On the Impossibility of Time Travel by J. C. N. Smith

J. C. N. Smith

Mr. Johnstone,

Thanks for the heads up. I'd been reading the essays in sequential order so as to minimize the chances of inadvertently overlooking any, but on your recommendation I jumped ahead to Mr. Lynds' essay, which was, as you said, heavily into topics of interest to us. Also of interest, of course, is G. F. R. Ellis's essay. Now, back to the reading! Unless any additional essays trickle in, my latest count was 113 total.

Cheers

Jonathan Dickau

Greetings J.C.N.,

It was a pleasure reading your essay. I'm not entirely certain it addresses the question of what's possible to know from/with Physics, but it was an interesting excursion into a subject worthy of exploration. It seems your main point is that each configuration of the universe is unique, and that therefore "if we weren't a part of it, when it was happening, we can't go to the past" and "since it hasn't happened yet, we can't go to the future."

To some extent, this does involve questions about what is knowable in physical reality, so it is perhaps germane to the discussion of concepts for this contest. I too have concerns about hidden assumptions that are endemic misconceptions about time. If time is not a variable, but a progression of 'configurations of the universe,' this does put a different slant on things. On some level, this begs the question of whether your argument can be turned inside out, though, so that your statements become a method for time travel instead.

As luck would have it; the answer which emerges therefrom is articulated by Don Juan to Castaneda, in one of the latter's books (I don't remember which one). Juan suggested to Carlos that if he wanted to transport himself, the way to accomplish this was by creating a new assemblage point - a new place to 'assemble the world' from. Specifically; he instructed Carlos to unmake the world of his origin point, and assemble the world of his destination - rather than transporting himself per se. The idea was to let go of one configuration of the universe, and latch onto another.

Of course; this is all rather fanciful, but if it could be made to work, it would apply equally well to moving through either, or both time and space. And it incorporates your insight of a moment in time being represented by a particular configuration, an assemblage of particular qualities and quantities which allow us to identify a given time and place unambiguously.

I've seen no evidence this is anything but fiction, and I have no idea how this mode of transportation can be utilized, in practical terms, but I note that a similar conceptualization is employed by you and Castaneda. It would seem that what you propose is impossible, however, is exactly what he has set out to explain how to do.

So; perhaps yours is not an air-tight argument, after all. Any thoughts on this?

All the Best,

Jonathan J. Dickau

J. C. N. Smith

Mr. Dickau,

Thank you for your comments and questions. First, to address your question regarding whether my essay falls within the theme of this year's competition, the theme deals with "what is ultimately possible in physics," with a related aspect being "what is ultimately IMpossible in physics." This was made explicit in the evaluation criteria, which I quote here:

"What role do 'impossibility' principles or other limits (e.g., sub-lightspeed signaling, Heisenberg uncertainty, cosmic censorship, the second law of thermodynamics, the holographic principle, computational limits, etc.) play in foundational physics and cosmology?"

In this light, an essay dealing with the impossibility of time travel strikes me as being well within theme's boundaries. As to whether my position is falsifiable or not (i.e., whether it is science or not), it is. All one need do to falsify it is to demonstrate conclusively that time travel of the variety portrayed in science fiction *is* possible. But there are also other, simpler, potentially actually achievable approaches to falsifying it as well; these are discussed in reference 4 of my current essay.

Now, having hopefully put that issue to rest, I'm delighted to address the very excellent and interesting story of Don Juan to which you alluded, because it is very germane to my argument regarding time. Thank you for bringing it to my attention. I'd not heard of it before, but now I'll plan to look it up to read in detail.

If I'd done a better job of writing my essay and explaining more clearly my argument, it would have been immediately clear to you exactly how the Don Juan story (as you've summarized it) actually serves as an illustration of the concept I'm trying to convey. Configurations of the universe are what it's all about. For example, Hollywood film-makers manage to "re-create" visual impressions of bygone eras by "re-creating" in carefully controlled environments the configurations of whatever era they're trying to portray in the film. If the film is about Al Capone, they drag out all the old cars from museums and all the period clothing and use them to re-create a small configuration, in the confines of a sound stage or elsewhere, which mimics a small part of the configuration of the universe as it existed during the gangster era, or whatever other era they're trying to re-create.

