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RECENT POSTS IN THIS TOPIC

Georgina Parry: on 8/21/12 at 3:40am UTC, wrote Dear Julian Barbour, its good to hear that you are working on another...

Julian Barbour: on 8/20/12 at 13:48pm UTC, wrote John, With this post I find myself in broad agreement. I am in fact working...

Georgina Parry: on 8/18/12 at 1:26am UTC, wrote Dear Julian Barbour, I apologise if I have caused any offence to you in...

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John Merryman: on 8/17/12 at 2:03am UTC, wrote Julian, I suspect you are right, that we will continue to differ on this...

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FQXi BLOGS

January 24, 2020

CATEGORY: Blog [back]
TOPIC: From Time to Shape [refresh]

Blogger Julian Barbour wrote on Jul. 18, 2012 @ 14:45 GMT

(FQXi Member Julian Barbour has launched a project to create a series of short, public outreach films that present his approach to time and shape in foundational physics. He has allowed us at FQXi to debut the latest film below.)

FQXI have suggested putting their various items relating to my work together in a blog post, including this new short video From Time to Shape Dynamics, in which Margherita Cappelletto interviewed me for an Italian online journal. I am very happy with this idea, especially since several collaborators are now working actively on Shape Dynamics. The blog will be an ideal site for posting details of new developments and answering questions.

Let me conclude by saying what a great help my FQXi grants have been to my research project. It is almost entirely thanks to the grants that my collaborators and I have been able to get together in different combinations in different locations. As a result, my collaborators (Henrique Gomes, Sean Gryb, Tim Koslowski, Matteo Lostaglio, and Flavio Mercati) are now developing the basic ideas of Shape Dynamics in quite new directions that I could never have thought of let alone explored had I continued working on my own. Thanks to them and the grants, Shape Dynamics is on the way to becoming a full fledged research program.

The progress we have made is reflected in contributions to the workshop The Conformal Nature of the Universe hosted by the Perimeter Institute in May 2012. These can be viewed at Perimeter's PIRSA website. In terms of conceptual and technical development, they are best viewed in the order PIRSA:12050050 (my colloquium talk that was also part of the workshop) and then the talks by Flavio Mercati, Henrique Gomes, Tim Koslowski, and Sean Gryb (all available at PIRSA.org/C12027). Also very relevant are the talks by Renate Loll, James Isenberg, and (FQXi Member) Edward Anderson.

-------

For more on Julian Barbour's work, visit Platonia.com.

Article by Margherita Cappelletto in oggiscienza, Questione di Forme

FQXi profile article, The Non-Expanding Universe

First-prize essay from our 2008 contest on The Nature of Time

Winning essay It From Bit, from our 2010 contest on Reality, Digital or Analog?

Talks from the FQXi 2011 conference Setting Time Aright, on Existence of Time:

and a Mock Debate on Time, with Tim Maudlin:

this post has been edited by the author since its original submission

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Pentcho Valev wrote on Jul. 18, 2012 @ 15:11 GMT

Julian Barbour,

You believe in absolute simultaneity:

http://www2.warwick.ac.uk/fac/cross_fac/ias/ear
lycareer/events/time/programme/julian_barbour.pdf

Aspects of Time, Julian Barbour, Warwick, August 24th 2011: "Was Spacetime Glorious Historical Accident? (...) ABSOLUTE SIMULTANEITY RESTORED!"

However the relativity of simultaneity is a direct consequence of Einstein's 1905 light postulate. So if you reject the consequence, you will have to reject the postulate as well. Do you (secretly) think the light postulate is false? The following text suggests you do:

http://discovermagazine.com/2012/mar/09-is-einsteins-grea
test-work-wrong-didnt-go-far

"But numerous experiments failed to discover any evidence of the ether, and Einstein realized the speed of light must stay constant no matter which direction it came from or how an observer moved. That understanding contradicted Newton's view of space. In his physics, you could catch up to anything, even light, if you moved fast enough. But if the speed of light holds steady no matter where you were or how you were moving, it would always seem to zoom away from you at the same constant 186,000 miles per second. Einstein enshrined that principle in his first theory of relativity (special relativity), which states that you can never catch up to a light beam no matter how hard you might try. Barbour first heard these ideas as a teenage schoolboy in the early 1950s, a time when Einstein was still alive. As a 3-year-old child Barbour had earned the nickname "Why?" from a friend of his mother's because of his ever-curious nature. Yet upon learning of relativity, he uncharacteristically did not question it. "I was lost in admiration," he says. "Everyone thought Einstein was the greatest figure after Newton, and so I took it on trust, almost like someone being indoctrinated into a religion."

Pentcho Valev pvalev@yahoo.com

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Julian Barbour replied on Jul. 19, 2012 @ 07:41 GMT

Pentcho Valev's query is very much to the point.However, it reads too much into what I said in in the Discover article. I certainly do not question Einstein's light postulate, but when he created special relativity he assumed the existence of inertial frames of reference and of rods and clocks that behave in a definite way. He did not attempt to create a theory that explains why they exist. Even in general relativity he did not attempt to do that. Mach's principle, on which I have worked all my life, aims to explain how local inertial frames arise.I believe that Shape Dynamics (developed in the last 13 years with my collaborators and presented in my Perimeter colloquium PIRSA:12050050 at the recent workshop) does explain the origin of local inertial frames and why all of Einstein's conclusions in special relativity hold in them. It is not challenging special relativity but explaining from relational Machian first principles why its conclusions are correct. The intriguing aspect of this work is that the explanation of why special relativity is correct of necessity singles out a definition of absolute simultaneity in the universe as a whole while showing that, just as Einstein concluded, there is no way it can be detected locally. If Shape Dynamics is the correct way to describe the universe (and everything in science must be qualified by an 'if' since every theory starts with hypotheses that may be incorrect), I believe it has a fair chance to lead to an explanation of key large scale features of the universe for which there is no current good theory (for example, the nature of the Big Bang), but I do not expect it to disprove any of the predictions of special relativity relating to the outcome of local experiments.

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Pentcho Valev replied on Jul. 19, 2012 @ 08:26 GMT

Einstein couldn't explain why rods contract (or clocks retard) because they don't. The ad hoc length contraction hypothesis was advanced by FitzGerald and Lorentz in order to make the null result of the Michelson-Morley experiment compatible with the ether theory's assumption that the speed of light is independent of the speed of the light source, an assumption that Einstein adopted in 1905. Originally the experiment unequivocally refuted that assumption and confirmed the antithesis: The speed of light varies with the speed of the light source as predicted by Newton's emission theory of light:

http://philsci-archive.pitt.edu/1743/2/Norton.pdf

John Norton: "In addition to his work as editor of the Einstein papers in finding source material, Stachel assembled the many small clues that reveal Einstein's serious consideration of an emission theory of light; and he gave us the crucial insight that Einstein regarded the Michelson-Morley experiment as evidence for the principle of relativity, whereas later writers almost universally use it as support for the light postulate of special relativity. Even today, this point needs emphasis. The Michelson-Morley experiment is fully compatible with an emission theory of light that CONTRADICTS THE LIGHT POSTULATE."

http://www.amazon.com/Relativity-Its-Roots-Banesh-Hoffmann/d
p/0486406768

"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 pvalev@yahoo.com

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Pentcho Valev replied on Jul. 19, 2012 @ 13:24 GMT

Julian Barbour wrote: "The intriguing aspect of this work is that the explanation of why special relativity is correct of necessity singles out a definition of absolute simultaneity in the universe as a whole while showing that, just as Einstein concluded, there is no way it can be detected locally."

I am afraid this is an oxymoron. The definition of absolute simultaneity is unambiguous: both observers find the two events simultaneous. So is the definition of the relativity of simultaneity: the first observer finds the events simultaneous, the second doesn't. So you cannot have "the first observer finds the events simultaneous, the second doesn't" locally and "both observers find the two events simultaneous" globally, "in the universe as a whole". Perhaps by "absolute simultaneity" you mean something that has nothing to do with the above definition.

Pentcho Valev pvalev@yahoo.com

this post was moved here from a different topic

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Julian Barbour wrote on Jul. 19, 2012 @ 14:59 GMT

I find it hard to work out the significance of the post at 08.26 GMT, and so will not attempt to answer it.As regards the post at 13.24 GMT, the only theory-independent verification of absolute simultaneity is when events happen at the same position and same time. In the framework of special relativity, Einstein showed that one can speak of relativity in distinguished (inertial) frames of reference but that there is a whole family of these distinguished frames, so simultaneity is relative to the chosen frame. He constructed his general theory of relativity with the explicit aim of eliminating all distinguished frames of reference.As long as one looks at general relativity in the way Einstein did,as a theory of spacetime, one certainly cannot find absolute simultaneity within it. But general relativity has a rich mathematical structure and it has been known for 50 years that it can also be viewed as a theory of the evolution of three-dimensional geometry.My collaborators and I have taken this approach to what seems to me its logical conclusion; it leads us to Shape Dynamics, which can be called a theory of gravity dual to general relativity.In Shape Dynamics there is a unique frame of reference in which the laws of nature take a distinguished simplest form analogous but not identical to the distinguished inertial frames of special relativity. The remarkable thing is that the frame is unique. However, one would need to have observers spread out over the whole universe to pin it down.That does not mean it will not have observable consequences, especially for the yet to be constructed theory of quantum gravity.If Pentcho has not already looked at the PIRSA lectures mentioned in my post, that would be a good way to get into the details of Shape Dynamics.

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Pentcho Valev replied on Jul. 19, 2012 @ 15:36 GMT

Julian Barbour wrote: "In the framework of special relativity, Einstein showed that one can speak of relativity in distinguished (inertial) frames of reference but that there is a whole family of these distinguished frames, so simultaneity is relative to the chosen frame."

In other words, the relativity of simultaneity implies that, if the observer in some inertial frame sees two distant events as simultaneous, observers in other inertial frames do not see them as simultaneous. Hence the only possible definition of absolute simultaneity: If the observer in some inertial frame sees two distant events as simultaneous, all inertial observers see them as simultaneous.

Do you still claim that the relativity of simultaneity and the absolute simultaneity somehow coexist in your theory - the former is valid "locally" and the latter "in the universe as a whole"? If you do, I don't think getting into the details of Shape Dynamics will change my opinion - the oxymoron will remain an oxymoron.

