Understanding the Direction of Time: A Philosophical and Scientific Exploration

[madness]

This is a topic relating to physics but philosophical in nature. Physicists are talking about explaing why the "arrow of time" flows forward the way it does, instead of flowing in any other direction. My questions are these:
1) How do we know that time flows at all? is it not possible that we simply experience time to be flowing as a feature of our consciousness and that all moments in time simply exist with no flow from one to the next. Is there any scientific way to distinguish between time flowing or not?
2) Does it make any sense at all to ask why time flows in the direction it does? surely the direction of time being labelled as "forwards" is arbitrary. What would be strange is if time suddenly changed direction. But even then, would we even notice? If time were to change direction, we would have no idea as we ourselved would be going back in time, retracing our steps.
Basically, i have no idea what physicists mean when they ask why time has an arrow

 

[octelcogopod]

I think it is because most scientists separate between what we perceive and what the physical reality of the situation is.
If the arrow of time was to change direction, then that would be a physical event, as such scientists want to figure out the math and logic behind that event.

If however the arrow of time has had the same direction since the big bang or whatever started it all, then it is a pointless theory, unless it changes direction.

As for your first question, it is my belief that we do need a physical time dimension for mass to be able to move, and that this time is different from our mental time, the time we create by retreiving memories and experiencing time with our senses.

 

[selfAdjoint]

This is a topic relating to physics but philosophical in nature. Physicists are talking about explaing why the "arrow of time" flows forward the way it does, instead of flowing in any other direction. My questions are these:
1) How do we know that time flows at all? is it not possible that we simply experience time to be flowing as a feature of our consciousness and that all moments in time simply exist with no flow from one to the next. Is there any scientific way to distinguish between time flowing or not?
2) Does it make any sense at all to ask why time flows in the direction it does? surely the direction of time being labelled as "forwards" is arbitrary. What would be strange is if time suddenly changed direction. But even then, would we even notice? If time were to change direction, we would have no idea as we ourselved would be going back in time, retracing our steps.
Basically, i have no idea what physicists mean when they ask why time has an arrow

1) When some scientist, or popular book on science, talks about time flowing, you can't take it seriously. They are not using language critically there, but just trying to communicate with ordinary people who use the image of time flowing.

2) What scientists really mean about the arrow of time is the direction of cause and effect. You can run a movie of a breaking egg backwards to show the egg reassembling itself, but this does not happen in reality. This gives a preset direction to physical events, and that direction is "the arrow of time".

There is another example, related to the above; the direction in which entropy increases. Entropy is a measure of disorder, or "lots-of-ways-to-wiggle-ness". If no other cause is acting, the number of ways to wiggle just keeps getting bigger. That gives an arrow of time too, which always points the same direction as the cause and effect one.

 

[madness]

That doesn't really answer my original question. What I want to know is how physicists can objectively establish that time flows at all. Time could equally be a concept invoked by our consciousness. For example what does it mean to say that a particular moment in time is the present, other than to say that we are consciously experiencing that moment. What is the distinguishing feature about the present moment that sets it apart from all other moments in time.
Secondly, surely the reason an egg never reassembles itself is because of the extremely complex interplay of forces required to do so which are immensely unlikely to occur naturally. If time were really to reverse for a while so that the egg did reassemble, we would never know since we would be simultaneously traveling back in time, retracing our thoughts and feelings exactly as they occurred but in reverse.
I see no objective way to show that time really does flow and addresses these problems.

 

[BetaDecay]

Time is relative. It's true, when we say we are looking at something in the present, that's not really accurate. It takes time for the light reflected off of what we are seeing to hit our eyes. Therefore we are really looking into the very recent past when we are looking at another person or our hand or something. If someone from way out in outerspace could see us on Earth somehow, they would see the Earth as it was a hundred years ago, if that's how long it took the light to get to their planet from earth. So, it is possible to go back in time, but it's not possible for time to go backwards. There is no specific direction that light is traveling in. Different light rays travel in all different directions. But whatever direction a light ray travels in, it is not traveling in the opposite direction from itself.
I guess you are not so much concerned with the direction in which time flows, which is used as a visual aid, but more with the fact that there really is no time whatsoever.
Some physicists believe that without light there would be no time. So you may be right and time is only something specific to our universe or any universe who's living would depend on light for life. I don't see why that's not possible, since time is relative even within our universe.
As far as how we know one moment is different from the last - I suppose that would also be the nature of the universe in which we exist. Once there was nothing, then there was a universe.
Since time really has no affect on the existence of matter in its smallest states, then time is only an issue when talking about states of matter. That would be where one moment would be different from the previous, when matter is no longer in its previous state.
Of course, I am far from knowing the answer, but that's my stab at it.

 

[octelcogopod]

We can objectively say that time flows because things move.
We move, the universe moves.

Time isn't so much a defined static dimension, as it is an elusive set of rules that emerges from mass moving.
Finding out those rules is of utmost importance, but nobody seems to have done it yet.

 

[Tournesol]

2) Does it make any sense at all to ask why time flows in the direction it does? ...
Basically, i have no idea what physicists mean when they ask why time has an arrow

Time has a number of arrows which is what makes it meaningful
to ask about time reversal. Off the top of my head, they are:-
The expansion of the universe since the BB; the arrow
entropy; the arrow of causality; and the subjective arrow.

Of course they are not necessarily all different under some
final analysis.

1) How do we know that time flows at all? is it not possible that we simply experience time to be flowing as a feature of our consciousness and that all moments in time simply exist with no flow from one to the next. Is there any scientific way to distinguish between time flowing or not?

Consciousness is generated by the brain, which is a physical
system ? Does it fall under some special set of physical
laws giving it a unique gift of time-flow-generation ? Or, if it
falls under the same laws as everything else, why shouldn't
those laws be capable of generating an objective flow of time ?

 

[Tournesol]

1) When some scientist, or popular book on science, talks about time flowing, you can't take it seriously. They are not using language critically there, but just trying to communicate with ordinary people who use the image of time flowing.

Whilst that may not be the ideal metaphor, it does not
help to ignore the flow of time entirely and insist on
a static universe. Dismissing the flow of time a subjective doesn't
help either, since it suggests cosnciousness is exempt from physics.

 

[Rade]

Why must time always "flow" as an arrow. If time is a "movement", why only flow either one direction or another (forward, backward), why not also move (oscillate) in place, perhaps at speed of light. Thus no "flow" to time at speed of light, more like a spinning wheel ?

 

[madness]

of course consciousness is exempt from the laws of physics. It would be meaningless to try to explain thoughts and feeling and perceptions in terms of matter and energy. The physical processes in the brain are subject to the laws of physics, but science has yet to explain how these processes give rise to our subjective experiences. I find problems with viewing time as a physically occurring process because there seems to be no physical explanation for what gives the present moment its uniqueness. According to physics the present moment is no different to any other moment in time. The reason we see time flowing could be a facet of our consciousness. Is it not possible that all moments in time simply exist, and our consciousness gives us the experience of the "present", which has no physical difference to any other moment in time

 

[selfAdjoint]

of course consciousness is exempt from the laws of physics. It would be meaningless to try to explain thoughts and feeling and perceptions in terms of matter and energy. The physical processes in the brain are subject to the laws of physics, but science has yet to explain how these processes give rise to our subjective experiences. I find problems with viewing time as a physically occurring process because there seems to be no physical explanation for what gives the present moment its uniqueness. According to physics the present moment is no different to any other moment in time. The reason we see time flowing could be a facet of our consciousness. Is it not possible that all moments in time simply exist, and our consciousness gives us the experience of the "present", which has no physical difference to any other moment in time

I hate to use such a harsh expression, but this is just bosh. I have explained above in this thread how physics has perfectly good accounts of how different moments may be ordered. As for representing feelings and such, neurobiology has already managed a lot with feelings, through studies of serotonin and such. Did you know that the instance of suicide has fallen in recent years? Since the introduction of Prozac, in fact.

