as Ken Wharton and Leo KoGuan see the world from different lenses. As you wrote "the W's are now microhistories, span- ning 4D instead of 3D." Yes, KQID views micro histories are block all-at-once Multiverse moving along Lm Multiverse time line in the zeroth dimension as the 4thD that brings back time as we normally use time. Ken, your is an erudite essay encompasses everything. I read it at least three times and I need to read your article "The Universe is not a Computer" (arXiv:1211.7081). Excellent rating and please review and rate my essay Child of Qbit in time. Thanks, Leo KoGuan
Dear Ken,
I found your essay very well-argued and I was especially impressed how you tailored your conclusion to the theme of the contest, i.e. that"Instead of winning the argument by default, then, It from Bit proponents now need to argue that it's better to give up reality."
I have two questions:
1. How is your framework different from Bell's "Superdeterminism"?
It seems that if one wanted to express Superdeterminism in terms of 4-dimensional space-time one would arrive essentially at your way of looking at things. If that is true, then you are of course correct that your framework overcomes most of the objections to deterministic explanations for quantum phenomena. Is that what you are driving towards? In some of your previous works, I remember you mentioning that one should perhaps not be so quick to give up retrocausality, and if your present work is meant to be along the same lines, it seems to me that there really is no retrocausality in it because there is only one effect (The coming into existence of spacetime "as a whole"), whereas retrocausality requires at least two effects in a causal relation.
2. Can one really sensibly attribute a definite path to photons?
Of course one can use an affine parameter to substitute for the proper time in those contexts where one needs to give an expression for the time evolution of the photon as it "moves" in space, but as I understand it, the parameter is completely arbitrary. It seems to me that fixing the path of a photon removes the arbitrariness of the affine parameter and thereby transforms it into something as "real" as proper time itself. But if the parameter has a reality of its own, then it must also define relationships to the analogous affine parameters associated with all other objects. In effect, it seems to me that fixing the path of a photon then introduces a whole new parallel layer of a web of relations analogous to the web of relations between the worldlines of objects but now in terms of the integrals of the affine parameters (let me call these 'affine parameter worldlines' for lack of a better term).
Although one might look at it as metaphysical baggage, I don't think this is necessarily a bad thing because it may permit your framework to be experimentally tested. One would have to be able to deduce how the attribution of a fixed path to a photon or a set of photon(s) in some situation fixes the 'affine parameter worldlines' and see whether one can set up an experiment where one might encounter effects beyond those predicted by quantum mechanics based on the requirement that 1) these be consistent with one another and 2) they be consistent with the 'affine worldline parameters' of other objects, such as the emitters and absorbers.
I'm not sure how I would go about this mathematically, but otherwise the prospects for testing your framework experimentally do not seem very good. And, as you know, this a pretty much indispensable before your work can be accepted widely as a physical, as opposed to metaphysical, framework.
In any event, I enjoyed reading your work and wish you all the best,
Armin
Hello,
If I may be allowed to inject myself into this discussion: I think that without further specifications, the 'meta-time' in 5D cannot be part of the 4D universe because when transformed to a frame in which it is a proper time, it is constituted of one more quantity than spacetime proper times (i.e. 4+1 vs. 3+1).
In order for it to play any role in 4D there needs to exist a map which defines the relation between events in 4D and 5D. In Euclidean space, this is obviously not a problem because such a map is nothing other than an embedding, by which one may view 4D as a surface in 5D. I don't know whether such a map exists or can even be defined for the Lorentzian metric.
If someone knows the answer to this, I would greatly appreciate it as it plays a crucial role in the framework that I am working on.
All the best,
Armin
Dear Ken,
It occurred to me that the experimental approach that I suggested to you might more likely work better the other way around from the way I described above, namely, that the real affine parameter and the web of affine parameter worldlines may introduce additional constraints not present in standard QM which forecloses certain results (or configurations of results) in your framework that are allowed under standard QM. Of course, to be sure, one needs to do the math, but I hope that you nonetheless found my suggestion useful.
Armin
Hi Ken,
Your explanation of the Independence Fallacy and your account of a realistic QM is great!
