Ontology of time

[tar]

Swansont,

 

I think I am in agreement with you, but I may not be in total agreement. Truth and validity have a certain ability to change, from one reference frame to another. At great distances from my here and now, and at great speeds in reference to my here and now's rest frame, the universe is not "currently" doing any one thing. It is doing many things. And those things will not reach my here and now all at once, they all come to me, as "past" events. Philosophically, my now, is composed of the rest of the universe's past, and the rest of the universe will experience me in its future. Closer things sooner, farther things later. What I was doing 4 and a half years ago is currently true on Alpha Centuri. On a planet 100 lightyears from here, I have not yet been born. If something is to match with observation it by definition must be a confirmation of a past truth, if a "current now" is imagined to exist similtaneously across the entire universe. And with a changing, distant event, viewed in this manner, the "truth" you are witnessing is no longer, what is really happening "currently" at that distant moving event site.

 

So if Alpha Centuri has a record of 53 years of my life, and the planet 100 light years from here has no record at all, and I remember being in the universe for 57 years, where and when exactly should be considered the current true universe, where something is either valid or not? (and hence Owl's concern of objective and subjective truth)

 

Regards, TAR2

Edited July 10, 2011 by tar

[owl]

Tar,

Here is the Wikipedia link to presentism:

http://en.wikipedia.org/wiki/Presentism_%28philosophy_of_time%29

 

It contrasts the well known “light cone” concept of relativity to a very common sense version of time, with which I agree.

 

In the modern theory of relativity, the conceptual observer is at a geometric point in both space and time at the apex of the 'light cone' which observes events laid out in time as well as space.

 

Stcherbatsky, ...: "Everything past is unreal, everything future is unreal, everything imagined, absent, mental… is unreal… Ultimately real is only the present moment of physical efficiency [i.e., causation]."[2]

 

As I've argued repeatedly in this thread (and it seems absolutely obvious to me), the past is dead and gone, and the future is not yet present (duh!) Time is not such an entity as the "light cone" or spacetime concept assumes. The "block universe" has everything that has ever existed and everything that will ever exist as "real" and dependiing only on point of view from individual points of perception in each possible "light cone."

In contrast, one version of presentism (with which I agree) asserts that now is ongoing, everywhere, i.e., that the present is present everywhere, that there are not an infinite number of "time environments" as in the "light cone" model.

Philosophically this perspective transcends relativity's focus on (and obsession with, I would say) what frame of reference sees what images (or gets what information) from where and when. In other words this version of presentism does not take the speed limit of light and resulting "signal delay" to be the ultimate limit and ontological absolute for what is real and existing in the present in the whole universe. Relativity can not be denied for for what it covers (leaving length contraction and time dilation out of it for now.)

 

Once we get over the reification of time as an entity (see my argument for time as only event duration for physical processes, EDPP) we can begin to see that the present is omni-present.

We must begin by realizing that "is" means now... the present, and there are no local "time environments" for each supposed "point in spacetime" at the apex of each imaginary "light cone."

[swansont]

Once we get over the reification of time as an entity

The "we" to whom you refer — who is that? You and the straw man in your pocket? I'd like to know who is reifying time as an entity.

[owl]

The "we" to whom you refer — who is that? You and the straw man in your pocket? I'd like to know who is reifying time as an entity.

Wikipedia on reification:

# Reification (fallacy), fallacy of treating an abstraction as if it were a real thing...

 

‘In other words, it is the error of treating as a "real thing" something which is not a real thing, but merely an idea.

 

As you know from my threads on the ontology of time and spacetime I have often asked what it is that gets "morphed" when relativity talks about curved spacetime or dilated time (what "dilates" other than clocks ticking slower?)... or... what expands in the cosmology of "expanding space" besides the fact that things in space (empty volume, no entity) get further apart?

 

Anyway, rather than to keep repeating myself, I took a brief net tour on reification and time dilation, and gleaned the following:

 

From answers.yahoo.com:

How is our reification of time, as a concept, ("tick, tick, tick") different from 'space-time' and relativity?

Jensen:

The tick, tick, tick, of a clock is just about as tangible as you can get.

Zerzan:

Yes, it makes time concrete; it reifies it. Reification is when an abstract concept is treated as a material thing. A second of time is nothing, and to grant it independent existence runs counter to our experience of life. Anthro- pologist Lucien Levy-Bruhl wrote: "Our idea of time seems to be a natural attribute of the human mind, but that is a delusion. Such an idea scarcely exists where primitive mentality is concerned."