 

[moving finger]

Entropy is a measure of disorder, or "lots-of-ways-to-wiggle-ness". If no other cause is acting, the number of ways to wiggle just keeps getting bigger. That gives an arrow of time too, which always points the same direction as the cause and effect one.

Agreed.

The "arrow of time" is a metaphor used by Arther Eddington for the first time in 1928 to represent the asymmetric properties of time that have no analogue in space.

It's important to distinguish between the arrow of time (why events seem to be asymmetric in time), and the apparent illusion of the "flow of time". These are two very different things.

There are in fact many "arrows" of time, including the psychological arrow (we can remember the past, but not the future), the thermodynamic or entropy arrow (the one described by selfAdjoint above), the cosmological arrow (the fact that the universe is expanding), and many more.

We may ask : Why does our psychological "arrow" always seem aligned with the thermodynamic "arrow"? The answer is (imho) as follows :

The Origin of the Psychological Arrow of Time
At the microscopic level of individual particles it turns out that time seems perfectly symmetric – we say that the dynamical laws of physics are invariant (do not change) under time-reversal. Thus there seems to be no fundamental difference between past and future directions of time at the level of individual particle interactions. But at the macroscopic level (the level at which our brains, and almost every other object we interact with, work), it seems to be a fundamental characteristic of our world that there is an inherent “entropy gradient” within spacetime. What this means is that if we take different “timeslices” through 4-dimensional spacetime we find that we can identify an overall asymmetry wherein the total entropy of the universe increases in one time direction (and conversely of course decreases in the reverse time direction). Unlike space, therefore, the time dimension contains an inbuilt arrow, often referred to as the thermodynamic arrow of time.

Next we need to consider how memories are formed in the brain. A memory is in general terms simply a record or a form of “representation” of one part of a timeslice (let’s say t0) within another timeslice (let’s say t1). This applies to things like computer memories, photographs, drawings, descriptions, and human memories. To form a “memory” requires an extraordinary and inherently improbable correlation between the “worldlines” of many particles. A footprint on a beach, for example, might have appeared spontaneously (there is a vanishingly small chance that this might happen), but the patterns (which represent information) within a footprint are so highly correlated that there is an incredibly overwhelming probability that the footprint is associated with some identifiable “cause” at some other timeslice which we say “formed” the footprint. The “directionality” of this correlation, in the way that the correlations between worldlines change on going from one time-slice to another, is almost always aligned with the directionality of the overall entropy gradient between those timeslices.

We see cups break, but we never see them spontaneously re-assemble, because our internal psychological arrow of time is aligned with the thermodynamic arrow of time (the entropy gradient). And the reason our psychological arrow is aligned with the thermodynamic arrow is precisely because the processes which produce “records” in our brain, representations of one timeslice within another timeslice, are themselves thermodynamic processes. Our psychological arrow is “locked” into the same directionality as the thermodynamic arrow because both arrows share a common source – the entropy asymmetry of the time dimension.

The upshot of all this is that for any macroscopic record of time t0 contained within time t1, the entropy at t0 is always lower than at t1. All of our “memories” therefore are of times of lower entropy. We simply do not have memories of times where the entropy is higher. It is simply by convention that we refer to the timeslices where entropy is lower as “the past”, and timeslices where entropy is higher as “the future”. Hence we have records and memories of the past, but not of the future.

Best Regards

 

[moving finger]

Whilst that may not be the ideal metaphor, it does not
help to ignore the flow of time entirely and insist on a static universe. Dismissing the flow of time a subjective doesn't help either, since it suggests cosnciousness is exempt from physics.

Not at all. The conscious illusion that we have of time "flowing" from past to future may be explained very simply on the basis that we have memories only of the past, and never of the future (and the reason why this is the case is explained in the previous post).

Assuming that the universe is deterministic (and this is another topic entirely) then the future is just as "fixed" as the past. But what the conscious agent perceives is that the past is fixed, but the future seems to be open, or not fixed. Given these perceptions, it would not make rational sense (it would in fact be irrational) for the agent to believe that time flowed from future to past (because the agent perceives that the past is fixed).

It also would not make rational sense (from the agent's perspective) for the agent to believe that time was not flowing at all, and the agent is simply "frozen in time".

The only rational interpretation that the conscious agent can place upon its perception that the past is fixed whereas the future seems "open" is that it (the agent) is actually "flowing through time", from past to future.

Best Regards

 

[Tyris]

That doesn't really answer my original question. What I want to know is how physicists can objectively establish that time flows at all. Time could equally be a concept invoked by our consciousness.

Only in the same way that anything else can, e.g., distance, tables, sound...

 

[Tournesol]

Not at all. The conscious illusion that we have of time "flowing" from past to future may be explained very simply on the basis that we have memories only of the past, and never of the future (and the reason why this is the case is explained in the previous post).

Assuming that the universe is deterministic (and this is another topic entirely) then the future is just as "fixed" as the past. But what the conscious agent perceives is that the past is fixed, but the future seems to be open, or not fixed.

if the universe is not merely deterministic, but a static, eternal
4D structure, then the future "already" exists, then I "already" exist in it.
But that doesn't explain the feeling of getting from one state to
another (which must be an illusion, but the source of the
illusion is not explained.)

OTOH, if future states are continually coming into freshly-mineted
being, the feeling of flow reflects the phsycial situation and is
therefore not an illusion.

I know of no theory that explains the feeling of flow as an
illusion. It is either illlusory and inexplicable or explicable
and non-illusory.

Given these perceptions, it would not make rational sense (it would in fact be irrational) for the agent to believe that time flowed from future to past (because the agent perceives that the past is fixed).

The question of why there is a "flow" at all is separate from the
question of the direction of flow.

It also would not make rational sense (from the agent's perspective) for the agent to believe that time was not flowing at all, and the agent is simply "frozen in time".

Not in face of the feeling of flow, but the feeling is not
explained under the block-universe theory.

The only rational interpretation that the conscious agent can place upon its perception that the past is fixed whereas the future seems "open" is that it (the agent) is actually "flowing through time", from past to future.

It is perfectly possible to conceive an agent which has
a fixed set of memories of the past no knowledge of the future..
and no "flow". The flow is something extra.

 

[madness]

It's not botch. You didn't explain what makes the present moment a unique moment in time, or how time flows in a universe in which can just as equally be considered as 4-dimensional and static. Neurobiologists may have discovered what is happening in the brain when we feel certain emotions, but how something material actually gives rise to mental formations is not known.

 

[Drachir]

Understanding Time

madness asked excellent probing questions at the top of this thread. Let’s see how they can be answered.

