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December 9, 2022

CATEGORY: The Nature of Time Essay Contest (2008) [back]
TOPIC: The Nature of Time by Julian Barbour [refresh]
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Julian Barbour wrote on Dec. 1, 2008 @ 14:20 GMT
Essay Abstract

A review of some basic facts of classical dynamics shows that time, or precisely duration, is redundant as a fundamental concept. Duration and the behaviour of clocks emerge from a timeless law that governs change.

Author Bio

After completing a PhD in theoretical physics, I became an independent researcher. I wished to study fundamental issues and avoid the publish-or-perish syndrome. For forty years I have worked on the nature of time and motion and have published numerous papers (details on my website I have written two books: The Discovery of Dynamics and The End of Time. I was also the joint editor of the conference proceedings Mach's Principle: From Newton's Bucket to Quantum Gravity. I have recently been made a Visiting Professor in Physics at the University of Oxford.

Download Essay PDF File

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Dr. E (The Real McCoy) wrote on Dec. 2, 2008 @ 04:49 GMT
Thanks for the paper!

I also greatly enjoyed your book: THE END OF TIME.

Loved your quote: "As Ernst Mach said (1883) [3]: It is utterly beyond our power to measure the changes of things by time ... time is an abstraction at which we arrive by means of the changes of things; made because we are not restricted to any one de¯nite measure, all being interconnected. Einstein, an...

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Pentcho Valev replied on Aug. 7, 2011 @ 14:42 GMT
Dr. E wrote: "Finally we have been liberated from frozen time and the block universe, with a simple postulate and equation..."

This is not very reasonable. The block universe is a deductive consequence of Einstein's 1905 constant-speed-of-light postulate: if you don't like the consequence, logic says you should replace the premise. Banesh Hoffmann gives you a clue:

"Relativity and Its Roots" By Banesh Hoffmann

"Moreover, if light consists of particles, as Einstein had suggested in his paper submitted just thirteen weeks before this one, the second principle seems absurd: A stone thrown from a speeding train can do far more damage than one thrown from a train at rest; the speed of the particle is not independent of the motion of the object emitting it. And if we take light to consist of particles and assume that these particles obey Newton's laws, they will conform to Newtonian relativity and thus automatically account for the null result of the Michelson-Morley experiment without recourse to contracting lengths, local time, or Lorentz transformations. Yet, as we have seen, Einstein resisted the temptation to account for the null result in terms of particles of light and simple, familiar Newtonian ideas, and introduced as his second postulate something that was more or less obvious when thought of in terms of waves in an ether."

Pentcho Valev

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Dimi Chakalov wrote on Dec. 2, 2008 @ 05:20 GMT
Julian Barbour is again trying to suggest that (quote) "time should be banished" (end of quote), but the simple proof against his hypothesis is the fact that his brain is working.

Namely, no living brain can operate in a "block universe", because it will have to function as a Turing machine installed in some IGUS, and the perpetual "encoding of information", by any conceivable "code", will lead to decreasing of the entropy of the "hard drive", until the poor Turing machine develops severe structural damages and breaks down with a stroke.

Please check out the essay 'Quantum Mechanics 101'.

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Cristi Stoica wrote on Dec. 2, 2008 @ 09:53 GMT
Dear Dimi,

A Turing machine can be viewed as a succession of states, and the relation (transition, in a temporal view) between states is governed by the physical laws. Any Turing Machine can be embedded in a block universe, exactly as any algorithm can be stored on a storage device. You are right that the entropy is the enemy of such a machine, but nobody claims that our brains will live forever (although Tipler seems to overcome this problem).

Cristi Stoica

“Flowing with a Frozen River”,

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Cristi Stoica wrote on Dec. 2, 2008 @ 10:24 GMT
Dear Dr. Barbour,

Contrary to the common impression, that the Newtonian Mechanics provides too little room for a more profound analysis of time, your essay proves the contrary. Thank you for this beautiful exposure.

Cristi Stoica

“Flowing with a Frozen River”,

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Peter Lynds wrote on Dec. 3, 2008 @ 00:56 GMT
Dear Julian,

As with your recent talk at the Perimeter Institute on the same subject, I enjoyed your essay. I also very much agree with you that duration/interval does not exist and is merely an out-flow of motion. I have a question though. Do you still believe that instants and instantaneous magnitudes exist? If you perhaps do, and I get the impression from reading your essay that this is the case, I think that your view about time has some issues. Firstly, as they would constitute the building blocks of time, if one assumes the existence of instants (and instantaneous magnitudes), one also necessarily assumes the existence of time. Secondly, to deny the existence of interval, and yet hold onto instants, is not consistent, as, by definition, an interval is simply a duration bounded by two instants; as long as the instants are still there, the interval will be too. Indeed, if such instants existed, it can be shown that they would render change, motion, and as such, the idea of a clock, impossible.

Best wishes


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Chi Ming Hung wrote on Dec. 3, 2008 @ 01:44 GMT
Peter, not that I'm trying to answer for Julian, but I believe that the existence of instants does not necessarily have to entail the existence of intervening durations/intervals. In fact I argued in my essay that one can have a perfectly consistent theory of Time and Becoming where only instants (or moments of Becoming) are real, while the supposedly continuous happenings (e.g. the evolution of the wave function) in between instants are just mathematical artifacts. Let me give an example of how one might define intervals/durations in a theory with only instants:

Consider a certain number of cycles of a certain stable regularly recurring process, say 9192631770 cycles of the process corresponding to the radiation from the transition between the two hyperfine levels of the ground state of the Caesium 133 atom. We DEFINE this to be our unit of Time (it's the actual definition of a second). All other "intervels/durations" of Time are then measured with respect to this process. e.g. if two instants of certain events coincide with the 10th and 11th cycles of the photon process above, then we say the duration/interval between the two instants is 1/9192631770 second. That doesn't mean that anything real has to happen or exist in this duration/interval, because we can define change as simply the discrete transition from the state at one instant to the state at the next instant, WITHOUT ANYTHING HAPPENING IN BETWEEN. There's nothing wrong with such a theory of change, and in fact it seems to me that quantum mechanics demands such a theory of change.

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Yoron replied on Jan. 29, 2011 @ 17:55 GMT
Chi, your idea creates a 'background' needed for those 'instant's' to glue into a causality chain. Better to look at as a 'flow', not instants. In a 'flow' the idea is that the 'flow' both will be your 'instants' as well as being its own 'background' as what you then deem to be 'instants/events/transitions' then will be your definition of 'separating' that flow.