All the "stuff" in the universe always has some configuration, i.e., some arrangement, which is constantly changing, i.e., evolving. We are all perpetually and unavoidably "letting go of one configuration of the universe and latching onto another." We have no choice in the matter. It's an inevitable consequence of being ourselves parts of the evolving universe. In this sense, and in this sense only, we are all time travelers. We are all continually making new "assemblage points" for ourselves, whether we want to or not and whether we know it or not; we are continually burning some old bridges and building some new ones. But we're basically always just shuffling around the same stuff from one place in the universe to another. As in the Don Juan story.

If I've still failed in giving a sufficiently clear explanation of the point I'm trying to convey, please don't hesitate to ask for further clarification. I'll be happy to give it another try, as needed. And thank you for the lead to the Don Juan story!

Cheers

J. C. N. Smith

Mr. Dickau,

As an addendum to my previous post, I'd like to amend one image which I offered there. Rather than the image that we're "continually burning some old bridges and building some new ones," I think it's more helpful to say that we're continually "selectively using parts of old bridges to assemble newer ones." And this is more in line with the image in the Don Juan story, "Specifically; he instructed Carlos to unmake the world of his origin point, and assemble the world of his destination . . . ."

Perhaps the best way to get an intuitive "feeling" for my concept of time is to simply ask yourself what makes today different than yesterday. In the final analysis, I believe that the only satisfactory answer is that the configuration of the universe is different. I believe that any other answer to that question which we might propose ultimately boils down, in one way or another, to being merely another way of saying that the configuration of the universe is different.

Most, but not all, of the ways in which the configuration of the universe will evolve from today forward are beyond our control. But chaos theory, a la the butterfly flapping its wings in China and thereby unknowingly contributing to initial conditions which ultimately lead to a hurricane in Florida, suggests that we should not underestimate our influence on future configurations of the universe. Unfortunately, most of the long-term consequences of our actions and/or lack of actions are nearly impossible to predict, leaving us in the position of doing our best to use the tools at our disposal, in the form of our understanding of the laws of Nature, to ascertain and implement actions which are as constructive as possible toward whatever long-term goals we have.

Cheers

Jonathan Dickau

Hello again,

Thanks for the thoughtful attention to my comments. I have read your response. I may return to this page for more insights. Nothing more to say right now.

Good Luck,

Jonathan

J. C. N. Smith

While thinking about the example mentioned in an earlier post about how film-makers create illusions of returning us visually to bygone eras, another example came to mind which far better illustrates the nature of time.

It is a relatively simple matter to re-create realistic outdoor settings for films of the "western" genre (formerly known as "cowboy movies" and more recently as "spaghetti westerns"), which are intended to replicate the American "wild west" of the 19th Century. All one needs is a barren desert landscape, some horses, some tough-looking, well-tanned, leathery-skinned humans (a la Clint Eastwood and Lee Van Cleef in 'The Good, the Bad, and the Ugly'), and some period clothing and accoutrements. Because the visual "essence" of these key ingredients has not changed appreciably since the 19th Century it is relatively easy to re-create an extremely realistic replica of that era.

The illusion thus created would be immediately destroyed, however, if we were to notice an obvious contrail of a jet aircraft in the sky. Contrails of jet aircraft are not part of the set of configurations of the universe which defines the 19th Century. This or any other anachronistic detail tells us instantly that the scene is not what it purports to be. Our subconscious minds know that particular times are identically equivalent to, and are completely defined by, and only by, particular configurations of the universe even if our conscious minds don't.

Film-makers who wish to portray futuristic settings, on the other hand, are less apt to be tripped up by anachronistic details, because no one knows what the future is "supposed" to look like. Items in such films which obviously are throw-backs to times pre-dating that portrayed in the film can be explained, if need be, as antiques or relics from the past.

