I don't think there is any science which truly reveals how long the present is for a human being, but I've seen reports of lengths up to a couple seconds. This is not the duration of the present, in any objective sense, because human experience is. purely subjective.

Also, I think that when you speak of your awareness of an event which just happened, as part of your experience of the present, I think you need to include your awareness (anticipation) of an event which is about to happen, as part of your awareness of the present.

Perhaps neither time or space are ontologically primary. Space is just a relationship between events and time (and duration) are just the formation and perishing of events. So the process philosophers would tell us and some interpretations of Quantum would not contradict.

Also, I think that when you speak of your awareness of an event which just happened, as part of your experience of the present, I think you need to include your awareness (anticipation) of an event which is about to happen, as part of your awareness of the present. — Metaphysician Undercover

How can I perceive a duration if I exist within this duration?

I have an experience of the present, and this experience might be a moment of time or might be a duration.

Prior to this moment in time or duration is the past. My memories of past events must be part of my present experience. My anticipation of future events must also be part of my present experience.

I am aware of my existence.

If I existed outside a duration, then I could be objectively aware of it.

In order to subjectively perceive a duration, I cannot exist at only one moment in time, but must exist within this duration.

But if I existed within a duration, then my awareness, which has a duration, cannot be aware of its own duration. My only awareness could be of a timelessness.

It seems that our perceptions may not be of duration but of timelessness.

So I walk. My friend walks two meters away from me..the space we occupy and between is. Is secondary to my friend and I?
What would that mean. That first matter existed and space is just something that existed afterwards as a result from matter existing and changing?

I get that there is a relationship between them. In the traditional sense. in space exists matter and it changes. But I can't imagine matter existing first. It seems more that the relationship is interdependent or that space is primary.

The meaning of absolute space (independent of events) or of absolute time (independent of events) escapes me and many philosophers and physicists.

Newton thought of space like an rigid empty box into which events and matter were placed.
Einstein modified space into a deformable box more like a trampoline or sponge, deformable by matter.

Without events (in a completely empty universe) what would the meaning of space be?
Without events in relations to each other how would we measure, experience or conceive of space?

How can I perceive a duration if I exist within this duration? — RussellA

Why not? You have a multitude of senses, a brain, and all sorts of tools within your body, which could enable you to experience the very duration which you live in. Your question is like asking how can I experience the same world which I exist within?

But if I existed within a duration, then my awareness, which has a duration, cannot be aware of its own duration. My only awareness could be of a timelessness. — RussellA

I do not see the logic here.

Why not? You have a multitude of senses, a brain, and all sorts of tools within your body, which could enable you to experience the very duration which you live in. Your question is like asking how can I experience the same world which I exist within? — Metaphysician Undercover

I exist within a world of trees and mountains, but I am external to these trees and mountains.

The problem arises when I am not external to what I experience.

Can an experience experience itself. Can a thought think about itself.

Can a duration be aware of its own duration?

I exist within a world of trees and mountains, but I am external to these trees and mountains.

The problem arises when I am not external to what I experience. — RussellA

You're really not making sense Russel. People are not external to their experiences. Experience is an intrinsic aspect of being a human being. It doesn't make sense to talk about experiences which you are external to, or which are external to you.

Can an experience experience itself. Can a thought think about itself. — RussellA

Sure, Aristotle claimed that thinking about thinking is the highest virtue. Why would you move to exclude the possibility of such activities?

Can a duration be aware of its own duration? — RussellA

Isn't this the only way that a duration could be accurately measured? The thing experiencing duration must be aware of its own duration in order to measure that duration. This is the case of all measurements, they are inherently subjective, being interpretations made by a subject, of the subject's experience.

That is what constitutes "empirical science", human beings being aware of their own sense experiences, and using conventional tools, established standards, to measure these sense observations. The conventional standards which are applied, are said to be "objective", because they have been justified, but the thing measured is subjective, as a sense observation, and the act of measurement is also subjective, as an act of the subject. So the subject is aware of its own subjectivity, and making measurements of that subjective experience, using objective standards.

Therefore we ought to conclude that a subject can be aware of its own duration, just like it can be aware of any sense experiences, and proceed to make measurements of that duration in a similar way to the way that it makes measurements of any sense observations, by being aware of them, and applying "objective" standards to measure them.

