Dear Ken. Hello, and apologies if this does not apply to you. I have read and rated your essay and about 50 others. If you have not read, or did not rate my essay The Cloud of Unknowing please consider doing so. With best wishes.

Vladimir

Hi Ian,

Thanks for some interesting comments! Yes, there are lots of things not addressed/explained in the essay (contextuality, etc.), so thanks for raising the issues.

I'm very curious about your impression that I'm denying contextuality; it makes me think you're reading quite deeply into this. On one level, my central example is explicitly contextual. In the double-slit experiment, there are entirely different (mutually exclusive!) pasts that correspond to different future measurements; if you choose to measure which slit it goes through, it really went through only one slit. But if you choose to measure the interference pattern, it really went through both slits. Depending on your definition of contextuality, that's most of the game right there. It certainly explicitly violates the assumptions of the Kochen-Specker (KS) theorem, without giving up on realism, via the so-called "retrocausal loophole". (People may not like retrocausality, but it's still a well-established way to violate the premises of the KS-theorem.)

That said, I'm intrigued by your impression, because in another sense I think my story *is* effectively noncontextual, in that one reality literally "pre-exists" before the measurement choice. I just had a very interesting meeting with Matt Leifer where he laid out a more general definition of contextuality that keeps the same basic spirit of the original but allows noncontextuality to be compatible with KS-contextuality in this sort of retrocausal framework. (I hope he writes it up soon!) So I think the story can in principle be KS-contextual but Leifer-noncontextual.

I *think* this is what you're getting at when you imply that I can't both have 1) an all-at-once story about reality, 2) an updating-story about our states of knowledge, and 3) contextuality. You obviously can have 2) in an all-at-once story, just as you can have a computer in a block universe, so 1) and 2) are fine together. I think here you're assuming that 1) and 3) are incompatible, but that's only true for something like Leifer-contextuality, not for KS-contextuality. So long as I have contextuality in the latter (which I explicitly do!), I don't need it in the former.

It's a bit similar to the "non-local" accusation I sometimes get; if you define locality as per Bell in a way that distinguishes the past and the future, my story is technically Bell-nonlocal, but if you define locality (as in GR) based on associating properties to points on the spacetime manifold, along with some topology that restricts action-at-a-distance, then my story becomes "local" again in some meaningful sense (though not, of course, BELL-local). See Matt's comment above for a promising set of research projects along these lines (generalizing locality and contextuality to deal with retrocausality in a meaningful way.)

Your time-symmetry questions will require another long subsequent post, but I will comment about the "frame" in which you're moving with light. This is actually the only frame *without* ordering, because in this frame every event has the same time-coordinate. Instead of a temporal order, everything literally happens at once. (The same is true for the spatial coordinate in the direction of lightspeed travel, with infinite Lorentz contraction.) So instead of a universe parameterized by four dimensions, that "frame" only is parameterized by 2 dimensions, with the other 2 dimensions squashed into the plane. In part because of this, it's not a true frame at all; you can't possibly unboost from such a "frame" back into a non-lightspeed frame and recover what you started with. And because of these problems I'm not sure it's a very good support of the point you're trying to make.

I'm not sure how you equate an order with an arrow. Spatial locations are certainly ordered, and yet have no inherent arrow. I'm just doing the same for time - isn't that how you thought of time when you worked on GR?

I'm in full agreement that the EM field goes through both slits when you measure interference! Are you in agreement that it only goes through one slit when you measure which-slit it went through? As for particles vs. fields, I can imagine fields that go through one slit and other fields that go through both slits. I can imagine particles that go through one slit but *not* particles that go through both slits. So if you think the photon is really going through both slits, why wouldn't you want a field ontology? (Assuming you want a realistic ontology in the first place, that is...)

More on time's arrow soon... Are there any other quantum effects that seem particularly problematic from my perspective? (For the quantum eraser story, you have to go back two essay contests to 'quantum theory without quantization'... But of course that has always seemed retrocausal, so that's sort of easy game.) I want to consider everything up front, before I get too deeply into this, to make sure there aren't any showstoppers that will stop me in my tracks further down the road.

In your response to Armin above, you asked "what was the point" of updating when you had it wrong the first time... I'll assume this is a bit tounge-in-cheek... But of course in *any* hidden-variable theory you have it wrong the first time, by definition; see my states of knowledge that describe the toy model in the essay. They're *explicitly* wrong, in that one *knows* that one doesn't know. Given such a situation, if you did gain new information (about the future setting, or outcome), of *course* you will update your knowledge. If not, "what was the point" in learning anything in the first place? :-)

Now, if you're problem is that I'm not giving an all-at-once account of *consciousness*, well... er... um...

That's not my field. ;-)

Thanks again!

Ken

PS; Daryl, I'm trying to find time to get to your mini-essay in the comments up above... hopefully next week.

Dear Ken,

You wrote: "I *think* this is what you're getting at when you imply that I can't both have 1) an all-at-once story about reality, 2) an updating-story about our states of knowledge, and 3) contextuality. You obviously can have 2) in an all-at-once story, just as you can have a computer in a block universe, so 1) and 2) are fine together."

