what is time?

[Vexen]

Einstein answered this question a lpng time ago.

[Robittybob1]

david345,

 

Colour of course. When I want to know the time, I look at the color of my clock, and I know what time it is. Don't you?

 

This is the most sensible answer I can give to your questions.

"The time" and time are different things aren't they? "The time" relates very much to the Earth.

Whereas time is the difference between two "the time" readings

[Eise]

Time and change are closely associated, but they are not the same.

 

You can have one without the other.

 

You are right, they are not the same. Time is an abstraction of change, not change itself. It is the idea that some universal clock is ticking in every inertial system.

 

Without change, there is no way to observe time.

 

Time is being used here for comparison, not change.

 

Comparision of what? I compare the two mice, and notice that after 5 clock ticks mouse 1 has reached the cheese, and that mouse 2 has reached the cheese in 15 clock ticks.

 

Temperature (with a large T) is another quantity we introduce to make comparisons like time (with a small t).

 

There is an explanation of what temperature is 'behind the scenes', namely a measure of the kinetic energy of the particles of which substances are made. There is no such thing for time.

[studiot]

 

Without change, there is no way to observe time.

 

 

I already showed one way to do that, and I believe others have also showed ways.

 

It follows inescapably that since we are agreed time and change are not the same, there must be some area of non-overlap ie somewhere where they are different.

 

Whatever that difference may be is a way to consider and even observe time without change.

 

 

Comparision of what? I compare the two mice, and notice that after 5 clock ticks mouse 1 has reached the cheese, and that mouse 2 has reached the cheese in 15 clock ticks.

 

I'm glad you asked for more information.

 

Comparison of actual events, of course.

 

I was trying for a light hearted illustration of a situation where only one event actually occurs and this will be a different event in different circumstances.

Since there is only one event there can be no change.

Nevertheless we can use the mouse run times to compare possible events.

 

So we are using time for a different purpose from measuring change.

 

 

There is an explanation of what temperature is 'behind the scenes', namely a measure of the kinetic energy of the particles of which substances are made. There is no such thing for time.

 

 

I did not say that temperature worked the same way as time, just that we could also use it to make comparisons.

I should have perhaps said comparisons of mutually exclusive events.

In fact temperature is defined for such non material things as empty space and therefore a particle kinetic energy explanation is incomplete.

Edited December 17, 2014 by studiot

[robinpike]

What is time?

 

One way to define time is as follows...

 

• Time is a consequence of motion - since without motion there is no concept of time.

• And motion is a consequence of the distance between 'stuff' changing - for without distance between stuff changing there is no concept of motion.

• And distance between stuff changing is a consequence of time - for without time there is no concept of distance between stuff changing.

 

That last one is not so obvious, but think of it like this - if time were to stop, then everything would 'stand still' (like in the Superman movie).

 

Interestingly, as Eise has mentioned, the above definitions are circular.

 

Anyway, the above appears to be one way to define what time is, although it does seem to suggest that time and motion are more abstractions of 'stuff' and space, than being things in themselves?

[swansont]

What is time?

 

One way to define time is as follows...

 

• Time is a consequence of motion - since without motion there is no concept of time.

 

 

Trivially disqualified with the examples of radioactive substances previously mentioned. They decay, thus time passes for them, even though it is not connected to motion. Also, in QM the concept of motion (trajectories) goes out the window, so you can't easily tie state changes to motion.

 

Another example of time not being the same as time measurement.

[elfmotat]

Sorry for the delay, I've been busy with exams.

 

Yes, I did. Physicists also work with all kind of idealisations, like black bodies and isolated systems. So why shouldn't I? But more to the point is: would you accept a definition which contains words you do not know?

 

You can't be serious. So you're claiming that because physicists sometimes analyze idealized systems to develop useful approximations or intuition, using a clearly unrealistic dictionary as the basis for a logical argument about reality is valid? That doesn't even begin to make sense.

 

Yes, I noted that. I also noted that you give no arguments for it. There are two possibilities: a (real) definition in words, which is logically necessary circular (even if it is over a long chain of other words). Or you give an operational definition, e.g. you point to something ('this here, this is red'). That is methodologically fully OK, but it is exactly what you cannot do directly with time. You cannot point to time: but you can point to change, e.g. a clock.

