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# Time Travel, Impossible Again!

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Time does not dilate or contract. I have to make this point at least once a week on average : No matter what physics may tell you , time is not subject to contraction. This does not mean that clocks do not slow down etc, just that even if they do, it is not because time is some sort of dimension ( which seems to refer to some mathematical construct with no physical referents in that case), just that *something* is happening.

And that "something" is called time dilation. Time is that what a clock indicates. If clocks are slowing down time is dilating. With "clocks" I mean of course here not just some bad clocks, but all possible clocks, i.e. all physical, chemical and biological processes (some of those processes that are regular of character, e.g. a harmonic oscillator, can be used for constructing practical clocks). Therefore the twin traveling through space is in fact aging slower than his brother on Earth and could in principle survive him by 1000 years or more. Time is indeed a dimension with physical referents. By all definitions of time, the time for the traveling twin is running slower than for his brother on Earth, that's a fact that cannot be denied. And time dilation is just another word for the slowing down of time.

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And that "something" is called time dilation. Time is that what a clock indicates. If clocks are slowing down time is dilating. With "clocks" I mean of course here not just some bad clocks, but all possible clocks, i.e. all physical, chemical and biological processes (some of those processes that are regular of character, e.g. a harmonic oscillator, can be used for constructing practical clocks). Therefore the twin traveling through space is in fact aging slower than his brother on Earth and could in principle survive him by 1000 years or more. Time is indeed a dimension with physical referents. By all definitions of time, the time for the traveling twin is running slower than for his brother on Earth, that's a fact that cannot be denied. And time dilation is just another word for the slowing down of tim

No, that "something" is something which makes clocks and so forth operate differently in certain contexts. Clocks "measure" time in as far as they provide a means to track the units of time ( seconds, hours , minutes etc) . They do not actually measure time though, they are an instrument by which humans can perform the measurements involved in the concept of time. They are purely mechanical / electrical devicse which are designed to track periodic phenomena and report back to the user so that they can measure time.

Clocks are not slowed down (etc) because they have some strange connection to time the dimension ( or whatever you want to consider time to be), but because of some process which apparently we do not yet understand properly. If you think about how a clock actually works, it does not make sense to claim that it measures time per se, or that somehow speed could slow down time. Physics claims time is a dimension, but how could dimension dilation/contraction make clocks slow down/speed up? Does not make any sense. Sure, this may not be how physicists claim that you are meant to view it, but it is the *correct* way to analyze the matter. The confusion is compounded by the fact that the "concept" of dimension ( higher than the first 3) degenerates into pure "mathematics" ( except, is it really mathematics if it is this much of a floating abstraction and rationalistic?) with no physical meaning or referents , ie by the fact that the higher dimensions ( again past the first three ) are floating abstractions.

Edited by Prometheus98876
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No, that "something" is something which makes clocks and so forth operate differently in certain contexts. Clocks "measure" time in as far as they provide a means to track the units of time ( seconds, hours , minutes etc) . They do not actually measure time though, they are an instrument by which humans can perform the measurements involved in the concept of time. They are purely mechanical / electrical devicse which are designed to track periodic phenomena and report back to the user so that they can measure time.

Clocks are not slowed down (etc) because they have some strange connection to time the dimension ( or whatever you want to consider time to be), but because of some process which apparently we do not yet understand properly. If you think about how a clock actually works, it does not make sense to claim that it measures time per se, or that somehow speed could slow down time. Physics claims time is a dimension, but how could dimension dilation/contraction make clocks slow down? Does not make any sense. Sure, this may not be how physicists claim that you are meant to view it, but it is the *correct* way to analyze the matter. The confusion is compounded by the fact that the "concept" of dimension ( higher than the first 3) degenerates into pure mathematics with no physical meaning or referents , ie by the fact that the higher dimensions ( again past the first three ) are floating abstractions.

I agree.

I think it is helpful to consider Aristotle's analysis of time in his Physics. Time is not, properly, a continuum of events but a measurement of change or motion. ("It is clear, then, that time is â€˜number of movement in respect of the before and afterâ€™, and is continuous since it is an attribute of what is continuous.") Time, like space, is relative, space being a way to describe the relative distance between objects and time being a way to describe the relative motion of objects. We measure time by the motion of an object which moves in equal increments, like the earth around the sun, a clock's hand, or an atom's decay.

I am not a physics expert and cannot claim to fully understand "time dilation", but insofar as I do, this is how I would explain it in terms of a non-dimensional conception of time: consider the "twin paradox" in which one twin stays on Earth and another goes in a spaceship at the speed of light for a time and comes back to find himself much younger than his twin. The conventional explanation is that time itself somehow dilated or slowed down for him relative to his twin on earth. An alternate explanation is that the acceleration of his ship through space (or the aether, whatever term you like) somehow acted to slow down the motion of all processes inside it. Therefore, to him, it seems as if the clocks are ticking at the same speed, but in fact they have slowed relative to their speed on Earth. There may, of course, be something wrong with my alternate explanation, but that is just an example of one that could be made.