I have to strongly disagree with this. In an all-at-once universe, where everything "pre-exists" and nothing "is", you really can't have an updating story about states of knowledge. I think Ian's right about that. The sequencing of your "updating story" still presupposes some sort of temporality. In an all-at-once universe, every instance of knowledge acquisition "pre-exists" as well, all at once. It's a set, not a sequence. You can try to define it as a sequence because of the "spatial" order, but the only way to get from one element to the next and "update" is in time. You can't have an updating sequence if the too-easily-smuggled-in fifth dimension that we know all about is *truly* singular--i.e. if the block doesn't exist, but really "pre-exists" *all-at-once*.

I know you know of the danger of conceiving of the block as an existing thing itself, because you've cautioned a couple of people about thinking that way in the comments here. I personally think it's the greatest and most common mis-conception that occurs when buying, hook, line, and sinker, into Einstein's relativity of simultaneity--which is why I spent so much of my (actual) essay discussing that. A block universe doesn't exist, whether one takes your view or mine on relativity and what constitutes an appropriate definition of "simultaneity".

The true all-at-once block universe can't in any way "update" because there's no temporality left in the description whatsoever--it's a purely mathematical model; a Lorentzian geometry that *isn't*. The alternative is that it's just a map of all the events that occur in reality--i.e. not a representation of reality itself, which is completely impossible to reconcile with reality, because something *is* updating.

The simplest alternative to the completely unrealistic model is to admit, as a first principle, absolute space, and therefore absolute motion and absolute simultaneity. This is completely consistent with the cosmologcal evidence anyway. For some reason, people get all hepped up about calling a cosmic rest-frame a "preferred" frame or a "privileged" frame. As my first post above indicates, this is complete nonsense and utterly ridiculous. The notion that the observers in such a frame are "privileged" supposes that all inertial observers should consider themselves as being "at rest"; that they can't stick out a measuring tape to use, that they conceive as "really moving" and use it to describe events. It's baffling that anyone ever bought the notion that the "man on the street" walking around considers himself to be at rest while the whole world just moves around him;--that two "men on the street" who walk towards each other will both think of themselves as being "at rest" while everything's moving around them, and that there's a day's difference in what they describe as happening "now" in Andromeda.

But that is *exactly* what the initial argument in your essay supposes.

Both men on the street are, however, thinking the same thing about what's at rest and what's moving around--and what they think is at rest is not a bunch of stuff in "space" that's orthogonal to their proper time axes; it's the Earth.

An absolute rest-frame is perfectly natural to understand, even if it's not the rest-frame of our everyday lives (the Earth) AND it's supported by the cosmological evidence--which is all that matters, because relativity theory tells us (i.e. due to the principle of relativity) that the physics has to work regardless of one's frame of reference and their associated preception/conception of "actual" motion; i.e., it tells us that we can do physics under the assumption that the Earth is "at rest".

Daryl

P.S. Thanks for saying you'd respond to my "mini-essay" above. I'm sorry it had to be so long. By the way, the two posts I left the next day are off-topic, and only meant to justify the claim in the first paragraph of my response, becasue I don't think you'd trust the claim as truly justified (sort of in the way that Leibniz saw Clarke's claim of appreciating and agreeing with the principle of sufficient reason as actually not being the actual case). Similarly, what I'm saying in this post is that while you're claiming that your conception of "an all-at-once block universe that updates" is only four-dimensional, and even though you understand that it's too easy to start thinking of it five-dimensionally, I think you do still have a five-dimensional perspective. Maybe you can show me why I'm wrong. I'm ready to listen, and I don't mean this in any disrespectful or insulting way--I just personally think it's impossible to think of otherwise, because the true four-dimensional view really is impossible to reconcile with an updating reality.

"It's a set, not a sequence. You can try to define it as a sequence because of the "spatial" order, but the only way to get from one element to the next and "update" is in time."

Sorry: more accurately, due to the metrical structure, it is a sequence, but one which doesn't *unfold*. It's temporally singular, and for that reason it couldn't possibly be distinguished from an unordered, temporally singular (and more clearly conceived as such) *set* by "inhabitants", whose perceptions could never "update" in any way. The only way for the sequence to *unfold* is if there is some temporality; some tense. The Lorentzian signature, which distinguishes the "timelike" direction from the "spacelike" one, just doesn't cut it; it's just a particular "other" kind of four-dimensional geometry. (And in that regard, the first result I posted in my addendum above shows very neatly just how very much *like* a "Riemannian" geometry a "pseudo-Riemannian" geometry can be (and I was hoping, because of Ian's interest in Eddington, that he could have a look through that derivation, because I think it goes some way towards supporting Eddington's views on what R_ab=Lambda*g_ab really means, and might say something about *why* the geometry of space-time should be Lorentzian anyway)).

Regards,

Daryl

Hello again, Ian,

Okay -- time to tackle this paragraph from your original comment:

> 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?

Sure, but it's important to recognize that just because space and time are equivalent in some senses (they're both dimensions, and neither has a inherent direction) doesn't mean that they're equivalent in *all* senses. Yes, the signature of the metric is such that there is always a (highly-)local inertial frame with a time-like axis, but the whole point of GR is that one isn't forced to do physics in such frames. The mere fact that it's *possible* to do physics in other frames (using the same equations!) means that there must be essential features shared between space and time. And those features are topological: ordered, but without preferred direction. (Otherwise space would inherit a preferred direction in such non-inertial local frames, or *any* single global frame.)

