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Paul,

I may be hallucinating, but I sense that we're making progress.

"So, yes, we have particular time, particular existent state (incidentally, this is in respect of anything, could be the universe, or a ball, or you)."

We agree here, Paul, and this, for me, is the key to the whole concept. I simply choose to think in terms of the existent state of the most inclusive thing...

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Paul,

I may be hallucinating, but I sense that we're making progress.

"So, yes, we have particular time, particular existent state (incidentally, this is in respect of anything, could be the universe, or a ball, or you)."

We agree here, Paul, and this, for me, is the key to the whole concept. I simply choose to think in terms of the existent state of the most inclusive thing I can imagine, which is the universe, which of course includes balls and us and mulberry bushes and leaves, etc.

"The expression is sort of correct, but the "wrong" way round. A point in time (ie a unit, as in timing) is, by definition, definable by the quickest at which any given alteration occurs."

Curses! Foiled again! The dreaded "but" rears its ugly head. Here, Paul, is one place where our thinking diverges. What you call "a point in time" (which I believe is the same as what I call "a particular time," and what others commonly refer to as a "moment" or as a "moment in time" is not, according to my view, "a unit, as in timing," nor is it, "by definition, definable by the quickest at which any given alteration occurs."

Quickest relative to what, Paul? You've already built a clock into the universe with this statement. Forget clocks for now. Banish clocks from the universe. (A difficult feat, given that virtually any process may be viewed as a clock.) The "quickness" with which any one alteration occurs is only meaningful if we compare it with some other alteration. For convenience, we arbitrarily select one alteration and call it our clock. (A wise - - i.e., optimally useful - - selection of what to use as a clock clearly is not totally arbitrary, but I'm speaking purely theoretically.)

"There is a particular physically existent state, then another, and another, and so on. A property of the "stuff" (technical word!) which comprises any given state causes alteration."

Again, we are in total agreement here. The "property" which causes alteration in any given state is what we humans have, in our infinite wisdom, named the laws of physics or the laws of nature. Some of the best thinkers ever to have lived have taken it as their mission to understand and codify these laws.

"But in physical terms, there never was an "it" ("leaf"), there was just a sequence of different physically existent states."

Here we diverge again. I say that there was indeed a leaf. "Leaf" is the term we use to describe a particular configuration of "stuff." (I tend to use the technical term "bits and pieces" rather than "stuff," but I can live with your terminology.) The configuration of the ensemble of atoms (stuff) which had come together in the form of a leaf subsequently becomes altered (in compliance with the laws of physics) to become an ensemble of stuff we call "mulch." This subsequently will be scattered (again, in compliance with the laws of physics) and some will be taken up by plant roots and eventually become another leaf, which may be eaten by an animal, which is in turn eaten by another animal, and which eventually may become a part of you or me.

jcns

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Eintein and an urban myth

It is commonly assumed that Special Relativity is that which was written in 1905, or at least most of it. This is not so. In propounding General Relativity, of which 1905 was effectively a ‘first draft’, Einstein had to resolve the significance of light. There are two key words in 1905. When stating the two postulates, he writes that they are: “only...

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Eintein and an urban myth

It is commonly assumed that Special Relativity is that which was written in 1905, or at least most of it. This is not so. In propounding General Relativity, of which 1905 was effectively a ‘first draft’, Einstein had to resolve the significance of light. There are two key words in 1905. When stating the two postulates, he writes that they are: “only apparently irreconcilable”. This is, of itself, a peculiar statement, because he is proposing a new theory which is based only on these (“These two postulates suffice for the attainment of a simple and consistent theory of the electrodynamics of moving bodies based on Maxwell's theory for stationary bodies”). And both are understandable statements in their own right. Yet he is already aware of a potential conflict. That is, all the variables as stated in 1905 cannot co-exist in a cohesive theory.

The first postulate (the principle of relativity) is a logical truism, ie for physical laws to be valid they must hold whatever reference point is used. Another way of putting this is that physical existence is independent. Use of phrases such as ‘frame of reference’ have nothing to do with observation, per se, they are about referencing. That is, as there is no known absolute, everything has to be deemed in terms of its relativity, ie difference when compared to another. And in order then to ensure comparability, that reference must be used consistently, and logically (as opposed to practically) any potential reference could be chosen. But there must be one, otherwise a judgement cannot be made. Something is only X when compared to something else, and the calibration of X is dependent upon that reference. But the physically existent state which manifests X does not alter.