Cheers

J. C. N. Smith

"Hostage photos" (i.e., photos of people who are being held hostage by criminals) are another illustration, albeit a grim one, of the nature of time. As a way to prove that a hostage was still alive as of a certain date, criminals occasionally make available photos of the hostage. Do the photos typically show a hostage holding up a calendar or a clock? No, of course not, and why not? Because calendars and clocks, per se, have very little to do with defining and identifying particular times. Hostage photos typically show a hostage holding up the front page of a newspaper, thereby placing the hostage in the context of some known broader configuration of the universe. (Of course, due to the availability of technologies such as "photoshop" it is now a relatively simple matter to fake images, i.e., older images could have a more recent image of a newspaper "photoshopped" into them.) The point of this illustration, however, is simply to emphasize that in order even to begin to identify a particular time it is necessary to have some information about a corresponding configuration of some known portion of the universe.

jcns

Jonathan Dickau

Agreed.

Your comments make perfect sense. Whether this 'proves' somehow, that time travel is impossible, is still at issue. The point of the argument could be reversed by stating that it's exactly what any science fiction time traveler would say.

One could imagine Dr. Who, perhaps, turning to his companion as they exit the TARDIS, and saying "In order even to begin to identify a particular time it is necessary to have some information about a corresponding configuration of some known portion of the universe."

Have a great day!

Jonathan

J. C. N. Smith

Mr. Dickau,

You appear to be headed in the correct direction with your thinking about time. Unfortunately, however, you are not yet taking into account several insurmountable difficulties which will continue to rule out time travel. First of all, in the broadest, most rigorous sense, particular times are defined by particular configurations of the entire universe, and the configuration of the entire universe is intrinsically unknowable. I discuss this problem in reference 4 to my current essay, which may be found here. If you've not had an opportunity to read it yet, I hope that doing so, as your time allows of course, may help clarify this point.

Just as a thought experiment, let us assume, purely for the sake of argument, however, that we could somehow miraculously overcome this problem. In other words, let us assume for the sake of argument that we *could* somehow know the configuration of the entire universe. This configuration would define a particular time. Next, since this is a thought experiment, let us further assume that we are even able miraculously to have complete knowledge about how the entire universe is evolving in real time. These evolving configurations are the flow of time.

Now, suppose for example that you want to "travel" from the time in which you find yourself now as you read this sentence, i.e., from the configuration of the universe which, roughly speaking, defines "today," to the configuration of the universe which defined the time of last year's Super Bowl game. How would you propose to actually *do* that, in practical terms?

The configuration of the universe which defines the time of last year's Super Bowl game was dramatically different from the configuration which defines today. To somehow "return" to that earlier time you would need somehow to physically return *all* of the many bits and pieces which comprise the universe to the precise configuration which they had during the Super Bowl game. This is not a trivial task. I would even venture out on a limb and say that it is an intrinsically impossible task.

The universe is made up of an impressive quantity of "stuff," much of it in the form of rather large and massive aggregate objects such as stars and planets. We do not rearrange these large, massive objects to suit our whim the way we rearrange our living room furniture! But this sort of whimsical rearrangement is exactly what would be necessary to make time travel feasible.

I hope this helps clarify my point.

Cheers

Jonathan Dickau

Hello again,

Yes I did read your wonderful essay Time Illusion and Reality. And I think I understand your point.

Allow me to summarize:

1. A moment in time is only fully described by the configuration of the universe, which though perhaps not knowable in its entirety, does have a unique state or description.

2. The flow of time is associated with the evolution of the configuration of the universe. That is; the progression of moments in time is defined by the changing configuration of the universe.

3. Owing to the fact that it is a progression with antecedents and products for any event or configuration, it may be possible for the universe to occupy any configuration only once.

4. It may be impossible to ever assemble the energy needed to bring things back to where they were, even if we could know the complete and exact configuration at an earlier time. And to go to the future this way, we would need to know its exact future configuration - another impossibility.

One could add:

5. If we were somehow able to put ourselves in the picture, it would not be the same universe as that specific configuration - without us. So even if the other objections could be handled (doubtful perhaps), you have not traveled to the past or future precisely - instead you are by default on another timeline. This I see as your 'trump card.'

Nonetheless; I see it as a proof obtained by clever definition of terms (which exclude other interpretations), rather than one which spells out the fundamental limits imposed by nature. Ari Stophrenic's essay on The Non-existence of TOEs suffers from this flaw, perhaps in greater measure than yours. He also excludes the possibility of knowing and predicting the universe's exact configuration, through logic.

