Wednesday, February 07, 2007

The Ontology of Time

Ontology is the study of being. Ontologists ask questions like "What does it mean to say something exists?" The ontology of time is therefore the study of what it means to say that time exists or that something exists in time. In other words, what is time? I discuss the ontology of time in some detail in Sense and Goodness without God (pp. 88-96).

In response to what I wrote there, Dave Matson asked:

Why should time be defined in terms of relativity physics where, presumably, it means a fixed future? I would think that time, as defined in quantum mechanics, would be equally preferable. As defined in this latter sense, time is presumably compatible with an undetermined future.

If we accept time as defined in relativity, then it seems that physicists would have to accept that there are "wheels within wheels" within quantum mechanics, which most physicists deny. That denial suggests that time as seen in quantum mechanics is defined differently than in relativity physics. One view seems compatible with a fixed future whereas the other does not obviously fit into that mold, if at all.

So arguing for a fixed future on the basis of relativity theory is tantamount to assuming that its definition of time should be preferred. Therein, I see a problem.

In answering this question
I will use RT for Relativity Theory and QM for Quantum Mechanics. And I will not repeat what I said in my book. So if you haven't read it, though you don't have to in order to understand what follows, you probably should read it before commenting on any of this.

I've made my answer easier to grapple with by breaking it into four parts, but I have to warn you: Since this is a highly cerebral issue, my answer might give you an ice-cream headache. In fact, I don't recommend anyone bother reading what follows at all, unless you have the patience of Job for scientific brain pain. Because this is the ultra-technical stuff that I deliberately didn't torture readers with in my book.



Okay. Here we go...

  • First, it really doesn't matter to me what the answer is, apart from how it alters our physics and cosmology. If, instead, you feel a desperate need for the answer to come out one way or another, you are never going to discover or accept the truth in this matter. Your emotional anxieties will stand in the path of your reason. My advice is to purge your irrational anxiety first before approaching problems like this.
What do I mean? Well, questions like Dave's often seem to come from people who feel a certain uneasiness about a deterministic future and thus press the possibility of an undetermined future merely because they really want there to be one. But this is a waste of their time. For the fact is, it makes no difference whether the future is determined or not. Either way, all our choices and abilities remain exactly the same.

That's right, you will gain nothing from the discovery that the future is not fixed. This knowledge will not change a single choice you ever make, or that anyone ever makes, and therefore the future will remain just as beyond your power to control and just as much within your power to control, as in any other universe. Your power to control (to "cause") certain events in the future rather than others will not be increased or decreased whether the future is fixed or not, because your abilities are the same in both a deterministic and an indeterministic universe. All your knowledge and intelligence and character and desires and everything else remains the same, while any random variables there may be are by definition never in your control anyway, no matter how they turn out (so knowing they could turn out differently won't help you one bit).

I demonstrate this in Sense and Goodness (pp. 97-118), where I also show how this question has no bearing on the validity of assigning responsibility to human actions. Responsibility assignment in the real world actually has nothing to do with the fixity of past, present, or future. Though many people are obsessed with the superstition that it does, I explain in my book why such a belief is illogical. As illogical, in fact, as fatalism, the peculiar disease that results from accepting determinism and then irrationally concluding that you have no control over your life or your future (pp. 115-18).

I won't be discussing any of that here today. I already demonstrate these points in my book. If you have a bug up your butt about free will, or if the "problem" of free will keeps you up at night or worries your little soul, please read my book and think it through. Nothing I say today concerns that question at all.

  • Second, the reason I cite RT (among other arguments and evidence) in favor of my hypothesis that the future is fixed, and the universe deterministic, is because ample evidence confirms RT is true, yet the only plausible model for RT entails a fixed future, therefore the current scientific evidence entails a fixed future.
RT entails this because it entails that our location in time is "relative" to all other objects in the universe. There is no absolute location in time. That's why time flows differently depending on your velocity, but only relative to objects moving at different speeds. For those not "up" on the science of relativity, I'll give some examples of what I'm talking about (for more detailed discussion you can read the wikibook chapter on space-time in the award-winning textbook Modern Physics).