I think your model is well worth developing but I believe it may be consistent with an underlying computational model, rather than foreclosing it: In the simulation paradigm, a computational substrate produces the effects that we observe. In one form of this, observers can see the "display screen" but not the "computer memory" of the system. An observer's timeline is a series of "explicate" snapshots from a particular perspective, which is computationally related to the "implicate" (hidden) state of the system.
Your "all at once" picture seems to me a good description of what such a system is doing internally. Internally, it does not have the past-present-future distinction that observers have, and so is free to propagate changes along the "4D links" you describe. In other words, there are two kinds of change: one that observers see as they view the cosmos along their timelines, and another kind of change that takes place "all at once" at each interaction of observer and cosmos.
This is the model that I explore in my essay Software Cosmos. What I call (after Bohm) the "implicate" seems to me what you describe as the "all at once" picture. We both agree that explicate observers do not have dynamics, the difference is that I see dynamics taking place in the implicate, rather than being discarded completely. I hope you get a chance to read it, as I would love to know what you think.
Hugh
Hey Ken,
I trust that you will take my comments in the spirit they are intended (besides, you can always take solace in the fact that you're better than me at Scrabble). And, of course, you already know that we agree on the final conclusion.
So I have a number of critiques about specific passages, but I think the broadly general issues I have are primarily centered around three things. First, I think that your argument basically flat-out denies that quantum contextuality even exists which is a pretty audacious claim given the evidence to the contrary. Second, I think you (and in all fairness a lot of people) mis-interpret relativity (I'll discuss that in a moment). Finally, you don't adequately explain how your model accounts for things like single-particle interference which is something that is routinely done in laboratories.
Expanding on the second point, I think there are a couple of problems. First, you say that there is no preferred reference frame in relativity. While this is certainly true in one sense, there, in fact, *is* at least one frame in which all observers will agree on the ordering of events and that is a frame that moves at the speed of light. It has always puzzled me as to why we ignore this fact. True, massive objects can't ever be in this frame, but it is nevertheless true that the closer two frames come to light speed, the more and more they will agree (does that make sense? if not I can e-mail you a more detailed response).
Second, you (again, like many, but definitely not all people) also take 4-D spacetime to literally mean that time and space are equivalent. But if they are perfectly equivalent, why, then do they appear to be different? Specifically, why does time always have the opposite sign of space in any realistic metric and isn't that alone evidence that they are, in fact, *not* the same? What mechanism produces time-asymmetry without producing an equivalent space-asymmetry? (Recall that there are, in fact, two different senses of time-reversal symmetry.) Where does the arrow of time come from (because if it doesn't exist, why haven't we reversed the aging process yet)? These are all questions that the 4-D spacetime literalists never seem to be able to satisfactorily answer (I've had this argument with someone at Fermi Lab once and he was unrelenting yet never could answer my points).
Finally (regarding spacetime), you deny dynamics but the moment that you imply some kind of ordering of events you are implying that something is no longer static. That's always been my biggest beef with the block universe concept. You can try to make time as much like space as you want, but by talking about any kind of "order" of events, you're essentially introducing an arrow of "time" in some sense of the term. For example, you say on p. 6 "When we lean about the experimental geometry of the future, this all-at-once analysis typically updates our probabilistic assessment of the past." But then it's not all-at-once! I mean, I see what you're trying to do: our information about the is dynamic while the universe is not. But then this goes back to my first point: that's only true if quantum contextuality doesn't exist and yet we have ample evidence that it does!
Now to some more specific comments, I disagree with your rose-tinted glasses assessment. I don't think it is at all like that. I also do not think that the various no-go theorems necessarily rule out an objective reality. The simply rule out the existence of some *inaccessible* reality (in fact it's only even one type of inaccessible reality that they even rule out). Regarding some of your interference experiment descriptions, in the single-particle Mach-Zehnder interferometer case, to get the quantum prediction the only possible explanation is that the particle must take both paths simultaneously. If it doesn't, you should never be able to repeat the experiment (see my blog post about this). I think that the photonic behavior disagreeing with Maxwell's theories is not a strike against dynamics as much as it is a strike against the field ontology, personally.
