Freethought & Rationalism Archive

Liquidrage · 07-27-2002, 08:30 PM

Quote:

Originally posted by tronvillain:
Well, my post was not intended to rebut Barbour's theories, so I don't see that as a problem.

Still, I fail to see what the problem with the question "What seperates the past from the present?" is supposed to be (other than its assumption that there is a unique present). If you are simply asking "What seperates 10:00 PM from 10:25 PM?" the obvious answer would seem to be "twenty-five minutes" or "time", just as the answer to "What seperates my parents house from town" would seem to be "twenty-five kilometres" or "distance."

Obviously his book isn't about the semantics of the issue nor after reading it does one throw away his/her watch.

I just did not want anyone to get the idea that Barbour's theories were what was being dicussed and rebutted here. Perhaps my attempt was poorly worded.

Your analogy though would lead me to many interesting questions then.

If you think you can treat time like distance then where does time go when it is done?
One can move back and forther between your house and your parents. One can see both houses at the same time.
Why cannot we do the same for time?

The fact the time (in obvious terms) has a 1 way arrow should throw up the flags that clearly it is not directly comparable to other dimensions.

Also, I know you have enough knowledge of this area to seperate classical thinking from quantum or relativistic thinking.
Barbour's theories treat time discretely. His "nows" are quanta of time. This and not "take the clock off the wall cause it don't measure a damn thing" is the theory.

tronvillain · 07-27-2002, 08:53 PM

Liquidrage:

Quote:

If you think you can treat time like distance then where does time go when it is done?

Pardon? I suspect that the universe is a static four dimensional object, so the question is somewhat meaningless.

Quote:

One can move back and forther between your house and your parents. One can see both houses at the same time. Why cannot we do the same for time?

Well, "I" do not actually move back and forth between here and there - I am here and my future self is there.

Quote:

The fact the time (in obvious terms) has a 1 way arrow should throw up the flags that clearly it is not directly comparable to other dimensions.

Well, what does it mean to say that "time has a one-way arrow? It appears to mean is that we can remember the past but not the future or that entropy is lower in the "past" and higher in the "future", but can we conclude from this that time is not like a spatial dimension? No. After all, one could easily construct a three dimensional object in which entropy increased over distance.

Quote:

Also, I know you have enough knowledge of this area to seperate classical thinking from quantum or relativistic thinking. Barbour's theories treat time discretely. His "nows" are quanta of time. This and not "take the clock off the wall cause it don't measure a damn thing" is the theory.

Well, I never thought it was. I may even agree with Barbour to a degree - it's hard to be sure without reading the book. I certainly think that our experience of time is an illusion.

Kharakov · 07-28-2002, 04:20 PM

Quote:

Originally posted by Liquidrage:

The fact the time (in obvious terms) has a 1 way arrow should throw up the flags that clearly it is not directly comparable to other dimensions.

What if the way our mind organizes our perceptions makes time appear to go in one direction?

Suppose time is moving backwards right now. Every perception we have would still seem to arise from perceptions from the past, because we are traveling from our future perception to what we previously perceived in the past.

If our mind travels back in time, it will end up perceiving things as it did previously.

What I am saying is that we might be free to travel upon the 4th dimension- but that everything does it together- our minds, matter, the whole universe.

-k

Bill · 07-28-2002, 05:23 PM

Quote:

Originally posted by Liquidrage:
I would also add that as a layman my opinion matter little. However, it appears to me that his research has been met with mostly positive reviews. And again, this book is not an easy read. It makes something like The Elegant Universe or Three Roads to Quantum Gravity look like Green Eggs and Ham.

OK, then, I went to Amazon.Com and looked the book up. Here it is: <a href="http://www.amazon.com/exec/obidos/ASIN/0195145925/qid=thesecularweb/" target="_blank">The End of Time: The Next Revolution in Physics</a> by Julian B. Barbour.

When I looked at the reviews, ignoring the puff pieces from the book's own publisher, the editorial reviews were pretty scanty. The reviews appeared to be publisher picks, carefully selected out of larger reviews that might not have been so complimentary if read in their entirety.