But both his proof and yours make me wonder about their value. Are they more than enjoyable mental exercises? I do not know for sure.

Warm Regards,

Jonathan

Jonathan Dickau

An afterthought;

In a comment on my paper, Uncle Al (Alan M. Schwartz) remarked that Quantum Mechanics treats G as negligible (equals zero), while Relativity treats h as non-existent. He also put c in the mix, for some reason, and it got me thinking.

We would set c=0 when speaking about a single instant in time, because if there is no time for a photon to travel in, it is as though light is infinitely slow. Perhaps setting the speed of light to zero would allow some sort of state equation to be crafted, for the universe at any instant.

Is that Wheeler-DeWitt? I'd need to think about it more, but not now.

Regards,

Jonathan

J. C. N. Smith

Bravo, Mr. Dickau! You have indeed done a masterful job of correctly summarizing my thinking; I'm impressed! It is gratifying to be so clearly understood.

As to your question about the value of these ideas, and about whether or not it's all simply an enjoyable mental exercise, I'd of course like to think that it's more than that. I'd like to think that it captures something fundamental about our reality. But your question certainly is a fair one, and one that needs to be asked and answered. The proof of an idea's value or lack thereof must come from testing its predictive power. In this regard, I was gratified that my definition of a particular time leads logically to the "prediction" of the equivalence of mass and energy. But was that simply a fluke? Can that success be repeated and extended? I'm not sure.

As I've noted elsewhere in this thread, I'm unfortunately not a professional physicist, so find myself somewhat frustratingly handicapped in terms of knowing how best to go about "exercising" the ideas, in terms of seeing what they're really good for. Any assistance along these lines from those better grounded in the mind-bogglingly technical intricacies of physics certainly would be welcomed.

As for your question regarding Uncle Al's comment, I can't say anything even remotely intelligent about it, so won't even go there.

Thank you very much once again for being such a careful, insightful, perceptive reader! You made my day!

Cheers!

J. C. N. Smith

So back to the original question which led us down this path: is time real or not? As mentioned earlier, the answer, in my opinion, teeters precariously on one's definitions of the words "time" and "real." In a sense, it becomes a virtually meaningless question, lacking suitable qualifiers. It's not the sort of question which can be satisfactorily answered with a simple "yes" or "no."

Cheers

J. C. N. Smith

As an addendum to my post two previous to this in which I wrote, "The proof of an idea's value or lack thereof must come from testing its predictive power." I'd like to add that one other measure of an idea's value lies in its explanatory power. By this measure, I believe that my proposed concept of time fares rather well.

I've found that "internalizing" this way of thinking about time (i.e., by gradually allowing it to become "second nature" to think of time this way), allows me to explain conundrums which have seemed previously to litter our path in what I've gradually come to regard as "the old-fashioned, conventional way of thinking about time." Examples which spring quickly to mind are paradoxes such as Zeno's paradox of the race between Achilles and the tortoise (which was addressed briefly in an earlier post), and, of course, the various time travel paradoxes generically referred to as "The Grandfather Paradox."

In a broader sense, thinking about time as I propose has helped me simply to put my own observations about the world into what I believe is a more logical, self-consistent, and therefore more satisfying, context. But then I've been thinking in these terms for quite some time. It takes a while to shift mental gears, as it were, and become comfortable thinking this way. As I'm sure it must have taken some serious shifting of mental gears to begin thinking in terms of the Earth not being the center of the universe, for example. But could it be worth it? Time will tell, or not, as the saying goes.

Unfortunately, I fear that shifting gears in this way could not be done without some cost and discomfort. As has been discussed in ongoing discussions between myself and Mr. Roy Johnstone and others in this forum, it is not at all clear (certainly not to me at any rate) exactly how we will do physics if we take these proposed ideas about time seriously. I suspect it might not be a trivial matter to make the needed adjustments. As Lee Smolin suggested in 'The Trouble With Physics,' our thinking about the nature of time got off track (certainly in my opinion at any rate) during the infancy of physics (p. 256 TTWP), and that unfortunate miscue has reverberated in one way or another throughout virtually all of what has followed.