Pentcho Valev pvalev@yahoo.com

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Daryl Janzen replied on Jul. 20, 2012 @ 18:42 GMT

Dear Julian and Pentcho,

This was an interesting exchange. I've discussed the differences between absolute and relative simultaneity, and argued for absolute simultaneity and a privileged frame from the perspective of cosmology in my essay for the current FQXi contest. I'd be very interested to hear your reactions to my argument.

Regards,

Daryl

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T H Ray replied on Jul. 23, 2012 @ 09:45 GMT

"the Michelson-Morley experiment is fully compatible with an emission theory of light that CONTRADICTS THE LIGHT POSTULATE". How can you react?"

You have more than a few things to learn about science, Pentcho. That certain experimental results are compatible with some theory or another does not imply that the same result as predicted by a mathematically complete theory is therefore obviated. One can always add assumptions that change any experimental conclusion -- a valid scientific conclusion, however, does not rest on philosophical assumptions; it rests on measured correspondence of theory and result.

If you were really interested in challenging relativity on a scientific basis, you would learn the physics that leads to it, and attempt a mathematical model that incorporates a closed logical judgment predicting contradictory results.

Tom

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Julian Barbour wrote on Jul. 19, 2012 @ 15:48 GMT

If you do not feel like getting in the details of Shape Dynamics there is clearly nothing I can do to change your mind.

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T H Ray replied on Jul. 19, 2012 @ 19:13 GMT

"Even if I knew nothing about special relativity, I could still see the absurdity of the prediction and conclude that some postulate must be false."

No you couldn't. One would have to know what relativity means in order to understand that the privileged rest frame you insist on does not apply.

Tom

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T H Ray replied on Jul. 19, 2012 @ 19:16 GMT

And furthermore, Pentcho, one would have to have some familiarity with Mach's Principle -- on which general relativity is founded -- to profit from Julian's research.

Tom

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Anonymous wrote on Jul. 20, 2012 @ 16:28 GMT

It never fails to amaze me that a century after relativity was introduced, and with all the relativistic experiments conducted since, there remain a significant number of people who -- like Pentcho -- are scandalized by the idea that there exists no privileged reference frame. Because relativity is a mathematically complete theory, its mathematical results are entirely independent of its experimental predictions, so there is no room to waffle.

Sophisticated extensions of relativity -- such as those of Julian Barbour & group, and Joy Christian -- are easily enough shown to be logically coherent.

It begins with a simple arithmetic theorem (one can find it discussed in the introduction to Rosza Peter's wonderful classic, *Playing with Infinity*) that a single point may be mapped simultaneously to any set of points, provided that it is far enough away.

In our 4-dimensional spacetime, one often hears, "where did the big bang start?" One forgets that in this expanding and apparently isotropic domain, the "start" is any fixed point one chooses. The spacetime is continuous.

So given the simultaneous point mapping of a freely chosen point at infinity to every point of the finite set we inhabit, it can be shown that the universe *has* a shape locally whose dynamic geometry is the Barbour group's research interest -- but also globally, i.e., topologically, as Joy Christian has established. Both are angle-preserving, i.e., conformal, to infinity.

By logical entailment, then -- the simultaneity imparted by the point at infinity supports Julian's claim that causality limited by special relativity is not limited by Mach's Principle (the true relativity which underlies the general theory).

What I perceive as the consequences of Christian's program are discussed in my essay "The Perfect First Question."

Thank you, Julian, Tim and FQXi, for making this discussion available. Most enjoyable.

Tom

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T H Ray replied on Jul. 20, 2012 @ 17:35 GMT

Then I apologize for misrepresenting your view, Pentcho. So how is it that you reach your relativity denial?

Tom

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Pentcho Valev replied on Jul. 20, 2012 @ 21:34 GMT

The speed of light is variable, not constant. This would be obvious if a century of mythology had not made people believe in the opposite, like in Orwell's scenario:

http://www.liferesearchuniversal.com/1984-7

George Orwell: "In the end the Party would announce that two and two made five, and you would have to believe it. It was inevitable that they should make that claim sooner or later: the logic of their position demanded it. Not merely the validity of experience, but the very existence of external reality, was tacitly denied by their philosophy. The heresy of heresies was common sense. And what was terrifying was not that they would kill you for thinking otherwise, but that they might be right. For, after all, how do we know that two and two make four? Or that the force of gravity works? Or that the past is unchangeable? If both the past and the external world exist only in the mind, and if the mind itself is controllable what then?"

Pentcho Valev pvalev@yahoo.com

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T H Ray replied on Jul. 21, 2012 @ 11:13 GMT

"The speed of light is variable, not constant."

Right. It's only constant in vacuo.

Tom

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T H Ray wrote on Jul. 20, 2012 @ 16:29 GMT

Sorry, I must have logged out.

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Lawrence B. Crowell wrote on Jul. 20, 2012 @ 21:16 GMT

I might be off here, but this seems to be something similar to Desargue’s theorem about projective rays passing through the vertices of polytopes. In general this defines the “heavenly sphere” for spaces with a Jordan product rule.

I am not sure what shapes are projected,unless they are polytopes that correspond to the weights of certain algebras. In 8 dimensions this would be the E_8 group.

Cheers LC

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Georgina Parry wrote on Jul. 21, 2012 @ 01:17 GMT

Dear Julian Barbour,

thank you very much for the videos you have made about your work. Shape space is very interesting to me, you explain it well. I think it is a useful model. Getting rid of an absolute background makes a great deal of sense to me. (I have wondered to myself how many observers it would take to fully describe an object.) I have mentioned my like of your Shape Space previously in the FQXi blogs.

I could have talked about how it is, in my mind, related to my own work in my current essay- if I had not run out of room. I think it should have been mentioned but, given the word limit, I wanted to talk about something I had not mentioned before and therefore mentioned very briefly about Stephen Wolfram's cellular automata instead.( I might write another essay just concentrating on how my work fits with other people's, in my opinion, rather than filling your thread.)

I commented on your essay thread last year. You don't need me to tell you your writing is very good. You have the prizes. You don't need me to tell you the potential of your work is recognised, you have had collaborators and have had the grant money to concentrate on developing your ideas- because of its potential and interest to others. Though you don't need me to say it, as I am sure you yourself know, it is (as I see it) a great contribution to modern physics that will last and continue to inspire others. Congratulations.

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Tommy Gilbertson replied on Jul. 21, 2012 @ 20:34 GMT

Mini-grant?!?

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Georgina Parry replied on Jul. 21, 2012 @ 22:10 GMT

Dear Julian Barbour,

here's a question you may be able answer for me. I heard you talking about conservation of volume. Perhaps I have misunderstood you.

I can comprehend many different diffeomorphisms all related to the same object seen at different orientations due to observer positions. Wouldn't there, for a number of observer positions, be the outcome where the "triangle" would appear to be a line?- edge on. Which though theoretically might have the same volume, since you are now regarding the observer's reality rather than the independently existing reality, wouldn't you have to go with the observer's impression of it? The triangle is a very simple shape I can think of more complex shapes that would perhaps illustrate the point better. A long thin cylinder, which could be oriented in many ways conserving volume but some observers are going to be looking at the base alone or base and a very foreshortened side.

I understand what you were saying about the temporal relationships of the diffeomorphisms. Which to me sounds like, the time at which they are seen can differ so the time difference can be compared, providing a ratio. They do not exist in time as such or along a time dimension. I can agree with that. I don't think observed diffeomorphisms exist in external euclidean space either but in a fabricated space produced by observation using received data. Which, by my way of thinking, would make your fibre bundles a model of the transmission of potential sensory data. So then perhaps the optical phenomenon of perspective would have to be included. As observers at different distances from the object, seeing a triangle face, would not see it at the same size and therefore same volume either.

Are the various observed triangles -mathematically altered- to have the same volume because they all have the same parent triangle which is not changing volume? Is it important to ignore what is seen and pretend that it is still the parent object for the purpose of calculating the physics of motion?

I haven't got to the end of the new videos I don't know if those queries would be answered later on. I also am not able to see the diagrams at the moment, which is a problem with my computer.Not sure if that would help or not.I don't mean any offence to you by trying to interpret what you are saying with my own way of thinking about things.If it is ignorant and unhelpful I am sorry for that, I am just trying to make sense of things.

Regards, Georgina

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Georgina Parry replied on Jul. 22, 2012 @ 04:07 GMT

Dear Julian Barbour,

I have just had a slight revelation. I said in my previous reply "Which, by my way of thinking, would make your fibre bundles a model of the transmission of potential sensory data." But that isn't right I have realised. Though you are considering the observer's viewpoint, you are by passing the observer. Linking the fabricated output, that has the appearance of external existence, directly to the object, by fibre bundles.

Those fibre bundles therefore don't have a physical counterpart (do they?)they are a mathematical abstraction.I think you probably have replaced one kind of abstraction, the dimensions assuming an absolute space for a different kind of abstraction where observed manifestations are joined to the source object (actualisation) directly by abstract entities. This is not a criticism but tying to make sense of what it is that you are doing. It is still very useful as it gives a way of mathematically handling all of the different observations and relating them to the single object or arrangement, without having to refer to an absolute background.

Please correct me if I am still mistaken.

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Georgina Parry replied on Jul. 22, 2012 @ 06:40 GMT

PS...by abstract entities I meant the mathematics converting from one kind of space to the other. I can't see a physical equivalent of it. Is the reproduction of relativity enough to suppose that this is a realistic model of physical reality in your opinion?

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Georgina Parry replied on Jul. 22, 2012 @ 21:29 GMT

Dear Julian Barbour,

re last comment maybe the mathematics could be a proxy for the data transmission -and- observer processing parts of reality, giving the shape output in euclidean space - as we do not know exactly what processing occurs.Or is this all pre observation ie it is just un-accessed data in an external euclidean environment that would give that shape in euclidean space if it was intercepted and processed? How do you regard it? What is the relationship of the pre space to the euclidean space physically rather than mathematically in your opinion?

Julian Barbour wrote: "The intriguing aspect of this work is that the explanation of why special relativity is correct of necessity singles out a definition of absolute simultaneity in the universe as a whole while showing that, just as Einstein concluded, there is no way it can be detected locally." I too have found that absolute simultaneity is necessary for an explanatory framework that works and agrees with Einstein's relativity. That enables me to think of your model a very useful way of considering what is occurring as there is that foundational correspondence.

It would be nice to hear what you think about those questions, but I will understand if you can't find the time.