>What mechanism produces time-asymmetry without producing an equivalent space-asymmetry?

Ah, now here you're getting into Eddington's idea that there might be some missing physics that we don't know to explain the evident time-asymmetry around us. And if you postulate such physics, sure, then you break CPT-symmetry with new physics. But it's widely understood that this isn't needed, and that the ultimate source of the apparent asymmetry is cosmological (widely, in the sense that it's accurately reported in many popular science books, from Carroll to Penrose to Greene).

To make a long story short, the asymmetry is in the boundary conditions, not the laws. We're closer to a low-entropy initial boundary than we are to any low-entropy final boundary. Therefore, here, there's an evident time-asymmetry. The spatial version of this would be a temperature gradient caused by asymmetric spatial boundary conditions. You don't need asymmetric physical law to get an asymmetry. (Yes, it's a mystery why the Big Bang was such low entropy, but that's an entirely different question.)

> (Recall that there are, in fact, two different senses of time-reversal symmetry.)

I think the relevant and useful sense here is the question: if you took a movie of events and time-reversed it, (or CPT-ed it), would it still describe a possible process?

>Where does the arrow of time come from (because if it doesn't exist, why haven't we reversed the aging process yet)?

Cosmological; see above.

>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).

I don't know how much patience you have for wading through philosophical arguments on such topics, but you might try this:

http://philsci-archive.pitt.edu/4829/

One upshot is that it's perfectly possible (and easy!) to think in terms of the block universe without thinking that time or change are unreal. They are REAL features of the "4D-static" block. To think that only a dynamic perspective can treat time "properly" is to sell us 4D-blockers short. And if there's some seemingly-important feature of time that vanishes in the block view, it's crucially important to ask yourself why this isn't evidence that such a feature perhaps doesn't objectively exist.

All the best,

Ken

But in that article, Price considers an explicitly 5D view and calls that presentism. He takes the 4D block and moves a spotlight along it. You can't move a spotlight along the block unless it exists. He finds this view of presentism inadequate, because why shouldn't all four dimensions just all exist; but that too is a 5D perspective. Greene, who you mentioned as well, puts the picture to us this way:

"Undeniably, our conscious experience seems to sweep through the slices. It is as though our minds provide the projector light referred to earlier, so that moments of time come to life when they are illuminated by the power of consciousness. The flowing sensation from one moment to the next arises from our conscious recognition of change in our thoughts, feelings, and perceptions. And the sequence of change seems to have a continuous motion; it seems to unfold into a coherent story... The intuitive image of a projector light that brings each new *now* to life just doesn't hold up to careful examination. Instead, every moment is illuminated, and every moment remains illuminated. Every moment *is*. Under close scrutiny, the flowing river of time more closely resembles a giant block of ice with every moment forever frozen into place.""

Broad's spotlight view of presentism *begins with* a 5D view of reality, so of course one ends by rejecting the extra structure of a 3D sweeping space that adds a bunch of extra structure by saying that's the only part of the four dimensions that are already conceived as existing that *really* exist. But that's not remotely what presentism is about. Presentism is the view that only the 3D universe exists. Because it exists, it has to be described by a 4D mathematical model, just as Greene's 4D "giant block of ice with every moment forever frozen into place" is a 5D view. Every moment *remains* illuminated. Every moment *is*.

Maybe consider this, from Einstein's autobiography:

"It is a wide-spread error that the theory of relativity is supposed to have, to a certain extent, first discovered, or at any rate, newly introduced, the four-dimensionality of the physical continuum. This, of course, is not the case. Classical mechanics, too, is based on the four-dimensional continuum of space and time. But in the four-dimensional continuum of classical physics the subspaces with constant time value have an absolute reality, independent of the choice of the reference system. Because of this the four-dimensional continuum falls naturally into a three-dimensional and a one-dimensional (time), so that the four-dimensional point of view does not force itself upon one as *necessary*."

So relativity forced the 4D point of view on us as necessary because space-time, according to relativity, is a 4D connected metric space, whereas in Newtonian theory it's a disjoint union of two metrics, E^3 and t. Because of this, the dimensionality of the physical continuum according to Newtonian theory wasn't obviously four. Relativity certainly clarified this. But in doing so, it seems for many, who have come to think of all four dimensions as real, to have introduced a fifth dimension, which is not represented at all in the mathematical model, but is nevertheless a part of the interpretation of the mathematical model in much the same way that the fourth dimension of Newtonian mechanics was always there even though some thought only of the three dimensions of space.

But Newtonian mechanics explicitly contains the fourth dimension (time) as a variable, and still people didn't always think of the dimensionality of the physical continuum as being four. So my question is this: is it really at all surprising, given that there's no justification for a fifth dimension which is anyway not formally accounted for anywhere in the theory, to think that people should have a difficult time understanding that their 5D conception of the block *actually is* 5D and not 4? Nevertheless, the "4D-static" conception of the block clearly is five-dimensional when you come to think of it.

That's a lot to digest when the temperature and humidity are both hovering near 100 ºF (hopefully it will break by evening). But I will say from a brief skim of the comments, it seems Daryl has nailed by concerns with the all-at-once problem.

