Evolving Time's Arrow

jcns,

I'll try, though I don't think (and I expect Lawrence will agree) that one can fully appreciate spacetime dynamics without understanding the mathematics. As Lawrence notes, there is more than one way to write the equations that lead to the same physics. We choose our models for their ability to explain current phenomena and to make additional novel predictions.

Classical physics is the domain of human experience. Even our quantum mechanical experiments are designed within classical parameters. What we've learned over the past three centuries or so, though, is that not even classical results are intutive. For example, one cannot intutively connect the falling of an apple from a tree with the falling of the moon toward the Earth without Newtonian mechanics. Even Galilean physics (as I discovered to my surprise recently, by the varied responses to a simple projectile problem) is not immediately intuitive even among people who should know better.

What all classical physics has in common is the mathematics of continuous functions. In other words, Newton's apple does not stop falling at the Earth's surface, but continues falling in principle -- just as the moon's orbit is continuous. Continuous functions are evident to the limit of classical physics, i.e., relativity.

Most of what we know of physics, objectively, is counterintuitive. Lawrence is quite correct that human experience and intuition play an insignificant role.

Quantum mechanical functions are algebraic, i.e., discrete. The basis is the analysis of probabilistic quantum events in a Hilbert space, which means a complex model -- because quantum mechanics does not allow space collapsed to a point (singularity), and the complex plane is fundamentally two-dimensional.

So far as experimental results go, and remembering that all are designed within classical parameters -- I offered a quasi-classical model in my FQXi 2008 essay ("Time counts") in which I constructed a complex analog to Kepler's second law. Because it is based on the (non) conservation of angular momentum using escape velocities between gravitating classical bodies, if each point of spacetime is characterized by a unique escape velocity (it is), the principle is already experimentally verified. What the mathematics shows is a very slight loss of information among bodies.

Point is, to get to these models where Lawrence among others can speak of group theory and noncommutative algebra to model physical phenomena, we have to go through what we know about the classical and quantum worlds and then follow the path where it leads without contradicting previous results. Intuition isn't much help.

Tom

Tom,

Quick reply to thank you for your reply to my question and to let you know I'm pondering what you wrote. More later, assuming I can think of anything resembling cogent to add.

jcns

Time is an epiphenomenon of change

Change is the fundamental property of material world. Time that we measure with clocks is the numerical order of change, i.e. motion in space. In physical world time exists as the numerical order of change in space. In physics time is a mathematical dimension used for description of change in material world. It is an utter misunderstanding to think time is part of space and change run in time. On the contrary: time is an epiphenomena of change, time we measure with clocks is the numerical order of change.

Amrit

Correct, just about.

Love the word epiphenomenon, the best I could come up with was conceptualisation.

Paul Reed

Tom and LC,

Without claiming that what follows resembles cogent, I'd like to keep this constructive discussion going. If you've read any of my other posts in this or other FQXi blogs you must know that my approach to physics is naive, primitive, and visceral, but I hope not unscientific, in the best sense of that word. I exist in a universe which, statistically, is mostly not hospitable to fragile life forms such as myself. Understanding physics, therefore, is, for me, a matter of survival as well as a matter of great intellectual curiosity and fascination.

The universe in which I find myself is extremely dynamical. There are lots of things in motion, cars, clouds, airplanes, planets, galaxies, occasionally (and frighteningly, during earthquakes and tornados) even pieces of buildings, trees, etc. If some of these objects were to collide with me it could be fatal at worst and uncomfortable at best. Again, understanding how this all works (i.e., understanding the laws of physics which appear to govern it all) on a visceral, intuitive level is essential to survival.

Tom, you wrote "Point is, to get to these models where Lawrence among others can speak of group theory and noncommutative algebra to model physical phenomena, we have to go through what we know about the classical and quantum worlds and then follow the path where it leads without contradicting previous results. Intuition isn't much help." My reply is that unless these models are taken to be purely academic, mathematical exercises they ultimately must tell us something of practical value about the universe in which we exist. It is this "something" which I'm trying to tease out of our discussion. How will these models ultimately allow me to improve my chances of survival?