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Tommy Gilbertson wrote on Jul. 21, 2012 @ 20:29 GMT

This was really good stuff... The Shape of Time, wow! Isn't it hard to keep the mind trained in the right direction while working with Time. Dr. Barbour has a particularly keen talent for doing so, and communicating it so well.

QuantumWidgets.com

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Steve Dufourny replied on Jul. 24, 2012 @ 19:38 GMT

He is an intresting person indeed, his philosophy about times is relevant. He speaks well also. Good stuff indeed.

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Julian Barbour wrote on Jul. 23, 2012 @ 07:24 GMT

Hello Georgina. I will be busy for the next few days, so cannot answer your questions in full immediately. However, they are important so I will do so as soon as I can. Here is a comment about this question you put:

"Are the various observed triangles -mathematically altered- to have the same volume because they all have the same parent triangle which is not changing volume? Is it important to ignore what is seen and pretend that it is still the parent object for the purpose of calculating the physics of motion?"

You are basically right with the notion of 'same parent triangle', but I go further and want to consider only the triangle shape. The simplest nontrivial model of a dynamical universe consists of three point particles in Euclidean space. They can form triangles of different shapes and sizes. But to speak of size you need some ruler in addition to measure the size. No such additional external ruler exists in the universe. There is nothing but the triangle. So all you have is the shape of the triangle defined by its angles. Because the triangle is by assumption in Euclidean space, the angles add up to 180 degrees. Now at this stage of the discussion, I don't want you to think about how you as an observer might see the triangle but only to imagine how you might position and orient it in Euclidean space, giving it moreover all possible sizes. If you were a god who could 'see' Euclidean space and were given the angles but no other information, so that you knew the shape, you would have all these possible representations of one and the same shape at your disposal. What I mean by a fibre is the collection, or set as mathematicians would call it, of all these possible representations of one given triangle shape. The set of all possible triangle shapes is what I call shape space and the fibre bundle associated with it is the set of all the fibres, one fibre for each shape.

So this is all to do with how you can imagine a shape represented in space. I'll comment on how you might actually see triangles in a further post together with comments on the relevance to dynamics of the universe.

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Georgina Parry replied on Jul. 23, 2012 @ 09:33 GMT

Hello Julian, thank you for your reply. So far I understand. From my point of view it is a -very- helpful way of thinking about what is potentially out there. I should wait to hear what you have to say before getting carried away mixing it up with what I'm thinking. I'll try not to say too much so you have a chance to answer the questions.I look forward to hearing more when it is convenient

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Georgina Parry replied on Jul. 24, 2012 @ 21:10 GMT

Dear Julian Barbour,

I think I'm getting it clear in my head. I'm still interested in why physically, in your opinion, volume is conserved not why it should ie. because it fits nicely with expansion of space. I have realised that -is- important as you say for the appearance of expansion of space. Also as I see it, so objects don't get larger and fuzzier the further away- as in a projection onto a wall using a light projector. This is something else. Seems to me, it could be explained as being because EM reflected from an object or arrangement of objects overall travels in straight lines, despite what each individual photon might be doing.

Could it be that each translation is a different angle of reflected or emitted light(?).That would make sense to me. The space between expands because the shell of data is spreading out but each shape is still made from the straight line projection? The space in between though is nothing and so not constrained in that way. This is me trying to make sense of what is happening in my own words, tying to relate the model to what I can understand, I do not have the intention of misrepresenting what you are describing yourself or causing offense.

I'm thinking of the light cone model described by Roger Penrose on the resources. Which should be compatible because he isn't talking about space-time but Hamilton's quaternion space and time, which I can imagine as the superimposing of lots of different iterations of 3D Euclidean space. Now it starts to seem like a wave function to me because there are many different possibilities that might be observed coexisting (your Shape Space ) but also distributed "over time" as there is a Shape Space related to each iteration (or different arrangement of the "material" universe).It also ties in with holographic ideas as the Shape Space will be, in ideal circumstances without other objects in the way, the 2D surface of a sphere-expanding with each new iteration. Please forgive me if this sounds irrelevant to what you are doing. I would be happy for you to tell me how I should be thinking about it.

I understand now that we haven't got to the observer yet and how his position and motion interacts with it. This is still observer independent even though I have imagined all the ways in which the arrangement might be seen.

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John Merryman replied on Jul. 25, 2012 @ 19:28 GMT

Julian,

What if the triangle is spinning? Wouldn't the centrifugal force suggest space as an equilibrium state? Consider an object in the deepest realms of intergalactic space; Would we be safe from being spun off by any potential rotation if there is no other reference point, but if we were to pull out a telescope and see distant galaxies moving across the horizon at a rapid rate, would this fixing of our particular motion be the cause of our ejection from that object? It just seems to me that while we measure space in terms of objects, there is still an inherent equilibrium which is overlooked.

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Tommy Gilbertson wrote on Jul. 24, 2012 @ 22:39 GMT

I just happened to pop in and saw Dr. Barbours elaboration on shape space. Wow. That's a brilliant generalization of shape and form: so the entire universe is shape space (a shape-field), and these shapes come in discrete fundamental fibres or bundles (nuggets) of shape. The quantum triangle as it were: three lines connected at certain angles. And all other triangular forms and shapes in the universe instantiate themselves as whole-number multiples of this plank-shape? Kind of like the fractal made out of triangles in triangles which get smaller and smaller, and as you 'zoom' out (or introduce a gravitational field) you can see the shape from differing perspectives 'move'. Oh, man i got sucked in here. Meant to only peek and run. Running. Really good stuff...

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Bee wrote on Jul. 25, 2012 @ 07:11 GMT

Dear Julian,

Just wanted to say hello and that I think it's great you're contributing here! All the best,

Sabine

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Steve Dufourny replied on Jul. 25, 2012 @ 23:19 GMT

hello bee, have you a little of spherical honney please ? :)

hymenopterialy yours

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Tommy Gilbertson wrote on Jul. 27, 2012 @ 06:50 GMT

Hi, can I just interject a point symbollogically and syllogistically? It will help to answer some of Georgina's question in the replies right above. There are two frameworks: Euclidean Space and Non-Euclidean space. It is hard to remember this thread when studying examples of non-euclid space (like Barbour's Shape Space is a specific example). The essential difference between Euclidean space (of which Georgina is speaking of in many of her counter-examples) and non=Euclidean is that in Euclidean space there is no Time; no motion. The objects of study are frozen in space and don't move: you can't spin a triangle in Euclidean space. You can move it around, resize it and do other linear operations to it, but you can't LIFT it up off the space (or paper if two dimensional Euclidean space). In a non-Euclidean space, motion and time are introduced. So often times you can't classically compare the two spaces at all, and a sentence like spinning have no meaning in Euclidean space. Thanks. I look forward to hearing Dr. Barbours Comments too. It is exciting to have him actively contribute with us mere mortals!

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Tommy Gilbertson replied on Jul. 27, 2012 @ 06:58 GMT

Therefore, a curved space is required to incorporate the quantum mechanical spin of physical reality experiments have revealed in any modern physical theory of everything. It takes a truly great mind to formulate this realization to taming that curved (non-Euclidean) Space in naming it Shape Space and defining it's properties...

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Tommy Gilbertson replied on Jul. 27, 2012 @ 07:07 GMT

I'm so sorry, for this will be roundly ignored but I'm inspired. This curve of fundamental space is mediated by force particles whose properties are determined by the quantum geometrical shape of the messenger particles. This superforce is the cause of the curve of space that is described by Dr. Barbour's Shape Space Field Theory. It's called SuperGravity, and as the Ancient Philosphers greatly and thouroughly studied and developed, there are sacred (or ubiquitously natural) shapes in nature that control physical reality. These shapes are most common in our Universe, and are in the form most suited to black hole optimization. 6 of the shapes are combined in a tiny, hidden dimension, and the four large spacetime dimensions we see are in fact symmetric geometrical shapes (again described by Barbour's Shape Space) but on a cosmic scale of 1/Plank distance light years, symettrically with the 1/R to R duality relation observed everywhere in nature. I call them white holes, and they are optimized in most universes in the multiverse to minimize black hole production in universes in which they reside. Man, I soooo need a job! Good luck all...

These white holes consist of infinitely-thin spheres of matter with a radius of 1/PL (in light years). Now, we are dealing with a absolutely large object with small mass, and thus general relativity is the dominant factor in some cases and quantum mechanics is dominant in others... These white holes are BPS states of the superpartner particles currently being searched for, on a 1/R duality cosmic scale. And due to the measured exponential expansion of space right now, they are about to intersect: each white hole is centered on a current black hole. For example, in the Milky Way's center there is a 4 million solar-mass BH. This leads directly to a mathematical theory of mass consciousness.

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Georgina Parry replied on Jul. 27, 2012 @ 10:27 GMT

Hi Tommy,

the space I am talking about, I think John knows, is the background to sequential iterations of the Object universe without a time dimension. (There is a high resolution file of the explanatory framework posted on the discussion thread of my current competition essay.) John has seen my explanatory framework and we had many discussions prior to and during its development. Each iteration is an arrangement that could be thought of as being in Euclidean space. So spinning the triangle is like flicking the pages of a flick book. In each new iteration of the universe the triangle has moved and each iteration is still in Euclidean space. There is no temporal spread "in a single page" everything there exists simultaneously.

I am thinking of the "parent" triangle as an object or arrangement of objects and I see no problem with describing motion of the unobserved objects as a sequence of positions within arrangements that are occurring sequentially rather than all existing together in a block space-time. Julian Barbour was talking about imagining the orientation of the "parent" triangle in Euclidean space. So those ideas don't seem incompatible to me.

I don't think I 'm thinking about actual Shape Space as Julian has described it to me. Which is "the set of all possible triangle shapes". I have tried to compare the "bundle" of transformations associated with one parent shape, ( which I have been mistakenly calling the Shape Space), to the data spreading out from the parent object, shells of potential sensory data accumulating with each new iteration of the Object universe.

That is because I would very much like a -physical- explanation for what is occurring rather than an abstract model. What I have described would I think be compatible with my explanatory framework, what Roger Penrose was saying about a quaternion model for the light cone (lecture available via FQXi resources), possibly also what Joy Christian has been discussing on FQXi as that's also a quaternion model. It might not exactly fit with what Julian and collaborators have developed. He might hate the way I'm thinking about it now. I haven't yet listened/watched all of the resources he has produced all the way through as I couldn't get the video to work for me and he hasn't yet been able to reply to the questions and misunderstandings about what he has created that were put to him. I would like to hear what he has to say. He is not here right now.