Before considering the arrow of time let’s be a little more basic and clarify our understanding of time. When we see the sun at sunrise, noon, and sunset, we remember not only those observations but also the order in which they were made. Each long term or short-term memory is ‘tagged’ with its sequential position in a string of memories. Our notions of the past, present, and future are based on our recognition of memory sequences. That is the source of our concept of time.

We are not the only animals that recall memory sequences. Animals that hunt often base their present actions on the action they anticipate of their prey. To distinguish between present and future requires some understanding of time.

In a few sentences I will use the term ‘abstraction.’ so let’s be clear about what I mean by that term. An abstraction expresses a quality or characteristic apart from any specific object or instance. For example, there are red apples, red sunsets, and red light. Red is an abstraction. Red does not have existence independent of the things it characterizes. There is no such thing as red itself.

Time is an abstraction we make from the motion of things. We cannot conceive of time without conceiving of things that move, such as the rhythmic beating of our hearts, the motion of the sun across the sky, the swinging of a pendulum, the oscillations of a quartz crystal, and the alternating electromagnetic field of a photon. We do not sense time; we sense things and observe and remember their changes. Therefore, time without things can have no meaning for us. Just as there is no such thing as red itself, there is no such thing as time itself.

Since there is no such thing as time itself, it is meaningless to consider time to have physical existence. Time, therefore, cannot have physical properties; it cannot spin, dilate, shrink, or flow. When we say that time flows, we are speaking metaphorically as if time were similar to the water flowing in a river. But water is a real thing, time is not.

The idea of going forward or backward in time presumes that the time traveler would be spared the effects of the travel, that he could even go to times before and after his own existence. I guess he would don a cloak that shields him from time.

The notion of time running backwards implies that all motions would be reversed and that all history would retrace its steps backward. It’s not possible. There are too many things that prohibit the reversal of time. Water can’t change its direction through a check valve. Electrons cannot change their direction through a diode or transistor.

The Earth would have to change its direction of rotation in order to make sundials tell time backwards. If it changed its direction instantaneously there wouldn’t be a human-built structure left standing and there would be horrific flooding. Instead of people getting younger they would be killed; that wouldn’t be a backward replay of history. And if it changed direction slowly, there would be terrible destruction as equatorial oceans moved towards the poles during the reversal. That, too, would not be a backward replay of history. The notion of time reversal, of history running backward, is self-contradictory.

As I said, it’s not possible. It’s as funny as a man jumping up upside down from a swimming pool and landing feet first on a diving board. Just because we’ve seen films run backward or wished we could take back some words we’ve said doesn’t make time running backwards possible, let alone a good idea The idea of the reversal of time, of going back in time, is fantasy.

If the arrow of time is stationary like a traffic sign, it can point only toward the future. If the arrow of time flies, it flew from the past to the present and now flies toward the future. The past no longer exists. The future does not yet exist. We are forever stuck in the present, observing the past, and anticipating the future.

Now let’s answer the questions posed in the opening of this thread.

1) How do we know that time flows at all?

Time can flow metaphorically but not physically. In the same way that time is an abstraction from the motions of things, the flow of time is an abstraction from the continuity of the motions of things. The continuity of things and their motions is based on our concept of object persistence, a concept formed during infancy.

Is there any scientific way to distinguish between time flowing or not?

If science deals with reality and not metaphors, there is no way for science to probe that question.

2} Does it make any sense at all to ask why time flows in the direction it does?

That question is equivalent to asking why all things move. I don’t think it makes sense to ask that kind of question.

What would be strange is if time suddenly changed direction. But even then, would we even notice?

The question is pointless since irreversible processes preclude time reversal. Think of light and heat going back to a lamp to create ac electricity. Think of the check valve and diode.

Basically, i have no idea what physicists mean when they ask why time has an arrow

Physicists who ask that question are incorrectly taking metaphoric descriptions of time literally. The direction of time is implicit in Newton’s first law: “Every body perseveres in its state of rest, or of uniform motion in a right line, unless it is compelled to change that state by forces impressed thereon”. The notion of continuity of motion is implicit in his (now archaic) use of the word ‘perseveres’ and his use of the term ‘uniform motion.’

 

[Canute]

Tournesol writes: "I know of no theory that explains the feeling of flow as an illusion. It is either illlusory and inexplicable or explicable
and non-illusory."

Try having a look at the theory of emptiness as expounded by Nagarjuna, or dhamma theory as expounded in the 'Abhidhamma' (one of the 'three baskets of teachings' in Buddhism). In this view spacetime is a psychological construct, as I think it was for Kant.

Nagarjuna's Fundamental Wisdom of the Middle Way is a proof that the notion of time as existent is inherently paradoxical. He makes a reductio argument similar to Zeno's. In this view, at the deepest level of analysis nothing really exists and nothing ever really happens (really!). Roughly speaking, he argues that the past does not exist, the future does not exist, and thus the notion of the present moment is incoherent (an argument related to the 'Dedekind Cut' in mathematics).

Many people conclude his proof is successful. The philosopher Francis Bradley attempts a similar (but far more complex) proof in his metaphysical essay Appearance and Reality.

The Wheeler-Feynman 'absorber theory' of time is, I think, still well thought of by physicists. In this entities can move both backwards and forwards in time quite happily, quite as if the flow of time is an illusion.

Cheers
Canute

 

[madness]

Thanks to Canute and Drachir, you offered interesting answers to my questions. However, I am still a bit confused about our concept of the present. In, a deterministic universe, all moments in time are preset, and would seem to have some kind of existence. For example some theologians have argued that when God created the universe he created all moments in time at once, rather than creation being related to the beginning of the universe. So what does it mean to say that a certain moment is happening now? Or does it make more sense to view the present as the only moment in existence, and the past and future as illusory? In this view, problems such as the above would be solved.

 

[moving finger]

I know of no theory that explains the feeling of flow as an illusion. It is either illlusory and inexplicable or explicable and non-illusory.

Is the Flow of Time an Illusion?

The argument seems to be : Conscious agents perceive time as if the agent is “flowing in time” from the past into the future, and from this perception it is allegedly safe to infer that such agents are not simply under the illusion of “flowing in time”, but indeed (and objectively) they are “flowing in time” from the past to the future.

I shall show that this inference is invalid.

Experiments by Libet and Grey Walter on the differences in the objective and subjective (experienced) correlations between temporally separated events show that the mind can reconstruct or rearrange the actual temporal sequence of perceptual information coming from phenomenal events, such that the consciously perceived (the experienced) sequence is not the same as the objective sequence of events (see the paper by Dennett and Kinsbourne referenced below). Libet explains this in terms of “backwards referral” or “backwards projection” of certain consciously experienced events with respect to other consciously experienced events. Dennett describes this kind of mental manipulatioon of the objective sequence of events in terms of Orwellian and Stalinesque models of mental representation.

(See attached figure)

View attachment figure.doc

As Libet remarks, there is

no method by which one could determine the absolute timing of a subjective xperience.

We perceive--and remember--perceptual events, not a successively analyzed trickle of perceptual elements or attributes locked into succession as if pinned into place on a continuous film. Different attributes of events are indeed extracted by different neural facilities at different rates, (e.g. location versus shape versus color) and people, if asked to respond to the presence of each one in isolation, would do so with different latencies, depending on which it was, and on other well-explored factors. The relative timing of inputs plays a necessary role in determining the information or content in experience, but it is not obligatorily tied to any stage or point of time during central processing. How soon we can respond to one in isolation, and how soon to the other, does not exactly indicate what will be the temporal relationship of the two in percepts that incorporate them both.