And the 'flow' is only a 'flow', as in having a arrow of time, macroscopically. Under Planck scale I expect that you can forget anything about a specific arrow 'pointing'. There you will have a 'whole sea', moving or not, as defined by from what frame of reference you look at it. Motion as well as time and 'distance' are all emergences applicable macroscopically, and possibly all the way from Plank scale. But under it those definitions breaks up.

One of the worst mistakes one can make is to assume that because we have a 'solid reality' macroscopically, that point of view will be applicable 'everywhere' and 'always'.

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Ken Sasaki. wrote on Dec. 3, 2008 @ 04:42 GMT
Dear Chi Ming:

You say, “That doesn't mean that anything real has to happen or exist in this duration/interval, because we can define change as simply the discrete transition from the state at one instant to the state at the next instant, WITHOUT ANYTHING HAPPENING IN BETWEEN.” But you can then do away with any concept, such as velocity, or length, or energy, because you don’t know anything about it, if you are not observing it. There isn’t anything wrong with this, but is it especially useful? You make an assumption, regardless of whether you choose to believe that something is in between, or not.

Commenting more generally:

It seems to me that there is no physics in the choice between time emerging from relations between events and relations between events reflecting an underlying time. If time must be eliminated to explain observations, then there will be physics; but this was not demonstrated in the essay, even if you assume (see the end of the essay) a finite universe and no black holes.

In the end (again, see the end of the essay), the argument comes down to Occam’s razor. There is no problem with arguments based on Occam’s Razor, I have used it myself; and, in the end, it is often necessary. But is anything really simplified by eliminating time? I don’t think so; because you are not only left with events, but also an ordering of them. And what does time do? It orders events. Even if you eliminate time, you must keep the ordering. The replacement of the concept of time, with some other conceptual ordering does not get you anything; even if you want to call it purely abstract, it is just time, by another name.

Or, with different semantics: Either you have time plus events producing an emergent order, or events plus an order producing an emergent time – there is a difference, but not a simplification; so Occam’s Razor cannot choose.

Finally, note that there is another essay, arguing for time but no space, at:

I think that you can define away space, just as easily as you can define away time; but, again, I see no physics in it (yet).

Take care,


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Ken Sasaki. wrote on Dec. 3, 2008 @ 04:53 GMT
I forgot to add, to my initial comments, that this essay did a really great job of presenting some very interesting material.


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Peter Lynds wrote on Dec. 3, 2008 @ 05:14 GMT
Dear Chi Ming Hung,

Thanks. I would recommend having a look at my essay for an explanation of what is I think is wrong with that idea.

Best wishes


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Chi Ming Hung wrote on Dec. 3, 2008 @ 23:06 GMT

I disagree that there's no physics if we "define away time". First of all, I'm not advocating the elimination of Time like some in the quantum gravity camp (and Julian) are advocating. The idea I'm trying to put across is that we should eliminate the Time **CONTINUUM** as something unphysical, because there's no need for it except as a mathematical convenience.

And this is not just a matter of convention either, because by treating Time as though it's a physical continuum, physicists are led to the inevitable paradoxes between continuous unitary evolution between measurements, and discontinuous non-unitary transitions during measurements. And to make matters worse, most physicists seem to think that the UNOBSERVABLE continuous evolution of the wave function is the true physics while the OBSERVABLE quantum jumps are the aberrations that needed to be explained away (e.g. using decoherence). This seems most illogical to me.

I think we can all learn a lesson from how things are done in the early days of Quantum Mechanics, when Heisenberg and company were trying to work out Matrix Mechanics in order to explain the correlations between observables (and only observables) like the frequencies of light from atomic spectra and their relative intensities, with a minimum of mathematical assumptions. It's true that even Heisenberg and company assumed the time continuum and wrote exp(-iwt) for a process of frequency w (omega), but my point is that we should keep the physically unobservable mathematical assumptions in our theories to a minimum and recognize that's what they are: just mathematical assumptions. In fact I think Quantum Mechanics would have developed very differently (and much more logically) had Heisenberg and company gone all the way with their philosophy and eliminated even the unobservable exp(-iwt) from their equations...

And you're right that if we eliminated the Time continuum, then all we're left with are just instants and their orders. But that's all we need! My contention is that modern physics (esp. Quantum Mechanics and General Relativity) can be recast into physics about only instants and their orders, and when this is done, we can gain deeper insights into physics that have been hidden from us by the unphysical Time continuum.

And I think that's not very far from Julian's ideas...

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RJ Vanhoy replied on Aug. 12, 2012 @ 22:07 GMT
Finally I can make some sense of Einstein's theories, knowing that a great deal of the problems do not sprout from my weak mind, but rather a flaw in underlying assumptions. I am a physicist by any means, but I do excel at logic puzzles- and I have been playing with this one for a while. After picking up an article by Mr Barbour, and thinking for some time that Einstein had to be wrong about his assumptions on distance, time, or both, I am finally getting some relief. I agree with Mr. Barbour that we should take Mach's theories to the next level, knowing that Einstein got almost got us to the finish line, and hold everything relative. In that kind of universe, time has to go!

What I want to know, is what does the size and expanse of the universe look like after removing time? I would tend to think that our current measurements of the expanse of space, along with our calculations of age both for the universe and the Earth, have to be thrown out. If that is the case, doesn't the universe get a lot smaller, and become a place that we cannot think of in terms of "how many miles to cross" or even in travel time. Also, doesn't this approach solve the issue of locality and move us vastly closer to a unified theory? If so, why has it taken so long to gain wide acceptance, I mean I am just a normal guy and I found profound and obvious logical error in current and accepted equations? I can understand making an assumption, or hypothesis, and then trying to prove it. But at some point someone had to say, wait, we have made fully 19 assumptions on which to build the current model, when do we say that we won't likely resolve them via observation, and maybe, just maybe, some of them are wrong and won't ever be proven.

Sorry to ramble, but it's exciting to find that I wasn't so crazy. And forgive me if I made some incorrect or very elementary mistakes. Again, I am just very good at logical puzzles, and no scientists, not even much of a math guy, but as I understand it, Physics is more about balance, and logic. So thank for any input you can provide.

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Ken Sasaki. wrote on Dec. 4, 2008 @ 01:03 GMT
Dear Chi Ming:

Thank you for your comments.

You state, “And this is not just a matter of convention either, because by treating Time as though it's a physical continuum, physicists are led to the inevitable paradoxes between continuous unitary evolution between measurements, and discontinuous non-unitary transitions during measurements.” You also state that you find certain attempts, to reconcile the continuous with the discontinuous, to be “most illogical”.

I don’t think that discretizing time is necessarily objectionable; but I think that there should be a real reason, based on observation. I do object to the idea that there is any utility in abandoning the concept of time entirely. In addition, I agree that there are certainly discontinuities in QM; and, if time must be discretized, to prevent a paradox, then doing so is mandatory. But is there really a paradox, as you say – a logical contradiction – in continuous time evolution, with discontinuities at certain interactions; or is it just something that seems odd? If there is a logical contradiction, can you please explain it to me?

