# Time and motion

Could a String be thought of, say a duration of time? I would think that as a single dimensional object it just might fit.

## Answers and Replies

Could a String be thought of, say a duration of time? I would think that as a single dimensional object it just might fit.

What you have in mind is similar to the notion of a 'string bit' moving along a string. If you'd like to learn more, check out the Sept. 2006 paper: http://arxiv.org/abs/hep-th/0609103" [Broken].

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Thank you, Kneemo. Could duration of time be thought of as this string? With two bits of motion that we think of as particles, one expanding and the other contracting, I would think it fits as one dimensional duration.

Can we separate time and motion? With this example no, but we can say that time, or the potential for motion, is expanding and or contracting ahead of the bit(s) of motion(s) we call particle(s). Is this a fair statement?

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josh1
Hi petm1,

Im not sure what your after here. Are you looking for natural phenonmena that could serve as some sort of clock?

For years I thought of time as a tool for the measurement of motion, and therefore space. Now I think that time as the forth dimension contains not only all motion but all potential for motion. Can we think of time as a potential for motion? Like the string from the paper that Kneemo showed us talks about (using that string as a temporal object), and the motion as being just a small part of that one dimensional duration. If time is potential motion and we can picture it as a string could it be broken into three separate dimensions one each for the other three dimensions? By adding these strings of potential, could different combinations make the idea of a point charge easier to understand? I was thinking of time as a one dimensional object because all motion was contained in it but now I am wondering if the bits on time strings of potential movement have to be combined before we would be able to detect them as a one dimensional motion. I guess what I am asking is if we have three dimensions for the meter, why don't we have three dimensions for a second?

As for josh1's question, no I am not trying to reinvent the clock.

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Chronos
Gold Member
The concept ot motion makes no sense without time. For example, velocity equals distance / time. Since 'space' is merely the relationship between objects traveling along a time line, it is pointless to attempt to separate the two concepts.

The concept ot motion makes no sense without time. For example, velocity equals distance / time. Since 'space' is merely the relationship between objects traveling along a time line, it is pointless to attempt to separate the two concepts

The concept of motion without time does not make sense to me either, but the concept of time with out motion does seem reasonable to me. It could explain how the universe could be expanding faster than light, dark energy could be explained by the difference between motion and its limit to c, and time's expanding potential for motion that we cannot "see" because motion has not caught up with it yet. Time as a forth dimension containing all motion has to be an object such as our visible universe and at the same time it has to contain all the potential motion that our universe is expanding into. Yet time as a one dimensional duration has to have direction in this case two directions the potential to expand and the potential to contract with motion between. Three separate dimensions of time with only the motion portions "visible".

The concept ot motion makes no sense without time. For example, velocity equals distance / time. Since 'space' is merely the relationship between objects traveling along a time line, it is pointless to attempt to separate the two concepts.

Not only the notions of time and motion are inseparable but also speed (velocity). Moreover, since the notion of speed implies both time and motion, it is the former that might be considered as a fundamental entity rather than the latters. In principle, it is known that time could be excluded from the equations of motion (unlike velocity).

Chronos
Gold Member
How is that? Motion is merely a different way of describing velocity.

I can imagine an unmoving space, devoid of time,
but what motion could take place in time devoid of circumstance?

So is space more fundamental than time?

How is that? Motion is merely a different way of describing velocity.

Exactly! For simplicity one can imaging a two-body system with a potential well (say, an oscillator). It can be described using only space coordinates, velocity and acceleration.

I can imagine an unmoving space, devoid of time,
but what motion could take place in time devoid of circumstance?

So is space more fundamental than time?

To elaborate, it is possible to imagine a world which has spatial relationships but has no moving parts. There would be no motion, no change, no evolution of time in such a world.

On the other hand, if I try to imagine a time world, in which there are no spatial relationships, no objects, no place in which any change could occur, what am I imagining?

I am posting the above simultaneously in one of the philosopy forums.
So, a priori, I conclude that space may exist without the need for any presense of time, but that time cannot exist without space.

For this reason I propose that an operational definition of time can be made from spatial concepts alone. However no operational definition of space is possible from temporal concepts alone.

Therefore, a priori, space is fundamental and time is derived from space.

I will post this simultaneously in one of the philosophy forums, but it was generated here.

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Chronos
Gold Member
I think space and time are inseparable. Neither concept makes sense without the other component. The concept of space is only meaninful in terms of the time required to go from point A to point B: d = vt. If d or t is set to zero [or infinity], the other quantity cannot be quantified.

1d, 2d, 3d.... 4d..