(Please read "primitive" as "natural", ontologically "existing in reality", not just a concept.)

 

From the “Time Dilation” section at www.thebigview.com/spacetime/timedilation.html :

As stated earlier, if the speed of light is constant, time cannot be constant. In fact, it doesn't make sense to speak of time as being constant or absolute, when we think of it as one dimension of spacetime. Special Relativity states that time is measured according to the relative velocity of the reference frame it is measured in.

 

Interestingly, while time expands from the perspective of the stationary observer, space contracts from the perspective of the moving observer.

 

Unfortunately, time dilation is completely outside of human experience, because we have not yet devised a way of travelling at speeds where relativistic effects become noticeable.

 

(Not quite true, as seen in sub-atomic particle accelerators, but with no transference to larger scale... as discussed here in detail.)

 

"...Time expands..." How is this NOT a reification of time. Something is seen as expanding. And you have said that it is more than just the slowing down of clocks, which means that you do reify time as an expanding (I know, you prefer "dilating") entity of some kind. (Ontology identifies a range of meanings for "entity.")

 

swansont:

Straw man, appeal to ridicule, straw man. (In case you're scoring at home: equating

science with philosophy, using "magically" and "actually" to describe length

contraction and equating it with an illusion, describing the earth as "deforming")

 

Do you have a substantive rebuttal to the argument that earth does not actually flatten out under any circumstances even though it appears to do so, or are you going to keep repeating “straw man” as if that addresses the substance of my argument?

 

And the Cap 'n still hasn't clarified the apparent contradiction cited again in my last post. If earth does not morph out of shape, then the observation which says that it appears that it does shows that appearances can be deceiving (my point about illusion in last post), which is well known in the psychology of sensation and perception as well as being a basic principle of stage "magic."

[tar]

Owl,

 

I have to get ready for work and think and write quite slowly, so I will have to complete this thought later...but, I do see a reality, that is addressed by all the philosophies being considered here. What seems to happen though is imagination is considered "unreal" which I do not believe is true.

 

One way to "look" at this, is that the entire universe, has not yet done what it is going to do next. Each point in the universe is at this knife edge. All points are real, and existant. And all points consist of the reality that, up to this knife edge point, have happened to it.

 

The past is thusly not "unreal" but the actual compilation of all of the rest of the universe that has reached that particular "spacial" knife edge point.

 

This is not inconsistant with any of the philosophies, or sciences studying the universe.

 

If we "imagine" the universe this way, it describes the reality of the situation, even if we do not "see" it all at once.

 

Got to go.

 

Regards, TAR2

[swansont]

"...Time expands..." How is this NOT a reification of time. Something is seen as expanding. And you have said that it is more than just the slowing down of clocks, which means that you do reify time as an expanding (I know, you prefer "dilating") entity of some kind. (Ontology identifies a range of meanings for "entity.")

 

It's from sloppiness and lack of a better description. It's also from inference; if you asked physicists if time was a substance, you would get a lot of "no" responses. But that never really comes up, because it doesn't get in the way of doing physics. People speaking as if a model was reality is not the same as insisting that a conceptual point is a real thing. It's a convenience because with the limitations of spoken language it's awkward to do it otherwise. Nobody wants to have to recite a disclaimer before everything they say or write, on the off chance a layperson is listening or reading who doesn't understand the basic nature of science.

 

Do you have a substantive rebuttal to the argument that earth does not actually flatten out under any circumstances even though it appears to do so, or are you going to keep repeating “straw man” as if that addresses the substance of my argument?

 

And the Cap 'n still hasn't clarified the apparent contradiction cited again in my last post. If earth does not morph out of shape, then the observation which says that it appears that it does shows that appearances can be deceiving (my point about illusion in last post), which is well known in the psychology of sensation and perception as well as being a basic principle of stage "magic."

I suspect Cap'n is getting tired of repeating himself, and I know I've answered this before. The concept has been clarified, and yet you continue to repeat the same misconceptions. Each frame of reference yields a different answer. None can be regarded as universally true, i.e. there is no "real" length with all the others being "fake" or illusory. There cannot be, because there is no objective way to determine who is at rest and who is moving.