And, by "order" in the spatial sense, what do you mean? Because, in the sense I think of it, there absolutely is an arrow (heck, that's how we draw axes!).

Hi Ken,

With more than a little bit of astonishment, I read Ian Durham's claim that you do not properly understand relativity, because of the existence of "at least one" preferred frame. Ian is wrong -- the preferred frame is not "at least one," it is a zero frame, and in general relativity the universe is a 4D quantum.

Only in the static model of quantum complex Hilbert space where time is treated independently and unitarily does such a preferred frame exist -- mathematically. Physically, too? Only if one disregards the demonstrable fact of classical time reversibility. One recalls that mathematics is never "about" anything -- whether preferred frames or any other physical concept -- while as you say, physical theories *must* be about something.

Yesterday my wife forwarded to me from another source, some optical illusion puzzles -- one of them was a silhouette of a twirling dancer; one can see the dancer twirl one way, and after some concentration see her twirling in the opposite direction. I already knew how this trick works -- like Thompson's lamp, the left-facing extended dancer's leg is 'on' while the right-facing leg is 'off' and vice versa. If I had remembered this phenomenon when I wrote my essay I would have referenced it as an example of time reversibility in two dimensions.

It's kind of ironic that I agree with you on classical time reversibility and reach the opposite conclusion about the foundational status of information -- I think Wheeler was right that information is all there is. Time reversibility, though -- as in the above example -- is also information independent of the physical status of an object. The dancer's extended leg is orientable, so the question "In which direction is she twirling?" has a definite answer in a particular moment, though no such answer is available in the case of a symmetric object at the speed of light *except* when measured. Just as with the optical illusion, however, a measurement only begs the question; the initial condition determines the direction of rotation, and that initial condition is *our* choice, not nature's.

Anyway, your implying that physical theories have to be about something reminds me of arguments I used to get into years ago with creationists. What, I ask is creationism a theory *of*? In contrast, Darwin's theory is a theory of common ancestry. Likewise, general relativity is a mathematically complete theory of gravity. What is quantum mechanics a theory of? Wheeler's answer -- a theory of information -- appeals to me, because it suggests that a fully relativistic theory of the quantum *can* be made mathematically complete.

As usual, Ken, I just like the way you think and write. You have my vote of confidence -- all best in the essay competition.

Tom

    I feel compelled to reproduce a comment that I made in your last year's essay forum:

    "I love your statement, 'Now there's one last anthropocentric attitude that needs to go, the idea that the computations we perform are the same computations performed by the universe, the idea that the universe is as 'in the dark' about the future as we are ourselves.'"

    Absolutely.

    Tom

    Hi Ian and Daryl,

    Ian: Sorry about the heat; I hope it cools off soon! And I'm relieved to see that last point you made; It means we aren't far apart after all. Yes, your "arrows" on your spatial axes are just fine, for time and space both. We have to choose an ordering parameter, I suppose, and given this arbitrary choice it's true that one direction has a parameter that goes up and in the other direction the parameter goes down.

    All I'm trying to say about the arrow of time is that we shouldn't say anything about it that we shouldn't say about the arrow of space *given known symmetries*. There are no accepted physical theories that allows a process to occur in the +x direction that could not also occur in the -x direction, and the same is true for +t and -t.

    By an fundamental "arrow" of time I was talking about processes that are allowed in one direction but disallowed in the other, and if you generalize to CPT symmetry, there are no such accepted processes (depending on the status of objective collapse, which is the crazy exception that proves the rule is a good one!). So I think we can avoid my arrows and yet have your arrows, bringing us into more agreement. (The other type of arrow, that of evident T-asymmetries on the macroscopic scale, are due to T-asymmetric boundary conditions. But again we can have X-asymmetric boundary conditions that produce spatial arrows, so again time and space are still on the same footing in this regard.)

    Daryl: Your argument seems to be that the 4D block view of Price or Greene is really a 5D view in disguise. Those are "fightin' words"! :-)

    Suppose I have in my possession a DVD, that encodes (discrete) 2D video. The data on this DVD then can be expressed in a (discrete) 3D block, 2 spatial dimensions + 1 time dimension. The block is just as static as the DVD itself. Your argument seems to be that this 3D data is "really 4D", because in order to play it I need to introduce a new dimension. But this is evidently not true. The DVD does not encode a 4D structure. Playing it just projects it back to 2 space + 1 time.

    I'm not sure exactly which logical error you're making that convinces you that the 4D block universe needs to be represented in 5D... Perhaps you're thinking of it from the perspective of some 3D structure in the 4D block? (Equivalent to thinking about the DVD from the perspective of a 2D character in the video.) If so, that's a mistake: you need to adopt Price's "view from no-when", outside the block in the same way that we're outside the DVD. Otherwise it's too easy to mix up objective and subjective notions (lots of sub-fallacies follow from this, but adopting the proper perspective solves them all with one fell swoop).