Without a doubt, mathematical models play an important role in physics. At some point, however, mathematical models must somehow come into contact with empirical observations if they are to be of any real value, in my opinion. Granted, human experience and intuition are known to be extremely fallible, but that not withstanding they are still our only real basis for doing science (as opposed to pure mathematics).

Mathematicians presumably could develop a model of the Ptolemaic picture of the universe as readily as they could develop a model of the post-Copernican picture. We then could talk about these two models in purely mathematical terms ad nauseam, but it is also satisfying to be able to talk also about the fact that one model has the sun revolving around the Earth whereas the other model has the Earth revolving around the sun while simultaneously rotating on its axis. One model ultimately is more useful than the other, despite the fact that human intuition accepted the less useful model as being "obviously" true for centuries.

As repeatedly noted elsewhere in these blogs, I'm a huge advocate of zeroing in on better and better paradigms. And I've long been concerned that the mainstream, prevailing paradigm for the fundamental nature of time is lacking. Not "wrong" perhaps, but lacking, or incomplete. Inasmuch as "time" plays such a central and crucial role in physics I believe it's worthwhile being certain that we have this paradigm nailed down as correct as possible.

Unless I'm mistaken (please correct me if I am), the prevailing paradigm for the nature of time may be summarized by the so-called "operational" definition, i.e., "time is that which is measured by clocks." Clocks are then typically defined in some sort of slippery way as being devices which measure time by way of some sort of "regular motion," but it is never made perfectly clear how one would know whether motion was "regular" or not without resorting to the use of a clock. I'm not saying that this is "wrong" per se, but only that it seems, at best, incomplete. This view of time apparently leads logically to concepts such as block time.

In some of my essays such as 'Time: Illusion and Reality,' I've tried to suggest another paradigm, another way of looking at the nature of time, which, unfortunately, is also, in and of itself, incomplete I fear. In this way of looking at time our dynamical universe is the clock. Different physical configurations of the universe define, and are identically equivalent to, different particular times. This view does not allow for block time, and it makes a "causal arrow of time" an inevitability. It further rules out time travel (at least of the variety portrayed in science fiction literature).

Lawrence actually appeared to key in on this view in one of his posts to the article on 'Breaking the Universe's Speed Limit' when he wrote, "A[s] for block time being contrary to human experience or intution, those do not really count for much. The non-block time is just a system of spatial geometries which are related to each other by a diffeomorphism group. The notion of time is actually somewhat lost in this picture." Yes, in my view non-block time is indeed a system of spatial geometries! Exactly! But as he points out, the conventional notion of time is somewhat lost in this picture. And this may be where this paradigm is incomplete.

I can't help thinking that if some very clever person could somehow meld these two views of time the resulting paradigm might offer a more useful way of looking at the universe than any previously proposed. Unfortunately, I do not know how to accomplish this melding, but I sense that it would not be easy.

Apologies for rattling on for so long.

Regards,

jcns

JCNS,

You wrote, "If you've read any of my other posts in this or other FQXi blogs you must know that my approach to physics is naive, primitive, and visceral, but I hope not unscientific, in the best sense of that word."

Sure.

"I exist in a universe which, statistically, is mostly not hospitable to fragile life forms such as myself. Understanding physics, therefore, is, for me, a matter of survival as well as a matter of great intellectual curiosity and fascination."

I agree. I touched on this in my 2010 FQXi essay. "When one calculates

outcomes from a field of infinite parameters, the great majority lead an organism to extinction. Yet conscious creatures play with loaded dice; 'good' and 'bad' choices, assuming that all strategies are rational, i.e., survival-based, depend on having at least one good choice independent of all environmental influences considered as a continuum. E.g., if a one-celled creature needs light to survive, it either has the motive ability to seek

a light source in order to 'be,' or it ceases to be when the light goes away."