If A speeds away in a spaceship at a high speed relative to B, then time flows slower for A than it does for B. Not only does RT predict this, we've done it, and confirmed it empirically. A does not notice any change in time flow for itself, and in fact sees time flow more slowly for B instead, but because A (and not B) accelerates and decelerates (hence undergoing transformations of its "reference frame"), when A gets back to B, B will actually have crossed more time than A. So, for example, A might return to B and find that B crossed an entire extra hour of time more than A, although now they are both standing next to each other at the same time. So where was A during that extra hour?

The only way to answer that question is to accept that this extra hour existed in A's future, at least in the sense that it had already been crossed by B before A got there, but A ended up crossing fewer points in time to get to the same place. But this means there was a whole hour of A's future already there for B to cross and A to skip around. This is only true for A relative to B, however, since "time" is only a measure of the amount of time (the temporal "distance") between A and B and their conjunctions. But even so, A still crosses less time than B despite ending up at the same place. Therefore, more time has passed for B than A.

Consider A's journey on a space-time diagram. On the diagrams below, the vertical axis is moving up in time and the horizontal axis represents one of the three dimensions in space (the dimension along which A flies away and back). To make it easier, I shall also
stipulate that A's acceleration and deceleration are sufficiently rapid to fall below the resolution of these graphs. Okay. If RT were not true, then A's journey would look like this:


But we now know that doesn't happen. The space-time coordinates above show A passing through five hours of time, but in fact A only passes through four hours of time. So A's journey actually looks more like this:


This means something is happening that our first diagram didn't show. For A, the time dimension is warped. As shown on this new diagram, A appears to be moving through a different grid of time coordinates than B, so when B is at 1:30 on the time axis, A is still at 1 pm, half an hour behind. In other words, at half past one, B thinks A is sharing the same point in time (1:30 pm by B's clock). However, B finds that A's clock has been moving in slow motion over the past hour and now shows that it's only one o'clock for A. But it's not as if A is lagging behind, since at the end of A's trip, A catches up with B without crossing the same amount of time. A only crosses four hours of time, while B crossed five.

Scientists can only make sense of this if time is a location, part of a four-dimensional structure, so where you are in time is definable only relative to where everything else is in time. Which means everything else must already be there. So there is no absolute location in time. There is no "now" and thus no "then" or "later," except relative to other things in time (or other parts of you in time, since on RT you are a kind of four-dimensional person-tube, and you only see a cross-sectional slice of you at any given moment in time).

Paul Davies illustrates this relativistic time warping with the following diagram in his book About Time.
Again, the vertical axis marks the passage of time, while the other axes mark dimensions in space:


The plane drawn at each moment of time here represents everything in space that you will see as happening simultaneously at that point in time. In other words, it contans everything that
(relative to you) is located at the same point in time. The top diagram is how things always look to you no matter how fast you go. But as you start moving faster, space-time folds up in the direction of your motion, so someone still "at rest" (relative to you) will see that you are observing as simultaneous all events on the slanted plane in space, instead of events in a perpendicular plane (like the diagram above). So different events will appear simultaneous to you than for them. In other words, different events will be located at the same point in time for you than for them.

As you go faster and faster, this warping increases, the plane of simultaneity slants further and further up, until, at the speed of light, it folds completely into the time axis, and everything in your direction of motion is what you now see as simultaneous. In other words, your entire future becomes simultaneous with your entire past and present. In effect, you then have no "future" because everything that will ever happen to you already immediately happens to you, all at the same time. This is how a ray of light experiences the universe. Every event in its future happens simultaneously with its present. Relative to photons, all future time is fixed and instantaneous.

If a ray of light still had time to think, it could perhaps talk about "later" events and "earlier" events in its timeline, but only by arbitrarily choosing some event as the dividing line between them. In other words, it can say "relative to what is happening at t = 1 (the first plane marked on Davies' diagram), the points in time above it are in the future and the points of time below it are in the past, but only with respect to that point in time."

Objects moving slower than light haven't folded space-time completely, so they still have a non-arbitrary "present," but only relative to other objects moving through time. Remember, it's all relative: so, relative to a beam of light, you are travelling at the speed of light, so every event in your future has already happened, simultaneously with every other event in your past and present. You are in the same position as the ray of light. You only don't know this because you are moving so slow
(at least from your point of view) .

RT further entails that a beam of light passes through all points of space that exist in its path instantaneously, owing to the contraction of space-time in its direction of motion, which reduces even an infinite distance to zero. In exactly the same way, a beam of light passes through all the points in time associated with all the points in space it simultaneously occupies. For some beams of light, which go on into the dead of space forever, this means infinite time is crossed in zero time.