 

The substance of your argument is that you are the one reifying time and distance, which makes it very convenient to rebut, since nobody else is truly reifying them. That's why it's a strawman. You are misrepresenting relativity. It would behoove you to study the physics and develop an understanding of it before you trash it.

[owl]

swansont:

I suspect Cap'n is getting tired of repeating himself, and I know I've answered this before. The concept has been clarified, and yet you continue to repeat the same misconceptions. Each frame of reference yields a different answer. None can be regarded as universally true, i.e. there is no "real" length with all the others being "fake" or illusory. There cannot be, because there is no objective way to determine who is at rest and who is moving.

 

The substance of your argument is that you are the one reifying time and distance, which makes it very convenient to rebut, since nobody else is truly reifying them. That's why it's a strawman. You are misrepresenting relativity. It would behoove you to study the physics and develop an understanding of it before you trash it.

 

I will reply in my thread in philosophy on frame of reference as subject in subjective idealism, as that is where this topic belongs.

[tar]

Owl,

 

If I do something, the effects of it, the notice of it having occurred, goes out, from my location in all directions (depending on the medium available) at the speed the medium transfers "messages". There are sound waves, compression waves, electrical signals, changes in magnetic fields, and a host of photons launched off at various wavelengths.

 

Of all the above, photons, (whether wave or particle,) are the "fastest". There is nothing faster (but thought.)

 

The photons leaving my event reach event location B in a particular time.

 

Here, the EDPP, is not happening at my location, it is happening between A and B. The event is the release of the photons at A and the arrival of said photon at B. The "time" the event took (that is the release at A and arrival at B) is unknown, by either A or B. Now if B reflects the signal back and A "times" the duration of the new event (A signals B, B reflects signal back), A can divide the amount of ticks on his clock by 2 and know the "time" it takes to send a signal to B. (if A and B are are at rest in regards to each other in the medium the signal is transmitted through.)

 

Now if B is moving in regards to this medium all bets are off. Dividing A to B to A, by 2 will still define the time A to B took.

But unlike the at rest pair, the next signal test, will show A to B to A took a different time.

 

In the "at rest" situation, I can synchronize my ticks with B's ticks, and even though B may be receiving my tick 3 ticks later (A to B to A takes 6 ticks) both A and B can imagine the other on the same tick, by subtracting or adding the 3 ticks as appropriate. The EDPP of the ticks will be the same.

 

However, "now" becomes a bit harder to determine when A and B are moving toward or away from each other (or both, in the case of a particle in an accelerator) because the ticks are not in sync, and not only do you have to add or subtract the three ticks, but each successive A to B to A event times out differently, so it isn't easy to know, not only when to add or subtract to imagine a now, but how much to add or subtract. If you go by the information derived from the first A to B to A passage of time, to determine the next, you will be wrong. And if B is moving away, its ticks will come to you at a longer wavelength (red shift). I would guess this means as well, that A sees B and B sees A in slow motion.

 

If A and B are moving toward each other (at a good percentage of C,) I suppose the blue shift would make each other see the other in fast motion.

 

But this is all the EDPP of A to B to A, changing, in terms of how A and B sycn up to the other's now.

 

It does not say that EDPP at B "actually" slows down, at B, depending on B's speed, or depth in a gravity well.

 

Except that experimentation with the cesium clocks flying East and West shows that EDPP actually does change with distance from the center of the Earth, and when flown with and against the rotation of the Earth.

 

What's that about?

 

What is "it" that is changing?

 

Regards, TAR2

[owl]

Tar,

Seems you went the long way around to get to the core question:

"What is "it" that is changing?"

Except that experimentation with the cesium clocks flying East and West shows that EDPP actually does change with distance from the center of the Earth, and when flown with and against the rotation of the Earth.

 

What's that about?

 

What is "it" that is changing?

 

What is changing is the rate of clocks' ticking, the Event Duration of Physical Process in this case. There is no 'thing, time' changing.

[md65536]

In contrast, one version of presentism (with which I agree) asserts that now is ongoing, everywhere, i.e., that the present is present everywhere, that there are not an infinite number of "time environments" as in the "light cone" model.

Philosophically this perspective transcends relativity's focus on (and obsession with, I would say) what frame of reference sees what images (or gets what information) from where and when. In other words this version of presentism does not take the speed limit of light and resulting "signal delay" to be the ultimate limit and ontological absolute for what is real and existing in the present in the whole universe. Relativity can not be denied for for what it covers (leaving length contraction and time dilation out of it for now.)