 

Even if I granted you that there is no operational definition of time, that does not preclude a definition in terms of other terms which are operationally defined. So no circularity necessary.

 

But it hardly makes for a description or definition of 'change'. Of course you can say 'Change is change in time', but then you have used the word change itself.

 

So are you saying that changes can occur without any time elapsing?

 

I'll give it another try: time is the most general abstraction of all changes. Now I am also not completely satisfied with this, but at least it shows that you cannot turn it around. How can individual changes be abstractions of something that is more general?

 

That doesn't answer the question of how changes can occur without time.

 

Right. You show how physicists use the Lagrangian to solve problems of mechanics. But I asked for a definition, first of the Lagrangian,

 

Different Lagrangians are used for different problems, as I'm quite sure I've stated multiple times already. You can define whatever type of Lagrangian you want.

 

and then of kinetic energy and potential energy. Obviously you immediately refrain from defining. 'Defining' is something else than knowing how to follow a recipe.

 

It depends on the type of kinetic or potential energy you're considering. I really thought I made this easy to follow last time around, but the "kinetic" and "potential" are just names given to terms in Lagrangians which happen to be useful. The names themselves can apply to a whole variety of things, including field kinetic terms, gravitational potentials, self-interaction potentials, etc., etc. It is generally understood what is meant by the context of the problem.

 

Plus, I gave you a wonderful definition of energy which you previously ignored: the conserved Noether current generated by time-translation symmetry.

 

Let me help you, with the dimension of energy:

[J] = [kg . m²/s²]

What does the kg stand for?

 

That's not the "dimension of energy" (whatever that means), that's 1 Joule expressed in terms of kilograms, meters, and seconds. What does that have to do with anything?

 

Sorry, you are just wrong. Take the definition 'a bachelor is a man who never married'. Now I substitute the meaning of 'bachelor' in the definition. I get 'a man who never married is a man who never married'. Isn't that a tautology? (Maybe you are confusing tautology with one of its subclasses, the propositional tautology (A or not A).)

 

What do you even mean by "you're wrong"? That doesn't even make sense. I accused you of using fallacious arguments (specifically rhetorical tautologies, which are not the same as logical tautologies). You somehow twisted this into an argument over the definition of "tautology," completely missing the point. READ WHAT I'M SAYING.

 

Except that you did not follow the rules.

 

I wasn't aware there were rules. Whose rules are these?

 

Because it is an abstraction. You are like the middle age philosophers that discussed if 'whiteness', or 'horseness' existed, or even may be more real then a white plate or the horse standing in front of me.

 

This is too good. It's an abstraction because you say so. Wonderful. That's definitely not what we're arguing about or anything.

 

There is nothing to know about time except as a comparison between different processes. And of course the definition is pretty useless for a physicist. But the question of the thread is 'What is time?'. It is not 'Why all physics is completely wrong because they do not understand what time really is'.

 

So you've given us an admittedly circular and useless definition, yet you still cling to it? Bizarre. No wonder we're not getting anywhere.

[studiot]

 

That doesn't answer the question of how changes can occur without time.

 

I think I posited that you can have change without time so perhaps I ought to provide some examples.

 

Any system that has multivalued outputs (so hated by mathematicians) such as step functions, parallel computing, quantum distributions which can be in more than one state at the same time.

 

The change is clearly embodied in the selection process to obtain a particular output.

[Eise]

You can't be serious. So you're claiming that because physicists sometimes analyze idealized systems to develop useful approximations or intuition, using a clearly unrealistic dictionary as the basis for a logical argument about reality is valid? That doesn't even begin to make sense.

 

I hope others see the irony of your reaction. You seem to miss it completely. Obviously you define when something may be called a useful idealisation and when not.

 

Even if I granted you that there is no operational definition of time, that does not preclude a definition in terms of other terms which are operationally defined. So no circularity necessary.

 

Exactly what I am saying all the time. If you define, in words, you get circularity. If you define operational, in the case of time you must refer to... change.