That same beam of light only appears to us to be moving through time more slowly than that, because we are moving so slowly through space ourselves. If we were moving as fast as a beam of light, we would instantly cross the whole of time, too. From the point of view of a beam of light speeding off into the void (or any immortal human who went as fast for as long, if that were possible), the whole life of the universe has already happened--we (us slow pokes) just haven't caught up with it yet.

So far as I have seen, technicalities of wording aside, all RT scientists agree on all this. See my bibliography on the subject (on p. 95), including Davies' book About Time, which, by the way, discusses how QM also suggests a fixed time, as do other books I list there. We already know the two phenomena are somehow related...

Ever wonder how a photon in QM can magically "know" where it will end up? Well, since it instantly passes through every point in space-time it will ever cross, it simultaneously knows everywhere it will ever be--because it's already there. The photon simultaneously occupies its present and future, so the shape and structure of the photon's path is simultaneously determined by all the information on its path. It's only relative to us that it appears otherwise. We're just watching this photon unfold its destiny in slow-motion. But relative to the photon, it's already finished moving. It's already sitting in our future waiting for us to catch up with it.

This means our future already exists before we get there. Since all interactions, all impacts of one object against another (which require photon exchanges between electrons and protons) and all transfers of information (which are also carried by photons, like visible light), since all are produced by photons, and since all photons simultaneously occupy every point of space-time they will ever occupy, there is nothing we can do to change the outcome of the future. To change anything, we would need to move objects (like our arms) or send or gather information (like look or listen or speak), but doing those things requires exchanging photons, yet all the photons in the universe are already done moving. We can't change their paths now. Indeed, relative to these photons, our decisions and actions have already participated in determining their paths, and the paths of all other photons in the universe that are interconnected ("entangled") with those photons, and all objects entangled with any of those photons, and on and on.

Therefore, all future time is fixed on RT. The universe is done. We just haven't caught up with it yet. Even so, regardless of the fixity of the future,
our decisions still matter and we still have free will in the only worthwhile sense there is: we can think, plan, learn, change, and more or less do whatever we want. But you'll have to read my book to find out why.
  • Third, it is not true that QM entails a non-fixed future. QM is compatible with both possibilities. So far, RT is not. The only scientifically plausible conclusion on present evidence is that RT and QM somehow agree (though we don't know how yet), and since the only way they can agree (so far as we presently know) is for RT determinism to prevail, therefore RT determinism probably prevails.
Until we uncover any new evidence to the contrary, we have no scientific basis for concluding otherwise. In other words, the only way that both RT and QM can be true is if determinism is true. The evidence so far supports the conclusion that RT and QM are true. Therefore, the evidence so far supports the conclusion that determinism is true. The mere fact that QM allows for alternatives is irrelevant in the face of the evidence confirming RT.

Moreover, as I explain in Sense and Goodness (pp. 98-99) there are not one, but two ways that QM can be compatible with determinism. Only one of them is what Dave calls the "wheels within wheels" explanation, where some deterministic process actually underlies all QM phenomena, such that the latter only appears indeterministic. It's not true that most scientists "deny" this possibility. Most scientists concede only that we have no evidence yet that this is the case. Those same scientists concede that due to the particular nature of quantum data, we are very unlikely to gain access to that evidence even if it existed. Therefore, we are not in a position to issue denials. It's fallacious to conclude that because we can't look inside the box, therefore the box is empty.

Hence many scientists are still searching for and testing deterministic models of QM phenomena, and no one pooh-pooh's this effort as pseudoscientific or a waste of time. We've already seen how RT entails things about light that actually explain some QM strangeness. Likewise, current theories of antimatter propose that antimatter is normal matter traveling backwards in time. As a result, superluminal causation is becoming an increasingly acceptable hypothesis, and leading theories of quantum determinacy appeal to some form of it. Hence a "wheels within wheels" model (already confirmed as a viable path in the domain of particle physics) remains a viable way to unify RT and QM. It's at least worth searching for. Ultimately, the vote is not in.

But even if we conclude that we ought to have discovered by now some evidence of deterministic underpinnings to QM, and even if we therefore conclude it's "improbable" that there are such underpinnings (though I am not aware of any valid syllogism by which one would establish on present evidence that QM determinism is "improbable"), there is yet another way for QM to be deterministic. Quantum phenomena may be irreducibly indeterministic and still entail only one fixed future. This future would only be indeterministic in the sense that it can't be predicted, no algorithm determines its structure, since the structure of events through time is to some extent fundamentally random. But there is still only ever one structure that is realized, and it's already a fixed fact which structure that will be.