ZapperZ
Staff Emeritus
It is possible to imagine a world which has spatial relationships but has no moving parts. There would be no motion, no change, no evolution of time in such a world.

Er.. how so? How exactly are you able to "detect" space? How would you know that, for example, Point A is closer to you than Point B? And just in case you plan on bringing out a very long measuring tape to answer this question, consider what is necessary for you (i) calibrate that measuring tape and (ii) to actually observe various part of that measuring tape.

Of course, if you claim to have the ability to observe all parts of the universe instantaneously, then there's no reason why one can't answer your question by simply making things up as one goes along without regards to any physical laws.....

Zz.

ZapperZ
Staff Emeritus
I will post this simultaneously in one of the philosophy forums, but it was generated here.

Why are you cross-posting this when that has been explicitly prohibited in the Guidelines?

The other thread has been merged to this one. Please don't do this again.

Zz.

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Thanks, Zz

Well, I did say imagine, didn't I?

But I think you are right in physical terms. My little mental exercise does require an observer who can move from place to place, and must require time to do so. So I have merely moved the property of time into the obervation apparatus, not really removing it from the universe. That was part of the reason I chose to use the word "world" rather than using the word "universe."

I wouldn't try to measure an imaginary world, any more than I would try to calculate the unique value of an imaginary number.

I have learned this week from Wiki that the modern view of science, due to Kant and Liebnitz, is that time, space, and mass are fundamental units, which remain undefined. They are not to be thought of, as Newton did, as a kind of container in which objects float about, but as a part of the process of observing events. Not as things in themselves, but as part of the conceptual apparatus.

So as long as we are making up time and space without regard to any physical laws, why not make up an imaginary world for them to play in? And my point is that I can construct a concept of a world containing objects that do not experience time, but I am unable to construct a concept of a world without space. I can even make a picture of it. Any common photograph will do.

Then there is the idea of relitive events. I have just come across this so I am prone to mis-speak, but there is a category of events called light-like, in which the space-time interval is said to be zero. Nevertheless, there is a spacelike separation to such events, not so? So the timelike separation must be the zero factor.

This interpretation is supported, I think, by the notion of time dilation. When an event occurs very near the speed of light relitive to the observer, it experiences time dilated until it nearly passes not at all. If it is at the speed of light relitive to the observor, as in a light-like event, or just the radiation of energy in free space, then it experience zero time in the observors space.

So is light real or imaginary? We do consider it a physical quantity, and we need it for every kind of measurment I can think of.

I am honored that you have given my little thought consideration, Zz. It seems not unlikely that I have made a mishmash of physics, but I hope you can apply your critical skills to help me slice away everything that is not necessary or sufficient, so I can see for myself if anything "discreet" is left over.

Honest thanks,

Richard

Why are you cross-posting this when that has been explicitly prohibited in the Guidelines?

The other thread has been merged to this one. Please don't do this again.

Zz.

Sorry, I only wanted to try my idea out on the philosophers, who probably don't read much in this forum. And it wasn't the same exact post, I made some small changes to address the academics in the other forum.

Zz, do you really expect that everyone who visits physicsforums.com reads every post in every forum? I wasn't spamming, I was merely directing my question to a group who would not see it otherwise.

Nevertheless, I do want to follow the guidelines here, as I am a guest in your house. Is there some acceptable way to ask for evaluation from other forum users?

Sincerely, Thanks

R.

ZapperZ
Staff Emeritus
Thanks, Zz

Well, I did say imagine, didn't I?

But I think you are right in physical terms. My little mental exercise does require an observer who can move from place to place, and must require time to do so. So I have merely moved the property of time into the obervation apparatus, not really removing it from the universe. That was part of the reason I chose to use the word "world" rather than using the word "universe."

I wouldn't try to measure an imaginary world, any more than I would try to calculate the unique value of an imaginary number.

I have learned this week from Wiki that the modern view of science, due to Kant and Liebnitz, is that time, space, and mass are fundamental units, which remain undefined. They are not to be thought of, as Newton did, as a kind of container in which objects float about, but as a part of the process of observing events. Not as things in themselves, but as part of the conceptual apparatus.

So as long as we are making up time and space without regard to any physical laws, why not make up an imaginary world for them to play in? And my point is that I can construct a concept of a world containing objects that do not experience time, but I am unable to construct a concept of a world without space. I can even make a picture of it. Any common photograph will do.

Then there is the idea of relitive events. I have just come across this so I am prone to mis-speak, but there is a category of events called light-like, in which the space-time interval is said to be zero. Nevertheless, there is a spacelike separation to such events, not so? So the timelike separation must be the zero factor.