Consider also that, while there are situations that observably demonstrate discontinuity (EPR and other entanglement situations; many worlds not withstanding), most situations do not. Note also that “collapse of the wave function” is peculiar to certain interpretations of QM, but not all. If you are going to discretize time, to make everything look like wave-function collapse, then you are, in effect, choosing certain interpretations, over others; and to do this, you should have an observation that supports those interpretations, over the others. Can you please tell me if you have such an observation?

Take care,


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Chi Ming Hung wrote on Dec. 4, 2008 @ 02:11 GMT

you seemed to have misunderstood me when I said:

"And to make matters worse, most physicists seem to think that the UNOBSERVABLE continuous evolution of the wave function is the true physics while the OBSERVABLE quantum jumps are the aberrations that needed to be explained away (e.g. using decoherence). This seems most illogical to me."

What's illogical a priori is not that we may have a theory with "continuous time evolution, with discontinuities at certain interactions", but rather that physicists are treating the **UNOBSERVABLE** part of the wave function evolution as true physics, while treating the **OBSERVABLE** quantum jumps as aberrations. To me, it should be the other way round, treating observable phenomena as true physics, while relegating the unobservable part of physics as mere mathematical convenience.

As for the reality of quantum jumps or wave function collapses, I suppose many physicists are still unwilling to accept it because it contradicts what they believe to be the true physics behind quantum mechanics, namely the continuous and unitary evolution of the wave function. I guess what I prefer to call reality is not something that lives in a Platonic world of mathematical ideals, but rather what I see with my own eyes (and with the help of instruments): I see always a world of definite states, never fuzzy quantum superpositions. You asked me for evidence of my "interpretation" over others, that's what I submit.

But let me ask you for evidence to the contrary: Please show me any physical evidence of a wave function that evolves continuously in time. I don't think you can, because BY DEFINITION, it's unobservable! The best you can do is to point out experiments (e.g. interference and entanglement experiments) that INDIRECTLY implies the existence of a wave function that evolves continuously in time, but that's all. You never see a ghostly ether-like wave leisurely traversing space and time, all you ever see are dots and discrete events in your screens and instruments.

I'm not arguing against the utility of using a mathematical wave function that evolves continuously in time, what I'm arguing against is to take this mathematical convenience too seriously and think that it is physical reality.

The development of 20th century physics has taught us that what's not directly observable should not be treated as real. Such is the case for the ether, the absolute time of Newton, and a list of other ideas. My contention is simply that the Time continuum and the denizens that evolve in it should join the list and be recognized as what they are: mathematical conveniences, not physical realities.

(P.S. I should apologize to Julian for hogging the forum for his essay. I think we should continue this discussion in our essays' forums...)

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Mark Stuckey wrote on Dec. 4, 2008 @ 21:39 GMT
Dear Julian,

I appreciate your attempt to provide "an equation of time," thereby demoting time from its otherwise fundamental status. I've a question concerning this proposal that I'm hoping you will answer.

In order to use your definition, I need to unambiguously identify entities in different configurations, e.g., THAT planet in configuration 2 is Mars and it is the SAME planet I called Mars in configuration 1. I need this identification process articulated so I can measure the delta d’s, for example. How do you define this identification process without bringing time in the back door? Isn't this identification process precisely the basis of "trans-temporal identification?"



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Chris Clyde wrote on Dec. 5, 2008 @ 13:00 GMT
Dr. Julian

I am impressed with your handling of the "Big Picture".

The way I understand your proposal is, to answer Mark Stuckey above, yes time comes in the back door as the sidereal choice necessary to make eq. (3) a relational, quantitative measure. Then time is led right back out the front door when its utility is exhausted in finding the principle of least action it defines in the motion observed.

I found your analogy of the synchronous relation of arcs swept out by the tips of hands of different clocks very enlightening.

It seems both you and Carlo Rovelli propose time should emerge From and As the kinematics of observable (local) variables via the principle of general relativity.

i.e. "extremal curves" are not absolute but locally finite.

Your ideas on time can apply with equal efficiency to mass and space, for once you have set mechanics "fully adrift" in the relativistic sea, all three dimensions emerge in a similar way. Your "extremal curve" is a physical constant, an observable that is defined by its dynamical equivalent observed in the constancy of the speed of light. The kinematics expressed by the principle of least action arise from the dynamics that define the three fundamental dimensions as different aspects of the same thing.

Although my essay won't win or place in this competition and few will even realize what I've said, I am very grateful for your work here as both you and Carlo have offered methodology to my madness. The model I've presented is so far adrift in general relativistic scope, no one would dare jump aboard without the compass you have designed.

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Chris Kennedy wrote on Dec. 5, 2008 @ 18:15 GMT
Dr. Barbour,

Terrific essay. My questions are:

If the universe can tell perfect time and could be considered the perfect clock, how would that assumption be affected if it is determined that there is no absoulte age of the universe? If I am living on a far away galaxy accelerating at a much faster velocity than ours - then (assuming I take enough vitamins to live through the whole process) how old do I think the universe is from my perspective? Or, how old is the universe to me if I am near a black hole or better yet - If a very long time ago I watched the big bang from a safe distance (where my gravity and velocity would be very different compared to being "inside" the universe) how old would I think the universe is right now? Who would be correct?

Take care,


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anon wrote on Dec. 9, 2008 @ 00:27 GMT
"Duration" is not physical. It can't be found in the heavens. It has meaning only in the presence of an observer.

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Lawrence B. Crowell wrote on Dec. 12, 2008 @ 00:54 GMT

I thought your paper was fun. The ending was good.

I will say right off that I think the issue of whether time exists or not is irrelevant, even though time has some mysterious elements to it. I do think it is something which is operational with respect to the universe, and not something which the universe operates according to. I found your section one relative timess,in particular on page 7 with the ratio of times for two solar systems interesting. My paper #370 illustrates how time is a scaling principle. I illustrate a program for a renormalization group system for energy (or its conjugate time) on different scales. Your classical mechanical example at its kernel is I argue for.


Lawrence B. Crowell

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Anonymous wrote on Dec. 16, 2008 @ 00:53 GMT
Dr. Barbour:

Your paper was interesting for me to read, as it arrives at the same conclusions as mine, although clearly in a much more rigorous way.

After all that we have learned from science in the last few centuries, one might think that we would have learned to separate physical reality from what our senses perceive. Clearly, though, there are few that are ready to take that step.