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No, that "something" is something which makes clocks and so forth operate differently in certain contexts. Clocks "measure" time in as far as they provide a means to track the units of time ( seconds, hours , minutes etc) . They do not actually measure time though, they are an instrument by which humans can perform the measurements involved in the concept of time. They are purely mechanical / electrical devicse which are designed to track periodic phenomena and report back to the user so that they can measure time.

Time is defined on the basis of periodic phenomena. For many centuries periodic astronomical events like the movement of the Earth were used as a basis for the definition of time, but this standard was due to all kinds of small perturbations less regular in comparison with such elementary physical phenomena like the oscillation of a light wave with a given wavelength, so that this is the basis of the modern definition of time. Any definition must refer to some physical phenomenon - the check with reality - otherwise you're just really engaging in a "floating abstraction".

Clocks are not slowed down (etc) because they have some strange connection to time the dimension ( or whatever you want to consider time to be), but because of some process which apparently we do not yet understand properly.

On the contrary, this process is understood perfectly. It follows directly from Einstein's postulate (together with a few elementary assumptions) that the speed of light is constant and independent of the motion of the observer. Einstein's theory still stands firm after a century, having been experimentally confirmed with great accuracy countless times, that is the check with reality.

If you think about how a clock actually works, it does not make sense to claim that it measures time per se, or that somehow speed could slow down time. Physics claims time is a dimension, but how could dimension dilation/contraction make clocks slow down/speed up?

That's very simple. Dimension is a mathematical concept, which uses a ordered set of coordinates. When you compare two such sets, there is nothing impossible in a dilation or contraction of one set with regard to the other one.

Does not make any sense. Sure, this may not be how physicists claim that you are meant to view it, but it is the *correct* way to analyze the matter. The confusion is compounded by the fact that the "concept" of dimension ( higher than the first 3) degenerates into pure "mathematics" ( except, is it really mathematics if it is this much of a floating abstraction and rationalistic?) with no physical meaning or referents , ie by the fact that the higher dimensions ( again past the first three ) are floating abstractions.

Mathematics is all about abstractions, but there is nothing "floating" about it. Dimensions higher than 3 do have many, many physical referents. Thanks to theories that use such higher dimensions we have been able to create modern technology, from atomic bombs to lasers, electronics and computers, check with reality!

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I am not a physics expert and cannot claim to fully understand "time dilation", but insofar as I do, this is how I would explain it in terms of a non-dimensional conception of time: consider the "twin paradox" in which one twin stays on Earth and another goes in a spaceship at the speed of light for a time and comes back to find himself much younger than his twin. The conventional explanation is that time itself somehow dilated or slowed down for him relative to his twin on earth. An alternate explanation is that the acceleration of his ship through space (or the aether, whatever term you like) somehow acted to slow down the motion of all processes inside it.

And that slowing down of the motion of all processes is exactly what "time dilation" means, as time can only be defined in terms of physical processes. But there is nothing "somehow" about it, read Einstein's article from 1905 to see how he simply and elegantly explains this phenomenon.

Therefore, to him, it seems as if the clocks are ticking at the same speed, but in fact they have slowed relative to their speed on Earth.

That is correct, but that's also what the theory of relativity says.

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According to ASME Y14.5M-1994 (American Society of Mechanical Engineers)

Section 1.4 FUNDAMENTAL RULES

Subparagraph (k)

Unless otherwise specified, all dimensions are applicable at 20Â°C (68Â°F). Compensation may be made for measurements made at other temperatures.

From ITOE,

The requirements of a standard of measurement are: that it represent the appropriate attribute, that it be easily perceivable by man and that, once chosen, it remain immutable and absolute whenever used. (Please remember this; we will have reason to recall it.)

Please note carefully the key words "immutable" and "absolute". The citation from the Geometric Dimensioning and Tolerancing guide implicitly address a point here that is elaborated on quite concisely in both ITOE and OPAR which is that knowledge is contextual.

Different types of plastic, metal alloys, rubber compounds, etc, have physical properties. The instruments used to take measurements are made from some material which has physical properties. The implicit point that the GD&T manual captures here is that measurements are contextual.

Leonard Peikoff quite succinctly states: Time is a measurement of motion; as such, it is a type of relationship. As a measurement (a concept of method, I do believe) one of the requirements is that the unit, once chosen remain immutable and absolute whenever used. If there are physical factors that play into the accuracy of a measurement, the identification of the conditions under which it applies need be clearly delineated to prevent ambiguity and/or erroneous measurements. Compensation should be made for measurements taken under unique conditions, and the conversion factors need to take into consideration the relevant known criteria to ensure accuracy and provide a sound basis for relevant comparisons.