So, in short, there are so many quantum effects that you don't seem to explain and that is what I find most troubling. Of course, I'm happy to hear explanations if you have them. ;)
Ian
Dear Ian,
You made a number of very interesting comments, but I am afraid I did not follow all of them. I am really interested in better understanding your arguments, which is why I am taking the liberty to inject a couple of requests for clarification.
RE:c frame
Since all spacetime events in such a frame occur over a duration of exactly zero, I don't understand what you mean, unless you are referring to a 'simultaneous' time ordering?
RE:time ordering
It seems to me that when Ken mentioned an updating of probabilities, he was referring to a subjective phenomenon arising from our inability to experience spacetime all at once, but your critique seems to presume that there is an objective aspect to these. Is that correct?
RE:2 kinds of time reversal symmetry
Could you kindly distinguish between these?
I hope that these questions will also help others better understand your arguments.
Thank you,
Armin
Dear Ian,
I hope you'll excuse me butting in here as well, but you make a number of points that are of interest to me. I've been discussing the block universe issue with Ken above, and in my last posts (which he hasn't yet responded to) I wrote something about the Lorentzian signature of space-time, as well as something about a null frame, and I was hoping you could comment on that in light of what you had to say here. I'd also be interested to read the detailed response you said you could send regarding the frame that moves at the speed of light (my email address is daryl.janzen@usask.ca).
Also, your post has me intrigued to read more about quantum contextuality, so I'm going to read your essay on that. But in that regard, I'd be very interested to know what you might have to say in response to Ken's comments to me above.
Best regards,
Daryl
Hi Leo,
Thanks for your kind comments! I'm not sure I exactly understand your question/comment, but I get the impression you're not enamored of the block universe, and that you see a spatial "here" as being quite different from a temporal "now" in some objective sense.
I guess it's clear that I disagree, but I seem to be at a loss as to how best to persuade block-deniers that time is perfectly real in a block universe, just as real as space, but not essentially different. I do think it's fatally dangerous to think about our universe *without* freezing everything into a 4D block, because then our mental instincts about time and change can't be separated from the objective features we're trying to understand. (Nothing "moves" in 4D; motion occurs when the 4D block is sliced up and played as a movie, but there's a subjective choice involved in how one does this. This doesn't deny that what we think of as motion is an objective feature encoded in the block, but merely separates out which features are subjective.) I'll try a longer answer when I get to Ian's questions below; stay tuned!
Best,
Ken
Hi Armin,
Thanks for your nice comments and great questions!
1) What I'm proposing is usually termed retrocausality, which is completely different and opposed to superdeterminism (although often confused with it, including by Bell himself). In superdeterminism, a future event A is correlated with a past event B by virtue of an even-further-past event C, in the past light-cone of both A and B. This is purely forward-causal; C causes A and B. If A is an experimenter's choice, then it can *in principle* be correlated with the past hidden variables in B, resolving Bell's theorem. But this is a bizarre and conspiratorial explanation (why should my choices be correlated with distant hidden variables in just this manner?!) and I don't buy it for an instant.
Instead, I'm explaining correlations between A and B simply by virtue of the spacetime history which extends from A to B, so they have every reason to be correlated in just the proper way. Of course, if that history obeys some deterministic or stochastic equations, then we can't get the right sort of retrocausal correlations to resolve Bell's theorem. But as in the example model from the essay, as well as in the following discussion of the double-slit experiment, I hope it is clear that removing such dynamical equations (and assessing the histories via stat mech-type reasoning) naturally resolves this problem. The external (future) choice of the experimental setting is naturally correlated with the past hidden variables, not because of a joint common cause, but merely due to the fact that different settings lead to different classes of allowable histories.
For the full proof-of-principle, you'll have to wade through the toy Lagrangian in arXiv:1301.7012, but so far it seems to work quite nicely, at least at that level.
2) No, my approach doesn't assign well-defined paths to photons, merely well-defined EM field configurations. For example, in the double-slit experiment, when interference is measured, the EM field really does pass through both slits before converging on the screen. Even in the which-slit case, it's not so much a well-defined particle-path as an extended field distribution (think of a laser beam that fills one of the two slits, and then converges onto the point of measurement).