We're fragile only when we don't have options. More consciousness creates more survival options and more robust life. We're all complex systems of cooperating cells.

"The universe in which I find myself is extremely dynamical. There are lots of things in motion, cars, clouds, airplanes, planets, galaxies, occasionally (and frighteningly, during earthquakes and tornados) even pieces of buildings, trees, etc. If some of these objects were to collide with me it could be fatal at worst and uncomfortable at best. Again, understanding how this all works (i.e., understanding the laws of physics which appear to govern it all) on a visceral, intuitive level is essential to survival."

Absolutely.

"Tom, you wrote 'Point is, to get to these models where Lawrence among others can speak of group theory and noncommutative algebra to model physical phenomena, we have to go through what we know about the classical and quantum worlds and then follow the path where it leads without contradicting previous results. Intuition isn't much help.' My reply is that unless these models are taken to be purely academic, mathematical exercises they ultimately must tell us something of practical value about the universe in which we exist. It is this 'something' which I'm trying to tease out of our discussion. How will these models ultimately allow me to improve my chances of survival?"

Does electrical power improve your chances of survival? There's a story, maybe apocryphal but surely instructive, that a matron upon being introduced to Michael Faraday, asked of what use are his discoveries. Faraday supposedly replied, "Madame, of what use is a newborn baby?"

"Without a doubt, mathematical models play an important role in physics. At some point, however, mathematical models must somehow come into contact with empirical observations if they are to be of any real value, in my opinion. Granted, human experience and intuition are known to be extremely fallible, but that not withstanding they are still our only real basis for doing science (as opposed to pure mathematics)."

Actually, experience and intuition are of little use in doing science. Most of what we know, objectively, is counterintuitive. As Einsten said, "Imagination is more important than knowledge."

"Mathematicians presumably could develop a model of the Ptolemaic picture of the universe as readily as they could develop a model of the post-Copernican picture."

True.

"We then could talk about these two models in purely mathematical terms ad nauseam, but it is also satisfying to be able to talk also about the fact that one model has the sun revolving around the Earth whereas the other model has the Earth revolving around the sun while simultaneously rotating on its axis. One model ultimately is more useful than the other, despite the fact that human intuition accepted the less useful model as being "obviously" true for centuries."

They accepted it because of their quasi-religious philosophy that the circle represents perfection. A perfect universe, therefore, had to incorporate perfectly circular orbits (and they almost are, in fact). We should be wary of trying to impose religion or philosophy on science.

"As repeatedly noted elsewhere in these blogs, I'm a huge advocate of zeroing in on better and better paradigms. And I've long been concerned that the mainstream, prevailing paradigm for the fundamental nature of time is lacking. Not 'wrong' perhaps, but lacking, or incomplete. Inasmuch as 'time' plays such a central and crucial role in physics I believe it's worthwhile being certain that we have this paradigm nailed down as correct as possible."

How certain can we be of anything?

"Unless I'm mistaken (please correct me if I am), the prevailing paradigm for the nature of time may be summarized by the so-called 'operational' definition, i.e., 'time is that which is measured by clocks.' Clocks are then typically defined in some sort of slippery way as being devices which measure time by way of some sort of 'regular motion,' but it is never made perfectly clear how one would know whether motion was 'regular' or not without resorting to the use of a clock. I'm not saying that this is 'wrong' per se, but only that it seems, at best, incomplete. This view of time apparently leads logically to concepts such as block time."

Not regular motion -- regular physical processes. Motion is measured change in relative position among mass points. A physical process, however, need not involve classical motion. I won't get into a long discussion of the nature of time, about which I've written extensively. If you are interested, you can find my views here .

"In some of my essays such as 'Time: Illusion and Reality,' I've tried to suggest another paradigm, another way of looking at the nature of time, which, unfortunately, is also, in and of itself, incomplete I fear. In this way of looking at time our dynamical universe is the clock. Different physical configurations of the universe define, and are identically equivalent to, different particular times. This view does not allow for block time, and it makes a 'causal arrow of time' an inevitability. It further rules out time travel (at least of the variety portrayed in science fiction literature)."