On this view, the structure of the future is not fixed by any set of causes, but merely by the fact that all time has already run its course, and that from a point of view outside the universe, we (you and I) are actually in the past and only observing how that randomly patterned future has already unfolded. And since it can only unfold once, the future for us is fixed and unchangeable--as fixed and unchangeable as our past. After all, even if the whole universe is indeterministic, nearly everyone agrees there is still only one past, and that our past has only turned out one way, which is now fixed and can never be otherwise. No one claims the past is still undecided. Not even quantum indeterminists claim that. Thus, a singular, fixed past is clearly compatible with quantum indeterminism. But according to RT, we are already in the past--someone else's past. For example, we exist in the past of every beam of light that radiates into our future. Therefore, our future, being the universe's already-played-out past, is just as fixed and immutable as our own past, regardless of how undetermined that was.

Take again a beam of light, which instantly knows everywhere it will ever go because it goes through its entire path instantly. What determines what that path will be? If the universe is thoroughly deterministic (if it's all "wheels within wheels" as Dave puts it), then the path the light takes will be entirely determined by the structure of all the space and objects in its path, like a billiard ball on a snooker table. At every point, there is only one way it could have gone. And so it goes.

But if there is anything fundamentally indeterministic about how photons bounce around the universe, then there will be nothing about the space or objects on its path that guarantees it will take one path rather than another. Though QM still limits the options statistically, so it's not just "anything goes," nevertheless there is nothing that determines which available option plays out. Even so, that just means the photon will instantly freeze in a path that is partly random. But it's still frozen. There is still only one path. And that path has already been traveled before we get there. Therefore, even if QM is fundamentally indeterministic, if RT is true, then there is still only one fixed and immutable future. Until you empirically demonstrate that our current RT-model is false, you have no basis for arriving at any other conclusion.

  • Fourth, and finally, there is no "different definition" of time between QM and RT that relates to the fixity or non-fixity of the universe.
Although everyone obsesses on the oddities of QM, where subatomic events seem to exist in a state of remaining undecided until "observed" (i.e. "disturbed by outside forces"), this actually entails nothing about the nature of time. The only difference between the QM and RT definitions of time is that in RT, time is a continuous dimension, location in which is fundamentally relative, while in QM, time is a discrete quantity that doesn't depend on our location being either relative or absolute. So QM time is compatible with both RT and non-RT definitions of time--apart from the single issue of whether time is continuous (and thus infinitely divisible), or whether there is a smallest span of time, an actual minimum unit of time, which cannot be meaningfully divided.

But this difference has no bearing on whether the future is fixed or not. If the QM definition is true, all this means is that within a minimum unit of time (a Planck time), you can't have any definite location in time, but beyond that, on larger scales of time, you can. This may mean that objects must be spread over, blurred across, an entire Planck time, but this says nothing about whether future time is or is not fixed. However, RT does say this, and RT describes how space-time works on a larger scale.

According to RT's definition of time, where you are in time is only definable relative to other things in time (including other temporal slices of you). This means a future can only exist in RT if there is already a series of future events relative to which we are in their past. If there is something in the future relative to which we are in its past, only then does it remain meaningful on RT to say those events exist at a location in the future. Because their location is only in the future relative to us. Relative to those events, our future is in their past. And that entails all future events already exist--we just haven't gotten there yet.

All this entails a basic determinism: regardless of whether the world is fundamentally indeterministic, there is only one future and it will only play out one way. Because it already has.

13 comments:

Eric said...

Thanks for this post. This topic was one of the ones I had the most trouble understanding in your book, and this really helped clear it up.

Adam Lee said...

Also, I think Matson errs in assuming that quantum mechanics implies an indeterministic future. The Schrodinger wave function, which governs how all events play out in QM, evolves over time in a smooth and completely deterministic manner. The only catch is that the Schrodinger wave function corresponds not to one discrete outcome but to a superposition of outcomes; the seeming randomness lies in the way we perceive only one of those.

Jason said...

Great article.

Blue Devil Knight said...