You're really not making sense Russel. People are not external to their experiences. Experience is an intrinsic aspect of being a human being. It doesn't make sense to talk about experiences which you are external to, or which are external to you. — Metaphysician Undercover

Probably so, in that I am not explaining myself very well.

Trying analogies: i) can one hand wash itself, ii) can a snooker ball at rest start to move without any external force, iii) can the mind be conscious of its own consciousness, iv) can something arise from nothing, v) can there be an effect without a cause, vi) does an evil person think that they are a good person.

Suppose I experience an object moving from right to left. What is the relation between "me" and "my experience"? Is "my experience" external or internal to "me". "My experience" cannot be external to "me", otherwise I wouldn't know about it. Therefore "my experience" must be internal to "me".

However, if "my experience" is internal to "me" but separate to "me" then this is the homunculus problem (Homunculus argument - Wikipedia).

Therefore, "my experience" must be "me", in that I am my experiences rather than I have experiences.

So, if I am my experience, there are not two things, "me" and "my experience", but there is only one thing, "me", where "me" and "my experience" are one and the same thing.

I agree when you say "Experience is an intrinsic aspect of being a human being."

But that means there exists only one thing, "me" This one thing can be called either "me" or "my experience", as they are one and the same thing.

My question is, accepting that one thing can be aware of a second thing, how can one thing be aware of itself?

This takes me back to my analogies, how can one hand wash itself.

How can a single thought think about itself?

How can a single thought that has a duration think about its own duration?

Trying analogies: i) can one hand wash itself, ii) can a snooker ball at rest start to move without any external force, iii) can the mind be conscious of its own consciousness, iv) can something arise from nothing, v) can there be an effect without a cause, vi) does an evil person think that they are a good person. — RussellA

I would answer "yes" to some , "no" to others, so I don't see the relevance.

Suppose I experience an object moving from right to left. — RussellA

You are repeating the same basic mistake. You have an experience, within yourself, and you interpret the significance of that experience, as an object moving from right to left.

Notice how your description leaves out a key aspect, the means of sensation by which you drew that conclusion. So instead, your description would be more accurate if you said, I saw something move from right to left, or I heard something move from right to left, or I saw and heard something move from right to left.

When you include this, the means of sensation, you indicate that this part of your experience, seeing that, or hearing that, is not your complete experience. So "an object moving from right to left" is not what you experience, it's an interpretation of a part of your experience, what you saw, heard, etc. The interpretation itself is another part of your experience.

However, if "my experience" is internal to "me" but separate to "me" then this is the homunculus problem — RussellA

I didn't say it is separate, I said it is "is an intrinsic aspect of being a human being". This means that it is a part of being human, not something separate.

Therefore, "my experience" must be "me", in that I am my experiences rather than I have experiences. — RussellA

No, my experience is not "me", it is a part of me, just like my heart is, and my brain is, except it is a different type of part of me, a different category.

But that means there exists only one thing, "me" This one thing can be called either "me" or "my experience", as they are one and the same thing. — RussellA

Do you understand what "an aspect" means? It is impossible that the aspect is the same as the thing it is an aspect of, or else it wouldn't be "an aspect"?

My question is, accepting that one thing can be aware of a second thing, how can one thing be aware of itself? — RussellA

I really do not understand why you think that self-awareness is impossible. Are you not aware of yourself? If you think that you are not self aware, maybe you cold explain why?

This takes me back to my analogies, how can one hand wash itself.

How can a single thought think about itself?

How can a single thought that has a duration think about its own duration? — RussellA

A hand can easily wash itself, it uses tools, wash basin, scrub brush, etc.,. You may have experienced this if you've injured a hand. I really think you are placing undue restrictions, and trying to make a problem where there is none to be found. Why do you limit yourself to "a single thought" when you are thinking about duration?

Have you ever noticed that you can think a number of different thoughts at the same time? When you count the number of chairs in a room, you must think about what qualifies as a chair, and also count at the same time. That's how we measure, and make comparisons in general. So, you can see the object move from right to left, and also watch your clock, at the very same time, to measure how long it took. This is because the human experience is made up of many different aspects, all occurring at the same time.