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Julian Barbour wrote on Jul. 27, 2012 @ 15:19 GMT

Well I'm back now, having got some things done that could not be postponed. I think your ideas don't exactly match mine Georgina, but there is surely some overlap.I think the main difference relates to the role of perception, i.e., what we see, and how that guides us in formulating a theory.According to my Shape Space ideas, the triangle shapes 'do their thing' completely independently of any observer. In Shape Dynamics there is a law that determines a whole sequence of shapes given only very little information. Suppose we define the shape of a triangle by two of its angles, call them A and B (the third angle C is then fixed since we must have A+B+C=180 degrees in Euclidean space. Then given A, B, and dA/dB (i.e., the rate at which A changes as B changes), that is sufficient to determine a whole continuous sequence of triangles. You don't have to think of the triangles as existing 'somewhere' in space, and there is no time which says how fast the sequence is realized. There is also no direction on the sequence corresponding to a direction from a past to a future. How our sense of a passage of time arises is a matter for another day.

The main difference between Shape Dynamics and Newtonian dynamics is that the latter also predicts a sequence of shapes but needs more input to do it. You need more than the A, B, and dA/dB mentioned above. You must also give more derivatives of A with respect to B, not just the first dA/dB. Specifying initial data in Shape Dynamics is like specifying just a point and a direction of a curve and then knowing what the rest of the curve will be like. Newtonian dynamics is like having to specify that and further information about how the curve bends. It has to do that because Newton formulated dynamics in such a way that the rate of change of orientation in space and the rate of change of size affect the evolution. In Shape Dynamics no information like that is used. The only role that space plays (in the case of triangles) is in the rule that the angles must add up to 180 degrees. However, it turns out that in the formulation of the law governing Shape Dynamics it is very convenient to imagine all the different ways that you could position a given triangle in space if you could see space. This is where the fibres and the bundle they form come in, but let me postpone that to another day in order to come to the issue of what we actually see.

It is a fact easily forgotten that we cannot actually see distances. We only see angles. For example, when you open your eyes at night in the country, you see stars and the angles between them. You cannot possible 'see' the distance to the stars. You might counter that you see a distance when you lay a ruler next to an object that you wish to measure. However, all you actually see is the angle between the two ends of the ruler as it lies next to the ruler. The angles they subtend are equal. Of course, this will change as you change your point of view, and I think this perspective effect plays a role in your thinking Georgina. However, the important thing for me is that only angles are actually observable, distance is invisible. Distance therefore joins two other 'invisibles': space and time. My aim is to replace all three by differences between things that can actually be seen. Then we know that the things we are talking about are real, or at least have much more confidence that they are real.

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Georgina Parry replied on Jul. 28, 2012 @ 00:52 GMT

Dear Julian,

I am glad you are back to explain further. Sorry for rambling on in your absence. You are right my ideas don't match your own but where there is overlap they could possibly work together in a highly constructive way,I think anyway.

Thank you for clarifying that the triangles in Shape Space are independent of the observer. They are not the output of potential observer's sensory systems, got that now. I've been trying to compare them to potential sensory data in the environment but that's not actually what you are describing either.

You said: "You don't have to think of the triangles as existing 'somewhere' in space, and there is no time which says how fast the sequence is realized. There is also no direction on the sequence corresponding to a direction from a past to a future. How our sense of a passage of time arises is a matter for another day."

---That's hard for me because I need to think of some kind of existence for them somewhere/some-when to be real things rather than unreal abstractions. Which is one reason for wanting to think of them as data in the environment that might become observed triangles. I don't have such a problem with where in time (but to fit with my own way of thinking about things I would rather all of the possibilities existed simultaneously rather than as a sequence spread indefinitely in time.)Never mind I will try imagine them separate from the -space that is observed and time that is experienced-, in the same way I mentally separate the Object reality and image reality of my explanatory framework.

Your last paragraph is profound and I find it a bit puzzling. I can accept what you are saying about space and time being invisible. I can accept that we can't really measure distance (..for distant objects because it can vary according to observer position and distance from the object). I can understand that there is therefore something more reliable about the angles of a triangle so long as it is kept in Euclidean space.I'll have to let the rest of what you said sink in.

Thank you for clarifying your aim. It does seem sensible to try to find something from all that we perceive to exist, that can be relied upon as relating in some way to an underlying "firm" reality. Thank you very much for taking the time to explain here.It will be very interesting to learn more about the fibre bundles and triangle orientation.I'm really interested in learning more about this and particularly interested in how it becomes the observer's reality in your opinion.

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Georgina Parry replied on Jul. 29, 2012 @ 09:53 GMT

Dear Julian,

I take your point about seeing angles rather than distances.I've gone and read a little bit about visual angles and the early visual cortex's attention to lines and corners.

Making calculations simpler sounds good to me, though getting beyond the explanations for how and why it works, in order to really appreciate its simplicity and useful might be the hard work. Though I think it is worth while.

Still unsure what I ought to think of all of the transformations of the triangle to be thinking about them as you are. Are these all the triangle made by the ? positions of the -objects- or the single triangle -object- itself, but not imagined in space-time. (I'm not sure now whether they should have positions as they don't have distances. I said it was puzzling.) What if anything do parallax and perspective have to do with this? Do I need to imagine the triangle as something rigid just seen differently? or something that is itself actually changing?

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Georgina Parry replied on Jul. 31, 2012 @ 09:36 GMT

Hi Julian,

Good news, I have installed a new Flash player and now I can see your lecture videos with diagrams, rather than having just sound. So I'm going to watch them through to the end now. Which should help me at least get a little further in properly grasping your model. I don't know how much I'll understand but I'm keen to see how far I get before I'm thoroughly puzzled. From seeing your other videos, and your replies, I know you explain things well- so I am hopeful and still very enthusiastic about it.

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John Merryman wrote on Jul. 27, 2012 @ 17:32 GMT

Julian,

I not sure how it is that one dimension, distance, is invisible, but two dimensions, angles, are visible? It would seem what qualifies as "visible" is the existence of a reference, the degree of angle. Doesn't this speak more to our limited mental functions, that our mind is better designed to observe differences, than the connections from which they arise? It seems to me the problems in physics are not so much about what is visible, but making the connections underlaying the visible.

I see the problem of time is that we "see" a sequence of events, rather than the processes creating and dissolving them. For example, does the earth travel/exist along a vector from yesterday to tomorrow, or is it that tomorrow becomes yesterday because the earth rotates? If it is the latter, then time is an effect of motion, the rate of change. Much as temperature is level of activity. Increase the level of activity and you increase the rate of change and that's why clock rates are variable.

Since we "see" the events, rather than the processes, we confuse which is the scale and which is the needle. It is not the present moving along a deterministic sequence, but the events forming and dissolving within the context of what exists, ie. is present. Probabilities condensing into actualities. What determines the fate of the cat is not a progression from a determined past into a probabilistic future, but the actual playing out of those probabilities. Thus time as effect.

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Tommy Gilbertson wrote on Jul. 28, 2012 @ 01:43 GMT

Outstanding. And amazing reply Georgina, well done. I'll go check your link... and also shall shut up now and enjoy the discourse... Like a fly in the Shape of Timeless Space. For a while...

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Julian Barbour wrote on Jul. 29, 2012 @ 08:54 GMT

Let me deal with one thing at a time Georgina. I said:"You don't have to think of the triangles as existing 'somewhere' in space, and there is no time which says how fast the sequence is realized." You responded:

"That's hard for me because I need to think of some kind of existence for them somewhere/some-when to be real things rather than unreal abstractions. Which is one reason for wanting to think of them as data in the environment that might become observed triangles."

I sympathize and think the use of abstractions is a real issue (as does Penrose, who comments on the way physical reality seems to be reduced ever more to mathematical abstractions). I think the only way science could restore the world of direct experience would be to overturn the method of science entirely and make experience primary and seek to explain the appearance of an external world as our mistaken interpretation of rules that govern experience. Many artists and poets and even a few scientists have thought that way, but science has continued its triumphant way.

The belief that things should be 'somewhere and somewhen' underlies many of the objections to the many worlds interpretation of quantum mechanics. However, I do think it is possible to conceive structures (and Euclidean triangles are the simplest example) that are defined intrinsically - by their angles alone - and do not need to be placed in space and time. For me, the simplest model of many worlds is the set of all possible Euclidean triangles. It meets my mathematical requirements but it's a bleak world, bereft of colour and movement. Somehow consciousness must restore our world to us.

In a later post, I may be able to come some way to meet your desire to place a triangle somewhere.

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Georgina Parry replied on Jul. 29, 2012 @ 10:21 GMT

Dear Julian ,

thank you for that reply. I don't mind that they are abstractions because they can still be very useful. I don't think Einstein's space time continuum or Minkowski space is real but it is useful. Same with Bohr's atom. Far more useful to chemists and biochemists than more accurate electron cloud models. I just need to know what it is, so that I'm thinking about it as you are. How it can be related to a physical reality is something that can come later.I am interested to hear what you have to say.

I did write a reply Jul. 29, 2012 @ 09:53 GMT after my previous one but it crossed with yours.

I'm much happier about the superposition of "many worlds" now that I am able to see how it does not conflict with Einsteinian relativity but is IMHO due to our experienced reality being a fabrication from received data. Each present being one of many possibilities that might be fabricated from potential sensory data in the environment. So though the -objects- are somewhere/somewhen, the data which had the object as its source is distributed in the Uni-temporal environment and has many wheres and has originated from many whens.

I'm thinking it is a bit like a hologram because there isn't just one lot of data related to the object but lots an lots of variants of the data. It isn't one object any-more but data that might give many different versions of the object. Front, back, side, bottom, top and everything inbetween. Interaction with the observer leads to a single reality as that is the fabricated output.

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John Merryman replied on Jul. 29, 2012 @ 15:14 GMT

Julian,

"Somehow consciousness must restore our world to us.'

What if we were to think of consciousness as distance, the reaching out, while knowledge is the angle it encounters, the distinction that can be acknowledged and concentrates the consciousness?

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John Merryman replied on Jul. 29, 2012 @ 15:16 GMT

To reach and grasp.

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Tommy Gilbertson replied on Jul. 29, 2012 @ 19:30 GMT

To prestidigitate and clutch...

Mr. Barbour said, "Somehow consciousness must restore our world to us".