The "Customer Reviews" ranged from one star through four, with the most popular review giving the book four stars, but still claiming that it was an extremely badly written book for its particular genre. The key quote from this review is that:

Quote:

The "End of Time" devotes many pages to arguments in favour of the author's thesis, in a way that will bore the general reader but is unlikely to convince the physicist.

And even a philosopher who is predisposed to agree with Barbour's basic premise still didn't like Barbour's book as anything more than a sort-of "consciousness raising" exercise. See <a href="http://www.iwaynet.net/~wdc/book.htm" target="_blank">WILLIAM D. CONNER'S REVIEW</a>.

And then we have <a href="http://www.mfinley.com/articles/trouble-with-time.htm" target="_blank">Mike Finley's review</a>, which begins with the following quote from Wittgenstein:

Quote:

Time flies like arrows.
Fruit flies like bananas.

That quote juxtaposes two distinct senses of the words "flies" and "like" to arrive at a totally startling quip. That is the exact sort of linquistic exercise that Wittgenstein, and apparently Finley as well, really enjoyed.

I found most interesting the review (on Amazon.Com) written by J. J. K. Swart, who gives Barbour's book three stars out of five possible:

Quote:

There are, historically speaking, only two concepts of time.

The first is the Space+Time vision of Kant, Newton, etc., with two small modifications. One is that of Einstein Time + Space are fused into the idea of Space-time. In Relativity theory Space-time can be 'cut' by a 'now'-plane in different ways, under different angles, so that simultaneity is no longer absolute, but dependent on the state of motion. But this vision is just a further mathematical elaboration of Space + Time, and does not contain any essential new insight into time itself.

The second minor modification is implicit in Quantum Mechanics. One of the four famous Heisenberg relations dE * dt > h implies, that 'now' is not 'absolute, and 'infinitely small', as commonly is believed, but has an extension that depends on the energy content of any existing objects. The more mass the object has, the more energy it has, (through E = mc2) and therefore the smaller its 'now'-interval is. This implies, that the 'now' of different objects is different; dependent on how much energy they consist of. From it you can explain how come that electrons that spin around these atoms do not radiate electromagnetic radiation. For if the time they need to revolve around the atom is equal to the 'now' interval, they essentially do not have the 'time' to complete that movement, so that, in a sense, you can say that they do not move. For if they do not move, they do not accelerate, and therefore do not radiate.

The second vision on time is the Leibniz vision. According to Leibniz, time is 'not really existing', but it is the conceptual order that our minds puts on existence. It is an ordering imposed on existence in terms of 'sooner and later'. In a philosophical sense this implies, that past, present, and future all 'really exist'.

All of physics is based on the Space + Time vision. Newton used it, Einstein used it, Quantum Mechanics is based on it. Therefore physics has not changed the understanding of time significantly.

Basically, what Julian Barbour does, is nothing less than a total reconstruction of the whole of physics, based on the Leibniz vision of time. He first shows how classical physics can then be understood. Then he moves on to do the same with the special and general theories of relativity of Einstein. After having done that, he even moves on to quantum mechanics.

Does he succeed? I think he does. As such the book is very interesting. Next to these attempts, the book contains some interesting insights that only indirectly relate to time. Barbour shows, for example, that it is possible to integrate the two different visions of Newton and Leibniz about space by using Mach's principle. I find this part of the book the most fascinating I have ever read on the subject.

The only objection about Julian Barbour's approach is, essentially, the same you can rise against the Leibniz view of time as such. Philosophically speaking, if you begin by assuming that there is no real change, and that all change is 'illusion', only 'existing in the mind', then you have to explain how this 'illusion' can arise, without introducing movement ANYWHERE. All such attempts have failed. To give an example: if we go to the cinema, to see 'a picture', then what we see on the screen definitely 'appears to move'. We all know, however, that the 'the picture' consist of a lot of pictures that are all static. The movie projector, so to speak, creates the 'illusion of movement' by showing all of these pictures 'in succession', i.e., in time. It is able to do this, because it 'operates in time'. In this way, change, and therefore time, is introduced 'through the back door' so to speak. Besides, the static pictures themselves are a recording made of movements that have actually taking place. Therefore you can say, that the pictures are the RESULT of movements in the past, and not themselves identical with these movements. I think that the whole Leibniz vision on time is based on an inability to make exactly this distinction between movement and the result(s) of movement.