Of course you're right that the key is to come up with a testable experiment, and I'm hard at work trying to get to the point where I can devise one. I'm a (lapsed) experimental physicist myself, and fully recognize the importance of making contact with the laboratory. If you look through 1301.7012 you'll see lots of places where experimental differentiation from standard QM starts to look probable, but devising an actual, doable experiment still requires a stronger theoretical foundation than what I've managed to date.
Cheers,
Ken
Hi Hugh,
I'm glad you enjoyed the essay!
At the surface, at least, my 'universe is not a computer' premise (see last year's essay) seems wildly different from your 'software cosmos', but I did see that you favor the fields-over-particles framework, which I'm certainly on board with.
As far as talking about the all-at-once perspective, I think it's crucial not to talk about "change" or "propagation" in a 4D perspective; once time has been mapped to a space-like axis, there's no remaining time dimension for either of those concepts to make sense.
I certainly will agree that, given a block history, we can experience it as "snapshots from a particular perspective", complete with our usual experience of time. But if you try to put ordinary dynamical equations back in at that level, I don't see a way to rescue either time-symmetry or a spacetime-based reality. (Yes, we need to recover *average* dynamics to explain our macroscopic world, but that's not really the same thing if they don't hold at a fundamental level.)
Best,
Ken
[deleted]
Ken, Armin, and Daryl,
Let me see if I can respond to these questions adequately here.
First in regard to the c frame. So, since light travels at the same speed (set c=1 for simplicity) in any inertial frame, it would seem that all inertial frames would be at rest relative to light. But this can't quite be true because if it were, there should be absolutely no benefit to accelerating one's speed to near that of light, at yet we know that there is (e.g. relativistic muons and the whole Twin Paradox which isn't actually a paradox). True, it is the act of accelerating (and thus lengthening one's worldline) that does it, but you can't do it by *de*-celerating so it amounts to the same thing. So that means that there is some objective reality about the c-frame (because, for instance, in the Twin Paradox the space-faring twin really is younger upon their return).
So imagine two reference frames, each one traveling at some speed relative to a third frame that we will treat as being at rest. Also suppose that there are two events, A and B. It's fairly easy to determine t(AB) in the three frames and thus to calculate the difference between the values recorded in the two moving frames. Now accelerate suppose the two moving frames are moving faster, say by the same percentage (so, suppose they're really going 50% faster in reference to the rest frame than before). From the POV of the rest frame, they will each appear to be moving closer to the speed of light than they were. If you now calculate the values for t(AB) you will see that they do not differ as much as they did before. There's actually a simple graphical way to do this. At any rate, this is in line with the fact that there is some kind of objective reality about the c-frame (even though massive objects can never be in it). (Hopefully some of this answers both Daryl's and Armin's questions --- there is still relativity of simultaneity, it's just that there is one thing that actually is absolute in relativity and that is the c-frame).
Now, regarding the time-ordering thing, I'm not sure I'm necessarily saying one or the other regarding objectivity and subjectivity. All I'm saying is that if you're doing something "all-at-once" and then you say you "updated" something, well, it ain't "all-at-once" anymore. I think it's a bit of a cheat. So if you've updated your information, even if you analyzed the universe all at once, all that it tells you is essentially that your first analysis was wrong. So what's the point?
As for T-symmetry, an operational view interprets it as motion reversal, pure and simple. This is sometimes referred to as time reversal "of the first kind." In the Feynman-Stueckelberg formulation, however, it is interpreted as a simultaneous reversal of proper time as well as a particle/anti-particle conjugation. The latter differs from a full CPT transformation in that it lacks the parity flip. So it's a bit like a CT transformation. On the other hand, in order to guarantee an anti-particle on a conjugation, the full CPT operation needs to be used. To see how these things all compare, take a look at this paper (in particular Table 1 which shows which signs get flipped in the various situations): http://www.sdu.dk/media/bibpdf/Bind%2020-29/Bind/mfm-28-5.pdf. It should be noted that there are other interpretations of t-symmetry as well.
Ian