In respect of the second postulate about light, this is correct physically, as written. Light is created as the result of an atomic interaction (ie not a collision), and therefore always starts with the same physical speed. That is, the speed of that which was involved in the interaction is irrelevant. From the perspective of a sensory system, that resultant physical effect-light-is a representation of what was involved in the interaction, but of itself, it is a physical entity. And as such, it will continue to travel at that speed, just like any other physical entity, unless impeded in some way. Impediment does not occur in vacuo, by definition, a condition invoked in 1905.

It has to be remembered that the start point was concerns about light speed, earth movement and ether. This did not appear to be, or perhaps actually was not, borne out by the Michelson and Morley experiments. But to counterbalance that apparent result, and hence maintain the presumptions about light, the hypothesis was proposed that matter physically alters in dimension in the line of motion. That is, when forces acting thereon become imbalanced, the shape and momentum of the matter changes whilst that circumstance obtains. Equilibrium is subsequently restored, and matter regained its original shape and resumed its travel at a constant momentum. Whether this is physically correct or not is another issue. So, 1905 has a combination of alteration consequent upon alterations in force, with an ‘unaffected’ light. That is, it is in vacuo, but everything else is not. There must be one common condition.

The resolution of the ‘apparent irreconcilability’ was pursued by Einstein in section 7 of SR & GR 1916. The example used is incorrect, the ray of light and man walking are not equivalent (to be precise, the man is of the earth system, the ray of light is not). He has not considered light as a physically existent entity, and the application, as opposed to the principle, of relativity is flawed. So this has not proved his point from the previous section, that is, that the Theorem of the Addition of Velocities employed in classical mechanics, was no longer valid. And this cannot be so anyway, because in order to effect any judgement, a reference is necessary, and the calibration of the attribute will be a function of that reference. In simple terms, the variable of dimension alteration became subsumed by the supposed variability of time, but time does not vary and is not physically existent, there is only timing. Therefore, in essence, the problem was ‘resolved’, but for the wrong reason.

Because he then writes (para 5): “In view of this dilemna there appears to be nothing else for it than to abandon either the principle of relativity or the simple law of the propagation of light in vacuo. Those of you who have carefully followed the preceding discussion are almost sure to expect that we should retain the principle of relativity, which appeals so convincingly to the intellect because it is so natural and simple. The law of the propagation of light in vacuo would then have to be replaced by a more complicated law conformable to the principle of relativity.

That is, one of these variables cannot co-exist, assuming they are invoked properly and dimension alteration is a physical fact (leaving aside that the effect is being explained in terms of time variance).

And then he writes (para 6): At this juncture the theory of relativity entered the arena. As a result of an analysis of the physical conceptions of time and space, it became evident that in reality there is not the least incompatibilitiy between the principle of relativity and the law of propagation of light, and that by systematically holding fast to both these laws a logically rigid theory could be arrived at. This theory has been called the special theory of relativity to distinguish it from the extended theory, with which we shall deal later. In the following pages we shall present the fundamental ideas of the special theory of relativity.

That is, a special theoretical circumstance is invoked. Where, because of the circumstance invoked, everything can, by definition, co-exist, as defined. It proves nothing, and is a tautology. Neither is it the circumstance of 1905. It is also ‘disconnected’ from GR, ie that is not developed from it. GR is really the only theory.

Einstein defines SR as:

Einstein Foundation of GR 1916, section A, sub sec 1:

“We call this postulate "The Special Relativity Principle." By the word special, it is signified that the principle is limited to the case, when K’ has uniform translatory motion with reference to K, but the equivalence of K and K' does not extend to the case of non-uniform motion of K' relative to K. The special theory of relativity does not depart from classical mechanics through the postulate of relativity, but through the postulate of the constancy of the velocity of light in vacuo.”

“According to the special relativity theory, the theorems of geometry are to be looked upon as the laws about any possible relative positions of solid bodies at rest.”

Einstein Foundation of GR 1916, section A, sub sec 3:

“the case of special relativity appearing as a limiting case when there is no gravitation.”

Einstein SR & GR 1916, section 28:

“The special theory of relativity has reference to Galileian domains, ie to those in which no gravitational field exists.”

“In gravitational fields there are no such things as rigid bodies with Euclidean properties; thus the fictitious rigid body of reference is of no avail in the general theory of relativity.”

Einstein SR & GR 1916, section 18:

“the special principle of relativity, i.e. the principle of the physical relativity of all uniform motion. Let us once more analyse its meaning carefully. It was at all times clear that, from the point of view of the idea it conveys to us, every motion must only be considered as a relative motion.”