Physics is about finding answers to our questions. Philosophy is about understanding the questions first. Sound physics should therefore be preceded by sound philosophy. Julian Barbour's book is very strong in its physics department, giving at times very original insights. However, it is very weak in its philosophy. In fact, a philosophical treatment of a clarification of what we mean by the question: 'what is time?' is almost missing in the book. The book goes straight to physics. Julian Barbour therefore fails to see, that the above 'projection example' is a basic flaw in every explanation of time that is based on Leibniz philosophy. In other words, if you believe that Leibniz vision on time makes sense, then Julian Barbour shows how physics can be understood in terms of it. But if you think, as I do, that the Leibniz vision on time itself contains a basic flaw, then Julian Barbour's book fails to address this. For the book is primarily about the physics of time, not the metaphysics of time.

Conclusion: Do not expect, to find an explanation in this book how, philosophically speaking, 'change' can be understood in terms of 'the non-changing'. For it barely touches on this question. The only part of some awareness of this more basic problem of time I found in the book is by the idea of what Julian Barbour calls: 'ephemeris time'. Essentially this idea of 'ephemeris time' starts with the insight, that to understand what time is no more is required than an understanding of change. Ephemeris time follows from this as the ultimate result of change comparisons, through the use of the laws of physics that connect all changes with each other. This 'program' is similar to an explanation whereby space can be seen as the ultimate result of length comparisons.

At last I understand that Barbour is writing a book that, from the standpoint of physics, attempts to take Liebnitz seriously. However, Barbour ignores the necessary philosophical foundation and thus tosses his readers hither-thither, depending upon just what their pre-existing biases might be. This is not a good book. Perhaps if you begin by reading Liebnitz you might try Barbour next, but under these circumstances, you should not read Barbour's book as the first or only book on this topic. Read something else first in order to get properly "grounded," philosophically speaking.

== Bill

Bill · 07-28-2002, 05:34 PM

My own view of this topic remains this: yes, time is measured in terms of change. Yes, as Barbour asserts, without change, there would be no time. As our fundamental measure of time here on Earth, we look to the stable (in our view) oscillations of cesium beams to provide us with an atomic clock against which to measure all other sorts of changes and to apply some sort of a time-stamp to each changeless instant along the way.

We look at the sinusoidal waveform of the oscillating cesium beam and we naturally feel that the underlying change is continuous. Yes, it may well be an optical illusion of the exact sort produced by a motion picture projector. The brain itself does have a "frame rate" in terms of its visual observations. However, while our brain does interpolate between the frames of data it sees, there is no reason to believe that the reality is anything other than continuous.

No reason, that is, but for Barbour's argument that the physics would be so much simpler if his hypothesis (and Liebnitz's) were true.

Because I fail to see a philosophical distinction between using time to measure change and using change to measure time (the two concepts are philosophically equivalent), I don't see how the truth of the "time = change" equation necessarily leads to the idea of a universal "frame rate" of some sort. Analog design preceded digital by a heck of a lot. And analog design asserts that change is, in fact, continuous. At least, it is so long as space is continuous. Because an object moving through space (as all objects do, relative to some other object somewhere) necessarily has a continuous set of positional coordinates, there is an equally continuous set of change-happenings and, as a consequence, an equally continuous series of instants of time.

Thus, it is the "frame rate" idea that I find objectionable in Barbour's assertions. I could take the reference alteration of substituting change for time. But to assert that change is a series of incremental jumps just goes too far.

== Bill

Answerer · 07-28-2002, 11:25 PM

Quote:

Originally posted by Bill:
[QB

Because I fail to see a philosophical distinction between using time to measure change and using change to measure time (the two concepts are philosophically equivalent), I don't see how the truth of the "time = change" equation necessarily leads to the idea of a universal "frame rate" of some sort.
== Bill[/QB]

Well, I think its either the case of the existence of time is due to our awareness of change or the existence of change is due to our awareness of time. However, since time is never an absolute concept in physics, I tend to believe that the former is the case in reality.

phaedrus · 07-29-2002, 02:00 AM

Time is a manmade concept. Anyhows, for those who are interested....