Interesting. I'd say go for it, and build a mathematical model to accompany.

"Lawrence actually appeared to key in on this view in one of his posts to the article on 'Breaking the Universe's Speed Limit' when he wrote, "A[s] for block time being contrary to human experience or intution, those do not really count for much. The non-block time is just a system of spatial geometries which are related to each other by a diffeomorphism group. The notion of time is actually somewhat lost in this picture." Yes, in my view non-block time is indeed a system of spatial geometries! Exactly! But as he points out, the conventional notion of time is somewhat lost in this picture. And this may be where this paradigm is incomplete.

I can't help thinking that if some very clever person could somehow meld these two views of time the resulting paradigm might offer a more useful way of looking at the universe than any previously proposed. Unfortunately, I do not know how to accomplish this melding, but I sense that it would not be easy."

Easy or not, it's worthwhile. Google for Gerard 't Hooft's advice on how to be a theoretical physcist. Good list of prerequisites to study.

"Apologies for rattling on for so long."

Rattling makes music, too. :-)

Tom

How about:

Physical causality only operates in one temporal direction: crack the egg, mix it up with a bit of milk, cook it, eat it.

It can NEVER go the other way.

Wait for an eternity - the eggs won't unscramble.

Thus, the direction of physical causality defines the temporal order.

End of story.

Robert L. Oldershaw

...//www3.amherst.edu/~rloldershaw

Discrete Scale Relativity; Fractal Cosmology

Dear Robert Oldershaw,

Yes, there is no reason to doubt that in any PROcess time lapses from cause to effect.

You quoted Galileo Galilei who mentioned "honest reasoning". Doesn't such honesty demand to realize that a tense-less physics with symmetry between past and future cannot be correct?

I didn't expect you supporting Einsteinian relativity. Having looked at your paper on "Discrete Scale Relativity", which exclusively refers to General Relativity, I do not exclude that you are aware of the intrinsic link between the tacit denial of the arrow of causality in SR and the usual notion of spacetime while the GR might be nonetheless justified to some extent.

When I was a schoolboy, I was told that SR might be correct while GR is questionable. Could it be the other way round?

Regards,

Eckard

Tom,

Thank you for your thorough reply. Much appreciated. You have raised some interesting points.

To reverse the order of things somewhat, I've studied 't Hooft's advice to theoretical physicists, along with the Baez and Siegel "indices" and could not agree more. Questioning established wisdom is something which one must do with great caution and trepidation. Established wisdom is established for a reason, albeit not always a correct reason, as was somewhat rudely pointed out by Copernicus.

With regard to questioning established wisdom about the nature of time I'm encouraged by evidence that well respected scientists can be found among those doing so. In his book 'The Trouble With Physics,' Lee Smolin wrote, "More and more, I have the feeling that quantum theory and general relativity are both deeply wrong about the nature of time. It is not enough to combine them. There is a deeper problem, perhaps going back to the origin of physics." (p. 256) This is precisely the point I have made explicitly in my essay 'Time: Illusion and Reality,' and I have discussed there how I suspect the problem may have arisen.

In the context of zeroing in on optimum paradigms you asked "How certain can we be of anything?" Excellent question. It's my own view that paradigms should hold sway only for as long as they represent the most useful explanation for observed phenomena. Unless competing paradigms are fairly considered and evaluated, however, the process of evolution from one paradigm to another, hopefully better one will be impeded.