    Another possibility is that you are simply too wedded to the growing-block view to think in any other way, and this clearly does require 5D. In that case every event in the universe needs 5 numbers to describe it; 3 to describe where it is, one (t) to describe when it is, and one more (t') to describe when one is discussing that event. (In most growing-block views, if t' is less than t, then the event is given some new property like "undetermined", but if t' is greater than t, then the event is given some different new property like "determined".) In order to keep track of these new types of properties, one needs 5D. Obviously, I don't think these new type of properties are an objective feature of reality, so I don't need a fifth dimension to keep track of them, and can describe everything in 4D. Of course, maybe they are real, in which case the block universe misses out on actual 5D physics. But you still can't argue that the block universe *is* 5D; it's explicitly 4D!

    If you don't think you fall into either of the above fallacies, then maybe there's another conceptual framework that I need to be made aware of.

    Best,

    Ken

    Hi Tom,

    Thanks for your nice comments... I like that quote, too! :-)

    I'll have to look at your own essay to see if I can understand the rest of your comments; maybe I'll try to contrast our views on your comment page.

    Best,

    Ken

    Hello Ken,

    Apologies for commenting so late in the contest! I really like your essay and the approach is clever and up my street! Title sums it up well too.

    All at once makes excellent sense. I like the rose tinted specs analogy at the start. I too tend away from It from Bit.

    Your work here has made me consider my 3-spatial dimension, etc, mimicking the Fibonacci sequence around a Black Hole. As 4 corresponding to 4D space-time isn't in the sequence (when passing through zero) I omit time for the my purposes. I think that our two ways of considering the question sit well together.

    If you still have time to take a look at my essay, I'd very much appreciate it.

    I think you're going to do well in the contest & wish you all the very best!

    Congratulations on an excellent essay,

    Antony

      Hi Ken,

      What I meant when I was responding to Armin was not-so-much tongue-in-cheek (though I meant no offense) as it was trying to point out that the all-at-once paradigm doesn't make any sense to me when coupled with the concept of "updating." The former implies a singular while the latter implies a plural.

      So here's the way I see it. What you could be saying is that we do an "all-at-once" analysis of the universe and then as we learn more information about it (both past and future) we continue to do so and thus "update" our information. In this way the underlying universe remains essentially "static" while our knowledge of the universe possesses an arrow of sorts (since we are gaining information about it). Now, I'm not particularly familiar with Matt's notion of contextuality and I'll have to do some digging into it, but from my own notion of contextuality there's a problem: the universe does *not* remain static. In other words, it is not always possible to deduce *past* states from future ones. It would seem that your argument does not address this issue.

      Now, regarding the time-asymmetry issue, I disagree with Carroll, Penrose, et. al. Rather, I agree with Eddington who did not, necessarily, postulate new physics to explain this problem (he postulated new physics to address other issues). Eddington viewed the time-asymmetry question essentially entirely in terms of probabilities (actually, that's pretty much how he viewed everything). I really don't think it is that mysterious. The problem with the Carroll, Penrose, et. al. interpretation is that it assumes that the Standard Model is correct which in turn says that CPT-symmetry is inviolable. But there are notable problems with the Standard Model (it fails on a number of counts not the least of which is in relation to gravity). In addition, there is some evidence that CPT-symmetry is no inviolable. Recent studies of neutrinos suggest that it is possible that neutrinos and anti-neutrinos have slightly different masses. If so, this would be evidence of CPT-symmetry violation. All of this is to say that I think the cosmological case for the arrow of time is built upon some shaky ground (and I didn't even mention inflation). Heck, Sean Carroll himself addressed some of these issues at the last FQXi conference.

      Now, to the c-frame issue. Obviously you are correct in saying the the c-frame itself is unattainable and, perhaps, unphysical in some regards (though clearly it is at least partly physical since light exists!). But the bigger point is that there *is* an objective ontology to relativistic frames. Otherwise, the Twin Paradox would really be a paradox. But it's not. The space-faring twin really is older --- they both agree on that when they meet again. Likewise, relativistic muons created in the upper atmosphere really do take longer to decay. And as two frames get closer and closer to c, they get more and more in agreement. That's the objectivity that I'm talking about that we all tend to ignore. If reality were completely subjective (relative), then the twins would each think the other was older.

      This all goes back to that deep issue of time. While the laws of physics (mostly) seem to be time-symmetric, there's clearly a problem since we never see them run in reverse. If this is a purely cosmological problem, why is it that we never see, say, sub-atomic particles "un-decay?" Time is simply different. Relativity provides us with a convenient framework within which to treat time in a similar manner as space, but even *it* has a preferential arrow built into it --- allowing for complete time-symmetry in relativity produces logically absurd results. This is precisely because time is different in the metric --- it's sign is always opposite that of space. Incidentally, Lev Okun wrote an article about this very point a number of years ago but the cosmologists and many high-energy physicists still seem to cling to this notion that space and time are the same (and thus mass and energy also are the same), that the universe is really symmetric, that the Standard Model is correct, and that time-asymmetry is just an illusion perpetrated by cosmological expansion.

      I hope that answers some of the points you have raised. If I missed responding to something, let me know.

      Cheers,

      Ian

      P.S. It is thankfully much cooler today...

      Hi Ian,

      Yes, I think we're just about on the same page; at least I think we agree where we disagree.

      > What you could be saying is that we do an "all-at-once" analysis of the universe and then as we learn more information about it (both past and future) we continue to do so and thus "update" our information. In this way the underlying universe remains essentially "static" while our knowledge of the universe possesses an arrow of sorts (since we are gaining information about it).