I found all this discussion somewhat glib. That someone could come away thinking that there is no real problem because Schroedinger's equation is linear/deterministic shows he hasn't understood just how weird quantum measurement is. Have no doubt: there is no good account of measurement in quantum systems. If you invoke perception as necessary for measurement, you end up with Schroedinger's cat. If you are happy with that, then dear god. (note this isn't aimed at Carrier).

I also have a specific comment. From the experimental violation of Bell's inequality, we know that local hidden variable theories are false. So, either SR is false, or the world is indeterministic at a fundamental level, or both.

Carrier said that there are people working on 'deterministic' quantum mechanics. This is true, but all of these theories, which invoke hidden variables, violate SR. Ya' can't have both determinism (in the usual sense of the word) and SR.

Further, check out the most recent Nature (News and Views section) for more on this: more evidence that things are just strange, that measurement is a horrible problem that we don't yet understand.

I agree with the assessment that all this doesn't really matter for the interesting psychological questions of freedom etc.. Randomness is not freedom, so quantophiles don't have anything there. I would have left it at that rather than publish something on which I have no expertise.

Richard Carrier said...

Blue Devil Knight:

I'm not sure nonlocal models of QM actually violate RT. Although I suppose that depends on how you define "violate." In a trivial sense, every physical law is violated by some other physical law or in some physical condition. If that's all you mean, then it fuels no argument. But if you mean something more serious, like "that can only be true if RT is false" or something comparable to "the law of universal gravitation violates the theory of geocentrism" (or vice versa), then the evidence doesn't support you.

First of all, there is nothing in GR or SR that entails there is nothing that violates locality, only that the things we presently know do not. It has long been asserted by relativity physicists that RT is compatible with the possibility of wormholes and tachyons, which both allow superluminal travel in different ways, yet this does not make RT inconsistent. These things do not "violate" RT, but in fact are analyzed as possibilities within RT.

Secondly, it is already accepted that RT does not apply at quantum scales, yet physicists do not usually describe this as a "violation" of RT. By analogy, simply because RT entailed modifications to Newtonian mechanics does not mean RT "violates" Newtonian mechanics--to the contrary, RT explains Newtonian mechanics. In effect, Newtonian mechanics is what RT predicts in commonplace conditions and at commonplace scales. Likewise, locality can be violated at quantum scales without this being regarded as "violating" RT.

Although that's not relevant to deterministic models of QM, it establishes a generalization: if this can be the case, then there can be other conditions under which locality might be violated, which do render QM phenomena deterministic. In which case, like Newtonian mechanics, RT would become a special case of a more fundamental theory, rather than a "violated" theory, except in the trivial sense that every subordination constitutes violation of the subordinated theory.

Finally, nonlocality is not synonymous with superluminality. Wormholes actually allow faster-than-light travel without anything traveling faster than light (see link above). But for a different example, it is now a standard assumption that antimatter is matter traveling backwards in time, yet no physicist claims this violates SR. Because antimatter is not traveling faster than c, it's just traveling in reverse, at sub-c velocities. Since velocity is simply a function of space crossed per unit of time, traveling backwards in time is not superluminal.

Photons, of course, are their own antiparticle, and thus they are neither traveling forward nor backward in time--exactly as RT entails. In the way my blog explains, they experience no passage of time and are everywhere at once. But when things start going slower than c, they can do so either forward or backward in time, and then you get something other than massless particles, but either way, always crossing less than 300,000 meters over any given second. And once you allow that, you can have seemingly nonlocal QM events that are in fact caused by particles from the future, all without anything going faster than c.

Therefore, I would not assume that a deterministic model of QM violates RT. It may demonstrate conditions under which RT does not apply, or requires modification, but it is already accepted that this is probably the case, since QM and RT are already inconsistent, yet nevertheless both true. Therefore, there is something wrong with our formulation of either, or of both. The vote is not yet in.

P.S. For thoroughness, I suppose I should also add the Many Worlds interpretation, which I don't buy into, but if it were true, then QM is completely deterministic. It only appears not to be because each bifurcated observer only sees one tiny slice of every actual effect. There is no randomness, because every possibility is realized, and therefore the probability of each effect given each cause is always 100%. It only seems otherwise because we can't see the other observers in the alternate worlds or what those other observers are seeing.

starcourse said...