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And that slowing down of the motion of all processes is exactly what "time dilation" means, as time can only be defined in terms of physical processes. But there is nothing "somehow" about it, read Einstein's article from 1905 to see how he simply and elegantly explains this phenomenon.

The "somehow" would be: what sort of "resistance" (for lack of a better word) is being encountered in space which exerts a force on the processes inside the ship and causes them to slow down? If they are slowing down, something in reality must be responsible for slowing them down.

That is correct, but that's also what the theory of relativity says.

Perhaps you are interpreting this in a more rational way than most proponents of this theory? Because the way I have typically heard it is that there is a time-for-one-twin and a time-for-the-other and that time itself slows down for the twin in the spaceship, causing the two times to come out of sync. That sort of interpretation makes no sense. I don't think anyone here is disputing the facts of the matter, simply the interpretations.

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I think it is helpful to consider Aristotle's analysis of time in his Physics. Time is not, properly, a continuum of events but a measurement of change or motion. ("It is clear, then, that time is â€˜number of movement in respect of the before and afterâ€™, and is continuous since it is an attribute of what is continuous.") Time, like space, is relative, space being a way to describe the relative distance between objects and time being a way to describe the relative motion of objects. We measure time by the motion of an object which moves in equal increments, like the earth around the sun, a clock's hand, or an atom's decay.

Its been far too long since I have read much Aristotle, I had missed/forgotten all about that one. It is a pretty useful formulation though.

Time is defined on the basis of periodic phenomena. For many centuries periodic astronomical events like the movement of the Earth were used as a basis for the definition of time, but this standard was due to all kinds of small perturbations less regular in comparison with such elementary physical phenomena like the oscillation of a light wave with a given wavelength, so that this is the basis of the modern definition of time. Any definition must refer to some physical phenomenon - the check with reality - otherwise you're just really engaging in a "floating abstraction".

Almost true : The measurements of time are defined in such a manner. Time itself is not defined in such a manner per se. Though I do not know how you would measure it except by measurements which rely on periodic phenomena.

On the contrary, this process is understood perfectly. It follows directly from Einstein's postulate (together with a few elementary assumptions) that the speed of light is constant and independent of the motion of the observer. Einstein's theory still stands firm after a century, having been experimentally confirmed with great accuracy countless times, that is the check with reality.

On the contrary, the mathematics is understood perfectly and has been confirmed countless times. However, what is not understood is that despite how the mathematics is interpreted, it does not mean that time is dilating or that it is a dimension. What is not understood is the correct physical implications / meaning of some of all of the math.

That's very simple. Dimension is a mathematical concept, which uses a ordered set of coordinates. When you compare two such sets, there is nothing impossible in a dilation or contraction of one set with regard to the other one.

Yes, I know he mathematics involved. The problem is that once you get to the "higher" dimensions (4th and above) it becomes "pure mathematics" with no real meaning or physical referents. Time qua dimension has no physical meaning, even if mathemtically speaking it has a clear and conceptually relatively simple definition ( though as simple as you may find it, lots of students find it very tricky).

Mathematics is all about abstractions, but there is nothing "floating" about it. Dimensions higher than 3 do have many, many physical referents. Thanks to theories that use such higher dimensions we have been able to create modern technology, from atomic bombs to lasers, electronics and computers, check with reality!

Yes obviously mathematics is all about abstractions. But the abstractions exist to help us measure things or to discover abstract methods of measurement ( calculus would be a good example of something which lets us do this). I did not say *mathematics* was a floating abstraction, only that some things in mathematics are.

I challenge you to name the referents, physical or otherwise ( ie, valid lower level concepts which refer ultimately to "physical" objects ) of "time" qua dimension / as physics generally views it as.

The fact that the math allows us to do useful things does not validate arbitrary physical interpretations of it.

And that slowing down of the motion of all processes is exactly what "time dilation" means, as time can only be defined in terms of physical processes. But there is nothing "somehow" about it, read Einstein's article from 1905 to see how he simply and elegantly explains this phenomenon.

This sounds good, except that regardless of whether "time dilation" was meant to refer to purely mechanical processes experienced by clocks and such caused under specific conditions, the terminology is misleading and needlessly confusing. The way time is usually conceived of in physics is not consistent with time dilation referring only to changes in the manner in which devices used to measure time operate. If it did, maybe it would be simply a misleading way to refer to such things. However, if you then treat time as they do, it becomes far more confusing and nonsensical....

Edited by Prometheus98876

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