      Yes! That's it precisely.

      > Now, I'm not particularly familiar with Matt's notion of contextuality and I'll have to do some digging into it,

      You'll have to email him directly... Nothing's written up yet, I don't think.

      > but from my own notion of contextuality there's a problem: the universe does *not* remain static. In other words, it is not always possible to deduce *past* states from future ones. It would seem that your argument does not address this issue.

      Alas, I guess I didn't write a good essay, because this was the #1 goal I was trying to accomplish, above all else.

      I would hope though, that if I *was* able to successfully show that learning about a measurement setting would cause one to update the past in different ways for different settings (as I tried to do in my various examples), then one would have the *appearance* of contextuality, even if the past really was determined in some all-at-once sense.

      > Now, regarding the time-asymmetry issue, I disagree with Carroll, Penrose, et. al. Rather, I agree with Eddington...

      Yes, I knew your position of course... But it's important to state this outright when discussing time-symmetry; just because the asymmetries seem like common sense doesn't mean they're part of known physics. And while Eddington's challenge is possibly do-able, the difficulty is rather steep; not only does that viewpoint require that one show the current Carroll/Penrose/Greene/Price story is insufficient to explain observations, but it requires one to posit new physics that is (as far as I know) hypothetical and vague. So Eddington may have common sense on his side, but time-symmetry has pretty much all of modern theoretical physics on its side.

      > If reality were completely subjective (relative), then the twins would each think the other was older.

      But without acceleration, it *is* symmetrical; they *both* think the other is younger as they're moving apart. Until there is an acceleration and they come back to the same point (or at least to within a small-enough invariant spacetime interval), there is no objective fact of the matter as to which twin is really older.

      > If this is a purely cosmological problem, why is it that we never see, say, sub-atomic particles "un-decay?"

      The same logic as breaking-wineglasses applies here as well. Every process has its reverse. If there's one input and two outputs, the reverse simply requires a bit more coordination to bring two inputs together at the right place and time (as we can only control the inputs). Three-output decays, and reversing it gets quite tricky indeed. There's also the issue that decays which produce net energy require net input energy to occur in reverse; still do-able, but not nearly as likely (at least not without a low-entropy final boundary condition).

      I guess I don't understand how the different sign in the metric implies some new *asymmetry* in your mind. Sure, space and time are a bit different, but... *that* different? One is symmetric and one is not? Surely such an asymmetry would show up in Mawxell's equations or Einstein's equation? What about my earlier argument that in different reference frames this would imply that *space* inherits the time-asymmetry?

      Maybe we should move this to email, if you want... Let me know!

      Ken

      Hi Ken and Ian,

      Thanks for keeping this discussion going. And Ian, I'm glad to see that I wasn't mis-representing your point of view, and that we're in agreement.

      First of all, I just want to ask you guys once more to look at the post I left above, on Jul. 10, 2013 @ 23:39 GMT. In relation to Ken's point about the arrow of time--i.e.

      "All I'm trying to say about the arrow of time is that we shouldn't say anything about it that we shouldn't say about the arrow of space *given known symmetries*. There are no accepted physical theories that allows a process to occur in the +x direction that could not also occur in the -x direction, and the same is true for +t and -t."

      --that derivation presents a clear case in which he's completely, unmistakably right.

      Now, in response to Ken's comments for me: thank you very much for posting them, and taking up the challenge in the spirit that it's intended--i.e., seriously, and in good faith. In that sense, "them were fightin' words" indeed. I'm not able to respond properly right now, because I'm just heading out to a metaphysics of time workshop in (breathtakingly beautiful) Lausanne, but I wanted to let you know that I have seen your post, and I'm really looking forward to keeping up the discussion.

      Two things I will say: I'm very glad to see that we're in full agreement on the dimensionality of the growing block model--it's unmistakably 5D; and I agree that the DVD contains 3D data. On the latter point, my argument isn't that the data are "really 4D", any more than de Sitter space (see the post I mentioned) is "really 5D". I'll do a better job of explaining myself later, now that I have your argument to work with. Indeed, I do think the right conceptual framework has been missed in philosophy of time. Today, I'm going to look to either be shown that it hasn't, or to see which points in particular I need to address in order to clarify.

      Best regards,

      Daryl

      Outstanding: A beautiful description of the independence fallacy. This is an excellent way to describe why slices in Minkowski space are profoundly unreal, and lead to inconsistent statistics in the "information record" of Bell states and other quantum experiments.

      My favorite quote from the paper "But if one updates the past probabilities upon learning which measurement a system will encounter, the premises behind those theorems are explicitly violated."

      It appears, however, to be incomplete in one aspect, it needs a more distinguished understanding of what "dynamical evolution" means. I suspect the "dynamical evolution" aspect you are trying to stay away from is the "monotonic, irreversible flow of time".

      I have not yet read your other papers in the references, as soon as I get through this huge volume of FQXi material, I will be sure to go back and read all your papers. I really enjoyed this one, these are excellent ideas, and your writing style is very high quality.