There is nothing theoretically amiss with the goal of acquiring precise timing information on the mental operations or informational transactions in the brain. It is indeed crucial to developing a good theory of the brain's control functions to learn exactly when and where various informational streams converge, when "inferences" and "matches" and "bindings" occur. But these temporal and spatial details do not tell us directly about the contents of consciousness. The temporal sequence in consciousness is, within the limits of whatever temporal control window bounds our investigation, purely a matter of the content represented, not the timing of the representing.

Thus there is an “objective timeline”, and for each conscious observer we have an individual, subjective “experienced timeline”. The individual experienced timelines do not necessarily precisely match up either with each other, or with the objective timeline, in terms of their experienced sequence of events.

Thus if time really does “flow” (and we are to believe that this flow is not an illusion), then all but one of the above timelines (since they reflect different sequences of events) must be an illusion. Which of the above timelines would one think represents the real “flow of time” – the objective timeline or one of the the experienced timelines? It obviously cannot be one of the experienced timelines (because we each experience different timelines, and none of us is in a privileged position of being able to claim to have direct access to the “absolute flow of time”), therefore (if anyone timeline flows) it must be the objective timeline. But if this is the case, then it follows that we each sometimes perceive time as flowing in the opposite direction to the way it is objectively flowing! Thus, our subjective experience of the flow of time is indeed an illusion (whether the objective timeline really “flows” or not), and we thus cannot infer from our perceived or experienced flow of time that objective time is actually flowing at all.

References:

For Libet, see for example : Libet, B., 1981, "The experimental evidence for subjective referral of a sensory experience backwards in time: reply to P. S. Churchland," Philosophy of Science, 48, pp.182-97

Dennett, Daniel C. & Kinsbourne, Marcel (1992) “Time and the Observer”. Behavioral and Brain Sciences 15 (2) 183-247

 

[selfAdjoint]

Thanks for that instructive post Finger! I am sure we are going to be referring back to it. In fact Libet comes up so often that it might be useful to use your post to anchor a sticky FAQ on the subject.

Given certain facts in the current state of physics research, I wonder if the concept of "current moment" has any sure physical support.

1) GR has no global time evolution, as John Baez says, "You push your spacelike hypersurface ahead your way and I push mine ahead my way." And this is inherited by quantum gravity theories.

2) In QM, time evolution is an observable. Not observed = not well defined? But always observed = no evolution (quantum Zeno effect).

There's more, but I have to go now.

 

[Drachir]

Illusions?

madness wrote:

So what does it mean to say that a certain moment is happening now? Or does it make more sense to view the present as the only moment in existence, and the past and future as illusory?

Those questions arise for two reasons. First, it is so easy to confuse long-used metaphors with reality. Second, it is easy to confuse subjective existence with objective existence. Time is an abstraction from the motions of things. Abstractions have only mental existence. Time cannot have objective existence; it cannot have existence independent of thinking subjects. It follows that no time span, not even a moment, can have physical existence.

Physical events happen: the sun at the zenith, for example. However, abstractions do not happen. A moment of time is an abstraction and cannot happen. It is meaningless to say that a certain moment is happening now, or that the present is the only moment in existence.

An illusion is something that deceives by producing a false or misleading impression of reality. Barring neurological disorders, our minds do not deceive us. We know the difference between things of reality and things of the mind. Our memories of our past experiences with reality are not deceptive. The past is not illusory.

Many kinds of future events can be predicted with high levels of confidence from observations of the past and present, hence, the future is not illusory. Besides, how could the future retroactively deceive us in the present?

 

[Canute]

Moving Finger - that's very interesting, thanks. The quote from Libet bothers me though.

"[There is] no method by which one could determine the absolute timing of a subjective experience."

It's probably just that's this is quoted out of context but it seems to me that it is not true. Every experience I've ever had has happened right now. In this case Libet's statement is only true if my subjective 'now' is not the same as the objective 'now'. But there is no such thing as an objective 'now' therefore my subjective 'now' cannot be the same as it. In this case the statement is either meaningless or false, depending on how we read it. Perhaps in context this isn't a problem.

The second para. of the Dennett and Kinsbourne quote suggests, it seems to me, that the timing of neural events may not coincide with the timing of mental events. This would seem to have rather strange consequences for theories in which the two are precisely correlated. To avoid this problem we would have to say that the timing of mental events does coincide with the timing of neural events (quantum effects in microtubules, whatever) but events in phenomenal consciousness may not coincide with either. However, I'm very sure Dennett did not mean to imply this. Nevertheless, there seems something a little incoherent about that para. to me. Maybe I'm misunderstanding it. I nearly always have a problem with Dennett's pronouncements.

madness wrote: Time is an abstraction from the motions of things. Abstractions have only mental existence. Time cannot have objective existence; it cannot have existence independent of thinking subjects. It follows that no time span, not even a moment, can have physical existence.

Physical events happen: the sun at the zenith, for example. However, abstractions do not happen. A moment of time is an abstraction and cannot happen. It is meaningless to say that a certain moment is happening now, or that the present is the only moment in existence.

The point about time seems very well put IMHO. The notion of time has always been paradoxical. Perhaps we should consider it as just a hang-over from the days of naive realism. However the statement 'physical events happen' is false in many people's view, so perhaps should not be made so boldly.

Barring neurological disorders, our minds do not deceive us. We know the difference between things of reality and things of the mind. Our memories of our past experiences with reality are not deceptive. The past is not illusory.

I strongly disagree here. You assume things of the mind are less real than something else called 'reality'. I doubt if you can justify this assumption, or even that you can show these are two different things. It is a widely-held view that we are wholly deceived by psychophysical phenomena if we consider them as inherently existent thus 'real'. Clearly they cannot be inherently existent if time is not, since they time-based phenomena. I think you have to bite the bullet. If time is not real then neither are psychophysical phenomena. This view is not scientifically contentious, as far as I know, and Erwin Schrodinger argued for it for the last forty years of life.

Many kinds of future events can be predicted with high levels of confidence from observations of the past and present, hence, the future is not illusory. Besides, how could the future retroactively deceive us in the present?

I can't figure out if this is actually relevant to retroactive deception but I think it may be. According to Briane Greene (or was it John Gribben) a number of physicists theorise that in the present we (being conscious observers) can influence the past. He discusses the possibility that we created the fossil evidence for the dinosaurs in retrospect. The maths is too complex for me, but I gained the impression that the answer to your question may be that it is possible. The problem is trying to disentagle 'deception' and 'reality'. Schrodinger, for example, considered psychophysical phenomena (thus time, change etc.) to be deceptions, and 'reality' to be a different kind of phenomenon entirely.

Regards
Canute

 

[moving finger]

Thanks for that instructive post Finger! I am sure we are going to be referring back to it. In fact Libet comes up so often that it might be useful to use your post to anchor a sticky FAQ on the subject.

Given certain facts in the current state of physics research, I wonder if the concept of "current moment" has any sure physical support.

Agreed. But showing the “current moment” is either ill-defined or has no real meaning is not the same as showing that time does not flow.

1) GR has no global time evolution, as John Baez says, "You push your spacelike hypersurface ahead your way and I push mine ahead my way." And this is inherited by quantum gravity theories.