James Tyson

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Dimi Chakalov wrote on Dec. 19, 2008 @ 21:20 GMT
Dear colleagues,

I'm afraid there is no sense in posting our comments and questions here, because Julian Barbour lives in a different world, and just doesn't care.

Dimi Chakalov

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anon wrote on Dec. 20, 2008 @ 23:39 GMT
Isn't that the point? We all live in different worlds.

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amrit wrote on Dec. 23, 2008 @ 16:10 GMT
Dear friends,

we live all in the same world and all in his/her individual mind.

The spirit of science is to build up a model of the SAME world that we all agree on it.

Regarding time I do not agree with the Julian that motion and time are ilusions...According to my research time is a coordinate f motion...

yours amrit

attachments: 2_In_The_Theory_of_Relativity_Time_is_a_Coordinate_of_Motion__Sorli_2009.pdf

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amrit wrote on Dec. 28, 2008 @ 15:25 GMT
Eleven steps to right understanding of time

1. Motion of objects and particles do not happen in time, it happens in space only.

2. Time is what we measure with clocks: with clocks we measure duration and numerical order of massive objects and elementary particles motion into space.

3. As a “fourth” coordinate of space-time time is a “coordinate of motion”, it describes motion of massive bodies and particles into space.

4. Space-time is a math model only; space-time does not exist as a physical reality.

5. In a model of space-time we describe motion of objects and particles into space.

6. Space itself is atemporal.

7. Humans experience atemporal space as a present moment.

8. Past and future exists only in the mind; physical past and future do not exist.

9. Time as a coordinate of motion in atemporal space exists only when we measure it.

10. Time as a “coordinate of motion” is not elementary physical quantity as energy matter, space and motion are.

11. Universe is an atemporal phenomenon.

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Edward Thomas Medalis replied on Jul. 22, 2013 @ 16:17 GMT
To avoid repetition, I selected Amrit's Dec 28,2008 @ 15:25 GMT comments because they are identical to my belief.

I also have these comments:

The first obstacle for an observer to overcome is the tendency to project and mistake abstractions of thought to be physically part of the observed.

The laws and mathematical models of physics and the concept of time evolved in the minds of observers and are part of our understanding of physical reality but not a physical part of it.

Time is a mental construct that an observer must have to understand a real physical item of focus because that item is always in relative motion to every other physical thing.

Time has the purpose of helping us understand relative motion and all of the changes that result. The physical reality of the universe has no purpose. It simply exists and has always existed in one form or another.

All that is physically real including space is a form of energy.

How they change form is for physicists to figure out.

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Narendra Nath wrote on Dec. 30, 2008 @ 11:25 GMT
Both space and time are concepts formulated to relate the physical phenomena, all of these show some kind of motion.

Motions may be conceptualized otherwise. A new set of concepts may then emerge. Such concepts are checked by the correctness of theories based on them. Let us have alternate concepts to space and time that cover the entire range of physical phenomena. Merely if quantum gravity needs to be invoked to understand the behavior of black holes, does not mean that gravity has to be quantum in nature or even the quantum mechanics provides the only way to understand the phenomena at micro-level. Alternate explanations may emerge in the future, as Einstein himself indicated that he was not particularly happy with the probabilistic nature of quantum mechanics. Carrying one's own bandwagon all the time can be quite distressing for any individual! Openness and unbiased approach appears to be best to follow in the growth of any science worth the name.

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Julian Barbour wrote on Dec. 30, 2008 @ 16:48 GMT
Apologies for not responding to the postings until now. I would like to assure Dimi Chakalov that I do live in the same world and do care. However, personal circumstances make it difficult for me to keep up with things in the way I would like. Let me now answer some of the postings.

1. Peter Lynds, Dec. 2nd. In my view, instants have no magnitude. I liken them to snapshots. The basis of all my work about motion and time is that it is the difference between such snapshots that counts. The difference is found by a process called best matching, as I explained in my book The End of Time and in the papers cited on my website The best-matched difference between two nearly indentical 'snapshots' then measures the duration between them. The magnitude is 'between' the snapshots, not in them.

2. Ken Sasaki on Dec. 3rd. Your comments about Occam's razor are certainly correct as far as classical physics is concerned. However, quantum theories of the universe with and without time are likely to be very different and have correspondingly different observable predictions. Unfortunately, we have no such theory as yet with or without time. If my work does have value, I believe it will be for the hints that it may give about how to create a quantum theory of the universe.

3. Mark Stuckey, Dec. 4. Your comment is very well made and was the main reason why Bertotti and I introduced the idea of best matching in order to develop a theory of fields in which permanent identity cannot be postulated. This leads to comparison of complete field configurations. There is a PDF file of my 1982 paper with Bertotti on my website if you or anyone else are interested. In my essay I thought it was reasonable to take the short cut; I am confident that the whole theory can go through without "bringing time in the back door".

4. Chris Kennedy, Dec. 4. I described how duration arises only for a Newtonian-type situation. Something similar but much more sophisticated happens in general relativity. It may be that in the scenarios that you describe my way of accounting for the appearance of time fails, as I acknowledged briefly at the end of my essay.

5. anon, Dec. 9. I agree that we only learn about duration through our observations, but I am a realist and make the working assumption that there is a real universe 'out there'. I am not sure whether you are advocating solipsism.

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anon wrote on Dec. 31, 2008 @ 17:09 GMT
Julian, "solipsistic" only as to "duration" which seems to have no meaning apart from the psychological

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Peter Lynds wrote on Jan. 1, 2009 @ 00:18 GMT
Dear Julian,

Thanks for your reply. Can you see though that by asserting/assuming the existence of zero duration instants (the regular definition of an instant), snap-shots (another name for an instant), and nows (the present tense version of an instant), you are also asserting/assuming the existence of time? The same applies to assuming the existence of instantaneous magnitudes, such as velocity, momentum etc. Given that instants would constitute the building blocks of time, it is analogous to saying that water doesn't exist, but that water molecules (or ice-cubes) do (and in relation to instantaneous magnitudes, that things can also be frozen in such ice-cubes). The only difference is that instants have zero size, but this not effect the validity of the analogy.

If one accepts the existence of instants and instantaneous magnitudes, as well as this assuming the existence of time, one must also deny motion and change, which is violently at odds with observation, and I think, reason too. I realise that you do not believe in change and motion, and indeed, neither does one who accepts the standard interpretation of the block universe, so this need not signal a problem, but this leaves one unable to imply any continuity, including even the "sense" of it for an observer. In your work, you argue that there are countless zero duration instants/snap-shots underlying the universe. You argue that such instants are unrelated to each other and they do not progress from one to the next. The problem with this is that it renders it impossible for even a "sense" of succession or continuity to arise. In order for an observer to think that he observes things moving, there must be a succession of these instants for him. Because your model says that such a succession is not possible, even his perception of motion and change is impossible. Indeed, he is unable to even think. Again, this is violently at odds with observation.