This interpretation is supported, I think, by the notion of time dilation. When an event occurs very near the speed of light relitive to the observer, it experiences time dilated until it nearly passes not at all. If it is at the speed of light relitive to the observor, as in a light-like event, or just the radiation of energy in free space, then it experience zero time in the observors space.

So is light real or imaginary? We do consider it a physical quantity, and we need it for every kind of measurment I can think of.

I am honored that you have given my little thought consideration, Zz. It seems not unlikely that I have made a mishmash of physics, but I hope you can apply your critical skills to help me slice away everything that is not necessary or sufficient, so I can see for myself if anything "discreet" is left over.

Honest thanks,

Richard

I'm sorry, but if you want us to simply drop all of physics and just make things up, you're in the wrong forum. You want a science fiction forum.

And since you stated that you do abide by the rules of this forum, pay attention to the part on overly-speculative post.

Zz.

ok. goodbye.

I think space and time are inseparable. Neither concept makes sense without the other component. The concept of space is only meaninful in terms of the time required to go from point A to point B: d = vt. If d or t is set to zero [or infinity], the other quantity cannot be quantified.

The notions of space, time and motion are mostly discussed in philosophy where they are regarded as attributes of matter (i.e., they have no meaning separated from one another and, of course, from matter). In physics, however, sometimes they are used separately (for convenience). For example, take a system with a ball rolling back and forth in a potential well. This system (oscillator) can be described fully in terms of distance (spatial coordinate) and speed (as a function of spatial coordinate) alone, with the time parameter excluded. Then could it be so that the notion of time have had arised in the human mind as a reflection of periodic motions of matter around us?

ZapperZ
Staff Emeritus
The notions of space, time and motion are mostly discussed in philosophy where they are regarded as attributes of matter (i.e., they have no meaning separated from one another and, of course, from matter). In physics, however, sometimes they are used separately (for convenience). For example, take a system with a ball rolling back and forth in a potential well. This system (oscillator) can be described fully in terms of distance (spatial coordinate) and speed (as a function of spatial coordinate) alone, with the time parameter excluded. Then could it be so that the notion of time have had arised in the human mind as a reflection of periodic motions of matter around us?

Aren't you forgetting that "speed" is the time rate of change of displacement? It appears to me that time is an implicit part of such a dynamics.

And as far as time being arising "in the human mind as a reflection of periodic motion", would you care to explain why time is on equal footing with space in SR/GR, and in elementary particle physics as in the CPT symmetry?

Zz.

The notions of space, time and motion are mostly discussed in philosophy where they are regarded as attributes of matter (i.e., they have no meaning separated from one another and, of course, from matter). In physics, however, sometimes they are used separately (for convenience). For example, take a system with a ball rolling back and forth in a potential well. This system (oscillator) can be described fully in terms of distance (spatial coordinate) and speed (as a function of spatial coordinate) alone, with the time parameter excluded. Then could it be so that the notion of time have had arised in the human mind as a reflection of periodic motions of matter around us?

I think you need to distinguish two things : (a) the measurement of eigentime (b) time as a unmeasurable hidden variable (God's'' clock if you want to).
You cannot escape from using (b), any dynamical equation requires it. Now regarding (a), I agree that eigentime is the ticking of an internal clock of a particle (periodic motion) : there exist plenty such models in the literature for spinning particles (zitterbewegung, simple rotations,...). But this implies that time and space aren't on an equal footing at all (which is kind of logical since we never measure time'', we only count the number of ticks on our wrist watches).

Btw : these models are (of course) all relativistically invariant.

Time in special relativity is eigentime; Henri Poincare -for example- thought one should always consider time in the sense of (b) and think of eigentime as an auxilliary concept. The problem of relativistic simultaneity only arises when one *identifies* notions (a) and (b), a mistake too often made.

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And as far as time being arising "in the human mind as a reflection of periodic motion", would you care to explain why time is on equal footing with space in SR/GR, and in elementary particle physics as in the CPT symmetry?

"Equal footing" must mean the complete identification of space and time, which is not exactly what is happening in SR/GR, QFT, etc (Minkovskian metric is not exactly Euclidean, is it?)

I would say more: the fundamental difference between space and time is that the latter must be measured by using a periodic process/motion (a clock). Or can you propose measuring time by something else?

I think you need to distinguish two things : (a) the measurement of eigentime (b) time as a unmeasurable hidden variable (God's'' clock if you want to).
You cannot escape from using (b), any dynamical equation requires it.

