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Seiryuu
2008-Oct-17, 07:48 AM
As we know of GR, space and time are dependant on the frame of reference. In order to find an answer as to why this might be the case, I introduced the concept of variable durations in my ATM theory. What I'd like to know is if this concept is possible within the framework of GR.

This would mean that the amount of time that is measured by a second is not necessarily equal to the amount of time measured by another second. Obviously, it also means that the "amount of time" cannot be measured in seconds themselves, but rather in a number / second. I call this the concept of "stretcheable time" or "stretcheable seconds".

Again, just to clarify I'll repeat once more: the seconds themselves don't change, but rather the amount of time that "fits" in a second changes. This means that one second has a longer duration than another in a gravitational field and that changing from frame by switching to a different gravitational potential causes your seconds to become longer or shorter relative to the frames around it. You will still measure one second as a second in all frames of reference though, since that never changes.

In this sense, time dilation would be used to measure the ratio between two rates of time, but there would still be no way of measuring the actual "amount of time" that goes in a second. As you can see, I'm using "amount of time" in a context so that it becomes completely unrelated to the number of seconds though.

My apologies if this question is too ATM, but I'd really like to know if mainstream allows variable durations or not.

astromark
2008-Oct-17, 10:35 AM
Our perception of a period of time is defined by the standard time units of hours minutes seconds and parts there of. If you think that time itself has a different rate of passage some place else in this universe you are wrong. Being clear that the perception of time might be distorted by strong gravity forces ie; as found at the event horizon of the black hole. Remembering that only man measures time as he has so little of it. The universe does not bother with time. Only distance and movement and mass.

grant hutchison
2008-Oct-17, 10:53 AM
This would mean that the amount of time that is measured by a second is not necessarily equal to the amount of time measured by another second. Obviously, it also means that the "amount of time" cannot be measured in seconds themselves, but rather in a number / second. I call this the concept of "stretcheable time" or "stretcheable seconds".So how does this stretchy time differ from real time, apart from allowing you to stuff more of it into a second? Our understanding of physics works according to good old conventional time, measured in seconds. How could we access and measure your stretchy stuff, given that it's standing outside physical laws?

Grant Hutchison

Seiryuu
2008-Oct-17, 10:56 AM
Our perception of a period of time is defined by the standard time units of hours minutes seconds and parts there of. If you think that time itself has a different rate of passage some place else in this universe you are wrong. Being clear that the perception of time might be distorted by strong gravity forces ie; as found at the event horizon of the black hole. Remembering that only man measures time as he has so little of it. The universe does not bother with time. Only distance and movement and mass.

I do NOT claim that the seconds themselves pass any faster or slower in an other frame of reference. I am wondering if it is possible that the "amount of time" (really, for lack of a better word, I cannot call it anything else) in a second can be different to the "amount of time" in another second. This "amount of time" is not defined by our normal time units, as it's not being measured at all.

I do reckon that it might correspond with what you call "the perception of time can be distorted", since it's probably this distortion that I'm talking about and that I'm also calling time. So in this case, it might be possible?


So how does this stretchy time differ from real time, apart from allowing you to stuff more of it into a second? Our understanding of physics works according to good old conventional time, measured in seconds. How could we access and measure your stretchy stuff, given that it's standing outside physical laws?

Grant Hutchison

We can discuss that in the ATM forum I guess, but since I'm in Q&A, I'd like to keep it to the question: "assuming, for the sake of argument, that it exists, is it possible in GR, or is there something that would prevent this?"

Arcane
2008-Oct-17, 11:14 AM
Aren't you just stating what is already well known and described by Einstein?

A person traveling near the speed of light will see his clock ticking a second at a time just like the outside observer sees his own clock ticking a second at a time. But since the person who is traveling has less 'time' in each second he can travel a lot of light years and come back and be nearly the same age, while the other person who was on earth is long dead, or something to that affect.

To me, this means that while both observers saw seconds ticking at the same rate by their own clocks, there was actually more 'time' packed into each second that person on earth observed.

loglo
2008-Oct-17, 11:17 AM
Seiryuu,
GR talks about simultaneity and has nothing to say about duration. The only person I know of who has tried to incorporate duration into GR is Julian Barbour. He discusses it at length in his book "The End of Time" and in technical papers like "Relativity Without Relativity" and his studies on the "Machian" underpinnings of GR. He argues cogently against such schemes as yours where a rate of time is compared to a deeper or more fundamental rate of time.

Barbour's work isn't quite mainstream, but he is a published physicist attempting to derive a workable form GR using just his concept of duration, a type of action, and 3D space and some quantum theory. Last time I looked at his work there hadn't been a lot of progress in recent years. :)

Seiryuu
2008-Oct-17, 11:38 AM
To me, this means that while both observers saw seconds ticking at the same rate by their own clocks, there was actually more 'time' packed into each second that person on earth observed.

Yeah, this is what I'm trying to bring up, but I'm using this concept to turn it upside down in a larger theory, in which I start from the idea that if this 'time' does not pass, but we masses move through 'it', this would correspond with a motion in a fifth dimension that is not being measured at all. If one expresses it as "stretched time / normal time", we would get an indication of it's "speed".


Seiryuu,
GR talks about simultaneity and has nothing to say about duration. The only person I know of who has tried to incorporate duration into GR is Julian Barbour. He discusses it at length in his book "The End of Time" and in technical papers like "Relativity Without Relativity" and his studies on the "Machian" underpinnings of GR.

Thanks for pointing this out. Maybe I should do some searches on his work.


He argues cogently against such schemes as yours where a rate of time is compared to a deeper or more fundamental rate of time.