If one denies the existence the instants, instantaneous magnitudes, space-time points etc, however, motion and change suddenly become possible, the problems and paradoxes disappear, and this is still completely compatible with relativity and the lack of absolute simultaneity. That is, one gets an evolving block universe (with all times shown by a clock sharing equal footing) that is completely timeless.

Best wishes


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Julian Barbour wrote on Jan. 7, 2009 @ 17:55 GMT
In response to the last two posts, I am afraid the one from anon is too enigmatic for me to understand. With regard to your comments Peter, I agree that they seem reasonable on the basis of our conscious experiences, but direct experience has often proved a hindrance to advance in science. Galileo made this point with tremendous skill. As a theoretical physicist, I come to a position that does seem almost impossible to believe on the basis of direct experience, but I recognize that my theoretical model must contain structure correlated with experience. I believe that my idea of 'snapshot-within-snapshot' time capsules as presented in my The End of Time meets this minimum requirement and puts me very close to Boltzmann's position. I freely admit that at the end I must rely on the unknown way in which structure in the brain can lead to conscious experience.

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Peter Lynds wrote on Jan. 9, 2009 @ 02:25 GMT
Dear Julian,

Thanks for your thoughtful comments. I'm somewhat hesitant to say this, as I appreciate the manner of your replies, and I don't at all want to be confrontative (hopefully you won't take the following as such), but you seem reluctant to acknowledge my point that to assert/assume the existence of instants and instantaneous magnitudes, one also asserts/assumes the existence of time. In relation to instants (and instantaneous magnitudes), and although from reading your book, I already know at least part of the answer to this question, can I ask what the basis of your belief in them is?

I agree that direct experience has often proved a hindrance to advance in science. I think Galileo and Copernican vs. Ptolemaic theory, Mach's criticism of Boltzmann, the speed of light being frame independent, or our perception of time flowing, are all really good examples of this. I feel the issue of change/motion being illusionary is somewhat different, however, because, with the exception of what I see as being incorrect assumptions, I think pretty much everything, not only experience, but reason, physical intuition, the need to avoid paradox, etc, points against it too. Indeed, as I think motion and change are the actual basis of physics, without them, I don't see how one can even talk of physics. Of course, physicists who deny motion/change because of their interpretation of gr or qm and the related formalism, still write papers and do physics, but they also still assume change whenever they talk of evolution or accept and work with variable magnitudes or values (i.e. constantly). I find this situation – seeming apathetic acceptance of an overtly contradictory position – somewhat bizarre. Your proposal is obviously immune from this criticism, as there is no assumption of continuity there at all. I'm unable to see though how a changeless physical universe can give rise to the perception of change for physically based observers.

Best wishes


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John Merryman wrote on Jan. 10, 2009 @ 00:07 GMT

It poses some interesting conceptual analysis of the thought processes involved that the search for the immutable and unchanging laws of the universe have resulted in the conclusion that the universe is immutable and unchanging. That the dynamic which so overwhelms the physical reality in which we find ourselves is supposedly just an illusion. Is physics static, or is it just the institution of physics which is static?

I agree that time is linearity of motion, not the basis for motion. I also think it is quantized by intervals of non-linear motion, be it quantum fluctuations or geologic earthquakes. Complexity Theory offers some logical support.

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Dr. E (The Real McCoy) wrote on Jan. 10, 2009 @ 20:53 GMT
Hello All,

I am rather amazed and perplexed to read statements such as, "I agree that direct experience has often proved a hindrance to advance in science."

This is like George Bush's recent statement that to save the free market, he had to abandon free market principles.

Physics, and the quest for *physical* reality rooted in the senses and *physical* models has ever...

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John Matthewson wrote on Jan. 20, 2009 @ 19:02 GMT
What is the principle of least action in a four dimensional manifold? For surely we need to extend Barbour's 3D analysis in the light of temporal double slit experiments.

See Horwitz 2005 On the Significance of a Recent Experiment

Demonstrating Quantum Interference in Time

( ).

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Dr. E (The Real McCoy) wrote on Feb. 15, 2009 @ 18:53 GMT
Hello Julian! Hope all is well! I was wondering what your take might be on Lee Smolin's most recent comments-- reflecting his epic change of mind--that time is indeed now real.

It is great that Lee is coming around and seeing time as a *physically* real entity. MDT goes a step further in seeing time as a *physically* real entity that emerges because of a more fundamental, universal,...

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attachments: retina2.jpg, 1_2_wheeler_recommendation_mcgucken_medium2.jpg

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Zephir wrote on Mar. 9, 2009 @ 15:44 GMT
AWT uses a geometric definition of spatialized time. This definition explains, why time has an arrow, the physical meaning of dual time arrow, concept of many time dimensions etc.

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Georgina Parry wrote on Mar. 10, 2009 @ 01:51 GMT
Lee Smolin had better jump back on the fence.In my humble opinion.

Einstein is quoted as having said....."But the development of physics has shown that at any given moment, out of all conceivable constructions, a single one has always proved itself decidedly superior to all the rest."

MDT is nice in that a simple solution resolves such a lot.

I am pleased if it really will open up the minds of scientists to alternative frameworks of explanation.

Rather than the 4th dimension expanding, I would prefer to explain this as all of the matter of the universe changing position along the 4th dimension as potential energy decreases.This change in position along the 4th dimension (if it is visualised as spatial)or change in potential energy(if it is considered in energetic terms only) being equivalent to c measured in 3D vector space.The advantage of this model is that it enables explanation of objective reality without time, but time and relativity to be an emergent phenomena due to the changing position along the 4th dimension, which is change in potential energy.

So there are two separate realities. One, objective reality,in which there is no time and one in which there is time. The latter is subjective reality in which all observations are made and science is conducted.Time is therefore both real and not real depending on the reality under consideration.

The fence is the best place to sit in this situation because any other position on the reality of time would not be taking into account both realities and the Prime Reality Interface that separates them.

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DonLimuti ( wrote on Mar. 11, 2009 @ 07:02 GMT
Congratulations on your well-deserved winning of the essay contest.

Don l.

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amrit wrote on Mar. 12, 2009 @ 20:26 GMT
What Barbour says in a very complex way can be postulated in three points:

1. universe is timeless (atemporal)

2. with clocks we measure duration of material change in timeless universe

3. time is a mind model in which humans experience stream of material change

yours amrit

attachments: 4_ETERNITY_IS_NOW_Sorli_2009.pdf

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wanjohi wrote on Mar. 26, 2009 @ 17:21 GMT
Barbour's universe, if timeless, is also endless(infinite).It is non-existent or imaginary. Before we banish time-keeping in an everlasting bliss, stern science demands some accountability: How can death and radio-active decay be explained away in such an eternal set-up?