Not to plug my mediocre essay in the last contest, but in that essay I derived an equation for Consciousness based on the results of Young's double slit experiment results. Not saying this form of the equation 'restores our world to us' through it's interaction with reality, but some form probably will survive into a new theory?

But that is off-track. What is on track is two overarching concepts that seem to always survive when creating new theories in history: Order and Duration. Mr. Barbour has defined Order (or sequence) by the series of trangles obeying the 'sum of angles equals 180 deg. in flat space', and Duration is left to be developed as time is defined in this system. Maybe the 'rate' at which the succession of triangles is 'presented', i.e. the sequence of frozen Shape Spaces? So then time is defined from the theory itself and emerges naturally without assuming an Absolute Time...

Wow, I'm just glad to be here!

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Georgina Parry replied on Jul. 29, 2012 @ 21:19 GMT

Dear Tommy, All,

Tommy you said, referring to Julian Barbour's model: "Maybe the 'rate' at which the succession of triangles is 'presented', i.e. the sequence of frozen Shape Spaces? So then time is defined from the theory itself and emerges naturally without assuming an Absolute Time...", I think that the sequence of observed shapes -is- giving the subjective experience of a passage of time in Julian Barbour's model, rather than there being any objective absolute passage of time- though I would like to hear Julian's explanation.I don't want to misrepresent what he is saying.

In his model universe Plationia everything exists timelessly. I can see how that idea can be compatible with the Data pool of my explanatory framework because data produced during former iterations of the material universe persist in the environment and can become an experienced present when the data is received and processed by an observer.It is only potential sensory data though not the material objects.

In the explanatory framework that I have set out (High resolution diagram in my essay discussion thread) there is passage of time due to sequential change, (which is the sequence of arrangements of material objects from which sensory data is emitted or reflected.) -The sequence in which the data is received and processed is giving the sequence of presents experienced by the observer-,Also giving the experienced arrow of time. So it may also potentially work well with Julian's Shape Space model.

Julian Barbour said, "Somehow consciousness must restore our world to us".

It can do that because only partial data is received and a fabrication of external reality is formed from it. The data to fabricate a world in which I see the back of the cup and a world where I see the front of the cup both exist as potential sensory data in the environment, along with many other possibilities. Which world is my subjective experienced reality depends upon the data selected through the sequence of observer positions, relative to the objects in the environment.

EM radiation stimulates the cells of the retina and signals are sent to the visual cortex of the brain. Here there is an isomorphic arrangement of cells replicating the retina where the various stimuli are mapped. Higher levels of the visual cortex analyse the pattern of stimuli and it is interpreted, by association with learned ideas and vocabulary, into meaning.

Tommy, I would have to look back at your essay from last year as I don't rememberer that equation, so can't comment on its relevance.

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Georgina Parry replied on Jul. 31, 2012 @ 11:11 GMT

Hi Julian ,

I'm watching your lecture videos now I have a new Flash player that is working.

RE. Ernst Mach's quote. The point about how do you decide what is a true motion is interesting. I can see that it does, as you are saying, depend upon how it is thought about. I think I understand why you are using best matching. It seems to me that the small change has to happen before a bigger change so you orient the next triangle as closely to the former.Is that right? I am, as I thought I might, having trouble keeping thinking of these as abstract triangles when you begin relating them to motion. You are explaining things that relate to the physics of existing things, and I can't not imagine it very easily.

As I have been thinking about things for some time now, there are objects that are the source or origin of sensory data, and there is sensory data. Observers do not see objects but they receive sensory data and fabricate an output that is the image of an object. So when you talk about the triangles and observed motion I do not know whether this relates to the objects or the data distributed in the environment or the observer's fabricated output.Or non of those options.

Data distributed in the environment in a single iteration of the arrangement of an Object universe does not need a time dimension. So I seem to be agreeing with you about not needing time to have a sequence of triangles. It would be possible to distribute a number of observers in space at varying distances for the source object and for them to each simultaneously see a triangle that is different, which could then be put into a temporal sequence, even though they were all obtained from the same uni-temporal space (not space-time) ie simultaneously occurring everywhere.

A way to do that would be to have the object pulsating in different colours, or being different colours and rotating to give a sequence. The data from different iterations (different colours) is added to the environment and will be available to the spatially distributed observers in a single uni-temporal iteration ie. simultaneously. That's not space-time it seems to me, just space containing data originating from different arrangements of the Object universe.

I'm sorry to be rambling on again. I'm not going to understand everything that you are saying about the various ways of describing motion but I do think it is fascinating how many different kinds of description can arise out of the Shape Space model.I'm half way through but I think I need to let that bit sink in before tackling some more.

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Georgina Parry replied on Aug. 1, 2012 @ 08:54 GMT

Dear Julian ,

I think I've got the abstract Shape Space notion clear now. It is an imagined space that acts as a "workplace" for doing the necessary calculation. My understanding (or not) There is a triangle (I don't yet know -what- it is other than an abstract object or arrangement of abstract objects.)In the Shape Space all the possible orientations, translations rotations and dilatations are imagined. (That's the fibre bundle.) Then you decide which of those you are considering rotation, translation or dilatation and best match the triangle you have with the imagined ones in Shape Space, in order- getting a sequence by best matching.I will assume for the reason I gave in my previous post. Then that sequence can be used like the Lagrangian's are used in classic mechanics to get the Action and all of that happens without having to invoke time at all, which fits with Mach's ideas. That makes sense to me.I think what the triangle -is- will become clear later on and I should stop fretting about it.I will watch some more of the lectures.I'm really interested in what happens when the observer gets involved.

Please correct me if I am going wrong.

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Yuri Danoyan wrote on Aug. 1, 2012 @ 00:51 GMT

Dear Julian

I would like remind to you some correspondence between as in 2004:

At 23:28 06/06/2004, :

FirstName : Yuri

LastName : Danoyan

Email : yurdan@earthlink.net

>Country : usa

>Message :

Dear Julian

"We have 2 different kinds of symmetry: Discrete and continuous symmetries.

BASIC DIFFERENCE BETWEEN THEM DISCRETE SYMMETRY IS STATIC SYMMETRY(REFLECTIONS,PARITY,ETC). NOT DEMANDING MOTION,CHANGE IN TIME

CONTINUOUS SYMMETRY DEMANDING MOTION(ROTATIONS,TRANSLATIONS,SHIFTS,ETC)

CHANGE IN TIME. THE MOTION SUPPOSED TO BE DIFFERENT VELOCITY (FROM SMALL TO RELATIVISTIC).

WHEN WE GOING TO RELATIVISTIC VELOCITY OBJEKT GET DIFFERENT LORENTZIAN

DEFORMATION AND CONTINUOUS SYMMETRY LOST ITS SENSE.WE GET SOME KIND SELF-REJECTION OF CONTINUOUS SYMMETRY.

DOES DISCRETE SYMMETRY ONLY REAL SYMMETRY?

WHAT IS PRIMARY? SYMMETRY OR SPACE- TIME SYMMETRY? OR ONLY SPACE?

Thank you for advance.

Yuri"

"I do not know the answer to your questions. However, I do believe continuous symmetries are fundamental except perhaps the Lorentz boosts.

Best wishes, Julian Barbour."

Today, 8 years later I guess that answer to this question by introducing of the concept Broken Metasymmetry.I have a vague feeling that my concept is a confirmation of your "Anti-Time concept".

I would be grateful for your short comment.

http://www.fqxi.org/community/forum/topic/946

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Julian Barbour wrote on Aug. 1, 2012 @ 15:16 GMT

As regards Yuri's post, I'm afraid I cannot make much of it. Sorry about that. We seem to be speaking different languages.

As regards Georgina's comment

"I just need to know what it is, so that I'm thinking about it as you are. How it can be related to a physical reality is something that can come later.I am interested to hear what you have to say"

I cannot do better than to say that in my way of thinking about things the universe in any instant has a shape which we try to represent mathematically.As very young children, we learn to 'fit together' very different 2D images of, say, a cube and comprehend them as a cube in 3D Euclidean space.If there are differently coloured dots in space whose separations do not change, we could view them from many different positions and from comparison of the different 2D images build up a 3D understanding of their relative positions in space.In my view only the relative positions have meaning. The complete set of points has no position or orientation in space except in our imagination. However, the moment we focus our attention on any three points, the triangle they form does have a definite position relative to all the other points. The considered triangle has some physical reality in its own right, defined by its angles, but it gets much more when you consider it relative to all the other points. One can now speak meaningfully about the considered triangle's orientation and size relative to them. When I was speaking about triangles in the earlier post, I meant them to represent the entire universe. But nothing stops me considering universes made of an arbitrary fixed number of particles.Three just happens to be the simplest example in which one can define a shape.

I'm not sure that was the kind of answer you were hoping for but perhaps it helps.

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Yuri Danoyan replied on Aug. 1, 2012 @ 16:06 GMT

Julian

I try to use the same language.

"Euclidean triangles are the simplest example"

1)How about non-euclidean triangles(with positive or negative curvatures)?

2)How about fundamental constants?Vary or not vary or this question haven't sense?

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Georgina Parry replied on Aug. 2, 2012 @ 00:07 GMT

Dear Julian ,

thank you once again very much for your reply. It is a brilliant answer because you are thinking about this in a very interesting way. You are right IMHO -how the triangle looks (or is imagined to look ) depends upon how it is looked at (or imagined to appear). I was starting to realise your intended meaning, when you were talking in your lecture about choosing whether a rotation, translation or dilatation is considered to be occurring according to the observer, as it could be any of them. It sort of ties in with what I was saying about the Truth, talking to J.C. N Smith on my essay thread. Words to the effect that the Truth is something "seen" in every possible way, not just in part or fleeting glimpse.(Though something does not actually have to be seen to be a Truth.)- A coffee mug is a 2 dimensional circle but also everything else it can be seen to be as well.( The circle is a matter of fact but not the Truth, the Truth is the everything -The entirety of what it is.)

It gets interesting and a bit puzzling. Is it the imagination forming these triangles and their behaviour, so the triangle(form and behaviour) is the product of sensory data processing or is it an independent external reality? It seems to me that; what is seen to be is usually a partial truth, formed from the incomplete sensory data received and not the whole truth; everything the triangle is and might be seen to do, one might say.

Incidentally there are numerous optical illusions in which shapes are seen but do not correspond to the external source of the sensory data.Kanizsa triangle The Kanizsa triangle is the product of the way in which the data is processed, not something that exists independently.