This would indeed be a good way of describing it, as I am indeed considering a two dimensional time concept, of which one rate is compared to another rate.


Barbour's work isn't quite mainstream, but he is a published physicist attempting to derive a workable form GR using just his concept of duration, a type of action, and 3D space and some quantum theory. Last time I looked at his work there hadn't been a lot of progress in recent years. :)

Well, at least he has a better background than myself. Maybe I can learn a few things from him ;)

Neverfly
2008-Oct-17, 11:43 AM
Yeah, this is what I'm trying to bring up, but I'm using this concept to turn it upside down in a larger theory, in which I start from the idea that if this 'time' does not pass, but we masses move through 'it', this would correspond with a motion in a fifth dimension that is not being measured at all. If one expresses it as "stretched time / normal time", we would get an indication of it's "speed".

Holy Vulgarity Batman!!!


I get what You're Saying Now!!
You're saying that time is not passing- you're saying we're passing through it.

Seiryuu
2008-Oct-17, 11:58 AM
The sad thing is I cannot tell if you're being sarcastic or not :s

Arcane
2008-Oct-17, 12:00 PM
Holy Vulgarity Batman!!!


I get what You're Saying Now!!
You're saying that time is not passing- you're saying we're passing through it.


Wouldn't that mean that the faster you travel the faster you would age, instead of the other way around?

Neverfly
2008-Oct-17, 12:01 PM
The sad thing is I cannot tell if you're being sarcastic or not :s

I wasn't.
Had no idea that's what you were describing.
Novel idea... But I still don't see how it works. But I gotta go away now, anyway...

Seiryuu
2008-Oct-17, 12:12 PM
At risk of having this thread moved to ATM and having to defend it once more (which I may not be willing to do after having already opened one that is running near it's end)


Wouldn't that mean that the faster you travel the faster you would age, instead of the other way around?

Well, it depends on what makes us age. If we assume that it's our measured rate of time, then counter intuitively not, because the speed is the amount of 'time' in a second.

So the faster you travel, the more 'time' you can fit in a second, just like the faster you travel in space, the more distance you cross in less seconds. This would mean that theoretically you could live for centuries expressed in 'time' that corresponds with 1 second in our measured time, of which the latter would be the same in all frames of reference, but the first not.


But please, keep in mind that I was asking a question in Q&A if the concept was possible and that I cannot discuss my ATM ideas in this forum any further, as much as I would like to elaborate :)


Had no idea that's what you were describing.

There's a reason why I orignally titled my "goofy six-legged cat thought experiment", which was full of misconceptions: "Are we all time travellers?" :p

jlhredshift
2008-Oct-17, 12:32 PM
I study science history so I have no authority here. But, I always understood the twin paradox as a frame of reference concept describing time dilation; i. e. time flows differently in different frames. Also, I understood that it takes one more dimension to describe this so as to be "outside" the events, or something like that. So, if those of you that understand this could delve into it somewhat and in a manner that I could understand I would appreciate it.

grant hutchison
2008-Oct-17, 12:51 PM
We can discuss that in the ATM forum I guess, but since I'm in Q&A, I'd like to keep it to the question: "assuming, for the sake of argument, that it exists, is it possible in GR, or is there something that would prevent this?"Unfortunately, with your "more time per second" statement, you're saying something analogous to "assuming, for the sake of argument, that black is white, what colour would it be?"
You're invoking a measure of time that doesn't coincide with the standard measure of time.

Grant Hutchison

Seiryuu
2008-Oct-17, 01:05 PM
I study science history so I have no authority here. But, I always understood the twin paradox as a frame of reference concept describing time dilation; i. e. time flows differently in different frames. Also, I understood that it takes one more dimension to describe this so as to be "outside" the events, or something like that. So, if those of you that understand this could delve into it somewhat and in a manner that I could understand I would appreciate it.

Aye, my purpose of invoking two dimensions of time would be to explain both the existence of time dilation and spacetime curvature. I would love to hear more about it as well from the experts on this forum.


Unfortunately, with your "more time per second" statement, you're saying something analogous to "assuming, for the sake of argument, that black is white, what colour would it be?"
You're invoking a measure of time that doesn't coincide with the standard measure of time.

Grant Hutchison

The correct analogy would be that "assuming purple isn't just purple, but a mixture of both red and blue, is it possible that we're only seeing red and call it purple?".

The same thing for time. I don't deny there is a red, I'm just arguing there also has to exist a blue in order for time dilation as a phenomenon in nature to exist. Of course, this is based upon my understanding of GR and may be wrong, hence the reason I'm asking in this forum.

grant hutchison
2008-Oct-17, 03:01 PM
The correct analogy would be that "assuming purple isn't just purple, but a mixture of both red and blue, is it possible that we're only seeing red and call it purple?".

The same thing for time. I don't deny there is a red, I'm just arguing there also has to exist a blue in order for time dilation as a phenomenon in nature to exist. Of course, this is based upon my understanding of GR and may be wrong, hence the reason I'm asking in this forum.If you have understood from GR that there are two different types of time, then you are mistaken in your understanding.
From your PMs, I think I see the problem. You seem to be looking for a universal "correct" time, which lets us know how fast or slow the measured times in various reference frames is going. But under relativity there is no such thing: everyone's time is equally correct. We can find routes through spacetime which alter the elapsed time we measure between two events, just as we can alter the distance we travel between the two events.