 

Once we get over the reification of time as an entity (see my argument for time as only event duration for physical processes, EDPP) we can begin to see that the present is omni-present.

We must begin by realizing that "is" means now... the present, and there are no local "time environments" for each supposed "point in spacetime" at the apex of each imaginary "light cone."

How do you reconcile this presentism with lack of simultaneity?

No matter how you explain it, you will be able to find examples where events--non-causally related ones--are seen and determined to occur in different orders for different people. Do you have an explanation for that that is compatible with presentism?

 

I have my own interpretations of SR that I thought were compatible with presentism.

I tried to make it work but I just can't provide an explanation of how different events could occur in different orders, and yet have a single "present" that is shared by the different observers.

 

The only way I've been able to make it work is to "flatten" time at all locations to a single instant (meanwhile treating the universe as a point singularity).

This treats "duration" as completely subjective or perceptual.

If you remove duration to make presentism work, then time becomes nothing but causal relationships with no concept of anything "taking time".

But this removes so much from the concept of time, that the meaning of present is completely changed, if not lost entirely.

 

 

Are you willing to consider such bizarre ideas, or does your version of presentism work with evidence from "plain everyday experiences", while denying things like lack of simultaneity? If the latter, then I'm not interested.

 

 

[tar]

I tried to make it work but I just can't provide an explanation of how different events could occur in different orders, and yet have a single "present" that is shared by the different observers.

md65536,

 

I know you weren't asking me, but I personally accept the both.

 

The only way you can jive experience with all the experimentation that has been done, is to consider the entire universe being exactly as old as you are. Except, what we see of it is historical in nature, when the overall mental picture is considered.

 

I imagine it as photons going out from my location in an ever increasing (at the speed of light) sphere.

 

Each object that ever was in the universe has this sphere. If an object has a lifetime, I imagine its life of photon emmisions being an ever increasing "shell" with its birth at the outside surface and its death at the inside surface.

 

So a particular object we see has a number of "nows" we can consider. One is the momentarily thin spherical shell that is passing through me, at the "same time" that it is passing through everything that happens to be the same light travel time or radius from the object that I am from it. (adding motion to the object creates sort of a cone shape thing over time, but at any moment, its a thin spherical slice of a sphere.)

 

Another "now" is to consider the image we receive as an actual extension of the "event" that is that object.

 

Another is to imagine the object's condition the exact amount of time later, as light took to reach us.

 

Unfortunately for my mental image, there are an incredible amount of objects to consider, many of them, with an "outside" shell that has "already" passed through my location long ago, before my birth.

 

Causal relationwise if we see it, it has already been affecting us (or our location) because we are inside its outer shell and yet to see it disappear (its inside shell).

 

But us humans are built to be able to put ourselves in other entities shoes. We can do the frame shifting thing back and forth, and imagine how it sees us, and we it. Two way communication may take too long to ever occur, but it can be imagined. And each frame, as long as its consistent with the others, is "real".

 

What isn't real, is imagining "seeing" the whole operation at once, it can only be "thought of" at once. As it turns out, the way the universe actually looks, is the way we see it. With a star we see 4.5 lightyears distant, appearing to us as it was 4.5 years ago (considering it currently existing in the same "universal" moment, that all points, exactly as old as we are ( us being Earth's matter,) are in.

 

In this way, events happening in a different order from a vantage point of different stars is not hard.

 

Event A at Alpha Centuri will happen first on a planet orbiting it, second, 4.5 years later, here, and some hundreds of thousands of years later, on a planet on the other side of the milkyway, and 10s of billions of years later on a planet made of the stuff we see that appears to have "just" released its photons as the universe became transparent.

 

Why stick to one frame, or one philosophy, when you get a better view, switching realistically between them?

 

Regards, TAR

Edited July 19, 2011 by tar

[md65536]

In this way, events happening in a different order from a vantage point of different stars is not hard.

Well yes, a finite speed of light makes it easy to consider events being seen at different times from different locations.

 

But consider this:

If the current moment is a universal present, then it seems safe to assume that any previous moment could also be considered a universal past moment.

Then if you consider a past momentary event, that event would have to have occurred in a universal moment.

Some other event at a different time would have to have occurred in another universal moment.

Since these moments are universal, they would have to occur in the same order according to anyone (otherwise, when the first event occurred according to one person in a universal present, it had already happened according to another person, in which case it was a past moment, not the present).