 

So are you saying that changes can occur without any time elapsing?

 

No. I am saying that you add nothing to understanding of change by stipulating that change is change in time. We cannot understand change without reference to time: but we also cannot understand time without change. But where I have as many concrete changes as there can be, there seems to 'be' only one 'time'.

 

That doesn't answer the question of how changes can occur without time.

 

It answers why we cannot imagine change without time. But there is no way to know that there is time because there is change.

 

Plus, I gave you a wonderful definition of energy which you previously ignored: the conserved Noether current generated by time-translation symmetry.

 

Great. You just made a longer chain of, or better another circular definition.

(Just for the record: I think these Noether theorems belong to the deepest insights we have. But that is not what we are discussing about here. We are talking about circularity of definitions. Also don't forget: I am not critisising science for using circular definitions. The important point for scientific theories is that enough of the concepts are also empirically rooted.)

 

That's not the "dimension of energy" (whatever that means), that's 1 Joule expressed in terms of kilograms, meters, and seconds. What does that have to do with anything?

 

Don't be so tiresome, elfmotat. Must I rewrite it for you?

 

[Energy] = [ mass . distance²/time² ]

 

What do you even mean by "you're wrong"? That doesn't even make sense. I accused you of using fallacious arguments (specifically rhetorical tautologies, which are not the same as logical tautologies). You somehow twisted this into an argument over the definition of "tautology," completely missing the point. READ WHAT I'M SAYING.

I said, using the example of the definition of a bachelor, that all defintions are tautologies. I gave the definition of tautology I used: a proposition that is true in all possible worlds. Now show me that this concept of a tautology is a rhetorical tautology.

 

This is too good. It's an abstraction because you say so. Wonderful. That's definitely not what we're arguing about or anything.

You don't want to get the point. Say I measure the halftime of a radioactive substance (i.e. I count the clock ticks of my clock). It is one day. Then I measure how long it takes for a flower to open (again, I count clock ticks). It is also one day. So both processes are the same, when I reduce them to the aspect of time. There is however no way I can go back from '1 day' to radioactive decay or the flowering of a plant. That is what abstraction is: reduce to one of the aspects. But what I really did was comparing both processes to a 'standard changer': my clock. It seems to me you don't know what an abstraction is.

 

So you've given us an admittedly circular and useless definition, yet you still cling to it? Bizarre. No wonder we're not getting anywhere.

Where do you want to get? Again, the question of the thread is 'what is time?'. I did nothing else than give my answer. Already very early in the thread swansont gave a quite good reaction:

 

"What is time" is question of philosophy (metaphysics), not science, just as "what is length" would be. How time behaves and how it is measured are questions of physics.

So is it a useless definition? For physics, yes, definitely.

 

Are you looking for an analogy or an actual explanation? Time isn't a physical thing or interaction the way light and sound are. Time can't exert a force or impart momentum or transfer energy. It's an abstraction.

I only added of what time is an abstraction. And since then everybody is making trouble about this point. Including swansont himself.

 

It seems I touched on the religious feelings of some people. You seem to think I deny the existence of time. I don't. I only say that its existence is that of an abstraction, of change. Compare it with this: I deny that 'whiteness' exists als independent object. And then all people struggle over me as if I deny that white things exist.

 

[robinpike]

 

 

Trivially disqualified with the examples of radioactive substances previously mentioned. They decay, thus time passes for them, even though it is not connected to motion. Also, in QM the concept of motion (trajectories) goes out the window, so you can't easily tie state changes to motion.

 

Another example of time not being the same as time measurement.

 

The particular example of radioactive decay shows the problem with any counter example. That is, how do we know that motion is not involved in the radioactive decay?

 

To show that to be the case, it would need to be demonstrated that all motion has been removed from the nucleus. Is this what you meant? That the quarks in the proton are motionless, that the gluons in the nucleus are motionless? etc. I suspect that is not what you meant though.

 

If the approach is that the motion of the quarks and the motion of the gluons is not involved in radioactive decay - how has that been proved?

 

I think I posited that you can have change without time so perhaps I ought to provide some examples.