Time appears to be more puzzling than space because it seems to flow or pass or else people seem to advance through it. But the passage or advance seems to be unintelligible. The question of how many seconds per second time flows (or one advances through it) is obviously an absurd one, for it suggests that the flow or advance comprises a rate of change with respect to something else�to a sort of hypertime. But if this hypertime itself flows, then a hyper-hypertime is required, and so on, ad infinitum. Again, if the world is thought of as spread out in space�time, it might be asked whether human consciousness advances up a timelike direction of this world and, if so, how fast; whether future events pop into existence as the �now� reaches them or are there all along; and how such changes in space�time can be represented, since time is already within the picture. (Ordinary change can, of course, be represented in a space�time picture: for example, a particle at rest is represented by a straight line and an oscillating particle by a wavy line.)

In the face of these difficulties, philosophers tend to divide into two sorts: the �process philosophers� and the �philosophers of the manifold.� Process philosophers�such as Alfred North Whitehead, an Anglo-American metaphysician who died in 1947�hold that the flow of time (or human advance through it) is an important metaphysical fact. Like the French intuitionist Henri Bergson, they may hold that this flow can be grasped only by nonrational intuition. Bergson even held that the scientific concept of time as a dimension actually misrepresents reality. Philosophers of the manifold hold that the flow of time or human advance through time is an illusion. They argue, for example, that words such as past, future, and now, as well as the tenses of verbs, are indexical expressions that refer to the act of their own utterance. Hence, the alleged change of an event from being future to being past is an illusion. To say that the event is future is to assert that it is later than this utterance; then later yet, when one says that it is in the past, he or she asserts that it is earlier than that other utterance. Past and future are not real predicates of events in this view; and change in respect of them is not a genuine change.

Again, although process philosophers think of the future as somehow open or indeterminate, whereas the past is unchangeable, fixed, determinate, philosophers of the manifold hold that it is as much nonsense to talk of changing the future as it is to talk of changing the past. If a person decides to point left rather than to point right, then pointing left is what the future was. Moreover, this thesis of the determinateness of the future, they argue, must not be confused with determinism, the theory that there are laws whereby later states of the universe may be deduced from earlier states (or vice versa). The philosophy of the manifold is neutral about this issue. Future events may well exist and yet not be connected in a sufficiently lawlike way with earlier ones.

One of the features of time that puzzled the Platonist Augustine, in the 5th century AD, was the difficulty of defining it. In contemporary philosophy of language, however (influenced by Ludwig Wittgenstein, a Cambridge philosopher), no mystery is seen in this task. Learning to handle the word time involves a multiplicity of verbal skills, including the ability to handle such connected words as earlier, later, now, second, and hour. These verbal skills have to be picked up in very complex ways (partly by ostension), and it is not surprising that the meaning of the word time cannot be distilled into a neat verbal definition. (It is not, for example, an abbreviating word like bachelor.)

The philosophy of time bears powerfully on human emotions. Not only do individuals regret the past, they also fear the future, not least because the alleged flow of time seems to be sweeping them toward their deaths, as swimmers are swept toward a waterfall. Britannica

<a href="http://www.discover.com/recent_issue/index.html" target="_blank">Does the Universe Exist if We're Not Looking?</a>

<a href="http://serendip.brynmawr.edu/bb/neuro/neuro01/web2/Burdick.html" target="_blank">The Time Percept</a>

[ July 29, 2002: Message edited by: phaedrus ]

Defiant Heretic · 07-29-2002, 02:57 AM

Something like what we call "time" must exist in the universe because if it didn't, everything would happen at once, cause and effect would become a meaningless concept, change would be impossible, and other generally bad things would happen. If "time" didn't exist then I would be writing every word of this post while simultaneously, you would be reading it, I would be writing another post, joining the forum, being born, etc., and none of these events would be of any relation to each other. They would simply exist, continually and eternally. This is clearly not the case.

That being said, I think that the human definition of time is somewhat flawed. We consider time to be a dimension, something that can be altered. Time is a constant rate of change, delta x is constant, whereas x consists of anything and everything that has ever existed, and is constantly changing. Time is not relative. Our perception of it is. If an object appears to be moving faster than usual, it is not because time has sped up-the object has.