No, my experience is not "me", it is a part of me, just like my heart is, and my brain is, except it is a different type of part of me, a different category. — Metaphysician Undercover

I agree that "my experience" is a part of my being human, not being something separate.

But is it the case that my experiences are a part of me as my heart is a part of me?

My experiences being a part of me suggests that "I" could exist without them. But is this true?

"I" can exist without a heart, as long as I am on a life-support machine, but can "I" exist without my experiences. If "I" had no experiences, would there be an "I"?

"My experiences" are fundamental to the possibility of there being an "I" at all.

As there cannot be an "I" in the absence of experiences, my experiences cannot just be a part of what "I" am.
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So "an object moving from right to left" is not what you experience, it's an interpretation of a part of your experience, what you saw, heard, etc. The interpretation itself is another part of your experience. — Metaphysician Undercover

The words "experience" and "perceive" need to be defined. The word "experience" as with the word "perceive" has more than one meaning.

One meaning is independent of the senses and another meaning involves the sensations.

In the first meaning, contained within the mind, I am experiencing fear and I perceive their fear. In the second meaning, dependent upon the senses, I experience something moving from right to left and I perceive something moving from right to left.

When talking about being able to perceive duration, I would say that perceive is being used in the first sense.
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I believe we actually perceive motion, activity, and this requires temporal duration, therefore we do perceive duration. I think that the "moment in time" is an artificial construct. — Metaphysician Undercover

I am still interested in how we are able to perceive duration.

If I existed at one moment in time, I could not perceive the duration of time.

It is true, however, that if I did exist at one moment in time, I could compare my memory of the object being to the right at time 2pm and being to the left at time 2.05. This would allow me to perceive that there had been a duration of time.

Therefore, in order to be able to perceive the duration in time, it cannot be the case that I exist only at one moment in time, but in some way exist throughout that duration.

I can judge a duration from the viewpoint of one moment in time, but how can I judge a duration when I am part of that duration?

My experiences being a part of me suggests that "I" could exist without them. But is this true? — RussellA

This isn't really true, if it is what is called an essential part. This means that it is a necessary part,

I am still interested in how we are able to perceive duration. — RussellA

I think it has to do with what I said about being composed of different parts, and comparison between them. The brain compares information from various senses for example. This is like comparing different, yet concurrent experiences. So for example, you see something in the distance, and hear the sound a bit later, you can know from watching your watch how long it took for the sound to arrive relative to the visual image.

It is true, however, that if I did exist at one moment in time, I could compare my memory of the object being to the right at time 2pm and being to the left at time 2.05. This would allow me to perceive that there had been a duration of time. — RussellA

That is not perception, it is a deduction. Deduction does not qualify as "perceive" in either of your definitions.

I can judge a duration from the viewpoint of one moment in time, but how can I judge a duration when I am part of that duration? — RussellA

"Judge" is a much better word to use here than "perceive". The problem is that your preferred definition of "perceive" allows ambiguity in the division between what is sensed, and what is produced by judgement. So for example, if you say that you perceive a tree, that there is a thing you perceive, and it is a tree, is actually judgement. Judgement inheres within the perception. The actual sensation is just information. However, the information is always mediated through the brain, and therefore some degree, or form of judgement applied, before it is even present to the conscious mind.

You may want to excluded all judgement from sense perception, and ask whether we can perceive temporal duration. But that is not a realistic version of perception. Then if we allow judgement to inhere within perception, we have the problem of drawing the boundary between judgement prior to conscious judgement, and posterior to conscious judgement.

In other words, it appears to me, that you want to design your definitions of "judge" and "perceive", to allow that you can judge duration if there are moments in time, and deny that we could perceive duration if there are no moments in time. What's the point to this?

I believe we actually perceive motion, activity, and this requires temporal duration, therefore we do perceive duration. I think that the "moment in time" is an artificial construct. — Metaphysician Undercover

"Judge" is a much better word to use here than "perceive". — Metaphysician Undercover

From the Merriam Webster Dictionary, "perceive" can mean i) to attain awareness or understanding of, ii) to become aware of through the senses.

As regards sense ii), I perceive something and judge that it is a tree.

As regards sense i), I perceive not a moment in time but a duration of time. Judgment doesn't come into it

In order to be able to perceive not a moment in time but a duration of time, I must exist not at a moment in time but within a duration of time.