Regarding my proposed paradigm for the nature of time you wrote "Interesting. I'd say go for it, and build a mathematical model to accompany." I'd love nothing better, Tom, but not being a skilled physicist or mathematician I'm not in an ideal position to do so. I spent my most productive years pursuing another line of work, but for well over 50 years I have followed the course of this ongoing discussion in the popular literature, absorbing the thinking of Barbour, Carroll, Davies, Deutsch, Feynman, Greene, Hawking, Kuhn, and Smolin, to name but a few. My best hope is that one of these luminaries or some other will someday see fit to explore the view which I've outlined in purely qualitative terms in essays such as those here and here. Having studied what others have said on the topic, I continue to believe that my ideas have merit, and that they add something worthwhile to what others have already said. It's a bit of a frustrating position in which to find oneself. It's for this reason that I deeply appreciate forums such as FQXi in which ideas may be aired and discussed.

Speaking of which, I've begun reading your essays for which you so kindly provided a link. I can already see that they will be slow going for me, but I will do my best to understand the points you are trying to make in them.

Thank you again for engaging on this.

jcns

jcns,

The nature of time remains an unsettled (and often, unsettling) question. I've read your papers, and with your implied permission I'd like to offer a couple of quick observations:

You attribute to Feynman the observation that measures of space and time units are interchangeable. This concept actually originates with Minkowski and Einstein, where time is continuous with space in a field (metric tensor). Feynman's contribution is to convert this continuous-function model to an algebraic, i.e., discrete, model -- which is a natural step for Feynman the particle physicist to take, because he doesn't have to worry about singularities forming in particle interactions where space and time directions are orthogonal (quantum unitarity). Then another "Einstein" in the form of Stephen Hawking comes along and further extends the idea by reuniting it with relativity; i.e., because the quantum model is 2-dimensional, one can show by complex analysis that relativity avoids the singularity at the extreme of black hole thermodynamics, because in the imaginary part of the complex sphere, time is indistinguishable from space.

Are you getting the idea of how important it is to understand the mathematics in order to understand the physics? As Yogi Berra said, "If you don't know where you're going, you might end up somewhere else."

Another important application of mathematics is to the classical dynamic of time reverse symmetry. Don't listen to the crackpots who insist that time reversal is impossible and physicsts are just stupid -- time conservation is critical to classical physics. That doesn't mean that we witness broken teacups reassemble themselves and hop back up on the table, or that we are ever likely to. It means that the laws of physics, and its equations, work as well in reverse as they do forward in time; e.g., the Earth rotates in one direction and orbits in one direction. The physics would not change if the directions were reversed. Yes, there are esoteric theories not forbidden by general relativity where time travel can happen under high energies and special conditions. To everyday physics, they don't matter and classical scale time travel probably is impossible.

I suppose I might as well try and summarize my own research on the subject of time, if I can. In a nutshell, _processes_ are reversible in time, but _events_ are not. What I mean is that time has a specifically physical definition: "n-dimension infinitely orientable metric on self-avoiding random walk." You can read my ICCS 2006 paper to see how and why I arrived at that definition. As a consequence, detailed in ICCS 2006 and later in my "time barrier" paper, it follows straightforwardly that at a specific calculated limit a continuous curve is exchanged for a discrete point, with analytic continuation and dissipation over n-dimensional manifolds, supported by a Euclidean sphere kissing model. That exchange constitutes a discrete event emergent from a continuous process. Ultimately, gravity is identified with information entropy (as is also the case with the Jacobson-Verlinde model), with time dissipation asymptotic to length 1. My model extends general relativity which is finite in time and unbounded in space, to one which is finite in space and unbounded in time.

Point is, there certainly are theories of time that meet your criterion for giving a specific definition (actually, most do, but some definitions are well hidden and have to be abstracted from context). Julian Barbour is another theorist who is quite up front and specific with his definition, identifying time with the least action principle, as a non-physical abstraction. (Least action also figures into my theory, in a different way.)

Good luck to you in your own journey! FWIW, I'd say you've started well.

Best,

Tom

Tom,

Already the word process should tell you that something that pro-cedes (goes ahead) is in reality not reversible. You are reiterating an old half-truth: "the laws of physics, and its equations, work as well in reverse as they do forward in time ... The physics would not change if the directions were reversed."