The 'astronomers in a crow's nest taking snapshots from above the solar system' is theoretically and experimentally impossible, because such a vantage point is outside the universe; but not outside Barbour's universe, so he should try to prove his point by initially sending a satellite there!

The long and short of my opinion is that Barbour confuses a mathematical universe,where everthing is beautiful and perfect, with a physical universe which is ugly and imperfect. He eliminates the unpleasant duration but that also removes physicality itself.

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johan masreliez wrote on Apr. 3, 2009 @ 23:51 GMT
Dear Dr. Barbour,

It is very likely that it is premature to abandon the progression of time as a physical process. Perhaps our difficulty to understand it merely indicates missing physics.

As human beings we have always felt the need to confine our existence to a limited place in space and time. Maybe this is in order to avoid confronting our smallness in comparison to the immense vastness of the universe. But, gradually over the millenniums we have become aware that the world is much larger than we ever thought. And, now our last holdout will fall; we will come to realize that there is no beginning or end of time.

However, to make eternal existence possible, a dynamic process must exist that makes time progress, and is capable of energizing the world forever. The expansion of both space and time could do this, and the resulting cosmos would agree with all our observations. Furthermore, it would mean the existence of dimensions ‘beyond space and time’ given by vibrating metrics of spacetime, which could make the missing connection between general relativity and quantum mechanics. It would also explain the origin of Inertia. However, this new insight would require revision of physics going all the way back to Galileo, leaving most modern theories of the universe on the ash-heap of history.

The expansion of both time and space would in effect be an expansion in scale, which would not change Einstein’s field equations of General Relativity (GR). Consequently this process, which also might constitute the essence of the progression of time, may proceed ‘beyond’ the four dimensions of spacetime.

It is a physical process that cannot be modeled by current physics.

But, it may be modeled by a semi-discrete process whereby the cosmos expands in short time intervals terminated by discrete scale adjustments. The resulting Scale Expanding Cosmos (SEC) theory agrees with all observations. With this new model there is no missing dark energy and no accelerating expansion. And, as already mentioned, this new Dynamic Incremental Scale Transition (DIST) process could also explain the progression of time.

Therefore, it appears that our current inability to explain the progression of time merely indicates that we do not yet know enough. As usually is the case, what we do not know may appear mysterious and unexplainable.

Best regards,

Johan Masreliez

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johan masreliez wrote on Apr. 3, 2009 @ 23:54 GMT
The attached paper was published in Physica Scripta.

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Imre von Soos wrote on Apr. 12, 2009 @ 09:58 GMT

The concept dimension is defined as a measurable extent of any kind. Spatial and temporal dimensions exist only as the spatial and temporal demarcating relationships of events. They have no physical substance, but form parts of physical reality. Neither can be perceived as such: only the objects and events that fill them can be perceived and their respective relationships...

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Frank Martin DiMeglio wrote on Aug. 1, 2009 @ 03:44 GMT
Hello Julian and readers:

Importantly, time is dependent upon the integrated extensiveness of being and experience (including space and thought).

Here are some basics regarding the fundamental nature of being, experience, and time:

Since the self has extensiveness of being and experience (in and with time) in conjunction with the integrated and natural extensiveness of sensory experience, we spend less time dreaming (and sleeping) than waking. The integrated extensiveness of being and experience go hand in hand. Consistent with this, the integrated extensiveness of the being and experience of the Common Chimpanzee is understood to be in the middle (or between) that of our waking and dream experience. Accordingly, the Common Chimpanzees live two-thirds as long as we do (in captivity, of course). In comparison to the Common Chimpanzee, we are understood as being more conscious in conjunction with experience that is (on balance) more unconscious; and this is evident in our waking and dream experiences.

Dreams are an emotional experience that occur during the one third of our lives that we spend sleeping, because emotion is one part (or one third) of feeling, emotion, and thought. Consistent with this, both feeling and thought are proportionately reduced in the dream. Thoughts and emotions are differentiated feelings. Dreams are essential for thoughtful and emotional balance, integration, comprehensiveness, consistency, and resiliency. Indeed, emotion that is comprehensive and balanced advances consciousness. If the self did not represent, form, and experience a comprehensive approximation of experience in general, we would be incapable of growth and of becoming other than we are.

It can be seen that in comparison to the Common Chimpanzee, the self does represent, form, and experience a comprehensive approximation of experience IN GENERAL.

This is, indeed, not only a great truth, but it is also a new description/understanding of experience in general.

Your comments and questions are very welcome.

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Frank Martin DiMeglio wrote on Aug. 30, 2009 @ 02:49 GMT
FQXi participants:

Some important facts/truth regarding time:

Time is ultimately dependent upon the integrated extensiveness of being, experience (and space), and thought. You can see how this applies to photons in relation to time -- consider how the words "integrated extensiveness" apply.

Dreams improve upon memory and understanding by increasing (or adding to) the...

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0=v.i. wrote on Sep. 4, 2009 @ 09:49 GMT
In 1D x^2=(ct)^2 or dx/dt=c as well as dx4/dt=ic (if we cinsider c a constant).

Why MDT consinders that only x4 is expanding by time?

dx4/dx=i this means that x4 is moving relative to x by i (and not by c).

I feel that c=kt (k=costant) that means dx/dt =2k and dx4/dx=2ik.

In this case all "patial" dimensions are expanding by a factor of k and x4 by ik.


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Buz Craft wrote on Sep. 13, 2009 @ 14:40 GMT
Congrats Julian! Please remember this old East Texas rancher's conclusion: TIME IS TEMPERATURE!

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Charles Z. wrote on Oct. 13, 2009 @ 03:41 GMT
A photon, though travelling through space for 12 billion years, experiences no advance in time, because at the speed of light at which it moves time slows down to zero. This photon is and always has been in an actual state of timelessness.

Time must therefore be a real attribute of any object which moves slower than this photon.

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Michael wrote on May. 4, 2010 @ 09:08 GMT
This argument about time reminds me of Zeno's paradox -Achilles who runs ten times faster than a tortoise in a race of pre-determined length Achilles gives the tortoise one hundred yards start Achilles completes the hundred and the tortoise is ten yards ahead, Achilles completes the ten yards and the tortoise is 1 yard ahead -ad infinitum does this mean that Achilles will take infinitely smaller distances to catch the tortoise? never doing so? Obviously not.. Using the correct equation including the time taken for Achilles to cover the pre-determined distance at 1 yard per second and the tortoise at 1 yard per ten seconds we can calculate precisely where and when Achilles will pass the tortoise and the difference in time between Achilles finish and the Tortoise.. My question Is Julian Barbour a latter day Zeno?