If I exist within a duration of time, how can I know that I exist within a duration of time?

Without events (in a completely empty universe) what would the meaning of space be?
Without events in relations to each other how would we measure, experience or conceive of space?

The meaning of space if there was no matter? Meaning as in what it IS. Or what the purpose of it would be? If purpose. Does it need a purpose? If you mean what would space be without matter. Space. Rather than the three-dimensional thing we would point to in which matter is. It would be that same thing without matter.
If it is possible for it to exist without matter. As I said I would assume space to be primary or interdependent to matter (including quantum fields and so on) But not secondary.

Time I find to be harder. I don't know. Is it really some "thing" part of space or is it just something that helps us explain motion across extension. And which only emerges because of motion conceptually. And is there in some ultimate sense no time. That sounds very stupid even if I say it myself. But I don't know. Maybe our intuition is just of. Maybe we are bringing something to reality. Maybe everything just happens at the same moment. On the other hand it feels not intelligent to think that even though I am currently home. That when I was at work that it was just happening at the same moment and any notion of past and present and even moment is just arising from motion but isn't really there.

If there was no motion anywhere in the universe. Does time still exist? (Remind yourself if you imagine that scenario that you observing that state assumes motion and you'll probably assume as a result that time would still exist. But does it really since there would be no observer?)

Many physicists and philosophers argue that time might emerge from relationships between events rather than existing as an independent entity.

yes I agree. I think time isn't a thing part of space. It's just what we use to explain motion across extension (space). And motion and the natural ability to move is affected by the lack of or presence of other matter and forces. So if nothing moved at all, no time would exist.

If I exist within a duration of time, how can I know that I exist within a duration of time? — RussellA

As I said, it's basically the same way that you can know anything about the environment which you live in. You can be an extreme skeptic, and deny that you can know anything, but what's the point?

As I said, it's basically the same way that you can know anything about the environment which you live in. — Metaphysician Undercover

I know about my environment because I can see trees and mountains. But my experience of temporal duration only exists in my mind, and is not something that I can see in my environment.

Therefore, I cannot know about temporal duration in the same way that I know about my environment.
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You can be an extreme skeptic, and deny that you can know anything, but what's the point? — Metaphysician Undercover

A sceptic may deny that trees and mountains exist in the world. However, a sceptic cannot deny that they experience a sense of temporal duration.

Even for the sceptic, there is a difference between what exists in the mind and what exists outside the mind.

I know about my environment because I can see trees and mountains. But my experience of temporal duration only exists in my mind, and is not something that I can see in my environment.

Therefore, I cannot know about temporal duration in the same way that I know about my environment. — RussellA

When you look at a tree, do you not see the leaves moving in the breeze? When you look at a mountain, do you not see clouds moving? These activities are indications of temporal duration. In the very same way that you deductively conclude that you can see things called "trees" and "mountains", you can also deductively conclude that you are seeing temporal duration.

The problem here seems to be that you are not allowing that seeing activities qualifies as evidence of seeing temporal duration, yet you do allow that seeing something relatively static, an object, qualifies as evidence of seeing objects like trees and mountains. Therefore I insist that you are being inconsistent in the premises which you accept as true, in producing your deductive your conclusions. You allow that staticity is evidence of something, but you do not allow that activity is evidence of anything.

A sceptic may deny that trees and mountains exist in the world. However, a sceptic cannot deny that they experience a sense of temporal duration.

Even for the sceptic, there is a difference between what exists in the mind and what exists outside the mind. — RussellA

As explained above, you appear to be biased in your skepticism. You allow that perception of staticity is evidence of something real in the world, objects like trees and mountains, but you disallow that perception of activity is evidence of something real in the world, like temporal duration.

The problem here seems to be that you are not allowing that seeing activities qualifies as evidence of seeing temporal duration, yet you do allow that seeing something relatively static, an object, qualifies as evidence of seeing objects like trees and mountains. — Metaphysician Undercover

I am assuming by temporal duration we mean that time itself cannot be reduced to a moment in time. As the Planck length is the smallest measurable unit of length, there is a smallest unit of time. ie, a duration.