This looks like an idealised (theoretical) time unavoidable in mathematical models. But I think we must keep in mind that the mathematical models are part of our language for describing physical reality. A model might reproduce pretty well a physical process but never in full detail; and it would be crazy to identify a mathematical model with physical reality.

I
Now regarding (a), I agree that eigentime is the ticking of an internal clock of a particle (periodic motion) : there exist plenty such models in the literature for spinning particles (zitterbewegung, simple rotations,...). But this implies that time and space aren't on an equal footing at all (which is kind of logical since we never measure time'', we only count the number of ticks on our wrist watches).

Btw : these models are (of course) all relativistically invariant.

Time in special relativity is eigentime; Henri Poincare -for example- thought one should always consider time in the sense of (b) and think of eigentime as an auxilliary concept. The problem of relativistic simultaneity only arises when one *identifies* notions (a) and (b), a mistake too often made.

I agree completely

ZapperZ
Staff Emeritus
"Equal footing" must mean the complete identification of space and time, which is not exactly what is happening in SR/GR, QFT, etc (Minkovskian metric is not exactly Euclidean, is it?)

But that could easily be the "fault" of how we define space and have nothing to do directly with time. So why is time degraded to something lower?

I would say more: the fundamental difference between space and time is that the latter must be measured by using a periodic process/motion (a clock). Or can you propose measuring time by something else?

Note that the only reason why we use "periodic motion" to define time is because these are well-known time period that we know very well. It has nothing to do with these being fundamental to the quality we call time itself. That's like saying space is nothing more than that piece of bar sitting in a climate control room somewhere. You are confusing the CONCEPT of time with how we QUANTIFY time.

You still haven't addressed the fundamental CPT symmetry principle that part of how we describe our world. Why is T as fundamentally important as C and P in here, while you don't think so.

Zz.

This looks like an idealised (theoretical) time unavoidable in mathematical models. But I think we must keep in mind that the mathematical models are part of our language for describing physical reality. A model might reproduce pretty well a physical process but never in full detail; and it would be crazy to identify a mathematical model with physical reality.
It is impossible to get rid of this idealized time'' since one needs to express something like change of motion as Zapper noticed. Now, you may not like a hidden variable which you cannot measure (as do I), but I believe Newtonian time to be one of the few exceptions. Whether this t really exists or not is something we cannot decide but assuming the pragmatic attitude that something which is so deeply rooted into our general way of expressing things must be real isn't perhaps that dumb.

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But that could easily be the "fault" of how we define space and have nothing to do directly with time. So why is time degraded to something lower?

Equally, that could be a faulty definition of time. But I do not mean that the notion of time is "lower" that that of space. I mean that they are distinct. Time is very much related to motion (hence to energy), therefore, when searching for deeper models of reality and analysing these concepts in detail it would be logical to go beyond the earlier simplifications (such as putting space and time on equal footing).

Note that the only reason why we use "periodic motion" to define time is because these are well-known time period that we know very well. It has nothing to do with these being fundamental to the quality we call time itself. That's like saying space is nothing more than that piece of bar sitting in a climate control room somewhere. You are confusing the CONCEPT of time with how we QUANTIFY time.

Radioactive decay (being a stochastic process) is not a good example for a time measuring device. In addition, with this you are not going away from the oscillatory motion: in the case of alpha-decay this would correspond to some nonlinear (and, hence, stochastic) oscillatory motions of the nucleus constituents; as for beta-decay, it is assumed that the processes responsible for it to happen are currently not known, but it is quite likely that it happen due to (nonlinear) oscillatory motions of the nucleon components (quarks and gluons).

Perhaps all the physical clocks are nonlinear devices but using highly nonlinear clocks would result in extremely messy science. I bet there are no better clocks than photons whose oscillations are predictable and calculable at any circumstances.

The "concept" of time is that idealised notion which was introduced by Newton. But I am sure he was aware that, as any idealisation, it has its limitations. SR/GR made a step forward in the development of this notion. But what precludes us from moving further on? Be sure, I am not confusing the concept with the measuring (quantifying) procedure. The question of time is very deep.

You still haven't addressed the fundamental CPT symmetry principle that part of how we describe our world. Why is T as fundamentally important as C and P in here, while you don't think so.

Sorry, I have forgotten about that because I thought it is obvious: there is a branch of physics called "nonlinear science", in whose many textbooks it is shown how CPT symmetry is broken by nonlinear dissipative processes (motions). Irreversibility is not at all a problem.