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John wrote on May. 26, 2010 @ 13:32 GMT
It is ironic that this essay won just as the existence of time was being demonstrated by experiments (the first in 2005):

Attosecond double-slit experiment

Authors: F. Lindner, M. G. Schaetzel, H. Walther, A. Baltuska, E. Goulielmakis, F. Krausz, D. B. Milosevic, D. Bauer, W. Becker, G. G. Paulus

(which has been confirmed and repeated by several labs in several different ways)

But since then there have been few attempts to produce a new relativistic quantum theory. This is bizarre when, as Ashmead says, the area of study is an "experiment factory". Here are a few background articles that have come out since the first of these double slit experiments:

Overview: Quantum Time

by John Ashmead

On the significance of a recent experiment demonstrating quantum interference in time

Authors: Lawrence P. Horwitz

Kryukov's excellent papers on the subject

This area of study will be the big one in a decade or two. Come on physicists, get your fingers out, I dont want to wait 20 years!

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Patrick replied on Jul. 27, 2010 @ 22:33 GMT
Ironic, indeed.

This essay won because it seems to be one of the better written entrants. Barbour uses clear, easy language and develops his material in a very logical fashion (unlike other more difficult essays), but his central argument is incorrect. He relies on proving that one can have a "timeless" equation to quantify time-like phenomena. In his attempt, he uses V and E, ignoring the obvious fact that V embeds Newton's G which has dimensions which include time and that E embeds c, also requiring the dimension of time. Hence, his "timeless" equation is nothing more than a mathematical tautology.

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Kan wrote on Jul. 8, 2010 @ 08:52 GMT
Dr Barbour,

I have read your article The Nature of Time and some other pieces on your website and watched the video. I find them very interesting because I am interested in the subject as well and have done some thinking about it sometime ago.

If one has the privilege to observe the Universe from the outside, there seems to be a simple way to define (or...

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Rainsmith wrote on Sep. 15, 2010 @ 12:51 GMT
I am a little unsure what is being discussed here. Clearly, the idea that it is possible to obtain meaningful results on particular levels of observation but assuming a sequential sucession of events is a useful tool. It would seem that 'reality' is such that this paradigm which we call 'time' is valod for a great many situatioms but I do not see why one should limit reality to the limitations of this obvious and limited convenience.

Surely what is under question here is not the reality of time, but our definition of it. As an abstract concept that has a limited mapping to linear phemomina, we ought to consider that our concept of time is, far from being something illusionary, is actually lacking in features.

The existance of integral transforms is a clear indicationn that we must connect our concept of linear time to other topoligies if it is to be of use to us in many situations.

I am not an advocate for or against the existance of time its current conceptual form, which I believe ,serves as a measure of some aspects of our psychological state rather than a flawed concept in some contempoary models of the universe.

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Anonymous wrote on Jan. 29, 2011 @ 18:51 GMT
This is a general comment to what I read in this thread.

The mistake might rest in how too define 'time'. If you define it as instants you will have to look at durations too. Either that, or you will define a 'instant' as the shortest applicable amount of time, becoming a sort of 'still picture'. But then both ideas will need something more to start 'move'. And that should be our arrow of...

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Rodney Bartlett wrote on Jan. 30, 2011 @ 13:04 GMT
Dear Dr. Barbour,

Here's a post that tries to comment on FQXi's 2008 essay contest (The Nature of Time) as well as its 2010 essay contest (Is Reality Digital or Analog?)

We have to wonder if the Large Hadron Collider was worth all the time and money it took to build. It won't find the Higgs boson. It may well "prove" that strings exist but this will only deceive the world because...

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Rodney Bartlett wrote on Feb. 2, 2011 @ 03:16 GMT
I know I can't submit another essay. I don't plan to - these are just some comments that came to mind after thinking about my essay. They don't seem very relevant to the topic "Is Reality Digital or Analog?" but writing them has given even more satisfaction than writing the essay, and I'm in the mood to share them with the whole world. So if you've got time to read them...

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Rodney Bartlett wrote on Feb. 7, 2011 @ 02:53 GMT
According to the Community Ratings, my essay in the 2011 Essay Contest is sliding further down the ratings each day. But I'm having more luck with a science journal called General Science Journal - comments of mine inspired by the essay (which are nearly 20,000 words long and include comments about "The Nature of Time" as well as "Is Reality Digital or Analog?") were published in the Journal on Feb. 6 and may be viewed at

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Phyperereu wrote on May. 20, 2011 @ 04:39 GMT
Hi all, I'm glad that I came to this forum

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Robert Clemons wrote on Sep. 17, 2011 @ 23:31 GMT
Dr. Barbour, I can accept your idea that time is an illusion, but surely you must accept the possibility that all external reality is an illusion. A human being with normal intelligence and an active mind but with no access to the external world via the famous five senses would have no way of knowing, much less proving the reality of the external world. Such an unfortunate individual would only know that he thinks (a la Descartes).

You may respond that all of us, indeed most of us do in fact have the 5 transducers that pass along signals from the external world into our brains so that we can know of its existence. However, we are removed from immediate experience of the hypothetical external reality by the, dare I call it time it takes the signals to move from the sense organs to the brain to be perceived.

How can we know that the signals our 5 senses relay to our brains are from a physical reality at all. Perhaps, as conjectured by Bishop Berkeley there is no proof that an independent external world exists. Rather something, call it a spiritual reality or advanced aliens from somewhere else, something transmits the signals we receive through our onboard transducers giving us the impression there is an external physical reality.

How can we know such a reality is real? How can we trust our senses on faith that they are reporting the true reality? Perhaps time is not real as our senses tell us it is; but matter may not be real as well; the forces of electromagnetism, gravity, strong, and weak that we have "observed" may not be real either.

80 nanoseconds of "time" separates our mental selves from any immediate awareness of external reality. Our consciousness seems to be suspended in "time" in a sense, floating through a reality that we have no trustworthy resources for defining scientifically; rather, we merely believe on sensorial faith that it exists.

As long as I must assume that there is a physical reality, I may as well go the whole distance and assume that their is an independent feature within it that we refer to as time.

Please help me understand how my thinking may be incorrect.