All this rather confused posting boils down to is: to make the maths simple(r) RT assumes that the future is fixed. Therefore the future is fixed. But we know that RT does not represent the definitive model of reality - it is inconsistent with QM and no-one knows how to reconcile them. Read a real philosopher like Mary Midgley or a real scientist like John Polkinghorne. All this stuff shows is that "a little learning is a dangerous thing"

Blue Devil Knight said...

There is relativistic quantum theory already, usually called quantum field theory. They are not inconsistent. It is making it consistent with general relativity that is hard.

Bell's inequality, and its experimental violation, shows that there can be no local hidden variable theory. Here, 'local' means that the measurement at one location cannot be communicated to the entangled particle at another location faster than light. If such communicatino is possible, SR is violated. This isn't like newtonian versus relativistic mechanics.

The main workable hidden variables theory, by Bohm, is quite explicitly in violation of SR, as there are 'pilot waves' which bind together the particles and influence things faster than light in a way that violates SR.

That we are having this conversation shows that you don't know the literature. But again, for psychological purposes this doesn't matter.

Many worlds is very interesting, and solves the measurement problem, though as you suggest at an exhorbitant cost. I am not sure if it counts as local, hidden variable, or neither. Perhaps a supressed premise of Bell's inequality is that measurement occurs in a single universe.

Blue Devil Knight said...

Note: for those interested in a very good exposition of Bell's inequality and its relation to special relativity, read Maudlin's excellent book Quantum nonlocality and relativity. It is a superlative work.

It includes a wonderfully simple derivation of Bell's inequality as well as a clear analysis of the meaning of 'nonlocality', which types of nonlocality violate SR, and which types of nonlocality various quantum theories entail.

Must read for this debate.

Blue Devil Knight said...

A paper that just came out in nature puts another nail in the coffin of local deterministic theories, even Bohm's! This will be big.

News and views is here.

Richard Carrier said...

Starcourse: I won't bother responding to your insubstantial comments, which state no facts I did not already state myself, and which identify no logical fallacies or invalid statements in anything I did say, and which play the same old, useless, lazy game of "Oh you need to read Dr. Nobodygivesashit and that other guy Mr. Doesntmatter," without saying how anything they say contradicts or undermines anything I've said. Thanks. But that's just lame.

Richard Carrier said...

Blue Devil Knight: Bell's Theorem remains controversial and not everyone agrees it has been experimentally confirmed. But even that aside, I do not believe the Bell inequalities can prove there is no local hidden variable theory, unless you interpret "local" so strictly as to allow light-speed communication between particles and still not call that "local." But doing that becomes arbitrary--since then "local" is just whatever area of space you arbitrarily choose to cordon off, which becomes a human invention and not anything that exists in nature.

Hence Bell's inequalities do not challenge reverse time causation, or hidden wormholes or the many worlds hypothesis. Nor do they create any challenge for the entanglement of massless particles, since all massless particles are everywhere at once and therefore communicate with each other instantaneously even across the entire universe. This communication is only "nonlocal" relative to us. It is entirely local relative to, say, two entangled photons, since the distance between them is zero according to RT, even if we see them as a trillion lightyears apart. However, this brings up the question of how "locality" is defined (see below).

This only leaves the problem of mass-bearing particles, which is what recent EPR experiments usually employ. But seeing an obvious deterministic solution for photons leaves me wondering why the causes must be so different for electrons, even though the effects are identical (polarization of a photon, for instance, is directly analogous to electron spin characteristics). I don't pretend to know the answer, but it is very suspicious that the photon system is perfectly explicable while the electron system is not. My intuition tells me the same or effectively similar causes are operating, and if that's the case, and the system is deterministic for photons, it should also be for electrons.

Let me explain what I mean...

Besides Maudlin's book, for those who aren't subscribers, BDK also refers us to Alain Aspect, "Quantum Mechanics: To Be or Not to Be Local," Nature 446.7138 (19 April 2007): pp. 866-67.

In this article, Aspect starts by defining locality thus: "local realism...states that results of measurements on a system localized in space-time are fully determined by properties carried along by that system (its physical reality) and cannot be instantaneously influenced by a distant event (locality)." Notice the subjective element for localization: What counts as the "system"? Aren't entangled particles a single system?

If we split them apart in theory, then we do so only arbitrarily, which violates realism, so then we're no longer talking about reality, and that's just a waste of time. But if we accept that they are inseparably connected and thus an indivisible system, then everything that happens between them is local, no matter how far apart we see them to be. And since everything they will ever contact, ever, in the whole of history, is also unified with them as a single system, there is no way we can talk about "distant events" except events that never influence them, which are irrelevant.