 

Any system that has multivalued outputs (so hated by mathematicians) such as step functions, parallel computing, quantum distributions which can be in more than one state at the same time.

 

The change is clearly embodied in the selection process to obtain a particular output.

 

Studiot, sorry I didn't follow your example, can you explain a bit more please?

 

My view is that without change, time does not exist. I would like see an example that counters that view.

[studiot]

Robin, I said that change and time are different and that you can have one without the other (both ways).

 

I also posted some examples somehwere in the depths of this or another long thread, I will try to look them out for you, but it will take me some time.

 

 

Note that there is a difference between saying that some changes could still occur without time, and that time is not involved since time does exist so actual changes may occur over time. I would certainly grant that the majority of change needs different times for the two states involved in a change to occur.

[Commander]

According to me we exist in a Space with Length Coordinates X , Y , X [the three dimensions which are least number to define any natural Volume Space] which can be used to designate any Point in the Entire Cosmos.

 

We can fix the Origin of these three coordinates anywhere and calculate the distance of any other Point with respect to this origin.But as we are not able to make sure that this Origin is fixed and not moving in respect of rest of the Spaces, we are unable to do so.

 

However our this INABILITY does not mean that we can not imagine a Reference Frame of Coordinates. Also, we can not declare that the Axes are NOT INFINITE just because we can not traverse them endlessly with ourselves or with an object with a Mass or A ray of Light or Particle or Even @ the Speed of Imagination.

 

These coordinates are Endless and at the end of Space Occupied by some matter lies Limitless Nothingness or Empty Space.

 

If the Physical Laws created by the Creator are such that matter Gravitates and condenses together ENDLESSLY without any Limit THE ENTIRE MATTER IN THE COSMOS are related by Mutual Forces and therefore there can be only one Universe.

 

But, if there is a Limit to the amount of matter which can congregate together [Like the Limit which produces a star or Black Hole or Big Bang] then there is a possibility of many such Universes like our Own Earth-Universe in the Cosmos.

 

Whatever be the case BEYOND ALL THESE BOUNDS will lie rest of the Nothingness and Empty Spaces.

 

Therefore we need to understand exactly what happens with the Gravitational Forces and Behaviour of Matter as a Consequence.

 

TIME is one of the Dimensions adopted by us to evaluate the Changes in a Body and Relative Change wrt other Bodies.

The various Forces and Factors such as Mass, Weight , Temperature, Pressure and Fields etc gives raise to other dimensions too and when we handle Multidimensions to Observe and Evaluate changes we adopt higher Mathematical Functions and Complicated Theories.

 

But TIME in itself has been defined as a delay segment between two Events or States of a Body.

 

Except in the ABSOLUTE EMPTINESS or NIL-SPACE there are always CHANGES effected on any Point in Space or Body and its State and TIME ELAPSED becomes a very important Parameter.

 

Of course there is an ABSOLUTE TIME REFERENCE which too is only Imaginary and NOT REFERABLE.

 

We need to bank on possible Relative References to Fix the Current Time, Measure the Lapse of Time and Use our Measurement in the Equations to solve Problems and define States and Events.

[david345]

To quote the Wikipedia article on Abstraction "For example, many different things can be red. Likewise, many things sit on surfaces (as in picture 1, to the right). The property of redness and the relation sitting-on are therefore abstractions of those objects." A change in time is an instance of the abstraction "change". An instant in time is not an instance of the abstraction "change". When a road changes it's steepness that is an instance of the abstraction "change" and steepness has nothing to do with time. Calculus often deals with change that is not related to time. Change is an abstraction of a change in time, changes that occur over time, and other types of change. Redness is an abstraction of red apples, stop signs, and other red things.

[studiot]

David, I like it. +1

Short and logically coherent.

A clear simple example of change without time, I didn't think of.

 

I have been wondering about the word 'abstraction' since it was introduced here.

Thanks.

 

One question:

 

Nnouns can be 'concrete' or 'abstract'.

Abstract (the adjective) in this sense has a more restricted meaning than in abstraction (the noun), which can be 'abstract' as we are using it or concrete as in the syrup which is an abstraction from sugar cane.

 

What do you think?