Therefore, presentism and this line of reasoning implies that lack of simultaneity (not just the appearance of it) is impossible. Yet SR implies lack of simultaneity.

 

Is there any flaw in my reasoning?

It might be possible to argue that once the "present" passes, it loses its universality, and that past moments are not universal, making it possible to change the order of past events. However I don't know if this argument could be tenable.

 

 

Lack of simultaneity is a reality; the simplest form of presentism must not be.

[tar]

md65536,

 

I don't see the problem. I fully agree that our present is not the same present as any other place and time. This is probably the basis of relativity. A fact that can not be ignored, and should not be ignored. Light takes time to get around. But it is also the case that starlight enters our eyes, and reports to us the "presence" of said star. We have to admit that the star is real, and existant in the universe. It therefore must have existed to emit the photons, however long ago it took for the photons to get here. The "long ago" assumes a hypothetical, imaginary consideration, that a "now" that is not dependent on light to report its presence, but that can be "figured out", exists concurrently at my eye, and at every other "place" in the universe, that has exactly the same amount of history from the big bang that my eye has.

 

Us actually experiencing the events that are occuring "now" everywhere else in the universe, depends on their distance from us. What is happening at the other side of the room will reach me in nanoseconds, what is happening at your location will reach me in less than a second, what is happening at the Sun will reach me in 7

minutes, what is happening at Alpha Centuri will reach me in 4.5 years.

 

So what is happening similtaneously to my now, is every other positions "now". At every place in the universe, there exists "age of the universe" worth of history, "age of the universe" worth of photon emmission and reception, "age of the universe" worth of evolution of particle development and decay. And in a nanosecond, every location will experience a "new" moment, in which their location is "age of the universe"+1 nanosecond, which, as soon as the nanosecond passes, is the new "age of the universe".

 

What is difficult is to "know" this is the case, and never being able to "see" it. Light is too slow, to allow us to ever experience the entire universe, in this "now" condition.

 

In fact, we can only experience our own now, ever. That this is everything elses now as well, is a fact that we can only share in thought. We can never actually share the moment...till later...in retrospect.

 

So this universal now, has no practical importance, but to visualize the stage upon which we are set. And to comprehend the nature of that which we experience, and that which the "stuff" that makes us up, has experienced in the last 13.7 billion years.

 

What is nice about the arrangement, is that we get to actually see in the sky, what stuff was doing in the past, and by analogy can study our stuffs history. Close stuff, our recent history, and far away stuff our distant past.

 

But the separation, in time and distance, between ourselves and the rest of the universe's "now" is both real and immense. On the other hand, our involvement with all of the observable universe is immediate, because we experience it in our very real now. AND this input from the rest of the universe has been going on continually, since the universe became transparent. So we have had a constant historical connection, with it all.

 

Which now one talks about can vary. Whose shoes, when, are you putting yourself in the shoes of?

 

For instance, one has to define the collective observers you are lumping together, and the grain size of the moment you are considering, as in "now" meaning the early 21st century for Earthlings.

 

 

I think where you get in trouble is thinking that past present and future define the same subsets, from both our now, and the universal now. This is not the case. Remember, what we figure to be, is not the same as what we experience.

 

We always experience our present. We always remember our past and we always predict our future.

 

A different place experiencing our universal now, is what will actually appear in our future. And anything we actually see represents what was going on there, in one of our past universal nows.

 

There is no actual platform from which one can actually experience the universal now. (Other than human imagination).

 

Regards, TAR2

Edited July 19, 2011 by tar

[owl]

md65536:

How do you reconcile this presentism with lack of simultaneity?

No matter how you explain it, you will be able to find examples where events--non-causally related ones--are seen and determined to occur in different orders for different people. Do you have an explanation for that that is compatible with presentism?

 

Everything everywhere IS happening NOW, simultaneously. That is the version of presentism with which I agree. The focus of relativity is always on, as I’ve said repeatedly, “Who (frame of reference) sees what and when.” This obviously depends on the light speed limit as conveyor of images and information (signal delay.)But the "objective universe," as it is, does not depend on how and when we see what. This is philosophical realism as contrasted with subjective idealism where frame of reference is substituted for subject. (See my thread in Philosophy.)

 

If you remove duration to make presentism work, then time becomes nothing but causal relationships with no concept of anything "taking time".

But this removes so much from the concept of time, that the meaning of present is completely changed, if not lost entirely.