      I would differ with you in your description of the double slit experiment, where you talk of photons "not landing in the dark fringes". I assert that they do indeed "land" in the dark fringes, but they are "entangled" -- the photons are trapped between the emitter and detector bouncing back and forth in a timeless fashion. Entangled systems are DARK (from both an emission and an absorption perspective) [Ref: http://fqxi.org/community/forum/topic/1897 ]

        Hi Ken,

        Please excuse me if I don't address points in the exchange you've had with Ian. I want to be as brief as possible in response to what you wrote to me. I do, however, need to provide some context for my criticism of your view.

        My greater claim is that all accounts of any sense of temporal passage that I've read in my physicist's survey of the philosophy literature are abominations. They're no better (and maybe even worse because they're so explicitly wrong) than the physicist's foggy conception of temporal passage. All is a mess. And I think "subjective updating" falls right into this catagory. (Strong claim--and fightin' words indeed--so please allow me to explain. The upshot will be that you'll either see an error in a view that you support, that you weren't aware of before, or, by understanding my point, you'll be able to explain to me how subjective updating doesn't fall into this category).

        More specifically, I claim that all accounts (that I've read or heard) of the presentist viewpoint, whether in favour or against it, make a very specific (and often explicit) error, which has confused the issue to the point that I do feel justified in calling these accounts "abominations". Because of this error, many--and then in light of relativity, many more--have committed what I'll call the Abortionist Fallacy (meant in the more general sense of "a failure to develop to completion or maturity") of arguing *from those erroneous descriptions* that presentism is false. In fact, the usual claim is that temporal passage is not as we commonly think of it--the most famous example being perhaps McTaggart's argument for the unreality of time.

        Before I get to my main point, which is very simple, please let me explain what I mean by "Abortionist Fallacy". Consider the following (which I claim to be true): The purpose, or grand aim, of thought experiments, should be to make perfect sense of things that are not intuitively obvious to begin with (cf. Galileo's boat experiment). If this statement is true, then due to his prior definition of simultaneity, Einstein committed the Abortionist Fallacy when conducting his special relativistic thought experiments, from which he inferred the relativity of simultaneity, and therefore simply aborted the sensible notion of objective passage (cf. my first post above).

        So, now: what's the one thing that's wrong with all attempts to describe temporal passage? It's simply the all-too-common idea that events (the things that happen, occur, take place, etc., which make up space-time) *exist*.

        The error occurs whenever verbs are used to describe events. This is because all verbs--and particularly the copular verb 'is', 'will be', 'was', etc.--smuggle a sense of temporal passage into the mix because every last one of them has existential meaning. People are already dead wrong when they say, for instance, "look at this worldline, with a few points (t_1, t_2, t_3, etc.) labelled on it. The fact of the matter, in the presentist view, is that *at* t_1, only t_1 exists; at t_2, only t_2 exists, and t_1 no longer exists. The reductionist, or minimalist viewpoint--and what follows from McTaggart's argument--is that all t exists; i.e. the object represented by the worldline has temporal parts; etc."

        I'm claiming that "exists" in the first and second sentence, as well as "has" in the second sentence, are completely wrong words to use, which totally confuse the meaning.

        People might refer to events at certain times as being "real" or "Real", in a sweeping spotlight sort of way (the past is "real" in some sense, because I can talk about it, etc.). But the thing that actually matters isn't the big "R"/little "r" distinction. The thing that actually matters is the use of "being", which carries existential meaning.

        The reason is simple: in a Newtonian conception of reality (my previous essay shows that relativity presents no real problem either, as long as "simultaneous" isn't mis-defined a la Einstein), how many dimensions are there in the physical description of "this chair exists here?" Since the chair's a 3D object, I hope your answer is "4D" (otherwise we've got an even bigger issue; cf. quote from Einstein's autobiography, above). Similarly, when we say "t_1 exists" or "all t exists" or "an object has temporal parts", or "an observer's subjective knowledge updates", we smuggle in a further dimension.

        Just as "the existence of a 3D block" requires a fourth dimension in the physical description (even if the block doesn't change, still "while changing it exists"--Heraclitus), or the "existence" of an event needs 1D in order for the event to be described as something that exists, so the idea of events in 4D space-time as "existing" requires a 5D description. In essence, when we say (or think) "Jan 10, 1982, 1:26:32 exists", we think of the 3D world on Jan 10, 1982, at 1:26:32, as *existing* (i.e., when we say "is", "was", etc., we impose another dimension in the conception of that *instant*). The dimension in which events are described to "exist" is a hyper-time dimension, above and beyond the time-dimension describing the 3D universe's existence.

        No one in their right mind has every supported this view outright (except maybe science fiction writers and growing block supporters like Ellis--although there's an argument that he's therefore perhaps *not* in his right mind), yet what I'm claiming is that when people assume a "third person"-view of eternity, a "view from no-when", a "God's eye-view", there is an overwhelming tendency to think that "God", the "third person", *exists*. Then the confusion sets in. Greene very explicitly describes the frozen block as something that exists, for example, patently assuming this hyper-time-dimension.

        Now, how does this ubiquitous error factor into our debate? Basically, when you think that something subjectively updates their knowledge of the block, I'm saying you can't but assume such a hyper-time dimension. If everything really is singularly on par, you simply can't get this updating of knowledge within the block, any more than a fish can swim a distance through water, or electricity can flow through a wire, in an *instant*. In the sense of this hyper-time, the entire block has to be instantaneous, and therefore perceptions of it can't crawl along it and update.