(By the way, just read through your red/blue analogy again and think about it: it's a good analogy, because it fails to make sense in exactly the way your stretchy time fails to make sense. :))

Grant Hutchison

grant hutchison
2008-Oct-17, 03:18 PM
I wasn't.
Had no idea that's what you were describing.
Novel idea... But I still don't see how it works. But I gotta go away now, anyway...It's interesting that you haven't consciously encountered this idea of observers moving through time (rather than time flowing past observers). Both metaphors are deeply embedded in our language and thought about time. Steven Pinker calls the two views "Time Is A Procession" and "Time Is A Landscape". In the first, we think of event marching inexorably past us, from the future to the past; in the second, we imagine ourselves moving through a landscape studded with events.
So we get confused when people say things like "the meeting has been moved forward an hour": is that "forward" relative to the procession of time that is passing us, or "forward" relative to our movement across time's landscape? If our current mental metaphor doesn't match that of the speaker, we end up arriving at the wrong time.
Pinker talks about the linguistic and cultural aspects of this in fascinating detail, in his book The Stuff of Thought.

Michael Lockwood goes through the philosophical implications of these two views of time in the first chapter of his book The Labyrinth of Time. (The last chapter deals with our conscious perception of time, which is something else Seiryuu seems to be interested in. In fact, Seiryuu, consider that to be a book recommendation: I can't think of another that covers all the different aspects of time that you're thinking about. :))

Grant Hutchison

SagoSans
2008-Oct-17, 04:06 PM
So we get confused when people say things like "the meeting has been moved forward an hour"

Well, that's quite interesting: I was wondering why people would get confused (my association was FORWARD=LATER). Only after reading the following sentences it became clear to me that some people indeed may think FORWARD=EARLIER. Never crossed my mind before. Shows (again) how easy it is for people to not understand each other.

grant hutchison
2008-Oct-17, 04:31 PM
Well, that's quite interesting: I was wondering why people would get confused (my association was FORWARD=LATER). Only after reading the following sentences it became clear to me that some people indeed may think FORWARD=EARLIER. Never crossed my mind before. Shows (again) how easy it is for people to not understand each other.Yep, I'm an intuitive "FORWARD=EARLIER" thinker: the meeting has moved up along Pinker's Procession of Time so that it's closer to me.

Grant Hutchison

Seiryuu
2008-Oct-17, 06:39 PM
If you have understood from GR that there are two different types of time, then you are mistaken in your understanding.

Nope, the idea was not born from GR. This isn't something I understood of GR, I was just wondering if GR said anything about it and if the idea can fit into GR. Based on what you have told me, I still think it can.


From your PMs, I think I see the problem. You seem to be looking for a universal "correct" time, which lets us know how fast or slow the measured times in various reference frames is going. But under relativity there is no such thing: everyone's time is equally correct. We can find routes through spacetime which alter the elapsed time we measure between two events, just as we can alter the distance we travel between the two events.

I hadn't answered that one yet, but the time doesn't have to be "correct". Of course it would be relative to another, but I am however looking for a measurement of time that accurately reflects the change in time rates in various reference frames, something that a second does not, since a second remains a second, no matter in which frame you are.


(By the way, just read through your red/blue analogy again and think about it: it's a good analogy, because it fails to make sense in exactly the way your stretchy time fails to make sense. :))

I think I'm confused, but er... will ponder on it :p

grant hutchison
2008-Oct-17, 06:50 PM
Nope, the idea was not born from GR. This isn't something I understood of GR ...See, that's confusing, because you seemed to say that you based this on your understanding of GR:
The same thing for time. I don't deny there is a red, I'm just arguing there also has to exist a blue in order for time dilation as a phenomenon in nature to exist. Of course, this is based upon my understanding of GR and may be wrong, hence the reason I'm asking in this forum.

(my bold)


I hadn't answered that one yet, but the time doesn't have to be "correct". Of course it would be relative to another, but I am however looking for a measurement of time that accurately reflects the change in time rates in various reference frames, something that a second does not, since a second remains a second, no matter in which frame you are.By looking for a more fundamental time measurement, you seem to be seeking a "preferred" reference frame, one from which we get a better view of the laws of physics than from other frames. And that is specifically excluded in the theory of relativity.



(By the way, just read through your red/blue analogy again and think about it: it's a good analogy, because it fails to make sense in exactly the way your stretchy time fails to make sense. :))I think I'm confused, but er... will ponder on it :pYou changed the definition of "purple" during the course of your analogy: first it was red+blue, then it was red+nothing. We can only deduce that, in your argument, blue is equivalent to nothing: that it's irrelevant. The same seems to apply to your additional, stretchy kind of time.

Grant Hutchison

Seiryuu
2008-Oct-17, 07:16 PM
See, that's confusing, because you seemed to say that you based this on your understanding of GR

Ah, I see. I have to be more carful with my words. Let me clarify: the idea of two different times came from a thought experiment. When I read up on GR however, I couldn't help but wonder that if time passes at different rates in different reference frames and our system that measures it remains the same, it could be explained due to the idea that the amount of time in seconds, or the duration of a duration is variable, instead of fixed. Relative duration so to speak. But since we'd need to differentiate between the two rates, an extra dimension is required.


By looking for a more fundamental time measurement, you seem to be seeking a "preferred" reference frame, one from which we get a better view of the laws of physics than from other frames. And that is specifically excluded in the theory of relativity.

Relativity states that the laws of physics are the same everywhere yes. I reckon an extra dimension does not violate this principle, as it would just mean that this time passes at different rates in different frames, which would be true for all of them, just like the fact that a second would be measured as a second in all frames. It would mean though that we have no way of measuring the additional time parameter in one frame of reference.

Moreover, adding an extra dimension for a variable 'time' rate in a reference frame, means the rate can also change within the frame. This would still be true for all frames, so I don't see why you would have to seek a preferred frame that somehow has different laws. They'd all have the same laws.