 

So, as above, presentism doesn’t deny that it takes time for light to travel and convey info. The event duration for such travel of light from sun to earth is 8+ minutes, so when we see a given solar flair, for instance, we know that it actually happened 8 minutes ago. But this is not to deny that now is the present both here an on the sun... and throughout the universe.

[tar]

Owl,

 

But this is not to deny that now is the present both here an on the sun... and throughout the universe.

 

Well as long as you differentiate between the universe's now, and an observer's now.

 

The entire observable universe is visible "now" from an observer's point of view. But not in its universal now state. The universal now state can only be imagined to exist. But it (the universal now) can be reasoned to exist, because we have experiential proof, that an earlier observer's now (yesterday) coincided with an earlier universal now, by witnessing the arrival of images of the events that occurred one lightday away, in yesterday's universal now.

 

The trick (which I am still working on) is to advance ones own now, at the same rate as one advances the universal now, and factor in the distance/time between events that occur in the universal now, that show up here and now with various delays, depending on their distance. (Events happening in the Universal now, today, on the other side of the Milky Way, won't show up here for 100,000 years.) (And we consider the Milky Way our "home" and "nearby" galaxies our neighbors, as if we could run over and borrow a cup of sugar.)

 

The stars we see in the sky are "present". They were there yesterday, and will be there tomorrow. We can count on them. They exist in our reality, in just the condition we see them in. But from our observer point of view, our here and now.

 

Regards, TAR2

[owl]

TAR2:

Well as long as you differentiate between the universe's now, and an observer's now.

Presentism recognizes that the word IS needs no relativity discalimers about "my now" vs the "universe's now"... that "the present" is omnipresent, without local "nows" fro each supposed "time environment."

If you understand my definition of time as Event Duration for Physical Processes (EDPP), the explanation is mush easier. Every physical process (everywhere) has a duration between one designated "now" and another, between the clicks of a stopwatch held by the measurer, or "all by itself" like one complete revolution of earth, or one complete orbit. Time=event duration, whether or not a specific event, as above, is selected and measured.

 

Now, the present, on the other hand, has no duration. All that is, IS, right now, this instant (forget about the time it takes to say it), everywhere. Light traveling from one place to another is an event that takes time... in all cases.

Time is not a thing or an environment, as misrepresented in the phrase, "time dilation," for instance, in which something is thought to expand "from the frame of reference" of one point of view or another. Clocks just tick faster or slower for many reasons, including changes in speed or gravitational fields.

The above is time ontology, not just repetition of the relativity concept of time dilation as a proven given. Yes, some muons live longer and travel further than others, without morphing either time or distance traveled.

[tar]

Owl,

 

I believe there to be a few problems with "All the universe happening now".

 

For instance, if that was true yesterday, what is true today?

 

Or, which "now" are you considering happening "now" on Alpha Centuri?

 

Problem with, or perhaps the nature of, the universe is that it does not all arrive everywhere at the same time.

 

I have no problem with considering everything happening "now", from a God's eye view, that is not constrained by the speed of light, but that is an imaginary condition. Possibly a "true" way to view it, but the happenings in this "now" do not arrive here instantly. 8 minutes for happenings at the Sun, 4.5 years for those on Alpha Centuri, hundreds of thousands of years for distant parts of the Milkyway and so on.

 

And you can never "get to" those other nows. You can only be at the one you are at.

 

There remains a slippery thing, even to consider one's own now, much less the translation to something light-years away.

 

For instance, what happened to my now, that I was experiencing 2 hrs. ago at work. It is no longer present here and now. However somebody on Jupiter, or whatever platform is 2 lighthours from here, with a powerful telescope, trained on the building I work at, would see me outside, smoking, NOW!

 

So all the universe is not happening now. We can designate our now being shared immediately by every other point in the universe, and substract back and find out when that now will arrive here, and when our now will arrive there. But its a mental excercise, except for what we know had to have happened in retrospect. When we see light coming from the Sun, we know it had to have been shining 8 minutes ago, and when we see Alpha Centuri shining in the sky, we know it had to have been shining 4.5 years ago, but we have absolutely no way to see what it is doing now.

 

Unless of course if we consider, as far as we are concerned, what it is doing now, is what we see it doing.

 

These are the "two" nows I can count. The universal one we imagine, and the actual one we see.