ZapperZ
Staff Emeritus
Equally, that could be a faulty definition of time. But I do not mean that the notion of time is "lower" that that of space. I mean that they are distinct. Time is very much related to motion (hence to energy), therefore, when searching for deeper models of reality and analysing these concepts in detail it would be logical to go beyond the earlier simplifications (such as putting space and time on equal footing).

But I could also say that motion is very much related to time. You cannot define motion without time. If we all agree that they are all interrelated, then what's the issue here? Why are you picking on "time", when space is equally suspect, or equally valid?

Radioactive decay (being a stochastic process) is not a good example for a time measuring device.

Why not? In a neutron decay, it takes TIME for something to occur. And not only that, a conglomerate of such particle will ALWAYS decay according to the set decay rate, as if these particles know about time. So for something that you claim to not be "fundamental", nature sure knows how to obey it very, very strictly.

In addition, with this you are not going away from the oscillatory motion: in the case of alpha-decay this would correspond to some nonlinear (and, hence, stochastic) oscillatory motions of the nucleus constituents; as for beta-decay, it is assumed that the processes responsible for it to happen are currently not known, but it is quite likely that it happen due to (nonlinear) oscillatory motions of the nucleon components (quarks and gluons).

Come again? Alpha decay can be described as a tunneling process that is independent of any oscillatory motion of the nucleus consituents. In other words, even when they do not move, they will still tunnel through. And you're just grasping for speculative straws there with beta-decay. If you'd like to play make-things-up-as-we-go-along, then I can too.

Perhaps all the physical clocks are nonlinear devices but using highly nonlinear clocks would result in extremely messy science. I bet there are no better clocks than photons whose oscillations are predictable and calculable at any circumstances.

It doesn't matter. We are not talking about quantifying time. We're talking about time as the concept that you have degraded to some non-fundamental quantity. Yet, you have been unable to show how, without using it, you can describe ANY dynamical system fully. Your velocity requires the time rate of change, which you have not addressed.

The "concept" of time is that idealised notion which was introduced by Newton. But I am sure he was aware that, as any idealisation, it has its limitations. SR/GR made a step forward in the development of this notion. But what precludes us from moving further on? Be sure, I am not confusing the concept with the measuring (quantifying) procedure. The question of time is very deep.

Yes it is, and it simply cannot be dismissed as being not fundamental. If time is an "idealised notion", then so is space, and so is motion, and so is all other notion derived from them. Then what's the problem? Why are we simply picking on "time" here?

Sorry, I have forgotten about that because I thought it is obvious: there is a branch of physics called "nonlinear science", in whose many textbooks it is shown how CPT symmetry is broken by nonlinear dissipative processes (motions). Irreversibility is not at all a problem.

Nor is it MY point. The FACT that C, P, and T stand TOGETHER implies that you simply cannot downgrade T. Yet, you attempt to do just that.

You seem to be missing the whole point of what you are doing here. If you try to do something to "time", why are you ignoring the fact that in physics, "space" and "motion" ALSO follow along. If time is an "illusion", then so is space. I really do not understand why time would be any more special, or any less fundamental, than "space", especially when they are inseparable.

In condensed matter physics, there is a whole series of phenomena that is characterized broken time reversal symmetry. This is where such broken symmetry signifies the onset of a particular transition. Unconventional superconductors such as high-Tc superconductors are one such system. Several "ladder magnets" are also characterized by such symmetry. In other words, the time component is an essential ingredient in the description of such system, and nothing else will do. Such a description is as fundamental as describing broken spatial symmetry when water turns into ice.

This is not an argument of making "time" to be special. This is an argument on why you are picking on time when space and charge and others are part of the mob also! I have presented several aspects in which time is essential in these description. You have shown nothing in which one could make do without, or discard, time while still preserving the complete description.

Zz.

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It is impossible to get rid of this `idealized time'' since one needs to express something like change of motion as Zapper noticed. Now, you may not like a hidden variable which you cannot measure (as do I), but I believe Newtonian time to be one of the few exceptions. Whether this t really exists or not is something we cannot decide but assuming the pragmatic attitude that something which is so deeply rooted into our general way of expressing things must be real isn't perhaps that dumb.

Are you sure this is always the case? Of course, we have to parameterise our models. But the notion of the idealised time is completely gone, e.g., in GR, where the evolution of manifolds is represented "statically", since time is put almost on the same footing as space (as Zapper noticed). Everything is measured by using just distance (no time). Equally one can use time or speed (that of light), as I was proposing. Since they are interchangeable, conceptually they represent the same thing. The question is: does really the time concept represent deeply the corresponding aspect of physical reality?