Edited December 19, 2014 by studiot

[robinpike]

To quote the Wikipedia article on Abstraction "For example, many different things can be red. Likewise, many things sit on surfaces (as in picture 1, to the right). The property of redness and the relation sitting-on are therefore abstractions of those objects." A change in time is an instance of the abstraction "change". An instant in time is not an instance of the abstraction "change". When a road changes it's steepness that is an instance of the abstraction "change" and steepness has nothing to do with time. Calculus often deals with change that is not related to time. Change is an abstraction of a change in time, changes that occur over time, and other types of change. Redness is an abstraction of red apples, stop signs, and other red things.

 

The above uses an example of a road changing its steepness, and the conclusion that, that kind of change has nothing to do with time.

 

I don't think that conclusion holds true...

 

Surely, the existence of steepness is only possible if motion is present? And because of motion, also time?

 

Because... walking along the road and to reach the incline requires motion. And that incline is only an incline because it changes the direction of the motion.

 

If there were no time, then either no progress is possible along the road, or the opposite, everything happens 'in no time' - in an instant - in which case the change in direction is never detected, because it is not possible to be aware of the different directions before and after reaching the incline?

[swansont]

 

The particular example of radioactive decay shows the problem with any counter example. That is, how do we know that motion is not involved in the radioactive decay?

 

To show that to be the case, it would need to be demonstrated that all motion has been removed from the nucleus. Is this what you meant? That the quarks in the proton are motionless, that the gluons in the nucleus are motionless? etc. I suspect that is not what you meant though.

 

If the approach is that the motion of the quarks and the motion of the gluons is not involved in radioactive decay - how has that been proved?

 

Feel free to come up with a model that ties the decay to motion.

 

Physics make no such claim about motion and time. In relativity, time passes faster as motion decreases. It runs fastest when an object is at rest.

 

The only way the claim makes sense if it's a binary condition — no motion means no time, and any motion at all means time passes. Well, that's pretty useless, scientifically, since you can't have a condition where something has no motion at all, so there's no way to test it.

 

If it's not a binary condition, i.e. you have time slowing as an object's motion decreases, then it runs counter to relativity, and also counter to experimental evidence.

 

I only added of what time is an abstraction. And since then everybody is making trouble about this point. Including swansont himself.

 

It seems I touched on the religious feelings of some people. You seem to think I deny the existence of time. I don't. I only say that its existence is that of an abstraction, of change. Compare it with this: I deny that 'whiteness' exists als independent object. And then all people struggle over me as if I deny that white things exist.

 

 

No, that's a bit of revisionist history. Your assessment said that without change there is no time, which implies there is no time in regions of space where things are unchanging*. That's contrary to physics, and this is (supposedly) a physics discussion. You're discussing philosophy, and you can leave me out of it.

 

* or, as with the example I gave to robinpike, one could argue there are no places where there is no change, which means that this, too is unfalsifiable.

[david345]

The above uses an example of a road changing its steepness, and the conclusion that, that kind of change has nothing to do with time.

 

I don't think that conclusion holds true...

 

Surely, the existence of steepness is only possible if motion is present? And because of motion, also time?

 

Because... walking along the road and to reach the incline requires motion. And that incline is only an incline because it changes the direction of the motion.

 

If there were no time, then either no progress is possible along the road, or the opposite, everything happens 'in no time' - in an instant - in which case the change in direction is never detected, because it is not possible to be aware of the different directions before and after reaching the incline?

Slope is ∆x/∆y. You claim we can only have a slope if we walk up a hill. Without oxygen you would die and be unable to observe change. You could claim change is required for oxygen. I could argue oxygen is required for change. Edited December 19, 2014 by david345

[robinpike]

Slope is ∆x/∆y. You claim we can only have a slope if we walk up a hill. Without oxygen you would die and be unable to observe change. You could claim change is required for oxygen. I could argue oxygen is required for change.

 

This is tricky to get across easily... Using your reply...

 

To observe requires change, to die requires change, to breathe requires change (in that the electrons in carbon and oxygen react and change), but oxygen is not required for change, and change does not require oxygen.

 

Feel free to come up with a model that ties the decay to motion.