 

And in actuality the universal now comes into our actual now, at various times, depending on the distance of the event.

 

But I do not believe you can call both types of now, by the same name, without keeping them as separate conceptions. One that you experience, and one that you imagine occurring.

 

Regards, TAR2

[owl]

Well, TAR,

I must say that it sounds like you didn't even read (or understand) my last post, beginning with the following:

 

Presentism recognizes that the word IS needs no relativity disclaimers about "my now" vs the "universe's now"... that "the present" is omnipresent, without local "nows" for each supposed "time environment."

 

Of course it "takes time" for light/information to travel across any/all distance...signal delay. That does not create some medium, "time" through which light must travel or different "nows" at separated points/locations.

 

But you seem to totally ignore the above, saying:

For instance, if that was true yesterday, what is true today?

 

Or, which "now" are you considering happening "now" on Alpha Centuri?

 

Problem with, or perhaps the nature of, the universe is that it does not all arrive everywhere at the same time.

 

The following statements are all true, according to presentism:

Now, the present IS the present, not the past, not the future. The present is not a local phenomenon in each and every different "point/locus" in the universe. However, "it takes time" (event duration) for light and information to travel between loci.

 

I gave the example that now is the same now (events happening in the ongoing present) here and on the sun, and that, of course what we now see on the sun happened over eight minutes ago.

 

This all seems to me to belabor the obvious**, but the point relative to the thread subject is that neither time nor the omni-*present* now is a medium of any kind with malleable properties, for instance, in the case of "time" or local boundaries in the case of now, the present.

** I simply can not get your sense of meaning in:

 

So all the universe is not happening now.

 

(My bold.)Must we re-define "is" to make sense of it? In what sense can either the past or the future be considered, "now, the present?" (The first is not still present; the second is not yet present!)

 

Stuff happens. It "takes time." But events happening doesn't create something called time.

I hope this clarifies presentism and time ontology, because I can think of no better/clearer way to present it.

[tar]

Owl,

 

There may be some subtle, difficult to translate, but important differences to talk about here. I have read your posts carefully and some several times. I easily may be misunderstanding, and I have not read your thoughts, on threads other than the ones I post to.

 

There may be some areas we disagree on. And I restate similar ideas with some important distinctions that I think are pertinent. Not so much to prove that I don't understand, as to point out an area of disagreement.

 

I am also on the "twins" thread, in Physics/relativity and subjectivity/objectivity and the theory of relativity, and the Ontology of time. All having this in common. Our personal model of the world, is of the same world that everybody elses model is of. It is important for each of us to have a "correct" model, it is built into our nature, to feel good when we "get it" and get it right. And we have no hestitation in sharing our "correct" findings and discoveries with others.

 

However the search for the "correct" understanding is complicated by each of us holding our own "correct" model, that while it jives with reality, does not jive with somebody elses model in all cases.

 

Thus the power and draw of the special relativity, and the general relativity theories and the efforts to find the way the two domains complete each other in an overall theory that fits together seemlessly.

 

Here, outside of my floating my own concerns, with other people's models, including those of physicists, I have a pretty reasonable feeling that although I don't understand the equations and what they are saying and not saying, it is way more likely that "their" model is a correct model of reality, than is yours, or mine, alone. That is because they are addressing, and have been addressing the same reality that we are referring to, but have done it in a systematic, triple checked way, in concert with others with the same intent. For many years. Ideas that seemed reasonable, but did not hold up, under the strain of logic, precise definition and testing, were discarded. What remains is a vast body of work that not only fits reality, but fits the careful models of it that were built by others in the past.

 

If you and I say "time dilation" makes no sense, it is more likely that we "are not listening" to what they are saying, than it is that they are saying an incorrect thing. Hence the "strawman" that SwansonT brings up from time to time. We can't point to a misunderstanding of the theory, and say "there" you see where you are wrong.

 

I have to resign myself to the fact that I am not the first to look at this, not the only one to look at this, and certainly not the smartest to look at this. And the best train going to my destination, has already left the station. It is probably better to try and catch up, or take the next train, than to think the train is on the wrong track.

 

Regards, TAR2

[owl]

TAR:

If you and I say "time dilation" makes no sense, it is more likely that we "are not listening" to what they are saying, than it is that they are saying an incorrect thing. Hence the "strawman" that SwansonT brings up from time to time.