You changed the definition of "purple" during the course of your analogy: first it was red+blue, then it was red+nothing. We can only deduce that, in your argument, blue is equivalent to nothing: that it's irrelevant. The same seems to apply to your additional, stretchy kind of time.

Well, for everyday use, it would be irrelevant, unless it has a detectable effect. I reckon it is the cause of time dilation, meaning that if this is true, it would not be irrelevant :)

grant hutchison
2008-Oct-17, 07:42 PM
Relativity states that the laws of physics are the same everywhere yes. I reckon an extra dimension does not violate this principle, as it would just mean that this time passes at different rates in different frames, which would be true for all of them, just like the fact that a second would be measured as a second in all frames. It would mean though that we have no way of measuring the additional time parameter in one frame of reference.Yes, we already know that time passes at different rates in different frames, as observed from other frames, and that a second is always a second when observed within any given frame. So there seems to be no need for your additional stretchy time.


Moreover, adding an extra dimension for a variable 'time' rate in a reference frame, means the rate can also change within the frame.Although this is something we can't actually observe, you say. So there seems to be no need for it.


Well, for everyday use, it would be irrelevant, unless it has a detectable effect. I reckon it is the cause of time dilation, meaning that if this is true, it would not be irrelevant :)It would achieve relevance when (and only when) it made some useful prediction beyond what we already understand.
In the meantime, I simply counter your claim with my own claim that Van Rijn's invisible elf is the cause of time dilation.
Prove me wrong.

Grant Hutchison

Seiryuu
2008-Oct-17, 07:45 PM
It would achieve relevance when (and only when) it made some useful prediction beyond what we already understand.
In the meantime, I simply counter your claim with my own claim that Van Rijn's invisible elf is the cause of time dilation.
Prove me wrong.

Why should I? My question was if it is possible or if it conflicted with GR. Making it possible doesn't make my idea right, but at least I know it isn't necessarily wrong either. In the same way, your idea is also possible! Who knows, we can't know for sure :p

But yeah, as previously mentioned, the idea would be used in context, along with the idea that the 'rate of time passing' in a second would be reversed to, the 'rate of masses moving through time' in a second, which would have an effect on it's surroundings.

grant hutchison
2008-Oct-17, 07:55 PM
Why should I? My question was if it is possible or if it conflicted with GR. Making it possible doesn't make my idea right. In the same way, your idea is also possible! Who knows, we can't know for sure :pYou're missing my point, I think.
So long as you hide your stretchy time from GR, by claiming that it is not a preferred time reference, and stating that it is not detectable, then of course it can't conflict with GR, and more than Van Rijn's notoriously undetectable elf conflicts with GR.
But as soon as you wheel it out to say it explains some part of GR, then you have a burden of proof: you need to make testable claims.

So saying your stretchy time is causal but undetectable is a contentless claim, in the same way Van Rijn's claim about his invisible elf is contentless. (Which, in case you haven't encountered Van Rijn's sig (http://www.bautforum.com/members/van-rijn.html), is the point he's making with his invisible elf in the first place.)

Grant Hutchison

Seiryuu
2008-Oct-17, 08:02 PM
I understand that, but as far as I know, this is not the place for making testeable claims, so I won't do that as I'd like to keep this topic for the question on it's own, without going deeper into what I would use it for. I already have presented more than what is allowed from the rules I think.

I can give you the link if you're interested, but even then it's far from complete as it's conceptual and I would definitely need help in making it a scientific theory.

grant hutchison
2008-Oct-17, 08:16 PM
I understand that, but as far as I know, this is not the place for making testeable claims, so I won't do that as I'd like to keep this topic for the question on it's own, without going deeper into what I would use it for. I already have presented more than what is allowed from the rules I think.See, there's your problem.
So long as you make no testable claims and keep your stretchy time invisible to GR, then of course it's compatible with GR. But that doesn't mean it's acceptable within GR; just that you're managing to hide it outside GR.

If you have testable claims, then take them to ATM and see how they stand up.

Grant Hutchison

thorkil2
2008-Oct-17, 08:35 PM
I'll repeat what I said privately here. The second is always a second. There's never additional time squeezed into it. But you can treat it somewhat in the way you would treat a perspective drawing. If you view a building straight on you see certain proportions. If you stand at the corner, you see different proportions though none of the dimensions have actually changed. There's no gain or loss of length, there's only point of view. That's what's happening with time dilation. You will always experience a second as a second (as you have acknowledged), and 1 second events will always occur within and fill that second regardless of your viewpoint, but someone in a different relativistic frame will see the second stretched, and the events therein stretched as well. (edit) It's always dangerous to think in terms of different rates of time in different frames. That isn't really what's happening, even though we compare our perspectives with the number of ticks of identical clocks. That fact that the ticks don't match is a consequence of the difference in perspective, not differences in rates of time elapse. (end edit)

Seiryuu
2008-Oct-17, 08:39 PM
See, there's your problem.
So long as you make no testable claims and keep your stretchy time invisible to GR, then of course it's compatible with GR. But that doesn't mean it's acceptable within GR; just that you're managing to hide it outside GR.

If you have testable claims, then take them to ATM and see how they stand up.

Grant Hutchison

*Cough*


At risk of having this thread moved to ATM and having to defend it once more (which I may not be willing to do after having already opened one that is running near it's end)

The actual theory I submitted started out totally different, with a whole bunch of misconceptions that I have attempted to revise to the best of my abilities. But due to my lack of background, I doubt I can make it into anything more than that.

You see, I have a model based upon concepts, but I don't know how all of it translates in the actual physics, as I'm a layman when it comes to that. I can understand the concepts behind GR for example, but I just don't know what's possible and what isn't. I have to look al that stuff up or ask questions about them.