“If it is simply a question of detecting or of describing the motion involved, it is in principle immaterial to what reference-body we refer the motion. As already mentioned, this is self-evident, but it must not be confused with the much more comprehensive statement called “the principle of relativity,””

“we started out from the assumption that there exists a reference-body K, whose condition of motion is such that the Galileian law holds with respect to it: A particle left to itself and sufficiently far removed from all other particles moves uniformly in a straight line.”

“provided that they are in a state of uniform rectilinear and non-rotary motion with respect to K; all these bodies of reference are to be regarded as Galileian reference-bodies. The validity of the principle of relativity was assumed only for these reference-bodies, but not for others (e.g. those possessing motion of a different kind). In this sense we speak of the special principle of relativity, or special theory of relativity. In contrast to this we wish to understand by the "general principle of relativity" the following statement: All bodies of reference are equivalent for the description of natural phenomena (formulation of the general laws of nature), whatever may be their state of motion.”

So SR, as defined by Einstein, involves:

-no gravitation

-only motion that is uniform rectilinear and non-rotary (which is in effect, stillness)

-fixed shape bodies at rest (no dimension alteration)

-light which travels in straight lines at a constant speed

When gravity is present, then the condition of in vacuo, which was invoked in 1905, is withdrawn. In other words, light and matter co-exist in the same condition, ie a real world where they are subjected to common forces. Light is therefore affected, as Einstein states. One example being:

Einstein SR & GR 1916, section 22:

“However, we obtain a new result of fundamental importance when we carry out the analogous consideration for a ray of light. With respect to the Galileian reference-body K, such a ray of light is transmitted rectilinearly with the velocity c. It can easily be shown that the path of the same ray of light is no longer a straight line when we consider it with reference to the accelerated chest (reference-body K’). From this we conclude, that, in general, rays of light are propagated curvilinearly in gravitational fields. In two respects this result is of great importance…… In the second place our result shows that, according to the general theory of relativity, the law of the constancy of the velocity of light in vacuo, which constitutes one of the two fundamental assumptions in the special theory of relativity and to which we have already frequently referred, cannot claim any unlimited validity. A curvature of rays of light can only take place when the velocity of propagation of light varies with position. Now we might think that as a consequence of this, the special theory of relativity and with it the whole theory of relativity would be laid in the dust. But in reality this is not the case. We can only conclude that the special theory of relativity cannot claim an unlimited domain of validity; its results hold only so long as we are able to disregard the influences of gravitational fields on the phenomena (e.g. of light).”

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Hi JCNS,

I really enjoyed your post. It is one of the most lucid treatment of the problem of defining time that I have read. The exposition was clear and the reasoning easy to follow.

The only shortcoming that I can see is that, though you explain that time corresponds to the sequential rearrangement of the components of reality, in essence, that the accepted notion of time is an...

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Hi JCNS,

I really enjoyed your post. It is one of the most lucid treatment of the problem of defining time that I have read. The exposition was clear and the reasoning easy to follow.

The only shortcoming that I can see is that, though you explain that time corresponds to the sequential rearrangement of the components of reality, in essence, that the accepted notion of time is an illusion, you insist that we can still retain the operational notion of time and theories such as special relativity.

Special relativity needs time to be a physical aspect of reality. If it is not, then time cannot be unified with space. And space-time, doesn't not exist. You can't unify a concept, which corresponds to no physical aspect of reality with space, which is an aspect of physical reality. Special relativity can't exist without time being physical. Physical time is required for the effect of time dilatation to exist. Without time dilatation, there is no special relativity. Without time, there is no time dilatation.

I think the essay contrives its conclusion into agreeing with accepted theories. But you can't have it both ways. If time is not physical, then you must reevaluate, even reject many of the dominant theories.

That said I agree with you as far as how time is defined in terms of rearrangements or, in my terms, according to the principle of strict causality.

In regards to time, you might find my answer to the FQXi article titled "Killing Time"

"note: This is from a article I posted on my blog in 2010, which, coincidentally, is also titled "Killing Time."

The greatest problem with current physics theories is that they consider time as if it were a property of physical reality.

Time is a relational concept which is made to allow us to compare events with periodic and cyclic systems; in other words, clocks. But time has no more effect on reality than the clocks that are used to measure it? The fact, when you think of it, clocks don't really measure time.

Take an event consisting of the fall of an object from a point to "a" to a point "b". When we say we measured the time it took for that event to happen, what we actually did is count the number of cycles (seconds, or fraction of seconds for instance) from when the object was dropped from "a" and stopped the count when it reaches point "b". So we don't actually measure time. What we do is simply count the number of cycles the clock's mechanisms go through over the course of the event.

There is no reason why time should be anything more than a relational concept, a useful relational concept I admit, but only a concept. Yet time, physicists will argue, is necessary to the study of nature.