Cheers

J. C. N. Smith

Readers of this thread (especially those who have suggested that time travel is no longer a topic of serious scientific debate) may be interested to read an essay which was published in the science section of the 'New York Times' on 12 October 2009 and titled 'The Collider, the Particle and a Theory About Fate,' and which may be found here. Comments invited/welcomed.

Cheers

[deleted]

We can not travel in time because time is run of clocks in space. we can travel in space only. In space there is no past, no present and future. They all belong to the mind. Space is timeless.

yours amrit

[deleted]

Dear Mr. Smith,

You invited to take part in discussion of the term of time.

I agree, true time travel is impossible. However, a clear and direct link between entropy and the so-called "arrow of time" causes interest.

We can examine mathematical descriptions of causality in thermodynamics of irreversible processes. Usually it use with two conditions. a) Consequence cannot precede the reason. b) The small increment of the reason cannot entail an infinite increment of consequence. The second condition does not operate in strongly nonequilibrium (bifurcation) processes. The first condition does not operate in Mach systems. From the point of view of mathematics it makes attractors on a complex surface.

The relativistic thermodynamics has an interesting problem - the relativistic kinematics is not agreed with (quantum) thermodynamics. In my opinion, it enables to start with model of time.

Allow me to offer some steps in this direction.

1. The Relativism determines change of length (anisotropism of space) and delay of time. In relativistic thermodynamics the Law of conservation of energy demands the account of these changes. Anisotropism should be certain as the work of thermodynamic system. This work can be considered as already executed, when systems were accelerated, however the thermodynamics demands its account in the present, thus, we should consider "history" of evolution of system.

2. Relativistic anisotropism can be considered through distribution of energy on degrees of freedom of moving system. Thus, the universal R gas constant is not Lorentz invariant. GR is possibility to check up this assumption, using a gradient of temperature of a solar crown.

If it is interesting, the file is applied.

Yours faithfully,

Alexander Silin.Attachment #1: Thermodynamics_Silin.pdf

J. C. N. Smith

Mr. Silin,

Thank you for your comments.

You wrote, "We can examine mathematical descriptions of causality in thermodynamics of irreversible processes. Usually it use with two conditions. a) Consequence cannot precede the reason. b) The small increment of the reason cannot entail an infinite increment of consequence. The second condition does not operate in strongly nonequilibrium (bifurcation) processes. The first condition does not operate in Mach systems." Could you please explain why you say that the first condition (i.e., effect may not precede cause) does not operate in Mach systems?

I looked at the paper which you attached to your post, and also at the essay which you submitted for last year's FQXi competition. Due probably to my own lack of technical expertise (I'm not a professional physicist), I cannot claim to understand the technical details of your papers. But I also unfortunately do not understand the broad goals of your papers. Could you please be so kind as to explain the goals of your papers in some relatively concise non-technical terms? That would be helpful. Thank you.

Cheers

[deleted]

Hello Mr Smith

'The Collider, the Particle and a Theory About Fate,'

I can't believe that paper is still getting a run in the media! I don't think it is worth commenting on any more than the pounding it has already deservedly received in the "blogosphere". Any paper that includes "luck" as a testing principle surely cannot be science!!

On a more constructive note, I have just finished reading Arjen Dijksman's essay which I notice you have also read and posted a comment on. It is an excellent proposal with direct connections to the work of Durr, Goldstein et al in extending Bohm's ideas and may open the way to a more realistic interpretation of QM which can apply at all scales! I wonder if they have attempted to apply their Bohmian model to these sorts of macro experimental results? Must follow that up!

You might like to check recent comments over at Peter Lynd's discussion thread also.

Cheers for now,

Roy

[deleted]

Dear Mr. Smith,

Perhaps, I was inexact.

I meant systems in which it is impossible to avoid a condition « action on distance ». Such tasks has name of the self-consistent collective field. Any particle of system is simultaneously subject to influence of all other particles of system. For example: physics of plasma or model of synthesis of polymer.

As to the broad goals.

I wished to pay attention of community that our technology works by a principle of destruction of environment. Even, if it is sparing to ecology. The decision of a problem of the self-consistent collective field can be an incitement for development of new technologies.

Yours faithfully,

Alexander Silin.

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