I think our thinking is overlapping because you have the observer( or imaginer) selecting one of many different possibilities for how the triangle might appear to be and appear to be changing, rotating, transforming, changing size. So there isn't -a singular- macroscopic reality but many from which the observer selects one "at a time". Which fits with the QM many worlds in super-position idea.

When you say it is meant to represent the entire universe I am a little puzzled. I had thought you meant that the whole of external reality could be imagined broken down into various combinations of 3 points. Which sounds useful to me. Now I'm not sure that is what you meant. Are you considering the triangle as something separate from any outside influence and thus it is its own little model universe? As in nature, what the triangle is, and does, does not depend just upon how the observer looks at it but the forces acting independently of the observer that could alter the separations and give a foundationally different triangle rather than just an apparently different triangle.

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Georgina Parry replied on Aug. 6, 2012 @ 05:12 GMT

Dear Julian,

I have just noticed, looking again at your PIRSA lecture, you have a diagram of the Shape Space. Marked are fictitious vertical changes, which are the changes of the triangle that appear to occur, the gauge ones. Not physical alteration of the object. Then you have "nature generates real horizontal changes", (which are the ones that are changes to the shape itself). "It says on there defining it is the central problem".

It seems to me the vertical ones could be to do with how the object is perceived, so they must relate to sensory data in the environment, generated from EM interaction with the object. The horizontal changes are those that are the alteration of the arrangement of the universe, the sequential real changes of the material object or arrangement generating passage of time, (independently of the experienced time generated from the sequence of received and processed data.)

I also agree it is important that the seen and real changes do have to be separated and treated as different things. I like the diagram where you have the fibre bundles above the curved path on the shape space because it is to me like all of the different possibilities that could be seen related to the object. The observer could be "looking" anywhere along that fibre. Though if you are referring to the data in the environment when they are seen is not simultaneous with the existence of the shape on the shape space IE the actual form to which the bundle relates.They can be seen -whenever- the data is received and processed. So the fibre line does not represent spatial position or temporal simultaneity. ( You did explain to me that this diagram is not in space or time, that now makes sense.)Also the observer can be moving which will alter where -vertically- on the fibres, as well as "horizontally" the shape is selected (as well as there being ongoing "horizontal" change of the object generating the new "vertical" possibilities.)

It is also interesting to me when you say that you are not putting the triangle into space time but that space-time emerges. It seems to me that it is not so much space-time that is emerging from real changes but sequential iterations of the object/arrangement in 3D space as each new real arrangement replaces the previous one. This is the kind of scenario J.C. N Smith is also describing. This is different than for the seen triangles, as the data capable of making all of the possible output observed triangles persists in the environment, so there is temporal spread within the data (IE it relates to a particular source arrangement /iteration) when it was generated but there is no temporal spread of the space itself.

It gets complicated at the end and it starts to sound very different to what I have been imagining.I do think it is very important to separate what is seen from the material objects, (your vertical triangles from your horizontal ones). I can picture potential sensory data spreading out from a source giving a foliation of data where each leaf relates to a different source arrangement (One of your real shapes.) So there is a temporal foliation even though all of the data is co existing simultaneously in the environment. So the universe is deciding what data is there prior to the observer selecting it, it is not random.

The mathematics you are describing is complicated for me but I think I can follow why it is being done, if not what is being done. It would be nice to know what you think of what i have written. Perhaps you would consider correcting me if I am just not getting it, or let me know if the way I am relating the ideas to my own thinking is at all interesting or helpful in your opinion.

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John Merryman wrote on Aug. 1, 2012 @ 16:07 GMT

Julian,

"The complete set of points has no position or orientation in space except in our imagination."

I suppose you meant to say, "except from our point of view." As that is why three points would form a particular triangle.

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Yuri Danoyan wrote on Aug. 1, 2012 @ 17:55 GMT

Julian

I have great respect to your approach, but the same time i want to clarify for me some details:

I would like reminding you quote from Winterberg article:

http://bourabai.narod.ru/winter/relativ.htm

"5. Einstein - Parmenides and the Ontological Proof for the Non-Existence of God

The special theory of relativity understood by Einstein as a four-dimensional space-time continuum implies a kind of superdeterrninisrn with the future completely determined down to the smallest detail. This was the reason why Einstein believed time is an illusion and why Karl Popper told Einstein "You are Parmenides," the Greek philosopher (515-445) who believed that being is not becoming and time (becoming) an illusion. With everything exactly predetermined there can be no free will, not even a hypothetical God, and a God without free will is an ontological impossibility.

One therefore can say: If Einstein is right, then there can be no God. The opposite though, is not true; true rather is if God exists then Einstein must be wrong."

If the Universe is a sequence of identical cycles, according to Penrose, that is, time is a circle, how do you identify past from future and vice versa?

The Past is the a Future. The Future is the Past.

I will try to show concrete difference between the 2 approaches:

Parmenides and Heraclitus.

Suppose two options with the same content:

1. The written Text by Nature

2. The Audio-recording of the same Text.(We live and listeniing audio-recording regime)

Written is Parmenides.

Audio-recording is Heraclites.

Julian,

I am right?

Thank you for advance.

Yuri

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Yuri Danoyan replied on Aug. 3, 2012 @ 13:43 GMT

At first sight two approaches, Parmenides(book) and Heraclitus(audio-book) in a one picture seems as a schizophrenia. As Niels Bohr said:

"There are trivial truths and the great truths. The opposite of a trivial truth is plainly false. The opposite of a great truth is also true."

The Complementarity is also applicable here as well.

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Georgina Parry replied on Aug. 3, 2012 @ 23:44 GMT

Dear Yuri,

I think you are expressing your insight into how seemingly incompatible ideas can be important descriptions relating to the same thing.

Heraclitus understood continual change of the universe (and of the the observer). Parmenides understood that we can not rely entirely upon our senses to inform us of the whole truth or independently existing reality. So IMHO both had very important insights that are useful to science today.

Parmenides imagined deeper reality still and perfect. Hericlitus meditated on change. This difference of viewpoint is a bit like the measurement problem of QM, where either the position or momentum of a particle can be measured not both at once. It is useful IMHO to consider single timeless iterations of the universe but it is also useful to consider changes that occur; that might be traced as paths of particles or objects, or spreading out of potential sensory data, through many iterations.

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Yuri Danoyan replied on Aug. 4, 2012 @ 02:03 GMT

Dear Georgina

It seems to me Julian's approach look like Parmenides.

I don't think he is heretic.

Just for protect his point of view.

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Author Frank Martin DiMeglio wrote on Aug. 1, 2012 @ 18:14 GMT

Julian Time requires extensiveness and balance. It fundamentally requires past, present, and future. Physics happens in and with time. Time requires gravitational and inertial equivalency and balancing. Time requires space.

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Author Frank Martin DiMeglio wrote on Aug. 1, 2012 @ 18:20 GMT

Julian Time AND space ultimately require balanced and equivalent attraction and repulsion in conjunction with gravitational and inertial equilibrium/equivalency and balancing. Gravity cannot be shielded. Think about our experience directly. Gravity is key to distance in/of space.

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TommyG. wrote on Aug. 4, 2012 @ 06:48 GMT

Oh yeah, this is important. Wilhelmus was trying strongly to convince me to contribute and enter this contest because he said my comments were being referred to in threads, and it has been his impetus to write an essay here. I didn't have the heart to tell him that all new comments appear on the upper left of these pages and have nothing to do with any of their content. Dont' tell him: he's a great guy! He a Dutchman living in Paris, and has a cave full of wine he wants to share with me one day. Don't tell him. He's a sweet kid!

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Georgina Parry replied on Aug. 4, 2012 @ 22:09 GMT

Dear Tommy,

I've already said elsewhere that I would read your essay if you finish it. I would be happy to comment on it, according to my own abilities. There is only one person, who posts on FQXi, widely and purposefully ignored and it isn't you. Cheers!

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Anonymous wrote on Aug. 5, 2012 @ 14:13 GMT

Good Morning Julian Barbour,

NATURE OF TIME

I thought it is me, who does not understand the reality of time, and have to concentrate so much to evolve an understanding about reality of space and time. Now humans intuitively take space and time as strongly conserved, as is matter. The observation of disappearance of matter on heating, was resolved into conservation by introducing...

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Vijay Mohan Gupta wrote on Aug. 5, 2012 @ 14:15 GMT

Sorry the message got registered as Annonymous post.

Vijay Gupta

picophysics.org

Proponent: Unary Law 'Space contains Energy'

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Wilhelmus de Wilde de Wilde replied on Aug. 5, 2012 @ 16:53 GMT

pico-bello ?

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J. C. N. Smith wrote on Aug. 6, 2012 @ 14:49 GMT

Dear Julian Barbour,

Thank you very much for participating in these discussions. I have followed your writings about the nature of time with great interest since discovering your book 'The End of Time' soon after it was published.

I believe we share many views in common regarding the nature of time. You've written, "The relative configurations, or shapes, of the Universe do not occur at instants of time . . . they are the instants of time." My oft-used wording for what I believe is essentially the same idea is, "a particular time is identically equivalent to, and is completely defined by, and only by, a particular configuration of the universe."

Extending this notion a bit further, I've written "what we *perceive* as the flow of time is, in reality, nothing more and nothing less than the evolution of the physical universe, an evolution which is governed by rules which we strive to understand and which we refer to as the laws of physics."

Earlier in this blog (on 19 July) you wrote, ". . . general relativity has a rich mathematical structure and it has been known for 50 years that it can also be viewed as a theory of the evolution of three-dimensional geometry."

If you see any interesting commonality in our views, I would encourage you, if you can set aside the time, to read the essay I've entered in the current FQXi competition, Rethinking a Key Assumption About the Nature of Time.

Then, assuming you find anything at all to like in that essay (I'm extremely pleased and proud to say that George Ellis commented favorably on the essay!), you will find that I've written more on the topic in a series of essays, Toward a Helpful Paradigm for the Nature of Time, On the Impossibility of Time Travel, and Time: Illusion and Reality .

I believe you'll find my views on the nature of time to be both naive and primitive, but I mean that in a good way. I do not pretend to sophistication in mathematical modeling, but I believe that I have a solid grasp on objective reality. Moreover, I'm deeply troubled by thinking which is based on mathematical modeling of reality when it leads people to claim that perceived distinctions between past, present, and future are illusory, and that there is no objective flow of time. I fear that those who hold these views have lost sight of the distinction between the map and the terrain.