Right, but I don’t think we can actually get a relativistic reversal of event sequences can we? (like the reversal of event sequences implied by Libet’s backwards referral). So relativity alone would still be compatible with an objective flow of time?

2) In QM, time evolution is an observable. Not observed = not well defined? But always observed = no evolution (quantum Zeno effect).

Yep – but again this simply leads to a slowing down or stopping of events, not a reversal of event sequences. So QM alone would still be compatible with an objective flow of time?

An illusion is something that deceives by producing a false or misleading impression of reality. Barring neurological disorders, our minds do not deceive us.

Are you normally aware of your blind spot? No, one normally has to work hard to reveal the presence of the blind spot. Why? Because the mind has evolved to ignore the fact that information is missing from the blind spot, hence the fact that information is missing is not mentally flagged as a problem. It’s a classic illusion. There are many, many such illusions if one looks carefully enough.

Our minds have evolved to provide competitive advantage, they have not necessarily evolved to provide an accurate picture of reality (except insofar as that picture provides a competitive advantage).

We know the difference between things of reality and things of the mind. Our memories of our past experiences with reality are not deceptive. The past is not illusory.

There are countless documented cases of people having false or deceptive memories of past events, and Libet’s experiments confirm just one small aspect of this – the fact that we deliberately reconstruct conscious timelines.

Moving Finger - that's very interesting, thanks. The quote from Libet bothers me though. It's probably just that's this is quoted out of context but it seems to me that it is not true. Every experience I've ever had has happened right now.

What is “now” as far as your consciousness is concerned? “now” is just as uncertain as “here” from the perspective of your consciousness. Your conscious self is delocalized in space (it does not have a well defined location, it is just “somewhere within your brain”), and it is also delocalized in time – Libet’s experiments have confirmed this. The brain is able to reconstruct the temporal sequences of events such that an event A which in real time occurs before event B is actually consciously perceived (by the subject) as if A occurs after, and not before, B. How can this be the case, unless your conscious “now” is somehow delocalized and disconnected from the objective (external) now?

In this case Libet's statement is only true if my subjective 'now' is not the same as the objective 'now'. But there is no such thing as an objective 'now' therefore my subjective 'now' cannot be the same as it.

On what basis do you claim there is no objective “now”? Are you suggesting that time only exists in the presence of observers? (in other words, if a clock ticks in the forest and there is no-one to hear it, does it stop?)

The second para. of the Dennett and Kinsbourne quote suggests, it seems to me, that the timing of neural events may not coincide with the timing of mental events.

If by “neural events” you mean the objective event as witnessed by an external observer, and by “mental events” you mean the consciously registered event, then yes I agree. This is simply another way of saying that the objective timeline and the experienced timeline are not necessarily mapped linearly one to the other.

This would seem to have rather strange consequences for theories in which the two are precisely correlated. To avoid this problem we would have to say that the timing of mental events does coincide with the timing of neural events (quantum effects in microtubules, whatever) but events in phenomenal consciousness may not coincide with either. However, I'm very sure Dennett did not mean to imply this.

Agreed. I believe Dennett would equate mental events with events in phenomenal consciousness (ie they are one and the same).

Nevertheless, there seems something a little incoherent about that para. to me. Maybe I'm misunderstanding it. I nearly always have a problem with Dennett's pronouncements.

It seems quite coherent to me. In fact, there is no mention of the word “event” in the entire paragraph, so perhaps you are misinterpreting his intention?

Best Regards

 

[Canute]

What is “now” as far as your consciousness is concerned? “now” is just as uncertain as “here” from the perspective of your consciousness. Your conscious self is delocalized in space (it does not have a well defined location, it is just “somewhere within your brain”), and it is also delocalized in time – Libet’s experiments have confirmed this. The brain is able to reconstruct the temporal sequences of events such that an event A which in real time occurs before event B is actually consciously perceived (by the subject) as if A occurs after, and not before, B. How can this be the case, unless your conscious “now” is somehow delocalized and disconnected from the objective (external) now?

As far as my consciousness is concerned my 'now' is whenever I have an experience. I'm not suggesting that this is at some point in time relative to an objective 'now'. Far from it. You are assuming there is an objective 'now', I am denying it. My conscious 'now' is the only sort of 'now' I shall ever know, the 'eternal present' as it is sometimes characterised. What the phrase 'objective now' means I really don't know.

In my view it makes no sense to say that consciousness is delocalised in time and space. It assumes what is being questionned, namely the inherent existence of time and space. Certainly I would not accept that my consciousness is somewhere within my brain. The idea depends on an objective time and space more fundamental than my consciousness. But what if time and space are conceptual creations of consciousness? Perhaps the problem here, as usual, is clarifying what we mean by 'consciousness'.

On what basis do you claim there is no objective “now”? Are you suggesting that time only exists in the presence of observers? (in other words, if a clock ticks in the forest and there is no-one to hear it, does it stop?)

I thought nobody believed in an objective 'now' anymore. Is this not what relativity is all about? On the second question I'd say yes, time would only exist in the presence of observers (i.e. in the minds of observers).

If by “neural events” you mean the objective event as witnessed by an external observer, and by “mental events” you mean the consciously registered event, then yes I agree. This is simply another way of saying that the objective timeline and the experienced timeline are not necessarily mapped linearly one to the other.

What objective timeline? Do you mean an intersubjective timeline? Or do you mean time as measured by some central cosmic clock?

Agreed. I believe Dennett would equate mental events with events in phenomenal consciousness (ie they are one and the same).

In this case phenomenal events must happen at the same time as their neural correlates. If so, then they occur in a physically determined order, and the order of experienced events must be the same as the order of the physical events they are the experiences of. But, as you say, we know this is not always the case. The physicalist account of experiences, coupled with recent experimental findings that imply 'retro-causation' (e.g. the Damasio group) leads to the idea that neurons are clairvoyant. I don't think this idea makes much sense.

The temporal sequence in consciousness is, within the limits of whatever temporal control window bounds our investigation, purely a matter of the content represented, not the timing of the representing.

This is what I meant by incoherent, although I may be misreading the words. It seems to me that if the timing of the content represented and the timing of the representing are different then clearly experiences need not happen at the same time as the brain-events that cause them. In this case there is more to experiencing than brain-states, contrary to Dennett's usual thesis.

Btw, if my responses seem confused I apologise. I find the topic very confusing.

Cheers
Canute

 

[moving finger]

As far as my consciousness is concerned my 'now' is whenever I have an experience. I'm not suggesting that this is at some point in time relative to an objective 'now'. Far from it. You are assuming there is an objective 'now', I am denying it.

OK, that’s a different viewpoint certainly. I agree if one denies any objectivity to the temporal dimension, one is free to define “now” in any way that one wishes.

My conscious 'now' is the only sort of 'now' I shall ever know, the 'eternal present' as it is sometimes characterised. What the phrase 'objective now' means I really don't know.

One could say the same about space. Most people however seem to think that spatial and temporal dimensions have an objective “ontic” reality which is external to our conscious “epistemic” experience, but I agree one is entitled to assume this is not the case.

In my view it makes no sense to say that consciousness is delocalised in time and space. It assumes what is being questionned, namely the inherent existence of time and space. Certainly I would not accept that my consciousness is somewhere within my brain.

No? Where would you say it is?