This is what I am talking about. According to Aspect's definition (and it's not his own, obviously many scientists subscribe to it, though without I think noticing the fallacies involved: see below), two entangled photons on either end of the galaxy are not a single "system localized in space-time." But that's a scientist's fiction. In reality they are a single system. The distance between them is zero. The time between them is zero. And at that unified point of space-time they occupy every point in space-time they ever have and ever will occupy.

Thus, for example, suppose there is an instrument in the Andromeda galaxy that in a billion years will make a measurement on one of those photons, while the other speeds off in the other direction altogether. Indeed, suppose that instrument to be identical to the one Aspect is describing in the new experiment BDK refers to--it really doesn't matter. At the time where the paired photons just depart our galaxy, a scientist would arbitrarily isolate them and say the Andromeda-based instrument is a "distant event" and not a local part of the photon system. But that's baloney. That's only the way it seems to us. To the photon, the Andromeda instrument is not a billion lightyears away. It's exactly zero meters away. And it's not going to collide with that instrument a billion years from now. It will collide with it exactly zero seconds from now.

How scientists can call "nonlocal" a cause that is exactly zero meters and zero seconds away is beyond me. It only becomes plausible when we are talking about particles with mass, which do not travel at the speed of light. Thus, if we are talking about two entangled electrons departing opposite ends of our galaxy, and one of them is headed for an instrument in the Andromeda galaxy. But if that instrument can have a completely local effect on a photon a billion lightyears away, why not an electron?

All that would be required is something that does travel at the speed of light between the instrument and the electron. However, the electron, not being in a light-speed reference frame, is now like us: it should still have to wait for the signal to get to it. This is why it is assumed a signal must fly faster than the speed of light. This assumption does not hold for massless particles, which are always, by definition, in a light-speed reference frame. But it does hold for everything else.

For instance, if we rearrange the instrument a second after the electron forms, any signal our meddling sends will take a billion years to get to the electron. But Bell's Theorem (in effect) entails that the electron will already be affected the moment it is formed--not by the instrument as it was then, but by the instrument as it will be when the electron hits it a billion years later. Again, for a photon that's no problem. But for the electron, it's baffling. But since it isn't baffling for a photon, I suspect there is something we are missing about the system of mass-bearing particles, and I doubt scientists interpreting the components of Bell's Theorem can have accounted for things we haven't even thought of yet.

For example, time-reversed causation.

Or something weirder...

Like: as soon as an electron is about to form, a graviton wave is launched. This wave travels at the speed of light to the Andromeda instrument, but relative to the graviton that instrument is directly adjacent to where the electron is about to form, so the graviton is instantly altered by the way the instrument is arranged at that point in space-time. This alteration has causal effects on the structure of the electron that then forms, according to the instrument's arrangement a billion years hence. In this scenario, nothing travels faster than light yet the communication is instant: the electron's properties are determined by the far-off detector even before the electron materializes. The only hitch here is that the electron will hit the detector at some different time, not a billion years later, since it won't travel as fast as the graviton, so one would have to explain how the electron knows the structure of the instrument when the electron (and not the graviton) will hit it. And there are probably other problems besides this. But the point is that we can at least begin to think about nonlocal causation (in the strict sense) without anything moving faster than light.

Now, according to Aspect, what I am describing for photons (or even for "tachyons" or these hypothetical gravitons) is a nonlocal theory, even though he also says nonlocality entails superluminality. But as I have shown, it does not: photons travel the same speed as always (and tachyons travel that same speed, only in reverse). I thus think there is a confusion here between two different scientific definitions of "locality."

I think Aspect reveals this when he says a system can be "non-local in the relativistic sense" if "we must invoke a particular frame of reference" to explain what happens. But that's true even if the system never has anything traveling faster than light, since my explanation for the photon invokes a particular frame of reference (that of the entangled particles) but never has anything moving faster than light. So this definition of nonlocality does not entail faster-than-light communication. So there must be another definition of nonlocality that does entail faster-than-light communication. Thus I suspect Aspect (and others) are committing an amphibole fallacy by switching between these two definitions, but treating them as identical.