        When you describe reality as all of eternity, all four dimensions of the physical description of events that occur in reality, *at-once*, assuming a "God's eye view" of all the events that occur, you simply can't turn around and claim that your "God" exists *without adding the metaphysical structure associated with that*.

        Parsimony is supposed to favour the block universe view of reality, which doesn't assume the extra structure of "3D space that exists"--i.e. a foliation--but what I'm saying is that "blockers" really don't have the more parsimoneous theory anyway. In fact, the view that all of space-time exists (Greene's view, etc.) assumes the same amount of structure in the sense that it assumes that something (of any dimension) *exists*; but because the thing it assumes exists actually has one higher dimension, it actually assumes *way more* structure. That's argument 1 against the "Humean minimalist" view--i.e., it's not actually minimalist at all.

        Argument 2 is that the structure in the "anti-reductionist" view that "minimalists" want to do away with--viz. the foliation of space-time--is actually supported by cosmology anyway, so it's really a non-issue in the first place, if you take empirical evidence to be the supreme arbiter.

        That's pretty much my argument in a nutshell. I don't think I'm committing any of the errors that you mention, but simply saying that I don't think you can get what you want to get without committing them yourself. I'm ready to listen, though, if you think you can get out of argument 1. Then, even still, I think I win by argument 2, since empirical evidence is supposed to trump all. In order to argue against me there, you'll have to overturn a whole area of physics--but still, I am willing (eager, in fact) to listen.

        Best,

        Daryl

        Dear All,

        It is with utmost joy and love that I give you all the cosmological iSeries which spans the entire numerical spectrum from -infinity through 0 to +infinity and the simple principle underlying it is sum of any two consecutive numbers is the next number in the series. 0 is the base seed and i can be any seed between 0 and infinity.

        iSeries always yields two sub semi series, each of which has 0 as a base seed and 2i as the first seed.

        One of the sub series is always defined by the equation

        Sn = 2 * Sn-1 + Sigma (i=2 to n) Sn-i

        where S0 = 0 and S1 = 2 * i

        the second sub series is always defined by the equation

        Sn = 3 * Sn-1 -Sn-2

        where S0 = 0 and S1 = 2 * i

        Division of consecutive numbers in each of these subseries always eventually converges on 2.168 which is the Square of 1.618.

        Union of these series always yields another series which is just a new iSeries of a 2i first seed and can be defined by the universal equation

        Sn = Sn-1 + Sn-2

        where S0 = 0 and S1 = 2*i

        Division of consecutive numbers in the merged series always eventually converges on 1.618 which happens to be the golden ratio "Phi".

        Fibonacci series is just a subset of the iSeries where the first seed or S1 =1.

        Examples

        starting iSeries governed by Sn = Sn-1 + Sn-2

        where i = 0.5, S0 = 0 and S1 = 0.5

        -27.5 17 -10.5 6.5 -4 2.5 -1.5 1 -.5 .5 0 .5 .5 1 1.5 2.5 4 6.5 10.5 17 27.5

        Sub series governed by Sn = 2 * Sn-1 + Sigma (i=2 to n) Sn-i

        where S0 = 0 and S1 = 2i = 1

        0 1 2 5 13 34 ...

        Sub series governed by Sn = 3 * Sn-1 - Sn-2

        where S0 = 0 and S1 = 2i = 1

        0 1 3 8 21 55 ...

        Merged series governed by Sn = Sn-1 + Sn-2 where S0 = 0 and S1 = 2i = 1

        0 1 1 2 3 5 8 13 21 34 55 ...... (Fibonacci series is a subset of iSeries)

        The above equations hold true for any value of i, again confirming the singularity of i.

        As per Antony Ryan's suggestion, a fellow author in this contest, I searched google to see how Fibonacci type series can be used to explain Quantum Mechanics and General Relativity and found an interesting article.

        d-super.pdf"> The-Fibonacci-code-behind-superstring-theory](https://msel-naschie.com/pdf/The-Fibonacci-code-behin

        d-super.pdf)

        Now that I split the Fibonacci series in to two semi series, seems like each of the sub semi series corresponds to QM and GR and together they explain the Quantum Gravity. Seems like this duality is a commonality in nature once relativity takes effect or a series is kicked off. I can draw and analogy and say that this dual series with in the "iSeries" is like the double helix of our DNA. The only commonality between the two series is at the base seed 0 and first seed 1, which are the bits in our binary system.

        I have put forth the absolute truth in the Theory of everything that universe is an "iSphere" and we humans are capable of perceiving the 4 dimensional 3Sphere aspect of the universe and described it with an equation of S=BM^2.

        I have also conveyed the absolute mathematical truth of zero = I = infinity and proved the same using the newly found "iSeries" which is a super set of Fibonacci series.

        All this started with a simple question, who am I?

        I am drawn out of my self or singularity or i in to existence.

        I super positioned my self or I to be me.

        I am one of our kind, I is every one of all kinds.

        I am Fibonacci series in iSeries

        I am phi in zero = I = infinity

        I am 3Sphere in iSphere

        I am pi in zero = I = infinity

        I am human and I is GOD (Generator Organizer Destroyer).

        Love,

        Sridattadev.