I'd welcome your thoughts on all this. Thank you.

Best Regards,

jcns

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James Putnam wrote on Aug. 6, 2012 @ 16:07 GMT

Dear Dr. Barbour,

Thank you for sharing your view about the nature of the universe. With regard to your description of static configurations, could you please mention empirical evidence for the existence of static configurations? Thank you.

James

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Julian Barbour wrote on Aug. 7, 2012 @ 08:26 GMT

Hello again. Life is a bit hectic for me at the moment, so I won't be able to respond to everything. Luckily some posts don't seem to relate to me but are discussions between others.

First, Georgina commented yesterday

"It seems to me the vertical ones could be to do with how the object is perceived, so they must relate to sensory data in the environment, generated from EM interaction with the object. The horizontal changes are those that are the alteration of the arrangement of the universe, the sequential real changes of the material object or arrangement generating passage of time, (independently of the experienced time generated from the sequence of received and processed data.)''

The second sentence is correct. The first is not quite. If you fix a triangle somewhere in a room and then look at it from different points of view, you will get the changes of appearance that you correctly describe Georgina. However, this is not what I mean by the vertical changes. They are nothing to do with how one and the same triangle will be seen by an observer from different viewpoints. They can be likened to all the different ways a mathematician can imagine the triangle placed in the room (and also its size changed). This and a recent email exchange have made me realize how much care must be taken to get across abstract ideas. To make things really clear I fear I would need at least a few pages. Sadly other commitments and post limitations make that well nigh impossible.

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Georgina Parry replied on Aug. 7, 2012 @ 09:38 GMT

Hi Julian,

thank you for clarifying what the triangle is meant to be.I did understand that the triangle is an abstract mathematical thing as you and collaborators are using it. As you explained that to me. -I wanted to relate it to a physical reality-, because for me that is the point of maths. It should be representing the physics that is happening in reality and not just being abstract.

In my explanatory framework there are two aspects of reality that co-exist one is the arrangement of objects and media including the distribution of potential sensory data and the other is the output of data processing giving what the observer sees. The shape space model shown in the diagram may not have been developed with that picture of physical reality in mind but I do not know why it could not also serve that function. Can the mathematician orient the "vertical" triangle in any way, (other than "larger than life"), that the observer would not be able to see it? Assuming the observer is able to position himself anywhere around the triangle object.It would be bigger and smaller depending on how near or far the observer is.

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T H Ray replied on Aug. 7, 2012 @ 12:18 GMT

Hi Georgina,

When Julian says that triangles (or any geometric figure) are abstractions, I think he means to imply that there are no "triangles in the sky," except as we imaginatively connect those dots (as, e.g., the ancients did, to describe constellations).

In other words, physical matter plays no a priori role in how we do geometry (or any other mathematics) -- because free choice of spatial points is not constrained by physical reality. When it comes to the geometry that "should be representing the physics that is happening in reality and not just being abstract," as you put it, Barbour and group are firmly wedded to the physics of Mach's Principle, which is relativistic physics in its purest form. That is, how can the dynamic relations among mass points be described in terms of relations among spatial points? The answer would generalize in mathematical language the relativity of motion without encountering the need to prescribe arbitrary boundary conditions, as one does when drawing triangles on a sheet of paper or other surface. The triangles that nature makes, subsume those of our design -- in Mach's mechanics, space is a convenient fiction.

Just my $.02.

Tom

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T. H. Ray replied on Aug. 7, 2012 @ 12:43 GMT

P.S., Georgina -- if you haven't yet made a study of it, I think you will find that Mach's Science of Mechanics published in English in 1919 (link is a free download -- thank you, Universal Library)) is more than worthwhile reading, and ranks as a milestone scientific work. You will find that Mach agrees with most of your views, not the least of which is that "Mechanics will here be treated, not as a branch of mathematics, but as one of the physical sciences."

Best,

Tom

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Julian Barbour wrote on Aug. 7, 2012 @ 08:59 GMT

With regard to JCN Smith's post, your views are indeed close to mine. I also believe there is nothing wrong with 'primitive' concepts. However, as regards your final paragraph, I think we need deeper understanding of the quantum mechanics of the universe and the nature of consciousness before attempting definitive conclusions. I'm glad to hear George Ellis commented on your essay. I will try to have a look at it, but George, of whom I have seen quite a bit in the last few years, has an amazing capacity for work that I cannot match.

With regard to James Putnam's question, which is very much to the point, I think one must distinguish scientific descriptions from psychological experiences. There are people with the condition called motion blindness, who see the world as a series of static snapshots. I met one (after the condition had ceased) and had email communication with another. Does that count as empirical evidence? One might argue that such people are closer to reality than those of us who see motion.

Also, I would say empirical evidence is always cumulative, never absolutely final. On the basis of empirical evidence, Copernicus could predict what the solar system would look like from Mars. Newtonian theory made that prediction look much more secure. Only in the space age did humans actually get views of the solar system from viewpoints other than the earth.

We are very far from being in a position to say with confidence that the universe is best explained in terms of static configurations. I think there is relatively good evidence in support of the idea but cannot claim more. All science is based on hypotheses whose consequences have to be constantly developed and tested. That process is still going on for Copernicus's proposal.

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James Putnam replied on Aug. 7, 2012 @ 18:22 GMT

Dr. Barbour,

Thank you for responding.

James

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J. C. N. Smith wrote on Aug. 7, 2012 @ 13:04 GMT

Hi Julian,

Thank you for your comments on my post. I'm gratified that you see some likenesses in our views regarding the nature of time. The one part of your thinking which has eluded me, however, is your insistence on the importance of "static" configurations. Why static? Yes, I've read and re-read 'The End of Time' and made notes in the margins until the poor book is a shambles, and I've read other pieces you written and watched your PIRSA videos, etc., but despite my best efforts I still have failed to comprehend your insistence on "static" configurations. Why not smoothly flowing, smoothly evolving configurations (analog vs. digital)?

Modern physics strikes me as being close to what Thomas S. Kuhn described as a "crisis" state. I believe that emerging from this state will require a new consensus about some of our fundamental paradigms, the nature of time being just one of them.

"The way we converge with each other is by converging upon the truth." (D. Deutsch) I'm optimistic that we're all inching along in that general direction, but lasting progress is hard won.

jcns

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A.B. McLin replied on Aug. 7, 2012 @ 14:55 GMT

I think what Julian was trying to get at is that "static" configurations are the atoms out of which dynamic evolving configurations are composed of. To use a video analogy. What you see as a smoothly changing motion picture is actually a series of still frames being rapidly replaced by one after another. While the rapid swap-replace is done by the equipment running the video(along with some assistance by our sensory system), the analogous action in Julian's theory is done by, I think, essentially a mathematical perspective where a series of static configurations is linked up together and seen to compose a self-consistent history.

Each of the static configurations which contains an observer and form a consistent history is observed to be consistent by the sole power of mathematical consistency. One would see events unfolding continuously and naturally rather than abrupt nonsensical jumps around different non-congruent physical configurations.

One can pick an arbitrary set of configurations and see whether they line up to form a consistent history, or look like disconnected jumbled set that cannot build up a consistent history.

I think by simple logic that Julian's theory actually disallows constructing "histories" out of mutually conflicting configurations or I suppose that if one could construct such a history, it won't be possible to find an observer in it capable of seeing and understanding what's going on.

That's my take from my reading of 'The End of Time.'

A. B.

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J. C. N. Smith replied on Aug. 7, 2012 @ 17:19 GMT

Dear A. B. McLin,

While appreciating your interpretation of Julian's thinking (which seems reasonable and plausible), I'd like to get Julian's take on it as being the authoritative word on his thinking.

The other thing I failed to mention previously which troubled me about 'The End of Time' was Julian's disavowal of motion. I'm not at my home at the moment and so can't quote exact passages from the book in which he discusses this topic, but his disavowal of motion, together with his notion of a series of static configurations coalesced to leave me in a long-term state of befuddlement even more pronounced than is typical for me, which is saying quite a lot.

It's my own view, for whatever it's worth, that the universe has one, and only one, real history, albeit one which necessarily will be perceived differently by different observers.

jcns

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J. C. N. Smith wrote on Aug. 7, 2012 @ 16:44 GMT

Dear Yuri Danoyan,

Please accept my apologies for appearing to ignore your posts addressed to me. It was not my intention to be rude. A big reason I've not replied is that I don't know exactly *how* to reply.

You wrote in my blog "Only posible reconcilation between Parmenides and Heraclites is the Cyclic Universe in modern Penrose version or oldest Heraclitus version."

I regret to say that I have not yet studied Penrose's latest thinking on cycles of time (I intend to do so as soon as time permits!), but barring the unforeseen I must count myself among the disciples of Heraclitus as an unapologetic presentist.

I hope this helps. I'll post this again where your comments appear in my blog as well.

jcns

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Yuri Danoyan replied on Aug. 7, 2012 @ 18:48 GMT

Along with Present there is the Eternal, which Julian calls Platonia.

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John Merryman wrote on Aug. 8, 2012 @ 16:03 GMT

A simple question:

I recall Einstein said the present is just an illusion.

He also said time is what you measure with a clock.

A clock consists of two features, the face and hands and how they relate. Now many will say there different kinds of clocks, but the general principle remains the same. There is a regular cycle and a mark, detector, etc. to register when that cycle completes one unit of measure.

Now that mark essentially represents the present. The point the cycle is going through and marking delineations between one cycle and the next.

So if the present is just an illusion, what defines that point of detection? It would be like a clock face with no hands.

Blocktime is often compared to a book, or movie, where all the events exist and it is only a matter of what page or frame you are on. Yet a book or movie is like a clock without hands when it is on the shelf, or not being shown. In order to read a book, or watch a movie, you need to open it and read one page at a time, or put it in a projector, where the light shines through it, one frame at a time.

So the act of reading, or the projector light, is like the hand of the clock, moving from one event to the next.

In order to measure time, since physics is all about measurement, it seems extremely contradictory to say the face of the clock, the events being measured, are "real," but the act of measurement, the hands of the clock, are an illusion.

Now this might seem an extremely "philosophical" question and therefore not worthy of physics, but what seems more "real," The present? Or the particular arrangement of shapes manifested in it?

How is it that the configurations are supposed to be more real than the dynamic processes which create those configurations?