Well, in particular differential equations are likewise valid for both directions of time. They are, however, not the primary relationships but they were abstracted from the latter at the cost of lost embedding into the causal structure of reality. Is there anything absolutely isolated in the world? Is there any absolutely circular process? I only see spirals instead of circles. Absolutely closed systems are merely idealizations. I like them on condition they are not misused as to derive nonsensical conclusions.

Those who are ready to understand their own tools do not have problems with all practical important aspects of the notion time. Time just becomes an enigma to those who are in a similar situation as someone who made a mistake, tries to hide it, and gets increasing trouble to justify his excuses by exotic fabrications:

"n-dimension infinitely orientable metric on self-avoiding random walk."

"... at a specific calculated limit a continuous curve is exchanged for a discrete point, with analytic continuation and dissipation over n-dimensional manifolds, supported by a Euclidean sphere kissing model. That exchange constitutes a discrete event emergent from a continuous process."

Self-avoiding sounds funny. Dissipation does not necessarily relate to time and money since you used it in a strictly mathematical sense.

Hopefully you are aware why use of complex calculus needs analytic continuation.

If I recall correctly, items that relate to less well known names like Euclid begin with a capital letter while names that are so famous that they are well known to everybody like kissing do not need this profanity.

You are certainly proud of extending "general relativity which is finite in time and unbounded in space, to one which is finite in space and unbounded in time".

Congratulations.

Because you already refused to defend SR, I should perhaps finish our discussion.

Regards,

Eckard

Tom,

Thank you for reading my essays and for your encouraging words.

In one way or another we are all fellow travelers and collaborators doing our best to understand this amazing universe in which we find ourselves. Progress can be frustratingly slow, halting, and arduous, but I think we're all encouraged by a deep-seated belief in Einstein's observation that "the most incomprehensible thing about the universe is its comprehensibility." Persistence will not go forever unrewarded, and in some sense the journey itself is, at least for some of us, its own reward.

Good luck to you in your journey, too.

Best,

jcns

2011-05-14

Time does exist and is a local property as can be seen by the GPS corrections required to match satellites and Earth's time rates..

I met Callender in 2004 ( http://www.spacetimesociety.org/conferences/2004/attendees.html ) at the (first) spacetime conference in Montreal. His presentation was much about the biophysical perception of time as an argument against real time. I think it was the usual mix-up between two different domains. We judge all things by what we believe to be true. But unless one defines what truth means, this judgement is or can be really wrong. Truth is an absence of choice. Since we have no choice but to experience time in our reality ... it is true! Past, present and future is our lot. But physics shows us a bit of what the underlying universe is really like. And it is true for the underlying reality. Why do we always feel compelled to compare the truths of our very subjective reality with the truths that physics gives us about the underlying reality? They are two different and non-comparable domains! There is no need for comparison and there is no comparison possible.

Craig is doing physics to answer philosophical questions. He is not about to get a straight answer...

Marcel,

Marcel,

Craig wrote: "There is no special now, just as there's no special here."

The reason for me to deal with time was a practical one. What you are calling physics is obviously rather awkward if compared with audition. Should we really absolutely deny a better physics? I prefer purifying mathematical foundations of physics from inappropriate ontology. Let me claim: Physics must obey causal thinking in terms of here and now.

While negative distance is unconceivable we must not infer that imaginary numbers are useless. On the contrary, they are often superior. However, every scientist should know how to correctly interpret mathematics. I see a main mistake in the assumption of closed systems. We are not forced to believe in Gods, the Big Bang, Spacetime, Aleph_2, Quantum Computing, Antiworlds, etc.

We might be better off humbly accepting that there are several questions that cannot be reasonably answered at least for now. Let's rather listen to the way we listen and not shy back from logical consequences.

Regards,

Eckard

To Tom and Lawrence,

What do you perceive to be "intuition?"