As you wrote:

I believe we actually perceive motion, activity, and this requires temporal duration, therefore we do perceive duration. I think that the "moment in time" is an artificial construct.

I look at the world and can see a tree, static at one moment in time. I can also see the tree bending in the wind, an activity through time.

The static tree is evidence of there being an object, a tree, in the world. The tree actively bending in the wind is evidence of there being temporal duration in the world.

However, I believe that we approach this from different philosophical positions. I assume that you support Direct Realism (though I may be mistaken), whereas I support Indirect Realism.

From your position (if you do support Direct Realism), we perceive the world as it is, where trees and trees bending in the wind exist independently of our perception of them. From my position, the world of trees and trees bending in the wind exist in the mind.

From your position, within the world independent of any observer is temporal duration. From my position, as the world exists in the mind, temporal duration exists in the mind.

Therefore from your position, as the world exists independently of the mind, the temporal duration observed in the world exists external to any observer. From my position, as the world exists in the mind, the temporal duration observed in the world exists in the mind. It follows that for the Indirect Realist, whether there is or there is not temporal duration external to any observer is unknowable.

I am assuming by temporal duration we mean that time itself cannot be reduced to a moment in time. As the Planck length is the smallest measurable unit of length, there is a smallest unit of time. ie, a duration. — RussellA

There is a further problem involved, if we assume that time itself cannot be reduced to a moment. There is then the question of what exactly is a moment. If time itself is continuous duration, then "the moment" is artificial, fictitious, something just made up by us for practical purposes. For example, we assume "a moment" which separates before 7:00 AM from after 7:00 AM, and this moment provides the foundation for measurement. Therefore, if time itself is actually continuous, without moments, yet our measurements of time are dependent on the use of such moments, then our measurements are fundamentally flawed, because they employ a concept which is not representative of time in reality.

I look at the world and can see a tree, static at one moment in time. — RussellA

I am very skeptical of this statement, and I would ask you to reevaluate. If you saw a tree at a moment in time, how could you ever determine whether that tree is static or not? If activity requires passing time, and there is no passing time in a moment, you would not be able to determine whether the tree is static or active without watching it for a duration.

I do believe that if you reflect on your actual experience, you'd recognize that you do not ever see a tree at one moment in time.

However, I believe that we approach this from different philosophical positions. I assume that you support Direct Realism (though I may be mistaken), whereas I support Indirect Realism. — RussellA

This makes no sense to me.

Therefore, if time itself is actually continuous, without moments, yet our measurements of time are dependent on the use of such moments, then our measurements are fundamentally flawed, because they employ a concept which is not representative of time in reality. — Metaphysician Undercover

This is the same problem with space as there may be with time.

The Planck length is the smallest unit of length, approximately equal to 1.616 x 10^-35 meters.

In a sense, our measurements of both space and time may be fundamentally flawed, in that, as there is no position in space, there may be no moment in time.

However, this is not a problem in practice, as the minimum length and duration are so small. The standard metre bar introduced by the French more than 200 years ago has done pretty well at introducing a practical and usable system of linear measurement.

Our measurements may be approximate, but for most situations, approximate measurement are good enough
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If activity requires passing time, and there is no passing time in a moment, you would not be able to determine whether the tree is static or active without watching it for a duration. — Metaphysician Undercover

Even if time is just moments in time, we still have our memories.

Suppose time is just moments in time and has no duration. When I look at a tree in the present, I see the tree at only one moment in time, and I can only see a static tree.

However, at that moment in time in the present when looking at the tree, I also have a memory of the tree in the past. By comparing the state of the tree in the present to my memory of the tree in the past, I know that the state of the tree has changed, meaning that the tree has moved.

Even if time is just moments in time, because of my memories, I can still distinguish between a static tree and a moving tree.
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This makes no sense to me. — Metaphysician Undercover

One's opinion as to whether or not there are fixed moments in time in a large part depends on whether one believes objects such as trees exist independently of being observed (Direct Realism) or objects such as trees only exist in the mind. (Indirect Realism)

In part, when talking about a tree being static or moving, for the Direct Realist this tree (and the space and time it exists within) exists in a world independent of any observer and for the Indirect Realist this tree (and the space and time it exists within) only exists in the mind.

Direct Realism and Indirect Realism are obviously mainstream philosophical positions.