For example, Aspect says "I must admit...I am not comfortable with the notion of a physical reality that is instantaneously modified by something happening far away." Why isn't he comfortable with it? Relativity already entails that this must necessarily happen all the time. He would never be uncomfortable with two adjacent objects influencing each other. But on Relativity, a photon and a distant detector are literally adjacent to each other--the distance and time between them is zero--just not in our reference frame. If Aspect accepts instantaneous causation between adjacent objects, why is he troubled by distant objects that we already know are adjacent to each other in their own reference frame?

In summary, the photon as it forms here is instantly already at the Andromeda detector, the same detector which seems to us a billion lightyears away. It is not adjacent to it at the moment the photon forms, but is adjacent to the detector as it will be a billion years later. Thus, none of Bell's inequalities, not even the new experiment Aspect describes, can rule out ordinary deterministic causation in this case. It is only mass-bearing particles which present a problem, because they do not share a light-speed reference frame. But I am not convinced scientists have ruled out every possibility for them except faster-than-light communication.

Blue Devil Knight: Many worlds is very interesting, and solves the measurement problem, though as you suggest at an exhorbitant cost.

To be fair, we can't objectively say it's "an exhorbitant cost," since this is really a subjective human judgment. Nature works the way she works, regardless of whether she offends us by her methods. One could say the periodic table does away with the four elements "at an exhorbitant cost" by multiplying entities twenty times over, but of course this is no violation of Occham's Razor since the evidence actually compels this increase in explanatory entities. Hence nature doesn't give a hoot about our notions of neatness and simplicity.

So at most we can say the Multiple Worlds Hypothesis (MWH) is unnecessary to explain observations. But that only holds if there are still plausible alternatives on the table. If none remain, then the existence of quantum phenomena is not only evidence of MWH but evidence of that alone and of no other theory. Then MWH would be compelled by the evidence. Hence everything hinges on the existence of plausible alternatives. I don't mean, of course, that even in such a circumstance it would be impossible to discover an alternative we hadn't thought of, thus revising our conclusions, but until we did, MWH would be effectively proved, to a scientific degree of certainty.

I don't think that will happen, but I can't prove it won't. Nature has shocked me before.

Richard Carrier said...

I've learned that Canadian physicist Vesselin Petkov, in his commemorative essay "Time and Reality of Worldtubes," argues for a similar conclusion to mine, and that the idea that we are "person-tubes" extending over all space and time is no mere philosophical question but something that should be regarded as a scientific fact. I don't agree with everything he says, but it's a good example of what I'm talking about. He has also written on the topic Relativity and the Nature of Spacetime (Springer 2005) and edited Relativity and the Dimensionality of the World (Springer 2007).

Richard Carrier said...

Several people over time have asked me the same question, so I'll add data here that I can just refer to in future and not have to dig it up again. The general question is whether William Lane Craig is aware of the fact that Relativity implies B-Theory and B-Theory undermines some of his cosmological arguments (it would also undermine his use of the Free Will Defense against the Argument from Evil).

The answer is yes. Craig acknowledges that B-Theory presents a serious problem for him (and summarizes his case against B-Theory accordingly) in William Lane Craig, "Naturalism and Cosmology," Naturalism: A Critical Analysis (2000): pp. 215-52.

But, for his complete and highly technical response to this problem, you'll have to look over four rather rare (and dense and outrageously overpriced) books:

In The Tensed Theory of Time: A Critical Examination and The Tenseless Theory of Time: A Critical Examination (both published by Craig in 2000) he defends A-Theory and attacks B-Theory (respectively).

But the most damning problem (that Relativity supports B-Theory) Craig apparently had to reserve for yet a whole additional book, in which he advances his own new theory of relativity to replace Einstein's, IMO all simply to restore A-Theory without having to deny the evidence and math of established Relativity Theory: Time and the Metaphysics of Relativity (2001).

Realizing (I suspect) that he was a bit screwed having to depend on a new scientific theory proposed by a nonscientist (himself), he seems to have rounded up every fringe scientist and philosopher he could find who would offer any defense of reformulating Relativity Theory to accord with A-Theory, who all contributed (somewhat incongruous) chapters supporting that case in: Einstein, Relativity and Absolute Simultaneity, ed. by W.L. Craig and Quentin Smith (2008).

I formulated my case for B-Theory in Sense and Goodness without God specifically in response to the first two books, while the second two can be dismissed as unconfirmed (and IMO rather implausible) scientific speculation.