[ July 29, 2002: Message edited by: Defiant Heretic ]

excreationist · 07-29-2002, 05:13 AM

Quote:

Originally posted by Defiant Heretic:
Something like what we call "time" must exist in the universe because if it didn't, everything would happen at once, cause and effect would become a meaningless concept, change would be impossible, and other generally bad things would happen. If "time" didn't exist then I would be writing every word of this post while simultaneously, you would be reading it, I would be writing another post, joining the forum, being born, etc., and none of these events would be of any relation to each other. They would simply exist, continually and eternally. This is clearly not the case.

In <a href="http://www.platonia.com" target="_blank">Barbour's Platonia</a>, points in time just eternally exist as points on a static entity. The branches(?) on it have a virtual history that is based on rules - so that our memories make sense and appear to have happened in the past. (Something like that)

Quote:

That being said, I think that the human definition of time is somewhat flawed. We consider time to be a dimension, something that can be altered. Time is a constant rate of change, delta x is constant, whereas x consists of anything and everything that has ever existed, and is constantly changing. Time is not relative. Our perception of it is. If an object appears to be moving faster than usual, it is not because time has sped up-the object has.

If you have atomic clocks that are experiencing different gravitational forces (e.g. they're at different altitudes) they will actually stop being synchonized... i.e. one will be *physically older* than the other!

Tristan Scott · 07-29-2002, 03:15 PM

Quote:

Something like what we call "time" must exist in the universe because if it didn't, everything would happen at once, cause and effect would become a meaningless concept, change would be impossible, and other generally bad things would happen.

Also we would be everywhere at once. There would be nowhere to go because you would already be there. The universe would be a single point with no dimension, at least from the viewpoint of the timeless one.

I'm no phyisicist, and I'm sure a physicist will correct me here if I'm wrong, but I believe, that time does not exist relative to something that is traveling at the speed of light.

07-29-2002, 02:00 AM	#37
phaedrus Veteran Member Join Date: Oct 2000 Location: Indus Posts: 1,038	Time is a manmade concept. Anyhows, for those who are interested.... Time appears to be more puzzling than space because it seems to flow or pass or else people seem to advance through it. But the passage or advance seems to be unintelligible. The question of how many seconds per second time flows (or one advances through it) is obviously an absurd one, for it suggests that the flow or advance comprises a rate of change with respect to something else�to a sort of hypertime. But if this hypertime itself flows, then a hyper-hypertime is required, and so on, ad infinitum. Again, if the world is thought of as spread out in space�time, it might be asked whether human consciousness advances up a timelike direction of this world and, if so, how fast; whether future events pop into existence as the �now� reaches them or are there all along; and how such changes in space�time can be represented, since time is already within the picture. (Ordinary change can, of course, be represented in a space�time picture: for example, a particle at rest is represented by a straight line and an oscillating particle by a wavy line.) In the face of these difficulties, philosophers tend to divide into two sorts: the �process philosophers� and the �philosophers of the manifold.� Process philosophers�such as Alfred North Whitehead, an Anglo-American metaphysician who died in 1947�hold that the flow of time (or human advance through it) is an important metaphysical fact. Like the French intuitionist Henri Bergson, they may hold that this flow can be grasped only by nonrational intuition. Bergson even held that the scientific concept of time as a dimension actually misrepresents reality. Philosophers of the manifold hold that the flow of time or human advance through time is an illusion. They argue, for example, that words such as past, future, and now, as well as the tenses of verbs, are indexical expressions that refer to the act of their own utterance. Hence, the alleged change of an event from being future to being past is an illusion. To say that the event is future is to assert that it is later than this utterance; then later yet, when one says that it is in the past, he or she asserts that it is earlier than that other utterance. Past and future are not real predicates of events in this view; and change in respect of them is not a genuine change. Again, although process philosophers think of the future as somehow open or indeterminate, whereas the past is unchangeable, fixed, determinate, philosophers of the manifold hold that it is as much nonsense to talk of changing the future as it is to talk of changing the past. If a person decides to point left rather than to point right, then pointing left is what the future was. Moreover, this thesis of the determinateness of the future, they argue, must not be confused with determinism, the theory that there are laws whereby later states of the universe may be deduced from earlier states (or vice versa). The philosophy of the manifold is neutral about this issue. Future events may well exist and yet not be connected in a sufficiently lawlike way with earlier ones. One of the features of time that puzzled the Platonist Augustine, in the 5th century AD, was the difficulty of defining it. In contemporary philosophy of language, however (influenced by Ludwig Wittgenstein, a Cambridge philosopher), no mystery is seen in this task. Learning to handle the word time involves a multiplicity of verbal skills, including the ability to handle such connected words as earlier, later, now, second, and hour. These verbal skills have to be picked up in very complex ways (partly by ostension), and it is not surprising that the meaning of the word time cannot be distilled into a neat verbal definition. (It is not, for example, an abbreviating word like bachelor.) The philosophy of time bears powerfully on human emotions. Not only do individuals regret the past, they also fear the future, not least because the alleged flow of time seems to be sweeping them toward their deaths, as swimmers are swept toward a waterfall. Britannica <a href="http://www.discover.com/recent_issue/index.html" target="_blank">Does the Universe Exist if We're Not Looking?</a> <a href="http://serendip.brynmawr.edu/bb/neuro/neuro01/web2/Burdick.html" target="_blank">The Time Percept</a> [ July 29, 2002: Message edited by: phaedrus ]</p>