One of the reasons for this thread is an argument in that topic in that in order to describe the motion through time as I explained it, I don't need five coordinates at all and that all what I was doing was indeed simply using preferred reference frames. I strongly disagree with that, but wanted to be sure by asking in this topic. Now I'm confused again though, since I really don't see how the motion I'm describing could involve a preferred reference frame at all. Can you help me out on this one?

Seiryuu
2008-Oct-17, 08:49 PM
(edit) It's always dangerous to think in terms of different rates of time in different frames. That isn't really what's happening, even though we compare our perspectives with the number of ticks of identical clocks. That fact that the ticks don't match is a consequence of the difference in perspective, not differences in rates of time elapse. (end edit)

But if it was only a matter of perspective, how is then that clocks who were in a different frame can run slow or fast when they change back to the reference frame?

In the analogy with the building, if you change your position, you'll get to see the different sides accordingly. But if you change back, the building is still the same, no matter from which point you look at it.

For a clock this doesn't seem true. If it changes frame, it actually has undergone a change when it returns, in the sense that the time suddenly doesn't match anymore with a reference clock. How can this be explained in terms of perspective only?

grant hutchison
2008-Oct-17, 09:27 PM
*Cough*


At risk of having this thread moved to ATM and having to defend it once more (which I may not be willing to do after having already opened one that is running near it's end)Yes, I know. But either you have a claim you want to defend, or a claim you don't want to defend. It's up to you.


One of the reasons for this thread is an argument in that topic in that in order to describe the motion through time as I explained it, I don't need five coordinates at all and that all what I was doing was indeed simply using preferred reference frames. I strongly disagree with that, but wanted to be sure by asking in this topic. Now I'm confused again though, since I really don't see how the motion I'm describing could involve a preferred reference frame at all. Can you help me out on this one?Well, you've introduced a measure of time against which you judge all other measures of time, and you're telling us that that this measure of time can explain something about physics that we can't get at from standard reference frames.
Relativity doesn't work that way: all measures of time are equally valid, and all physics works out the same, across all reference frames.
So you're either introducing a preferred frame, or some sort of superframe, by which all other frames can be judged. And you're certainly not the first person to want to do that. :)

Grant Hutchison

Seiryuu
2008-Oct-17, 09:44 PM
Yes, I know. But either you have a claim you want to defend, or a claim you don't want to defend. It's up to you.

Yes, that's what I regret. I would love to see an option to just discuss ATM ideas in a more informal way, just like it happens here in Q&A.


Well, you've introduced a measure of time against which you judge all other measures of time, and you're telling us that that this measure of time can explain something about physics that we can't get at from standard reference frames.
Relativity doesn't work that way: all measures of time are equally valid, and all physics works out the same, across all reference frames.
So you're either introducing a preferred frame, or some sort of superframe, by which all other frames can be judged. And you're certainly not the first person to want to do that. :)

Hmm, I don't think I have, correct me if I'm wrong. The measure of time isn't used to judge other measures of time, it's simply that: another measure of time. This time is treated like a dimension of space in which one can move through. Just like you have meters and seconds, you would have the time and seconds. If you want to know the rate at which you move through time, it would be expressed in amount of time/second. The dimension would not judge frames, it would be part of the frames.

grant hutchison
2008-Oct-17, 09:50 PM
But if it was only a matter of perspective, how is then that clocks who were in a different frame can run slow or fast when they change back to the reference frame?

In the analogy with the building, if you change your position, you'll get to see the different sides accordingly. But if you change back, the building is still the same, no matter from which point you look at it.

For a clock this doesn't seem true. If it changes frame, it actually has undergone a change when it returns, in the sense that the time suddenly doesn't match anymore with a reference clock. How can this be explained in terms of perspective only?Thorkil2's analogy is good for imagining how one inertial frame observes another; it's less good for round trips, when one observer has to change inertial frames in order to make a return journey.
Here's another analogy, which applies more directly to the "twin paradox" of differential ageing. You and I start off from a street corner. You walk a city block directly north. I walk a block east, north, and then west, to rejoin you at the same finishing point. You're not surprised when I report that I have walked farther than you have, to get to the same point. You're content that simple geometry explains my "greater elapsed distance" between starting and finishing points. The straight line between two points in flat space always produces the smallest "elapsed distance"; a zigzag route is always longer.
However, in the peculiar geometry of Minkowski spacetime, the straight line between two spacetime events always produces the largest elapsed time along that worldline. Any other worldline that zigzags around the spacetime diagram will arrive at the finish event with a shorter elapsed time.

We don't need some sort of master clock to explain the time differences, any more than we need a master metre to explain the distance differences: it's just how the maths works.

Grant Hutchison

grant hutchison
2008-Oct-17, 09:57 PM
Hmm, I don't think I have, correct me if I'm wrong. The measure of time isn't used to judge other measures of time, it's simply that: another measure of time.And yet you're reporting that this new time of yours lets us see that some of our conventional seconds "contain more time" than other seconds.
Either your new time is intended to tell us something useful about our conventional time measurements, in which case you're introducing a universal time reference, willy-nilly; or it's not intended to say anything useful about our conventional time measurements, in which case we can just ignore it. Which do you prefer?

Grant Hutchison

Seiryuu
2008-Oct-17, 10:14 PM
However, in the peculiar geometry of Minkowski spacetime, the straight line between two spacetime events always produces the largest elapsed time along that worldline. Any other worldline that zigzags around the spacetime diagram will arrive at the finish event with a shorter elapsed time.

In order to understand this, can we compare the straight line as being similar to a straight line that is actually curved around the Earth?