It seems to me that while your understanding of math might be 21st century, your understanding of neurology is not. Intuition is simply that store of non-linear knowledge our minds can access without having to consciously consider it. I suspect you both have great stores of knowledge which frame your understanding of the world. That is your intuition. Someone in another profession, or another time would have different stores of knowledge and so would have different responses to new situations, or information.

Basically what you are saying is that anyone who does not share your understanding of reality is naive and shallow, but that's okay, because they just don't know how dumb they are.

I live in Baltimore, which is home to Johns Hopkins University, a prominent medical school, as well as being notable in other fields. Occasionally the local public radio station invites faculty on to discuss their areas of expertise. Some years ago the host had a neurologist on, discussing the mind/brain relationship. I happened to have the time to call and made the point I frequently make here about time. I described it by saying that if you have two physical objects and they hit each other, it creates an event. While the objects go from past events to future ones, the events go from being in the future to being in the past. The relationship between the brain and the mind is that while the brain is a physical object that goes from past events to future ones, the mind is a record of these events which are going in the opposite direction. His immediate response was, "That's deep." Then he started to launch into a description of how physics explains time as part of four dimensional spacetime. At which point the host cut us both off and went onto the next caller.

I suppose that by your reckoning, this neurologist's initial response would be "naive intuition."

My problem is; Why does the discipline of physics have the right to totally dominate the discussion of the nature of reality, insisting the rest of us are basically dumb, then project these vaunted "non-intuitive" mathematical models into multiworlds, wormholes, m theory, inflationary cosmology, multiverses and various other nonsense? Then if anyone questions what they are doing, the response is some form of, "Well, you just don't understand the math. Here, take this conceptual Rubik's Cube and when you figure it out, then you have the right to discuss reality."

Not to be rude, but to paraphrase the French anti-establishment economics, it's "Autistic Physics."

"Why does the discipline of physics have the right to totally dominate the discussion of the nature of reality ... "

Why would one come to a physics site to try and argue that it doesn't?

Tom,

I suppose I could have worded that a little more effectively. Though I don't suppose I have to explain my thoughts on the subject to you, as you are likely aware of my views.

That is a rather selective observation though. Does physics describe reality as effectively as possible, or have various schools of thought monopolized the conversation to the point that any idea which supports their models, no matter how outlandish, are considered valid proposals. While any idea which questions those models, no matter how rational, is considered quackery?

If evidence of galaxies at least as old as the presumed age of the universe, 13.7 billion years, was discovered, would you be more likely to consider the possibility of fundamental flaws in the entire concept of a temporally finite universe, or would you accept whatever conceptual patch is applied to this "anomaly" as a viable solution?

http://www.scientificamerican.com/article.cfm?id=is-time-an-illusion

Craig Callender in SCIENTIFIC AMERICAN: "Einstein mounted the next assault by doing away with the idea of absolute simultaneity. According to his special theory of relativity, what events are happening at the same time depends on how fast you are going. The true arena of events is not time or space, but their union: spacetime. Two observers moving at different velocities disagree on when and where an event occurs, but they agree on its spacetime location. Space and time are secondary concepts that, as mathematician Hermann Minkowski, who had been one of Einstein's university professors, famously declared, "are doomed to fade away into mere shadows." And things only get worse in 1915 with Einstein's general theory of relativity..."

Which of the postulates of special relativity - the principle of relativity or the principle of constancy of the speed of light - is false?

Pentcho Valev pvalev@yahoo.com

John,

If you're right, why do you care who considers it "quackery?"

Rational, as in scientific rationalism, is another matter. The models you criticize have exact correspondence to physical phenomena (not necessarily 1 to 1 correspondence as a wholly deterministic theory requires) and so are rational, whether you understand the correspondence or not. It is not rational to imply that such models are merely "conceptual patches."

I don't know why you ask _me_ about the possibility of a temporally finite universe being an incomplete model. I've already rigorously argued that Einstein's finite but unbounded (finite in time and unbounded in space) model can be extended to one that is finite in space and unbounded in time. Galaxies more distant than the present esitmated age would not falsify the theory, however.

Tom