Which bit makes no sense.

This is the same problem with space as there may be with time.
The Planck length is the smallest unit of length, approximately equal to 1.616 x 10^-35 meters.
In a sense, our measurements of both space and time may be fundamentally flawed, in that, as there is no position in space, there may be no moment in time. — RussellA

Actually, the Stoney scale is roughly 1/10 the duration of the Planck scale in time measurements. These are simply units of measurements, not ultimate bounds in a some philosophical sense. If you were to ride on that photon as it traverses a Planck length, time would vanish completely for you.

I have wondered why certain physical facts about time have not entered into these discussions. For example, as you stand on the side of the road and someone passes you in a car going 60mph, time is measured infinitesimally slower for them compared to you. And someone drifting above you in a balloon measures time infinitesimally faster than you. In the calculus of physics an instant of time is a limit concept, not an established fact.

This is the same problem with space as there may be with time. — RussellA

I don't think these two are similar at all. When we look at things in space, we see all sorts of boundaries, the edges to objects, etc., but we do not find any such boundaries in time. All boundaries in time, except the boundary between future and past, are completely arbitrary. And the boundary between future and past is very indefinite because it's always changing.

Would it be fair to say that duration is what all change has in common? And that some changes are simultaneous?
So, putting change first, i.e. going by change then trying to work out time.
Kind of rudimentary I suppose.

If so, then it might be possible to formalize duration as a metric, a positive number, and simultaneity as a relation, reflexive, symmetric, not transitive.
(Non-transitive because two simultaneous changes need not have the same duration, but I'm just throwing it out there.)

Time as an abstract could then be the pair — metric and relation — operating on change.
Don't know if that works, but it seems fairly close to what we do.

These are simply units of measurements, not ultimate bounds in a some philosophical sense. If you were to ride on that photon as it traverses a Planck length, time would vanish completely for you......................I have wondered why certain physical facts about time have not entered into these discussions. — jgill

I have taken the following from an article by Zhen Liang - IS SPACE DISCRETE? AN INQUIRY INTO THE REALITY OF PLANCK LENGTH AND ITS PHILOSOPHICAL IMPLICATIONS

For time to vanish sounds philosophical.

Philosophically, in the past, space has been considered infinitely divisible.

Space has always been considered infinitely divisible and thus continuous throughout the western philosophical traditions beginning with the ancient Greeks......................However, this notion of space has also been questioned and challenged since the very beginning. Zeno of Elea, a disciple of the pre-Socratic philosopher Parmenides who denies the reality of motion, was the first and foremost (at least that we know of) to disturb our notion of space with his famous paradoxes.

Einstein's theory of relativity has changed our conception of space, time and motion, but does not refer to whether space is continuous or not.

Therefore, Einstein’s theory of relativity, although forever changed our conception of space, time, and motion, still leaves the continuity of space untouched.

As the metaphysical reality of the Planck length is problematic, whether space is infinitely divisible or not, the same seems to apply also to time, whether time is infinitely divisible or not.

I don't think these two are similar at all. When we look at things in space, we see all sorts of boundaries, the edges to objects, etc., but we do not find any such boundaries in time. — Metaphysician Undercover

Imagine an object moving through space.

Suppose at t = 75 seconds the edge of the object is at x = 1.2 metres. Suppose at t = 80 seconds the edge of the object is at x = 1.6 metres.

As the edge x = 1.2 metres is a boundary between less than 1.2 m and more than 1.2 m, t = 75 seconds is a boundary between less that 75 seconds and more than 75 seconds.

And the point?

And the point? — Metaphysician Undercover

There are boundaries in time as well as space. Including the boundary between the present and past.

Your example doesn't show that, because "1.2 metres" requires two boundaries which are determined empirically, and "75 seconds" is designated arbitrarily.

The spatial boundaries are determined by empirical principles, while the temporal boundaries are stipulated arbitrarily.

The spatial boundaries are determined by empirical principles, while the temporal boundaries are stipulated arbitrarily. — Metaphysician Undercover

Yes, we can only know the object the edge of the object is at x = 1.2 metres empirically.

But how can we know that this happens when t = 75 seconds, if not empirically?

Yes, x = 1.2 metres is arbitrary, but also t = 75 seconds is arbitrary.