We don't need some sort of master clock to explain the time differences, any more than we need a master metre to explain the distance differences: it's just how the maths works.

I don't think I'm introducing a master clock though. I'm introducing an additional parameter, that combined with our known second system gives a ratio at which time passes. That ratio can then be compared to other frames and the ratio of one frame compared to the ratio of another would show up as the measured time dilation.


And yet you're reporting that this new time of yours lets us see that some of our conventional seconds "contain more time" than other seconds.
Either your new time is intended to tell us something useful about our conventional time measurements, in which case you're introducing a universal time reference, willy-nilly; or it's not intended to say anything useful about our conventional time measurements, in which case we can just ignore it. Which do you prefer?

Grant Hutchison

What does a meter say about a second? Nothing. There's no relation or anything useful to say, so I think it's the latter. When we combine the distance over time though, we can determine a speed through space. In the same way combining both parameters would give you a speed through time, which corresponds with the "ratio at which time passes". This is all within one frame.

Does this help to clarify? I'm actually confused :p

Neverfly
2008-Oct-17, 10:20 PM
It's interesting that you haven't consciously encountered this idea of observers moving through time (rather than time flowing past observers).

Embarrassing isn't it?

Ever know something for years but it never actually clicks into place? And then, one day, for whatever reason, it clicks... And your hair stands on end and you shout, 'OH! I GET IT!!!" And then you know it. Again. Only you know it more better.:p

grant hutchison
2008-Oct-17, 10:33 PM
In order to understand this, can we compare the straight line as being similar to a straight line that is actually curved around the Earth?No. Minkowski spacetime is flat. The straight line is a real straight line in spacetime. Maximum proper time is experienced along its length. That's spacetime geometry.


I don't think I'm introducing a master clock though. I'm introducing an additional parameter, that combined with our known second system gives a ratio at which time passes. That ratio can then be compared to other frames and the ratio of one frame compared to the ratio of another would show up as the measured time dilation.Either there is a physical significance to this "additional parameter", some real way in one which one second "contains more time" than another second (in which case you are introducing a master clock whether you know it or not); or the "additional parameter" is mere book-keeping, doing a job that we can already do very well with the mathematics of relativity (in which case we can ignore it).
Do you claim physical significance for this "additional parameter"?


What does a meter say about a second? Nothing. There's no relation or anything useful to say ...Oooh, but there are lots of deep connections between the metre and the second, which is what thorkil2 alludes to with his analogy of rotating a spacetime entity. He's analogizing the mathematics of the Lorentz transformations, in which my "pure space" turns out to be your "space-plus-a-little-time", if you're in motion relative to me. It's as if you see me rotated slightly in a "timewards" direction.


Does this help to clarify? I'm actually confused :pIt certainly clarifies that you're confused. :)

Grant Hutchison

grant hutchison
2008-Oct-17, 10:49 PM
Ever know something for years but it never actually clicks into place? And then, one day, for whatever reason, it clicks... And your hair stands on end and you shout, 'OH! I GET IT!!!" And then you know it. Again. Only you know it more better.:pNah. I tend to get the opposite.
I know something for years, and then suddenly it clicks out of place; at which point my hair stands on end and I shout "Oh, that's complete nonsense!" And then I have to go and find out what the real story is.
Life's just a treadmill of horrible realizations.

Grant Hutchison

Seiryuu
2008-Oct-17, 11:29 PM
No. Minkowski spacetime is flat. The straight line is a real straight line in spacetime. Maximum proper time is experienced along its length. That's spacetime geometry.

I see. Will try to look into this.


Either there is a physical significance to this "additional parameter", some real way in one which one second "contains more time" than another second (in which case you are introducing a master clock whether you know it or not); or the "additional parameter" is mere book-keeping, doing a job that we can already do very well with the mathematics of relativity (in which case we can ignore it).
Do you claim physical significance for this "additional parameter"?

I'm really not sure what to answer here, but it has no effect to anything we currently measure and observe, so I'm guessing it's the book-keeping option. This means it does the same job as the mathematics in the sense that you don't need it to explain time dilation, but that it offers an alternative way of doing so. I really see it as an extra coordinate (x, y, z, t1, t2)

If you could measure it, the time belongs to the frame, just as the seconds belong to the frame. Unlike the seconds though, the amount of time measured would be different in each frame. So an event could last 2 seconds and 5 units of time in one frame and the same event in another frame would last 2 seconds and 3 units of time. The speed through time would be 5/2 and 3/2 and the time dilation between both would be 5/3. Based upon the information of one frame, you have no information about the rate of any other frame, so I don't see how I could be introducing a master clock.


Oooh, but there are lots of deep connections between the metre and the second, which is what thorkil2 alludes to with his analogy of rotating a spacetime entity. He's analogizing the mathematics of the Lorentz transformations, in which my "pure space" turns out to be your "space-plus-a-little-time", if you're in motion relative to me. It's as if you see me rotated slightly in a "timewards" direction.

Are these connections not all motion related?

grant hutchison
2008-Oct-17, 11:56 PM
I'm really not sure what to answer here, but it has no effect to anything we currently measure and observe, so I'm guessing it's the book-keeping option. This means it does the same job as the mathematics in the sense that you don't need it to explain time dilation, but that it offers an alternative way of doing so. I really see it as an extra coordinate (x, y, z, t1, t2)OK. So if it's redundant book-keeping, what's the point?