The idea depends on an objective time and space more fundamental than my consciousness. But what if time and space are conceptual creations of consciousness?

Indeed. What if the whole of what the rest of us to take to be “objective reality”, including our own consciousnesses, is just a creation of your consciousness?

Perhaps the problem here, as usual, is clarifying what we mean by 'consciousness'.

Perhaps. But I think the problem is more to do with whether one accepts an objective spacetime reality which exists independently of your consciousness. It seems you do not. Re-defining or clarifying just what we mean by “consciousness” wouldn’t change your belief, presumably?

I thought nobody believed in an objective 'now' anymore. Is this not what relativity is all about?

Very good point. I agree. I shall re-phrase : Does the concept of time exist in the absence of conscious observers?

On the second question I'd say yes, time would only exist in the presence of observers (i.e. in the minds of observers).

OK, you answered. Interesting position you take here.

If by “neural events” you mean the objective event as witnessed by an external observer, and by “mental events” you mean the consciously registered event, then yes I agree. This is simply another way of saying that the objective timeline and the experienced timeline are not necessarily mapped linearly one to the other.

What objective timeline? Do you mean an intersubjective timeline? Or do you mean time as measured by some central cosmic clock?

I mean timeline as measured by any clock in absence of a conscious observer – but then you don’t believe in such a “non-experienced” timeline.

Agreed. I believe Dennett would equate mental events with events in phenomenal consciousness (ie they are one and the same).

In this case phenomenal events must happen at the same time as their neural correlates.

You have changed “neural events” to “neural corrlates”. Obviously a “correlate” must be correlated with something, otherwise we would not call it a correlate. But not all neural events are correlated with phenomenal consciousness.

If so, then they occur in a physically determined order, and the order of experienced events must be the same as the order of the physical events they are the experiences of.

Not necessarily.

But, as you say, we know this is not always the case. The physicalist account of experiences, coupled with recent experimental findings that imply 'retro-causation' (e.g. the Damasio group) leads to the idea that neurons are clairvoyant. I don't think this idea makes much sense.

Clairvoyant neurons? I have read a fair amount of Damasio’s work, I’m not aware of any such suggestion like this - knowing Damasio's approach I would be amazed if this came from his interpretation.

The temporal sequence in consciousness is, within the limits of whatever temporal control window bounds our investigation, purely a matter of the content represented, not the timing of the representing.

This is what I meant by incoherent, although I may be misreading the words. It seems to me that if the timing of the content represented and the timing of the representing are different then clearly experiences need not happen at the same time as the brain-events that cause them.

I interpret Dennetts’ phrase “timing of the representing” as the objective timeline of the representations (which you deny exists) and the “content represented” I interpret as the subjective phenomenal experience. Thus Dennett (on my interpretation) is saying that the subjectively experienced temporal sequence is purely a matter of the subjective phenomenal experience, and is not a matter of the objective timeline of the representations.

In this case there is more to experiencing than brain-states, contrary to Dennett's usual thesis.

On my interpretation, Dennett’s explanation is coherent, and consistent with conscious experience simply being a sequence of brain-states.

Btw, if my responses seem confused I apologise. I find the topic very confusing.

Probably not as confusing as I find it!

Best Regards

 

[Canute]

OK, that’s a different viewpoint certainly. I agree if one denies any objectivity to the temporal dimension, one is free to define “now” in any way that one wishes.

That's not quite what I meant. I wasn't being sloppy. I would define it as any moment that I (or you) experience as 'now'. I don't know what other meaning it could have.

One could say the same about space. Most people however seem to think that spatial and temporal dimensions have an objective “ontic” reality which is external to our conscious “epistemic” experience, but I agree one is entitled to assume this is not the case.

I would say the same about space. In physics the question of whether spacetime is fundamental is, I think, known as the 'background-dependence problem'. One solution recently proposed is the 'hypothesis of duality', by which spacetime is or is not fundamental depending on which way we look at it. In other words, it has so far proved impossible to show that there is not something more fundamental than space and time.

No? Where would you say it is?

If space is not fundamental then this question is meaningless. This may sound like insanity but it makes some sense in the context of a wider theory, honest.

Indeed. What if the whole of what the rest of us to take to be “objective reality”, including our own consciousnesses, is just a creation of your consciousness?

This is not quite what I'm suggesting, but is something like it. However, to answer fully would take us way off topic.

Perhaps. But I think the problem is more to do with whether one accepts an objective spacetime reality which exists independently of your consciousness. It seems you do not. Re-defining or clarifying just what we mean by “consciousness” wouldn’t change your belief, presumably?

It wouldn't change what I believe, but it would change how I'd express it. If by consciousness we mean what Dennett means then spacetime is more fundamental than consciousness. If we mean what Chalmers means then it would be the other way around. Sorry to be cryptic but I'm not trying to push any particular view on you, just point out that not all the assumptions you make are necessary.

Very good point. I agree. I shall re-phrase : Does the concept of time exist in the absence of conscious observers?

I think the answer is in the question. The only place a concept can exist is in a mind.

You have changed “neural events” to “neural corrlates”. Obviously a “correlate” must be correlated with something, otherwise we would not call it a correlate. But not all neural events are correlated with phenomenal consciousness.

I see what you mean. But I used the term quite carefully, to distinguish any old event from those that, according to the physicalist view, are responsible for (or identical with) experiences.

Clairvoyant neurons? I have read a fair amount of Damasio’s work, I’m not aware of any such suggestion like this - knowing+ Damasio's approach I would be amazed if this came from his interpretation.

I didn't mean to suggest that Damasio talks about clairvoyance. The interpretation came from an article by C. Whitehead in the Journal of Conscious Studies, in which he talks about experiments by Bierman showing that non-conscious physiological anticipation of decisions not only precedes conscious decision-making, but begins even before any implict learning can have occured. He writes 'In layman's terms this means that neurones appear to be clairvoyant'.

I interpret Dennetts’ phrase “timing of the representing” as the objective timeline of the representations (which you deny exists) and the “content represented” I interpret as the subjective phenomenal experience. Thus Dennett (on my interpretation) is saying that the subjectively experienced temporal sequence is purely a matter of the subjective phenomenal experience, and is not a matter of the objective timeline of the representations.

Yes, that is how I interpreted it also. It seems to me that if experiences can be experienced in a different sequence from the brain-events that (let us assume) cause them, then this shows a lack of correlation between phenomenal states and (observed) brain-states. This lack of correlation would seem to cause problems for Dennett's general theory. But I haven't thought this through very carefully so may be doing him an injustice.

On my interpretation, Dennett’s explanation is coherent, and consistent with conscious experience simply being a sequence of brain-states.

Could this be the case if the temporal order of each may sometimes not coincide? To me it seems not.

Btw, I'm not suggesting there is no such thing as the flow of time. Clearly there is. But the question remains as to whether this flow is more than something experienced by conscious beings. As soon as we assume it is more than this then the notion of time becomes paradoxical. This suggests to me that it is no more than a psychological phenomenon. If it exists inherently then how would it come into existence at the Big Bang and cease to exist at the Big Crunch?

Regards
Canute

 

[moving finger]

Hi Canute

I’m finding it hard to understand what it is you are trying to say in parts of your post, so I have tried to focus in my reply below on the main issues where I am having trouble. If you think I have missed important issues please do bring them up.