 

I have agreed many times in many different ways that clocks slow down at high velocity and changes in gravity field. This is empirical science. We observe the above physical process in clocks. But the claim of time dilation is that "time itself slows down" under these conditions. The difference is of paramount importance to the ontology of time... "what is it?"

 

We also observe that natural incoming muons have a longer than "expected" (from observing their lab cousins) "lifespan" during which they travel further than "expected." ("Time dilation" and "length contraction" are considered reciprocals in the above observations.)

 

So the longer lifespan is called "time dilation" as if "time expanded" for these high speed particles, rather than simply seeing that they live longer. And the atmosphere through which they travel, well known to be around 200 miles, is "seen" as "contracting" to much less distance "for the muons."

 

This is how time dilation and length contraction are examples of what I call "frame of reference idealism," negating an objective world independent of observation, and making all frames of reference ("for the muons" etc.) into equally accurate descriptions of the world.

 

So, Earth IS various shapes, according to various frames of reference; Meter rods ARE way shorter as viewed from high speed frames... and "time expands" at high speed, etc.

 

All of the above is ontology, about which most physicists don't give a hoot. Seems that the "objective nature of the world/cosmos" ( and philosophical realism) is not a relevant interest to many of them... and I though it (quoted) was the essence of science!

[tar]

Owl,

 

But there is such a thing as conventions.

 

My favorite example being, that if a group of explorers and scientists, talking to each other, comparing notes and building together a model of the world, created a globe, a model of the world, but they where from an area of the world, below the equator, they probably would have put Antartica at the top, and the Earth would be spinning in the opposite direction as we conventionaly have it going. (I came to this example while teaching a copier repair class, standing in front of a copier I asked a student behind the copier "which way is shaft A spinning" he replied "clockwise" when those in front clearly saw it spinning counter-clockwise. I thought he was looking at the wrong shaft, and we argued a bit, 'til I walked around the back to see what he was looking at, and (duh) the correctly identified shaft, WAS spinning clockwise.)

 

Regards, TAR2

 

Which way does the Earth spin? The way that appears counter-clockwise from the top, and clockwise from the bottom, of course. You take time to determine such things, because you have to look at it from different places, and different times, and determine the thing that stays the same in all cases. That is what is objectively real. Then you agree on a conventional way to call this direction and you have to carry with you all the same rules and conventions, and base the understanding on the "same" real objective examples for the "way you call it" to have meaning.

[Iggy]

I have agreed many times in many different ways that clocks slow down at high velocity and changes in gravity field. This is empirical science. We observe the above physical process in clocks. But the claim of time dilation is that "time itself slows down" under these conditions. The difference is of paramount importance to the ontology of time... "what is it?"

speaking of "what is it", what is "at high velocity"? Is the milky way at high velocity?

[owl]

speaking of "what is it", what is "at high velocity"? Is the milky way at high velocity?

Clocks on GPS satellites (I guess "satellites" is redundant here) are traveling at higher velocity around the center of earth than clocks on the surface.

Of course earth is traveling at extremely high velocity around the center of the galaxy, and the latter at unknown but ultra-high velocity of expansion outward from the bang.

But I don't think all of that is relevant to my point about clocks slowing down (observable) vs time slowing down (can't see "time".) The ongoing ontological question is, what slows here besides clocks?

[Iggy]

I maybe didn't ask very clearly. I'm asking what you mean by "at high velocity". How do you decide if something is "at high velocity"? ...edit... the question would be "how do you decide?", "how do you know", "what definition of 'high velocity' tells you that some things are at high velocity and some things are not" ...edit...

 

For GPS clocks, are you saying that all GPS clocks, no matter what direction they are moving, have a "higher velocity" than the surface of the earth?

 

For the big bang, do you think big bang cosmology proposes a point in space that is, or was, the origin of the bang from which earth is quickly receding?

 

Hopefully I worded these very clearly

Edited July 29, 2011 by Iggy

[owl]

Iggy,

I mean that clocks in orbit are traveling at higher velocity relative to earth's center than clocks on the surface, and they slow down compared to the latter, (and the gravity factor is different.)

Now, if you will re-read the "what slows down" point above again (clocks or "time") you will have the gist of my reply as per this thread's topic.

I will not here repeat my take on Big Bang cosmology. I have covered that in detail in other threads.

Leave it that cosmos is expanding outward at whatever velocity, and that its rate of expansion is accelerating.

Point: There are many different scales considering what is traveling at what velocity relative to what.