If you could measure it, the time belongs to the frame, just as the seconds belong to the frame. Unlike the seconds though, the amount of time measured would be different in each frame. So an event could last 2 seconds and 5 units of time in one frame and the same event in another frame would last 2 seconds and 3 units of time. The speed through time would be 5/2 and 3/2 and the time dilation between both would be 5/3. Based upon the information of one frame, you have no information about the rate of any other frame, so I don't see how I could be introducing a master clock.Well, the master clock is whatever is ticking off those "units" of yours.
But there's a problem above. Are you aware that time dilation is reciprocal, under special relativity? If you and I are in relative motion, and I measure your clock as running slow by a factor of (say) 5/3, then you will measure my clock as running slow by exactly the same amount. This is an example of how master clocks don't work, and I don't see how your "time units" are going to fare any better, if the measure "units per second" is unique to each frame.


Are these connections not all motion related?Motion is certainly involved, under SR. Under GR, we can actually exchange time and space axes under extreme conditions, such as prevail inside the event horizon of a black hole.
In general, we disagree about what is time and what is space. That's a deep connection.

Grant Hutchison

Seiryuu
2008-Oct-18, 12:54 AM
OK. So if it's redundant book-keeping, what's the point?

Point would be to have a concept that can be related to another concept in a different theory. Motion through time gives a unit of time/second. The first is merely a number, meaning I get 1/s, which is the unit of frequency. The idea would be that if masses move through time, this would be reflected in their frequencies. This implies that all masses have one (I don't know yet where or if that is possible), just as light has.


Well, the master clock is whatever is ticking off those "units" of yours.

The thing is that those units aren't ticking. Time is viewed as a dimension of space that allows motion. So they're units of distance in time, rather than in space, in analogy with meter/second.


But there's a problem above. Are you aware that time dilation is reciprocal, under special relativity? If you and I are in relative motion, and I measure your clock as running slow by a factor of (say) 5/3, then you will measure my clock as running slow by exactly the same amount.

I am aware of it. This goes for dilation by motion though. Gravitational dilation does not display this symmetry.


This is an example of how master clocks don't work, and I don't see how your "time units" are going to fare any better, if the measure "units per second" is unique to each frame.

I had to think one this one though, but I reckon the cause of time dilation is different compared to gravitational dilation.

In special relativity the dilation occurs due to differences in speed through space, but the rate at which they move through time remains the same. For gravitational dilation, the time dilation is caused due the difference in speed through time, but the rate at which they move through space remains the same. Both effects can of course be combined.


Motion is certainly involved, under SR. Under GR, we can actually exchange time and space axes under extreme conditions, such as prevail inside the event horizon of a black hole.
In general, we disagree about what is time and what is space. That's a deep connection.

Considering I also see time as a dimension of space, I guess I should have known :p

grant hutchison
2008-Oct-18, 01:06 AM
And that gets us to a post which is pretty much entirely ATM.
I'll say good night. :)

Grant Hutchison

Seiryuu
2008-Oct-18, 01:11 AM
Well, there was no way around it if I wanted to answer the need for redudancy, else there would indeed be no point in it :p

Anyway, thanks and good night.

grant hutchison
2008-Oct-18, 01:18 AM
The book recommendation still stands, by the way:
Michael Lockwood, The Labyrinth of Time: Introducing the Universe, OUP (ISBN 978-0-19-921726-7). :)

Grant Hutchison

Neverfly
2008-Oct-18, 02:15 AM
<Swipes ATM card on Seiryuu and withdraws all ATM statements statements.>

Seiryuu
2008-Oct-18, 12:57 PM
Oi, I wanted to keep the ATM out of the topic! :p

Anyway, I have another question about this


Here's another analogy, which applies more directly to the "twin paradox" of differential ageing. You and I start off from a street corner. You walk a city block directly north. I walk a block east, north, and then west, to rejoin you at the same finishing point. You're not surprised when I report that I have walked farther than you have, to get to the same point. You're content that simple geometry explains my "greater elapsed distance" between starting and finishing points. The straight line between two points in flat space always produces the smallest "elapsed distance"; a zigzag route is always longer.
However, in the peculiar geometry of Minkowski spacetime, the straight line between two spacetime events always produces the largest elapsed time along that worldline. Any other worldline that zigzags around the spacetime diagram will arrive at the finish event with a shorter elapsed time.

You say the math shows that the longest route, takes the least amount of time. Isn't this similar to what I'm claiming in that the "more 'time' that fits in a second", the less seconds pass in your frame of reference relative to another frame, giving this distortion?

And if so, is that what you meant with:


Oooh, but there are lots of deep connections between the metre and the second, which is what thorkil2 alludes to with his analogy of rotating a spacetime entity. He's analogizing the mathematics of the Lorentz transformations, in which my "pure space" turns out to be your "space-plus-a-little-time", if you're in motion relative to me. It's as if you see me rotated slightly in a "timewards" direction.


That I add a parameter for the same thing, while it's actually not necessary?

grant hutchison
2008-Oct-18, 01:14 PM
You say the math shows that the longest route, takes the least amount of time. Isn't this similar to what I'm claiming in that the "more 'time' that fits in a second", the less seconds pass in your frame of reference relative to another frame, giving this distortion?No, it isn't. The effect is a property of the geometry of spacetime, not a frame-specific ratio we plug in.


That I add a parameter for the same thing, while it's actually not necessary?That's right. You're adding a parameter for something that is already taken care of by space-time geometry. It's neither use nor decoration, to quote my grandmother. :)

Grant Hutchison

Seiryuu
2008-Oct-18, 01:23 PM
No, it isn't. The effect is a property of the geometry of spacetime, not a frame-specific ratio we plug in.