I would say the same about space. In physics the question of whether spacetime is fundamental is, I think, known as the 'background-dependence problem'. One solution recently proposed is the 'hypothesis of duality', by which spacetime is or is not fundamental depending on which way we look at it. In other words, it has so far proved impossible to show that there is not something more fundamental than space and time.

Are you suggesting that space does not exist (except as a creation of the conscious mind), or are you saying that space does exist independently of our conscious minds but that space may not be “fundamental” (whatever that might mean)?

No? Where would you say it is?

If space is not fundamental then this question is meaningless. This may sound like insanity but it makes some sense in the context of a wider theory, honest.

I disagree. If space exists independently of consciousness then the question "where in space does consciousness exist?" has meaning (regardless of whether that space is “fundamental” or not). Are you perhaps suggesting that space does not exist except as a creation of consciousness?

Sorry to be cryptic but I'm not trying to push any particular view on you, just point out that not all the assumptions you make are necessary.

No assumptions are “necessary”. If they were, they wouldn’t be assumptions, would they? An assumption (or premise) may be (logically) true or false, but it is never (logically) necessary.

To arrive at any attempted understanding or explanation of the world, we must make assumptions. Exactly which assumptions we make are up to us – each particular assumption is logically contingent and not logically necessary – but we cannot make any inferences (deductive or inductive) without at least some assumptions.

Does the concept of time exist in the absence of conscious observers?

I think the answer is in the question. The only place a concept can exist is in a mind.

I disagree, but again this would take us off-topic. A concept (to me) is simply a particular relationship between particular sets of information (in much the same way that an explanation is). We are used to experiencing concepts and explanations as properties of conscious minds, but to generalise and say that all concepts and explanations exist only within conscious minds would be to commit an anthropocentric error.

You have changed “neural events” to “neural corrlates”. Obviously a “correlate” must be correlated with something, otherwise we would not call it a correlate. But not all neural events are correlated with phenomenal consciousness.

I see what you mean. But I used the term quite carefully, to distinguish any old event from those that, according to the physicalist view, are responsible for (or identical with) experiences.

You used which term carefully? “neural event” or “neural correlate”? Your intention may have been to use the word “neural event” carefully, but how am I supposed to have known your intent without clarification? In your original post you said :

the timing of neural events may not coincide with the timing of mental events

And I agreed, partly because obviously not every neural event is correlated with phenomenal consciousness

The interpretation came from an article by C. Whitehead in the Journal of Conscious Studies, in which he talks about experiments by Bierman showing that non-conscious physiological anticipation of decisions not only precedes conscious decision-making, but begins even before any implict learning can have occured. He writes 'In layman's terms this means that neurones appear to be clairvoyant'.

Another (to me more rational) interpretation of the events you describe is that not all “mental decisions” originate within consciousness (or : So-called “conscious decisions” are often preceded by non-conscious decisions) – no need to invoke anything spooky!

This interpretation actually fits perfectly with the idea that (consciously) subjective timelines may reflect a different temporal sequence compared to objective timelines - because our minds are deliberately reconstructing the temporal sequence of events to aid subjective interpretation.

It seems to me that if experiences can be experienced in a different sequence from the brain-events that (let us assume) cause them, then this shows a lack of correlation between phenomenal states and (observed) brain-states. This lack of correlation would seem to cause problems for Dennett's general theory. But I haven't thought this through very carefully so may be doing him an injustice.

I agree it shows a lack of correlation between some phenomenal states and some (observed) brain states, but given that not all brain-states are correlated with phenomenal states anyway, I see no problem.

Here is one way it could happen (I am not suggesting this is a rigorous explanation, just a sketch of a possible explanation) : The subjectvely perceived temporal sequence (the phenomenal sequence of events) would effectively be a mental reconstruction based on (a set A of objectively observable) causal brain-states; that reconstruction would entail the creation of (a set B of objectively observable) additional brain states. The set B of brain-states would be temporally (sequentially) connected with the phenomenal temporal sequence, but the set A of brain-states need not be so temporally connected.

On my interpretation, Dennett’s explanation is coherent, and consistent with conscious experience simply being a sequence of brain-states.

Could this be the case if the temporal order of each may sometimes not coincide? To me it seems not.

Yes, it could be the case if we accept that not all brain-states have phenomenal correlates.

Btw, I'm not suggesting there is no such thing as the flow of time. Clearly there is.

It is not so clear to me. I do not believe that time flows, I believe that what we think of as the flow of time is an illusion.

But the question remains as to whether this flow is more than something experienced by conscious beings. As soon as we assume it is more than this then the notion of time becomes paradoxical. This suggests to me that it is no more than a psychological phenomenon.

Agreed. Isn’t that the definition of an illusion?

If it exists inherently then how would it come into existence at the Big Bang and cease to exist at the Big Crunch?

Even if time does not flow, this question still needs to be answered (but there are rational answers available)

Best Regards

 

[Canute]

I’m finding it hard to understand what it is you are trying to say in parts of your post

Sorry about that. Clarity is not my strongest suit.

Are you suggesting that space does not exist (except as a creation of the conscious mind), or are you saying that space does exist independently of our conscious minds but that space may not be “fundamental” (whatever that might mean)?

I'm suggesting that the phenomenal is ontologically prior to the psychophysical, including spacetime. In other words, that time is an epiphenomenon. By saying spacetime is not fundamental I mean that there is something prior to spacetime. Colin McGinn conjectures that consciousness originates in a 'pre-spatial reality prior the Big Bang'. This is more or less what I'm suggesting, although I wouldn't put it like this.

Are you perhaps suggesting that space does not exist except as a creation of consciousness?

Yep.

To arrive at any attempted understanding or explanation of the world, we must make assumptions.

That's an assumption. Still, although I could disagree let's assume it is true. The aim then would be to make as few assuptions as possible, and only those that are absolutely necessary in order to proceed.

... , but to generalise and say that all concepts and explanations exist only within conscious minds would be to commit an anthropocentric error.

How can a concept exist outside of a mind? You could argue that the referent of the concept refers exists outside the mind, but not the concept itself.

You used which term carefully? “neural event” or “neural correlate”? Your intention may have been to use the word “neural event” carefully, but how am I supposed to have known your intent without clarification?

You aren't, I should have been more clear. But I did clarify later.

Another (to me more rational) interpretation of the events you describe is that not all “mental decisions” originate within consciousness (or : So-called “conscious decisions” are often preceded by non-conscious decisions) – no need to invoke anything spooky!

The spookiness is necessary because the brain-states anticipate their cause. (Hence 'retro-causation'). It's not a question of the brain-states preceeding the phenomenal states. It's that the brain-states seem to anticipate the brain-states that cause them, a much tougher problem.

I agree it shows a lack of correlation between some phenomenal states and some (observed) brain states, but given that not all brain-states are correlated with phenomenal states anyway, I see no problem.

But according to Dennett the phenomenal states are a consequence of correlated brain-states. This idea would be called into question if phenomenal states can occur in a different order from the brain-states with which they are supposed to be correlated, or so it seems to me.

Here is one way it could happen (I am not suggesting this is a rigorous explanation, just a sketch of a possible explanation) : The subjectvely perceived temporal sequence (the phenomenal sequence of events) would effectively be a mental reconstruction based on (a set A of objectively observable) causal brain-states; that reconstruction would entail the creation of (a set B of objectively observable) additional brain states. The set B of brain-states would be temporally (sequentially) connected with the phenomenal temporal sequence, but the set A of brain-states need not be so temporally connected.