Is the answer to this conundrum so complex it cannot be computed, or so elemental that current theory cannot recognize it?

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Yuri Danoyan replied on Aug. 8, 2012 @ 16:59 GMT

I put more simple questions to Julian Barbour(see my post Aug.1)

"Euclidean triangles are the simplest example"(Barbour)

1)How about non-euclidean triangles(with positive or negative curvatures)?

The angles of triangles vary(>2pi

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Julian Barbour wrote on Aug. 9, 2012 @ 16:57 GMT

I fear I won't be able to keep up with all the posts and do justice to some qood points.

Let me start with the last post (Yuri, Aug. 8). Einstein said make things as simple as you can but not too simple. I use the 3-body problem, with Euclidean triangles as its possible configurations, to illustrate some important aspects of Einstein's general relativity because it is the simplest system that reproduces some key aspects of that theory. I could in principle do it with three bodies in spaces of positive or negative curvature, but the math would be far more complicated and, from the conceptual point of view, nothing would be gained.

John Merryman raises lots of points, all needing an answer. On this visit, let me just comment on his "How is it that the configurations are supposed to be more real than the dynamic processes which create those configurations?". My viewpoint is that things you can see are more real than their changes. I do not see how one can talk about galloping if one does not already have the concept (or sight) of a horse. This is why I say nouns (things) are more fundamental than verbs. I think this is ultimately the reason why Plato regarded being as real and becoming as illusion. This is philosophical and philosophers have been arguing about it since before Plato's time. What is remarkable is that modern attempts to create a quantum theory of the universe force us to address the question head on. But John, what makes you think dynamical processes create configurations? Is it not possible that the configurations simply exist? You can only describe galloping in terms of different configurations of a horse.

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John Merryman replied on Aug. 9, 2012 @ 19:16 GMT

Julian,

Thank you for taking the time to reply.

That is a fitting example for me, since I exercise racehorses in the morning and tend to view it much more in terms of verb, than noun.

As the architects put it, "Form follows function." For galloping, the function is forward motion, while the form is a sequential series of steps. The world of objects may be what is apparent, much as you say we only perceive angles, not distances, but that doesn't obviate the foundational necessity for the initial dimension, in order to perceive the distinction of the second dimension. Distinction may be foundational to thought, but without connections, there is no relationship to order those distinctions. The triangles alone are like fish without water.

Think in terms of a camera: How does it take pictures of objects in motion? With a very fast shutter speed. Why? Because the vastly more information collected by leaving the shutter open longer would only blur the distinction of the object. Our eyesight functions similarly, for the same reason. Our minds create "snapshot" impressions and then convert the sequence back into a simulation of motion, because in the absence of this distinction process the raw information would quickly blurr to white light and shadows. Our mental processes also function by creating sequential thoughts out of the flows of sensory and intellectual information. None of this processing of information negates the underlaying dynamic.

I don't know if you have the time to look at my entry in the contest, but it is about how we intuitively perceive time as a sequence of events, which physics re-enforces by treating it as a measure from one to the next, but the underlaying reality is that it is not a vector from past to future, but the changing configuration of the extant, turning future into past. Probabilities collapsing into actualities. Does the earth really exist along some vector from yesterday to tomorrow, or does tomorrow become yesterday because the earth rotates? The former seems extremely speculative, while the latter is simple observation. This makes time, rate of change, an effect of action, similar to temperature, the level of activity. Duration only exists within the present, not external to it.

If you are willing to consider this view, then it means there can be no dimensionless point in time. It would be like having the shutter speed set at zero. Equivalent to a temperature of absolute zero, ie. no motion, not even of atomic activity. So it would not be a freeze frame of reality as we sense it, with objects in their exact positions, but a void empty of any energy, ie. absolute zero. This means an object, micro, or macro, cannot be isolated from its motion.

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Julian Barbour wrote on Aug. 12, 2012 @ 15:51 GMT

Re the last post: John, How splendid that your response to my presenting my ideas about configurations and motion in terms of a galloping horse and you come back with "I exercise racehorses in the morning and tend to view it much more in terms of verb, than noun. As the architects put it, "Form follows function." For galloping, the function is forward motion, while the form is a sequential series of steps."

I accept your aphorism 'Form follows motion' for architecture and probably for the function of the parts of most living organisms. And of course you will think about racehorses in terms of their galloping, since that is what they must do to win races.

However, I am thinking about the most basic notions in physics, and I am not sure for that one can apply principles of architecture or the turf.I notice also you say of galloping that "the function is forward motion". So you agree it is not backward motion? But what is backward or forward? These key concepts can only be defined by the starting tape and finishing post, both of which are located in a racecourse set somewhere, no doubt, in a beautiful part of the world (Glorious Goodwood or Kentucky perhaps). So it seems to me the definition of 'function' presupposes' configuration before you can even talk about form.

It would nice to prove that the purpose of the universe is that Shakespeare could write plays, Beethoven compose symphonies, and you could race horses. Perhaps it is. But you cannot build cathedrals without bricks, perform plays without stages, symphonies without orchestras and race horses without courses. And all of this hardware relies on basic physics at the level of material configurations, how they are knit together, and how they change.

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John Merryman replied on Aug. 12, 2012 @ 19:52 GMT

Julian,

"how they change."

That is the crux of the issue. Is there a series of sequential states, or one state which changes?

Does the earth move/exist along a vector of configurations, from yesterday to tomorrow, or does tomorrow become yesterday because the earth rotates?

Is action an effect of the vector of time, or is time an effect of action?

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Georgina Parry replied on Aug. 15, 2012 @ 13:36 GMT

OK I realise death will not be instantaneous. The cat is either fully well or has undergone a lethal change. One or the other are the only options for the flesh and blood actualised cat. However the data in the environment can encode both options if live cat subsequently falls ill. There can be super position due to data from live and dead cat coexisting in the uni-temporal environment. (The box complicates matters.)

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Georgina Parry replied on Aug. 15, 2012 @ 13:44 GMT

Sorry last post is in the wrong place. Can be removed as I'll repost it correctly.

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Julian Barbour wrote on Aug. 14, 2012 @ 12:47 GMT

John, I'm afraid I can only attempt to answer your question in the first way you formulate it because you use the word 'vector' in what strikes me as a non-standard way that I fail to understand.

As I interpret classical (pre-quantum) physics, the universe has a series of different states rather like different beads on a piece of string. There is no intrinsic direction, or arrow, of time in the series. The law that determines which state follows which state is exactly the same in which ever direction you go. Moreover, to formulate the law, you can completely dispense with not only the idea that time has a direction but even with duration as a fundamental notion. You do not need to say one bead is at a certain time along the string from another. The only thing that counts in the order in which they come.

So at the level of classical physics, my answer is: There is a series of states; it can be read indifferently in either direction.

Things get much harder in quantum mechanics. The nature of the states is different and there is no way one can say they are arranged in a series. In laboratory quantum mechanics, a single initial state can become many different states that all coexist until a measurement is made, when only one is found to be present. This description is hard to apply to the universe since there is no one outside the universe to make a measurement. Many physicists, myself included, feel themselves forced to a 'many-worlds' interpretation, according to which all states are 'present' at once.

If people find any interpretation of quantum mechanics crazy, I suspect they should complain to nature. She seems to force these things upon us. In fact, to me they do not appear bizarre, but that is another story.

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John Merryman replied on Aug. 14, 2012 @ 15:48 GMT

Julian,

The point I keep making is that both interpretations, series of states and multiworlds, arise from treating the effect of action, different configurations, as fundamental, rather than viewing these different states as an effect of action.

There is only what is present; The cat in the box. It was alive when it went in, but that event is receding into memory, as the dynamics of quantum behavior decides its fate. Then we open the box and find out. We and the box did not move in any direction, only the dynamic process affected the conditions in the box as one state, the prior, is replaced by the subsequent state.

We do experience time as a series of events, but then we still see the sun as passing overhead, from east to west, yet all efforts to explain why came to naught, until we understood it was the earth spinning west to east. So it not that the present moves along this string of events, or even that the string exists, but the changing configuration of what is present that turns potential into actual and replaces it. Tomorrow becomes yesterday because the earth rotates.

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Julian Barbour wrote on Aug. 16, 2012 @ 17:12 GMT

John, I am afraid we are not going to come to agreement. I cannot work out what you mean in your first paragraph and the second seems to be in conflict with quantum mechanics. As regards the observed motion of the sun, there were perfectly sensible explanations for it before the idea of mobility of the earth was seen to be better. The many-worlds interpretation of quantum mechanics may not be right, but it is not possible to dismiss easily. It suggests that the past exists in the same way as the present does. This can be because the you experiencing what you call yesterday is not the same you as the one experiencing today. One can arrange the natural numbers in the order 1,2, 3, ..., but that does not allow 13 to say it is the present and 11 is dead. For mathematicians both exist as different numbers.

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John Merryman replied on Aug. 17, 2012 @ 02:03 GMT

Julian,

I suspect you are right, that we will continue to differ on this topic, so it would be both fruitless and impolite to continue arguing on your blog post.

I assume you have been considering the current essay and its rather provocative subject, Questioning the Foundations. I think time will show this to be a prescient topic, since so many of the current leading edge physics theories are far beyond the range of testing, from strings to multiworlds and future generations of physicists are not going to spend their careers expounding on ideas with little potential for proof. At such moments in history, the future becomes a reaction to the past, rather than a continuation of it.

We reach for the future, but we can only grasp the past.

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Julian Barbour wrote on Aug. 20, 2012 @ 13:48 GMT

John, With this post I find myself in broad agreement. I am in fact working on an essay but suspect the ideas I put forward are still far from being testable. Our best hope is that we are not merely grasping the past but standing on it to get a view forward. You recall what Newton said about the shoulders of giants.

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Georgina Parry replied on Aug. 21, 2012 @ 03:40 GMT

Dear Julian Barbour,

its good to hear that you are working on another essay. It will be another great contribution towards helping us understand nature. It has been very instructive having you here to talk to us briefly. I have realised how very little I have really understood of what you are actually doing. I had some notion but having heard your explanations and finally grasped them, it is now much clearer. I still think its great by the way.

I now at least feel I have taken a few baby steps closer to understanding:Your main reason for your approach, what it is and isn't- and now I think also the reason why that way not another. Which makes me want to continue learning more. Had hoped you might confirm that I am now on the right track but appreciate that you probably have much better, far more productive, worthwhile and rewarding things to do. Best of luck to you.

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