Well, the idea would be to relate curvature to the parameter :)


That's right. You're adding a parameter for something that is already taken care of by space-time geometry. It's neither use nor decoration, to quote my grandmother. :)

That's a good thing actually. I would be more worried if it wasn't the same thing, because then I had a problem, as I wouldn't have any way to relate it to GR.

thorkil2
2008-Oct-18, 05:13 PM
But if it was only a matter of perspective, how is then that clocks who were in a different frame can run slow or fast when they change back to the reference frame?

In the analogy with the building, if you change your position, you'll get to see the different sides accordingly. But if you change back, the building is still the same, no matter from which point you look at it.

For a clock this doesn't seem true. If it changes frame, it actually has undergone a change when it returns, in the sense that the time suddenly doesn't match anymore with a reference clock. How can this be explained in terms of perspective only?


No analogy is complete or perfect. A perfect analogy to a thing would be the thing itself. This is just a way of seeing why a second is a second, but this perspective involves motion instead of the static example I gave. You might try it from that approach. Kip Thorne talks about space-time mixing. In two different moving frames, my time is your space and time, while your time is my space and time. I prefer the word orientation. You can treat the difference as one of working perspective, as though you were seeing the other frame "rotated" away from you (the direction is not one you are capable of perceiving directly, so it appears as foreshortening). As the object is re-oriented for each difference in relative velocity, it's taking a different route through space and time. From my vantage point I observe an exchange of space for time in your frame, a re-orientation in space-time, but from the other frame, looking at my frame you observe the opposite (we are talking about two inertial frames with a relativistic difference in speed), but no change in your own. The re-orientation is real. In order for both of us to measure c as c from our respective frames, time and space have to be variable. Your clock comes back reading differently because you have actually travelled a different distance in space and time from your perspective than I have measured for your travel from mine. But it's important to understand that there is no "extra" time squeezed in anywhere. Your subjective clock still ticks off seconds as seconds, as does mine. Every event in either frame fills its seconds in exactly the same way. It's the reorientation makes the difference in clock time, a difference in routing.

Seiryuu
2008-Oct-18, 05:30 PM
Aha, I actually think I got that. I can see how this matches with special relativity time dilation.

But am I wrong to think that this doesn't account for the existence of gravitational time dilation?

thorkil2
2008-Oct-18, 05:50 PM
Aha, I actually think I got that. I can see how this matches with special relativity time dilation.

But am I wrong to think that this doesn't account for the existence of gravitational time dilation?

Don't know quite how to say this in just a few lines. Best nutshell I can come up with: Mass warps space-time, so anything within the range of influence of a (much larger) mass is subject to the curvature of the consequently warped geodesics, hence its route through (space-) time will be different from that of an object in an idealized gravity-less space. (edit) The degree of warping is inversely proportional to the square of the distance from the mass. (end edit) I think it's fair to say the principle is the same, but it takes a lot more explanation to support it. :)

Seiryuu
2008-Oct-18, 07:12 PM
However, in the peculiar geometry of Minkowski spacetime, the straight line between two spacetime events always produces the largest elapsed time along that worldline. Any other worldline that zigzags around the spacetime diagram will arrive at the finish event with a shorter elapsed time.

Ok, thanks to thorkil2's analogy I think I get this now. If time and space add up to a constant c, it makes sense that the person who zigzags will have a shorter time elapsed, compared to the person who did the shorter route.


Don't know quite how to say this in just a few lines. Best nutshell I can come up with: Mass warps space-time, so anything within the range of influence of a (much larger) mass is subject to the curvature of the consequently warped geodesics, hence its route through (space-) time will be different from that of an object in an idealized gravity-less space. (edit) The degree of warping is inversely proportional to the square of the distance from the mass. (end edit) I think it's fair to say the principle is the same, but it takes a lot more explanation to support it. :)

And ofc, the reason I asked is because warping spacetime is exactly what I'm trying to relate to a fifth dimension :)

Especially this is of interest to me

I think it's fair to say the principle is the same, but it takes a lot more explanation to support it. :)

Because I agree with it and in a sense, that is what I was getting at with the stretcheable time concept. Is it possible that a fifth dimension exists and masses, who appear to be at rest from our point of view, are actually still moving through it at different rates and that this might be responsible for the gravitational dilation? And that just like in special relativity the same principle would apply, but instead of space and time adding up to time, it would be due to the distance in the extra dimensionand normal time adding up.

Falstaff
2008-Oct-19, 01:43 AM
As we know of GR, space and time are dependant on the frame of reference. In order to find an answer as to why this might be the case, I introduced the concept of variable durations in my ATM theory. What I'd like to know is if this concept is possible within the framework of GR.

This would mean that the amount of time that is measured by a second is not necessarily equal to the amount of time measured by another second. Obviously, it also means that the "amount of time" cannot be measured in seconds themselves, but rather in a number / second. I call this the concept of "stretcheable time" or "stretcheable seconds".

Again, just to clarify I'll repeat once more: the seconds themselves don't change, but rather the amount of time that "fits" in a second changes. This means that one second has a longer duration than another in a gravitational field and that changing from frame by switching to a different gravitational potential causes your seconds to become longer or shorter relative to the frames around it. You will still measure one second as a second in all frames of reference though, since that never changes.

In this sense, time dilation would be used to measure the ratio between two rates of time, but there would still be no way of measuring the actual "amount of time" that goes in a second. As you can see, I'm using "amount of time" in a context so that it becomes completely unrelated to the number of seconds though.

My apologies if this question is too ATM, but I'd really like to know if mainstream allows variable durations or not.

Sure. The second we're in right now has so much time in it that the entire lifetime of the universe will pass during this second.

Some meters have more distance than others as well. The two meters that separate earth and mars have much more distance than the two meters that separate the top and bottom of my refrigerator.