If the set B are observable brain-states then the set A is irrelevant. It is the relationship between B and the experienced sequence that is the issue. To explain any lack of correlation between these you'd have to posit a set C of brain-states. Next you'd have to posit a set D, and so on.

Alternatively, suppose A is the set of all observable brain-states. In this case the temporal sequence of A and the experienced sequence should be strictly correlated. If not, then would it not follow that something is happening in experience that is not correlated to brain-states?

It is not so clear to me. I do not believe that time flows, I believe that what we think of as the flow of time is an illusion.

In this case we agree.

Even if time does not flow, this question still needs to be answered (but there are rational answers available)

We agree here also.

If time does not flow then how do explain its apparent flow? (You may have answered this earlier but I came in late).

Cheers
Canute

 

[moving finger]

If time does not flow then how do explain its apparent flow? (You may have answered this earlier but I came in late).

Will respond to rest of your latest post later, but see post #20 (which is where you came in). The argument in brief is :

Our intuition that time flows comes from our conscious subjective perception of the flow of time.
Subjective timeline sequences of events do not map linearly to objective timeline sequences of events.
Subjective event sequences can even sometimes run counter to objective event sequences (ie as if subjective time were somehow flowing “backwards” compared to objective time).
We each have different subjective timelines.
We have no reason to think that the “flow” of any individual subjective timeline is representative of the absolute flow of time (since different subjective flows can run counter not only to the objective timeline but also counter to each other).
Thus, if any timeline is “fundamentally flowing” in any particular direction, it must be the objective timeline (rather than the subjective) timelines.
But since we only ever experience subjective flow, it may also be the case that the objective timeline is static (not flowing).
Thus, we cannot conclude from our subjective perception of time’s “flow” that time does indeed flow.

 

[Tournesol]

Time is an abstraction we make from the motion of things.

This is a physics newsgroup, and in physics, motion is based on time, ntot he other way round.

Since there is no such thing as time itself, it is meaningless to consider time to have physical existence.

Your grounds for saying that there is no such thing
as "time itself" are that it doesn't exist separately
from specific instances. But you could say the same
about charge or mass, or anything else in physics
But we do grant them physical existence because
they have specific instances.

The notion of time running backwards implies that all motions would be reversed and that all history would retrace its steps backward. It’s not possible. There are too many things that prohibit the reversal of time. Water can’t change its direction through a check valve. Electrons cannot change their direction through a diode or transistor.

If you reverse all the laws of physics ,
you reverse all the laws of physics. The problems
you mention will "cancel through".

The Earth would have to change its direction of rotation in order to make sundials tell time backwards. If it changed its direction instantaneously there wouldn’t be a human-built structure left standing and there would be horrific flooding. Instead of people getting younger they would be killed; that wouldn’t be a backward replay of history. And if it changed direction slowly, there would be terrible destruction as equatorial oceans moved towards the poles during the reversal. That, too, would not be a backward replay of history. The notion of time reversal, of history running backward, is self-contradictory.

If you reverse the direction of the Earth and nothing else,
you will have that problem. because structures on its surface
will comntinue to have their old momentum.

If your reverse everything, you reverse everything, inlcuding the
momenta of structures on the Earth's surface.

 

[Tournesol]

Tournesol writes: "I know of no theory that explains the feeling of flow as an illusion. It is either illlusory and inexplicable or explicable
and non-illusory."

Try having a look at the theory of emptiness as expounded by Nagarjuna, or dhamma theory as expounded in the 'Abhidhamma' (one of the 'three baskets of teachings' in Buddhism). In this view spacetime is a psychological construct, as I think it was for Kant.

That would be illusory and inexplicable, then.

Nagarjuna's Fundamental Wisdom of the Middle Way is a proof that the notion of time as existent is inherently paradoxical. He makes a reductio argument similar to Zeno's. In this view, at the deepest level of analysis nothing really exists and nothing ever really happens (really!). Roughly speaking, he argues that the past does not exist, the future does not exist, and thus the notion of the present moment is incoherent (an argument related to the 'Dedekind Cut' in mathematics).

That kind of purely logical argument is just as applicable
to the mental as it is to the physical. If it shows that time
cannot exist outside the head, it equally shows that it
cannot exist inside, making it an inexplicable illusion,
it the conclusion that it is psyhcological is to be accepted.

The feeling of the flow of time is a quale. It is a characeteristic
of qualia that an "illusory" quale -- a hallucination of the colour
red, for instance, -- is every bit as real as a real one.

So saying that the flow-of-time is psychological
doesn't explain how it can exist psychologically,
if it can't exist physically. It is an inexplicable illusion,
if it is an illusion.

The Wheeler-Feynman 'absorber theory' of time is, I think, still well thought of by physicists. In this entities can move both backwards and forwards in time quite happily, quite as if the flow of time is an illusion.

AAAGh! That's the direction of time!

 

[Tournesol]

n, a deterministic universe, all moments in time are preset, and would seem to have some kind of existence.

In a block universe. Determinism is quite compatible with the
idea that the future doesn't exist yet.

 

[Tournesol]

Is the Flow of Time an Illusion?

The argument seems to be : Conscious agents perceive time as if the agent is “flowing in time” from the past into the future, and from this perception it is allegedly safe to infer that such agents are not simply under the illusion of “flowing in time”, but indeed (and objectively) they are “flowing in time” from the past to the future.

I shall show that this inference is invalid.

Experiments by Libet and Grey Walter on the differences in the objective and subjective (experienced) correlations between temporally separated events show that the mind can reconstruct or rearrange the actual temporal sequence of perceptual information coming from phenomenal events, such that the consciously perceived (the experienced) sequence is not the same as the objective sequence of events (see the paper by Dennett and Kinsbourne referenced below). Libet explains this in terms of “backwards referral” or “backwards projection” of certain consciously experienced events with respect to other consciously experienced events. Dennett describes this kind of mental manipulatioon of the objective sequence of events in terms of Orwellian and Stalinesque models of mental representation.

1) showing that we misinterpret temporal sequence doesn't show
there is no such thing (we misinterpret everything to some extent)...

2) ..Libet's setup assumes that there is an objective sequence of
events in the first place.

Thus if time really does “flow” (and we are to believe that this flow is not an illusion), then all but one of the above timelines (since they reflect different sequences of events) must be an illusion. Which of the above timelines would one think represents the real “flow of time” – the objective timeline or one of the the experienced timelines? It obviously cannot be one of the experienced timelines (because we each experience different timelines, and none of us is in a privileged position of being able to claim to have direct access to the “absolute flow of time”), therefore (if anyone timeline flows) it must be the objective timeline. But if this is the case, then it follows that we each sometimes perceive time as flowing in the opposite direction to the way it is objectively flowing! Thus, our subjective experience of the flow of time is indeed an illusion (whether the objective timeline really “flows” or not), and we thus cannot infer from our perceived or experienced flow of time that objective time is actually flowing at all.

You are confusing flow with sequence.

 

[Tournesol]

Given certain facts in the current state of physics research, I wonder if the concept of "current moment" has any sure physical support.

Global current moment or local current moment ?

1) GR has no global time evolution, as John Baez says,

Global, then.