 

Physics make no such claim about motion and time. In relativity, time passes faster as motion decreases. It runs fastest when an object is at rest.

 

The only way the claim makes sense if it's a binary condition — no motion means no time, and any motion at all means time passes. Well, that's pretty useless, scientifically, since you can't have a condition where something has no motion at all, so there's no way to test it.

 

If it's not a binary condition, i.e. you have time slowing as an object's motion decreases, then it runs counter to relativity, and also counter to experimental evidence.

 

Swansont, I appreciate your points above. There is a difficulty in using the term 'object' if the object refers to a collection of smaller objects. Discussing the rate of time only makes sense if the discussion refers to the smallest objects - that is the fundamental particles.

 

For example, one can observe a flower growing more slowly in winter than in summer, but because the flower is a collection of objects, that is the reason why it does not make sense to use that observation to declare that time is dependent on temperature.

 

 

Maybe applying the discussion to a very simple system might help.

 

If a system has fundamental particles that all move at the same single speed, and the space in the system does not expand nor contract, then as the particles move about that space, time would be present and that time would be the same at all points in that space and the same for all the particles.

 

Now take the observation of what happens if all the particles were to stop moving,.. not only does change stop, but time also disappears. That is why I suggest that time requires change, and time requires motion.

Edited December 19, 2014 by robinpike

[studiot]

 

The above uses an example of a road changing its steepness, and the conclusion that, that kind of change has nothing to do with time.

 

Exactly.

 

There is another kind of change that does not involve time.

 

Ergo you can have change without time.

 

There is nothing more to be said.

[robinpike]

 

The above uses an example of a road changing its steepness, and the conclusion that, that kind of change has nothing to do with time.

 

 

 

Exactly.

 

There is another kind of change that does not involve time.

 

Ergo you can have change without time.

 

There is nothing more to be said.

 

Not quite! I don't see how steepness of the road is possible without motion and change being present - that is without time?

 

Is the following causing the discussion to be at cross purposes...

 

Are you assuming that you are outside of the system, and your looking down on the road and noting that the road changes its steepness, is outside of the concept of motion and change of the system?

[studiot]

I'm sorry Robin, there can be no other explanation.

 

You must work for British Rail!

 

Points failure due to icing : 'The 'Wrong kind of snow'

 

Trains running slow : 'Wrong kind of leaves'

 

Water in signal box : 'Wrong kind of rain'

 

and now, ................wait for it..............., the 'Wrong kind of change'

 

Wow.

[swansont]

 

 

Swansont, I appreciate your points above. There is a difficulty in using the term 'object' if the object refers to a collection of smaller objects. Discussing the rate of time only makes sense if the discussion refers to the smallest objects - that is the fundamental particles.

 

For example, one can observe a flower growing more slowly in winter than in summer, but because the flower is a collection of objects, that is the reason why it does not make sense to use that observation to declare that time is dependent on temperature.

 

 

 

OK, let's discuss muons, whose lifetime gets longer when they are moving, just as relativity predicts.

[elfmotat]

I hope others see the irony of your reaction. You seem to miss it completely. Obviously you define when something may be called a useful idealisation and when not.

 

There is a big difference between "this scenario may make for useful approximations" and "I can imagine this hypothetical object, therefore all conclusions drawn about the hypothetical world in which it exists must also be true of our world." The former is perfectly fine. The latter makes zero sense.

 

Exactly what I am saying all the time. If you define, in words, you get circularity. If you define operational, in the case of time you must refer to... change.

 

So we're in agreement that there's no circularity necessary? Good.

 

No. I am saying that you add nothing to understanding of change by stipulating that change is change in time.

 

And you add nothing to our understanding of time by stipulating that time is change in time.

 

We cannot understand change without reference to time: but we also cannot understand time without change. But where I have as many concrete changes as there can be, there seems to 'be' only one 'time'.

 

I don't know what you mean by "only one time." This seems like it could be true or false, depending on exactly what you mean.

 

It answers why we cannot imagine change without time. But there is no way to know that there is time because there is change.

 

So we're arguing about unfalsifiable nonsense?