07-29-2002, 02:57 AM	#38
Defiant Heretic Veteran Member Join Date: Jul 2002 Posts: 1,288	Something like what we call "time" must exist in the universe because if it didn't, everything would happen at once, cause and effect would become a meaningless concept, change would be impossible, and other generally bad things would happen. If "time" didn't exist then I would be writing every word of this post while simultaneously, you would be reading it, I would be writing another post, joining the forum, being born, etc., and none of these events would be of any relation to each other. They would simply exist, continually and eternally. This is clearly not the case. That being said, I think that the human definition of time is somewhat flawed. We consider time to be a dimension, something that can be altered. Time is a constant rate of change, delta x is constant, whereas x consists of anything and everything that has ever existed, and is constantly changing. Time is not relative. Our perception of it is. If an object appears to be moving faster than usual, it is not because time has sped up-the object has. [ July 29, 2002: Message edited by: Defiant Heretic ]</p>

Thread Tools	Search this Thread
Show Printable Version	Search this Thread: Advanced Search

07-28-2002, 05:34 PM	#35
Bill Veteran Member Join Date: Dec 2002 Location: Gatorville, Florida Posts: 4,334	My own view of this topic remains this: yes, time is measured in terms of change. Yes, as Barbour asserts, without change, there would be no time. As our fundamental measure of time here on Earth, we look to the stable (in our view) oscillations of cesium beams to provide us with an atomic clock against which to measure all other sorts of changes and to apply some sort of a time-stamp to each changeless instant along the way. We look at the sinusoidal waveform of the oscillating cesium beam and we naturally feel that the underlying change is continuous. Yes, it may well be an optical illusion of the exact sort produced by a motion picture projector. The brain itself does have a "frame rate" in terms of its visual observations. However, while our brain does interpolate between the frames of data it sees, there is no reason to believe that the reality is anything other than continuous. No reason, that is, but for Barbour's argument that the physics would be so much simpler if his hypothesis (and Liebnitz's) were true. Because I fail to see a philosophical distinction between using time to measure change and using change to measure time (the two concepts are philosophically equivalent), I don't see how the truth of the "time = change" equation necessarily leads to the idea of a universal "frame rate" of some sort. Analog design preceded digital by a heck of a lot. And analog design asserts that change is, in fact, continuous. At least, it is so long as space is continuous. Because an object moving through space (as all objects do, relative to some other object somewhere) necessarily has a continuous set of positional coordinates, there is an equally continuous set of change-happenings and, as a consequence, an equally continuous series of instants of time. Thus, it is the "frame rate" idea that I find objectionable in Barbour's assertions. I could take the reference alteration of substituting change for time. But to assert that change is a series of incremental jumps just goes too far. == Bill

Freethought & Rationalism Archive

The archives are read only.