Every process, every event, transformation or phenomenon appears to happen in time. Without time, it is believed, the Universe would be static. Worse, there would be no Universe at all. What we fail to understand is that affirming the necessity of time is like saying that the atoms in the Universe could not exists without the number systems we use to count them. The argument is akin to the solipsistic argument that reality cannot exist without an observer (which is something many quantum-physicists actually try convince us of).

So let's make things clear for a start. Planet Earth, the solar system, our galaxy, our Universe existed before there were people to observe them and before the concept of time, which is a construct of the observers, was invented.

So what does it mean that time is really a relational concept? What it essentially means is that there are no physical interaction between a phenomenon and the number of cycles of the periodic system we may compare it to.

You'll notice that I didn't say there is no interaction between the phenomenon and the periodic mechanism. What I said is that there is no interaction between the phenomenon and the abstraction that is a number. That said, there is a very simple test to determine if a notion is a property of physical reality or if it's merely a concept. The test is one of necessity.

For the sake of argumentation, let's assume that time is a fundamental property of physical reality. If time is a fundamental physical property of reality, then the existence of time must be an axiom essential to any theory of physical reality. What this implies is that it should be impossible to describe any physical phenomenon without the use of time. Impossible! Are you sure?

A principle of strict causality which describes physical phenomena as sequences of events related through causality doesn't require the concept of time. Even concepts such as motion and speed can be described without ever using concept of time.

In fact, the only indication that time may be physical is the effect of time dilation. Time dilation is the inevitable consequence of two axioms: the constancy of the speed of light and the continuity of space. But it can be shown that if space is discrete,then there is no need to resort to the concept of time dilation to explain the constancy of the speed of light.

Then, if time is not an essential axiom, it follows that time is not a fundamental property of physical reality. As a consequence, time is nothing more than a relational concept.

In my opinion, we need to make a distinction between reality and representations of reality by models or concepts. I think we're confusing the two when it comes to time."

On that, congratulations on what, in my opinion, is a well written and lucid exposition of the problems relevant to the definition of time.

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Dear J. C. N. Smith,

Congratulations on your essay, which clearly presents our common world-view involving true temporal passage. As you know, I believe you have the right idea about what's basically wrong with the relativistic description of the nature of time, that leads to the logical conclusion of a block universe. I hope you won't mind my adding two comments as per our previous...

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Dear J. C. N. Smith,

Congratulations on your essay, which clearly presents our common world-view involving true temporal passage. As you know, I believe you have the right idea about what's basically wrong with the relativistic description of the nature of time, that leads to the logical conclusion of a block universe. I hope you won't mind my adding two comments as per our previous exchange.

First of all, I want to think of a modern day Galilean thought-experiment in which two atomic clocks at either end of the cabin of a ship have been calibrated so that they display the exact same time. Therefore, by standing in the centre of the cabin one should see the same time displayed on each of these clocks---the signal from each being transmitted by photons that travel equal space-time intervals at a constant speed. Therefore, as the discussion usually goes, because the same reading should be displayed on each clock at any particular time, two such events may be said to have truly occurred simultaneously. Then, this description of simultaneity can be continuously extended to the rest of the universe, and one has the common-sense description of a three-dimensional universe full of re-arranging things, in which different configurations correspond to different "particular times" in a universe that presently evolves.

Now, imagine that another such ship is constructed, and that the two head towards one another from opposite directions. According to relativity theory, which provides a continuous mathematical description of events, such as the times displayed on clocks, the notions of the presently evolving universe that are held by the two crews will differ; e.g., if one ship is heading towards the Andromeda galaxy while the other moves away from it, at the moment when the two ships cross paths, at that one space-time event, the notion held by the crew on the latter ship, of what's happening on Andromeda, will already be yesterday's news according to the former ship's crew.

I'm sure you know all this; but what I'm not sure of is that you know that the two crews also will not agree on what happens at any particular time locally as well. Because when Brian Greene and others describe a discrepancy between the freeze-frame images of the universe held by two relatively moving observers, they use large distances only as a tool to illustrate the relative discrepancy in intervals of time that are meaningful to us. However, even someone who walks through the cabin of their ship, after taking into account the changing distance between themself and the two clocks, if they postulate the constancy of the speed of light in all directions of all frames, will necessarily conclude that the two clocks are out of sync, and that different sets of events constitute the freeze-frame image of how the entire universe is arranged at any particular time. There's a relevant passage in Tom Ray's very interesting essay:

'One recalls that prior to Descartes, all geometry was done with compass and straightedge---all "here" and no "there." Only with the development of analytical geometry were we able to identify relations between numerically distant points and a local coordinate system.'