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Taylor smith wrote on Sep. 23, 2011 @ 14:05 GMT
Dear Julian,

As with your recent talk at the Perimeter Institute on the same subject, I enjoyed your essay. I also very much agree with you that duration/interval does not exist and is merely an out-flow of motion. I have a question though. Do you still believe that instants and instantaneous magnitudes exist? If you perhaps do, and I get the impression from reading your essay that this is the case, I think that your view about time has some issues. Firstly, as they would constitute the building blocks of time, if one assumes the existence of instants (and instantaneous magnitudes), one also necessarily assumes the existence of time. Secondly, to deny the existence of interval, and yet hold onto instants, is not consistent, as, by definition, an interval is simply a duration bounded by two instants; as long as the instants are still there, the interval will be too. Indeed, if such instants existed, it can be shown that they would render change, motion, and as such, the idea of a clock, impossible.

Best wishes

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Russ Otter wrote on Nov. 15, 2011 @ 21:44 GMT

The binding of existence

This is a story, built upon knowledge, intuition, and speculation. In the end, it is built upon some known theoretically successfully tested truths, and some unknowns conveyed in a formula that I consider trumps any objections – as we ponder the scope of existence. First we know of existence, by way of our...

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Sridattadev wrote on Feb. 17, 2012 @ 15:49 GMT
Dear All,

There is no space unless one chooses to measure and there is no time until one chooses to count. Time is the space between all of us in relative duality and there is "absolutely" no space-time but singularity or the conscience or universal i.

Conscience is the cosmological constant.

The absolute mathematical truth of singularity or universal i can be deduced as follows as well.

If 0 x 0 = 0 is true, then 0 / 0 = 0 is also true

If 0 x 1 = 0 is true, then 0 / 0 = 1 is also true

If 0 x 2 = 0 is true, then 0 / 0 = 2 is also true

If 0 x i = 0 is true, then 0 / 0 = i is also true

If 0 x ~ = 0 is true, then 0 / 0 = ~ is also true

It seems that mathematics, the universal language, is also pointing to the absolute truth that 0 = 1 = 2 = i = ~ (zero = i = infinity), where "i" can be any thing from zero to infinity. We have been looking at only first half of the if true statements in the relative world. As we can see it is not complete with out the then true statements whic are equally true. As all numbers are equal mathematically, so is all creation equal "absolutely".



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wucko wrote on Mar. 18, 2012 @ 22:29 GMT
Dear all,

it has come to my mind that time infact is a quantity in a noncontinuous space or there is no time at all.

Stretching of space in this view means only ther is more and more time between two discontinuous points of space, which applies: there is more and more time in universe, and that makes sense and also complyes with the arrow of time.

Space travel accours (for particles) as discrete jumps from position 1 to position 2,... the positions themselves are drifting apart from each other, but not space, bur time is the added quantity between them.



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KHALID MASOOD wrote on Apr. 29, 2012 @ 03:39 GMT

Created and Written by KHALID MASOOD

TIME COSMOLOGY: Time to re-study Time.

TIME THEORY OF EVERYTHING is The Time Universe Theory.

At the heart of physical science is physics, and at the heart of physics is TIME.

I propose, only Time exists in the Universe.

Time Creates Space, Life, Consciousness, and the Universe itself....

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Tad Boniecki wrote on Sep. 18, 2012 @ 03:30 GMT
Dear Julian,

Your fundamental paper is erudite, insightful and beautifully written. However, there is a key point that I find unconvincing. You derive equation (3) in order to show that time is not an absolute but depends on other basic quantities, each of which is independent of time. It seems to me that using the same logic one could argue that E = mc2 shows that energy is a superfluous concept reducible to mass, or vice versa. Such examples can be multiplied, each purporting to show that a fundamental concept can be dispensed with by means of a set of other fundamental concepts, depending on the particular equation and which concept is chosen for elimination.

Thus your equation could be reformulated to dispense with mass or distance, just as easily as time. An equation of physics is merely a conversion factor, it does not allow us to define one concept in terms of another.

Best regards

Tad Boniecki

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Roffik wrote on Sep. 28, 2012 @ 03:53 GMT
Hi Julian.

In Nov 2011 last year I wrote a notes in my book note about my perspective about time which is already in my mind months before. And right now i'm surprised after reading your ides in the internet that your idea that the time is just an illusion, is the same idea as mine.

I'm so excited since i'm not a physicists.

I was thinking that what we call "TIME" since human being exist on the planet is just our perspective about "CHANGE" from the motion of heavenly body to the atomic particle we see right now.

That is why according to Einstein, the "time" OR "change" on the space around stronger gravity is "SLOWER" than around the "WEAKER" gravity.

["SLOWER" means comparing to our daily perspective of "TIME"]. Because the TIME is change itself, and change request space or degree of freedom, until the center of the black hole, when the singularity creates, our conventional perspective about "TIME" should be stopped, or even transformed or should be redefined into another manifestations.

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K K Kan wrote on Nov. 28, 2013 @ 06:12 GMT
Time as a Derived Physical Quantity

Consider a physical system whose state changes and let us call it a Dynamical System.

Let a closed Dynamical System, S, whose state be described by a state function, ψ. ψ can take on the following specific states: ψ1,.. ψ2,.. ψi,..ψj,..ψk,... where i, j, k,.. are positive integers. Then one can define Time increment (Time...

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K K Kan replied on Sep. 4, 2014 @ 05:48 GMT
The following is to be added to the last paragraph"

"In other words, it is the change in the physical system that gives rise to the equation Âψ = aψ.

Knowing that total energy normally determines how a physical system evolves, it seems reasonable to identify A with the Hamiltonian and  with the Hamiltonian operator."

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Lee Bloomquist wrote on Aug. 7, 2016 @ 01:48 GMT
The arrow of time--

With a point moving on a line as the model of time ("dt"), there are both the possibilities of time moving backward or forward. However, a different kind of model where it's impossible that time move backward would be a "stream," as computer scientists call it. Such a model can be built using nonstandard analysis and non-wellfounded sets.


clockTime = (nonstandardFuture, standardPresent, nonstandardPast)

In nonstandard analysis "clockTime" would be a nonstandard monad, wherein "standardPresent" is a number from the real numbers surrounded by a halo of infinitesimally close nonstandard numbers. Given that time is one dimensional, this halo comprises (a) nonstandard numbers infinitesimally before standardPresent, called here the "nonstandardFuture," as well as (b) nonstandard numbers infinitesimally behind "standardPresent," called here the "nonstandardPast."


properTime = (clockTime, properTime)

This is an equation solved by a non-wellfounded set. If you continually substitute for "properTime" on the RHS of the equation the expression "(clockTime, properTime)", again and again for each equation you write down, you can see the stream emerge. It is impossible that such a stream go backward. Here, the problem of the arrow of time simply does not exist.

However, now there must be more to be say about how a particle gets assigned a properTime and how the properTimes are geared to each other. (The possibilities are geared to each other.)

More on these issues here:

And here:

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