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petm1
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Could a String be thought of, say a duration of time? I would think that as a single dimensional object it just might fit.
petm1 said:Could a String be thought of, say a duration of time? I would think that as a single dimensional object it just might fit.
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
Chronos said: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.
Chronos said:How is that? Motion is merely a different way of describing velocity.
rtharbaugh1 said: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?
rtharbaugh1 said: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.
rtharbaugh1 said:I will post this simultaneously in one of the philosophy forums, but it was generated here.
ZapperZ said: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.
rtharbaugh1 said: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
Chronos said: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.
vld said: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?
vld said: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 said: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?
Careful said: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.
Careful said: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.
vld said:"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?
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.vld said: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.
ZapperZ said: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?
ZapperZ said:Sure. Radioactive decay!
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.
ZapperZ said: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.
vld said: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).
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.
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.
Careful said: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.
vld said: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.
vld said: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).
ZapperZ said: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.
Your examples are irrelevant here. Yes, the concepts of space, and charge are also part of the mob, but this thread was about time and motion. Time is, indeed, a special case, at least, by being anisotropic, which is worth while discussing and exploring. My example was about a system whose motion is FULLY described by a trajectory in the phase space (x,p). The coordinate x IS NOT time; momentum p IS NOT time. If you prefer describing the radioactive decay in terms of tunneling, this kind of motion can be described through energies and probabilities, neither identified directly with the notion of time (although related to it). For better understanding of these motions we need an auxiliar parameter. In many cases it is suffice to simply use this parameter without thinking about any deeper implications, which does not necessarily mean that we have arrived at the complete description of physical reality. If you perceive these arguments as my intention to say that time is "illusion", your are wrong. This is not an illusion, this is an entity needed to be studied since we do not know enough about it.ZapperZ said: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.
vld said:I see that you are talking about a mathematical (model/theoretical/languistical) concept of time because in the CPT-theorem C, P and T do not stand together for charge, parity and time but rather for charge-reversal, mirror-reflection and time-reversal, which is not the same. These are mathematical operations needed for modelling but which do not actually occur in nature. The examples you give are all related (as you have correctly mentioned) to time irreversibility which is not a problem. However, anisotropy of time is the property making it distinct from space.
Your examples are irrelevant here. Yes, the concepts of space, and charge are also part of the mob, but this thread was about time and motion. Time is, indeed, a special case, at least, by being anisotropic, which is worth while discussing and exploring. My example was about a system whose motion is FULLY described by a trajectory in the phase space (x,p). The coordinate x IS NOT time; momentum p IS NOT time.
If you prefer describing the radioactive decay in terms of tunneling, this kind of motion can be described through energies and probabilities, neither identified directly with the notion of time (although related to it).
For better understanding of these motions we need an auxiliar parameter. In many cases it is suffice to simply use this parameter without thinking about any deeper implications, which does not necessarily mean that we have arrived at the complete description of physical reality. If you perceive these arguments as my intention to say that time is "illusion", your are wrong. This is not an illusion, this is an entity needed to be studied since we do not know enough about it.
You can measure space through motion. As an example, take a sphere and measure its Gaussian curvature in a point by applying the standard differential geometry procedure (i.e. by moving along a loop around the point). You can implement this operation instantly or (not being in rush) consuming an infinite amount of time. Therefore this measurement is time-independent but as a result you have measured the distance between two opposite points of your sphere (its diameter).ZapperZ said:Can you tell me how you are able to "measure" space without invoking ANY time? How are you able to know the distance between 2 points in space, a question that I had asked earlier to another person who made a similar point, but never gotten a reply? Before you pull out a measuring stick, consider a series of implicit assumption that you had to make to use such a thing.