Therefore, I see your attack on the argument from the relativity of simultaneity as potentially being directed more towards the relevance of using coordinate systems, than towards the ultimate relevance of the operational definition of time. So, I think the best way of attacking the problem of reconciling relativity theory with a presentist view in which all that ever exists is the Universe at any particular time, is to deny the operational definition of simultaneity. Thus, although someone standing in the centre of either ship's cabin will perceive that the two clocks always display the same time, and may interpret that as being so because the ticks of both clocks are simultaneous, in reality that can't be so if the ship is actually moving through the Universe; i.e., two events perceived to be synchronous by an intertial observer who moves through the Universe shouldn't truly have occurred simultaneously. For this reason, it's very useful that the Universe does provide us with a clear representation of its rest-frame, and that the relative velocities of celestial bodies do not appear as if drawn from a uniform distribution on [0,c)---for if the latter were true, we would have to admit reasonable scientific evidence for a Block Universe.

The other point, which I mentioned before, is that I think the passage of time has to take place prior to the rearrangement of things in the Universe; e.g., as Augustine realised, a day would pass in half the time if the Sun made its round twice as quickly as usual. Therefore, I prefer a more Heraclitean description whereby one should say "while changing it rests", thus expressing the priority of change even in a thing that rests.

All my best!

Daryl

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Dear Daryl,

"I hope you won't mind my adding two comments as per our previous exchange."

On the contrary, I welcome and appreciate your always thoughtful and insightful comments. There is much worthy of pondering in what you've written. I'll try to begin addressing a few of your specific points here. Before going there, however, I'd like to step back and look again at some basics....

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Dear Daryl,

"I hope you won't mind my adding two comments as per our previous exchange."

On the contrary, I welcome and appreciate your always thoughtful and insightful comments. There is much worthy of pondering in what you've written. I'll try to begin addressing a few of your specific points here. Before going there, however, I'd like to step back and look again at some basics. It's my view that much of what is troublesome in physics today can be traced back to a general misperception about the proper role and purpose of clocks. My view on this, as explained in my essay Time: Illusion and Reality, is that the fundamental, underlying purpose, role, and value of clocks is to provide a concise shorthand notation for communicating information about configurations of the universe. As I wrote there,

"Despite being relative newcomers on the historical scene, calendars and clocks rapidly have assumed an extremely important role in our lives, and this is true precisely because they serve the powerful and useful function of providing a concise shorthand for communicating information about configurations of the universe."

This point is beautifully illustrated in Dava Sobel's marvelous book 'Longitude' in which she tells the story of how the development of precision timepieces by John Harrison and others was motivated by the need of mariners to determine accurately their longitude on the high seas, a feat which required a fine correlation between the reading of a clock and a configuration of the universe, i.e., the ship's location relative to the Earth.

It's my perception that many of our current problems in physics began and then multiplied when we lost sight of this fundamental role of clocks, which perform the same fundamental role as calendars, but only on a much finer scale. The reading of a clock (or a calendar) has absolutely no value, in and of itself, other than as it can be correlated with a particular, specific configuration of the universe. This fact presented no practical problems in the case of mariners using chronometers to help navigate the high seas. Some reasonable amount of error ("slop") in the correlation between the ship's position as determined on the basis of the reading of a chronometer and the actual position of the ship was acceptable and even expected.

In modern physics, however, correlations between readings of atomic clocks and specific configurations of the universe are far more problematical. Just for openers, every observer of the universe will necessarily have a slightly different perception of its configuration. Moreover, due to practical limitations imposed by sensory data, our perceptions about configurations of the universe can be, at best, little more than "best approximations" of actual configurations, with those best approximations becoming less reliable as distance from the observer increases.

It is crucial to recognize that the true configuration of the universe is intrinsically unknowable. So-called freeze-frame mental images of its configuration are useful in hypothetical discussions, but are not even remotely possible in practice. Having made these observations, however, there is still much more that needs to be said about how they relate to the issues of relativity and simultaneity.

"The other point, which I mentioned before, is that I think the passage of time has to take place prior to the rearrangement of things in the Universe; e.g., as Augustine realised, a day would pass in half the time if the Sun made its round twice as quickly as usual."

Here we clearly are not in synch, Daryl, because it's my view that the passage of time and the rearrangement of things are precisely one and the same. They are identical. These are just two ways of saying the same thing. One cannot precede the other. This is a fundamental point. If we are not in synch on this, then we probably are not in synch on much more, I suspect. But perhaps enough on that for now.

Cheers!

jcns

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