 

Great. You just made a longer chain of, or better another circular definition.

 

I don't know how to argue with blanket assertions.

 

Don't be so tiresome, elfmotat. Must I rewrite it for you?

[Energy] = [ mass . distance²/time² ]

 

It's generally a good idea to learn physics before you try to make arguments based on physics. For any unit system, you need a basis set of quantities which spans the entire set. Sometimes, those basis quantities are chosen to be [time], [length], [mass], and [charge]. However, there's no particular reason to choose them. You could equally well use [acceleration], [density], [current], and [energy], for example. In that choice energy has fundamental dimensionality. The choice is completely arbitrary.

 

I said, using the example of the definition of a bachelor, that all defintions are tautologies. I gave the definition of tautology I used: a proposition that is true in all possible worlds. Now show me that this concept of a tautology is a rhetorical tautology.

 

So I guess we've established that you're incapable of reading.

 

Where do you want to get? Again, the question of the thread is 'what is time?'. I did nothing else than give my answer. Already very early in the thread swansont gave a quite good reaction:

 

I want to get a better understanding of time. Your definition has not done that for me. I also want to know why you're clinging to misleading, overtly circular, and useless metaphysical definitions. I can't wrap my brain around what you could possibly gain from thinking about time in this way.

 

So is it a useless definition? For physics, yes, definitely.

 

Well then, I suppose we're done, aren't we?

[david345]

This is tricky to get across easily... Using your reply...

 

To observe requires change, to die requires change, to breathe requires change (in that the electrons in carbon and oxygen react and change), but oxygen is not required for change, and change does not require oxygen.

Without oxygen you could never have been born. You would never observe one single change. You claim change occurs even if you don't observe it. You claim a slope can only exist if you walk up a hill. If a change or motion had 0 magnitude then that change or motion would not exist(it would be 0). Change and motion require magnitude. Does this mean change and motion are just magnitude?

[Eise]

No, that's a bit of revisionist history. Your assessment said that without change there is no time, which implies there is no time in regions of space where things are unchanging*. That's contrary to physics, and this is (supposedly) a physics discussion. You're discussing philosophy, and you can leave me out of it.

 

OK, sorry. But I think I stated it more precisely later. In a closed system in which there is no change, there is no time. Of course you can see why this must 'degrade' in a philosophical discussion: any observation about what 'happens' in the closed system contradicts the condition that it is a closed system. So we are talking about something we have principally no knowledge of.

 

So yes, the question 'what is time?' is a philosophical question, and the answer one gives has, per definition, no impact on the empirical science that physics is.

 

So I really don't understand why I get so much resistance. My answer has no impact at all on our daily life, nor on physics. But there are people who have this 'philosophical need', like the originator of this thread.

 

I gave my answer (it is an abstraction, namely of change), I gave my main arguments (we cannot observe time except through change; time in itself causes nothing, so it is not a physical category in the sense as objects, fields are).

 

There is a big difference between "this scenario may make for useful approximations" and "I can imagine this hypothetical object, therefore all conclusions drawn about the hypothetical world in which it exists must also be true of our world." The former is perfectly fine. The latter makes zero sense.

Would you accept a dictionary of physics in which there are no lemmas for certain physical concepts?

 

So we're in agreement that there's no circularity necessary? Good.

 

Mind what I said: defining in words is circular. And that is what we started about. You asked me to define change without use of the word time.

 

And you add nothing to our understanding of time by stipulating that time is change in time.

 

I am not adding something to physics. But the question 'what is time?' is a philosophical one.

 

I don't know what you mean by "only one time." This seems like it could be true or false, depending on exactly what you mean.

I mean something like the 'Newtonian time', that together with space forms the stage on what everything is happening. I gave an example already. After one hour my CD stops playing, and I am left with only half of my radioactive substance. These changes are completely different, but under the single aspect of time, they are the same. They both took one hour, i.e. there were equal amounts of clock ticks for both processes, and I started the CD and my measurement of the radioactivity at the same moment. So under the very abstract view of 'how long did the processes take', both are the same: 1 hour. But you see, I left out all the details. There is no way that I can get back from the concept of one hour to the playing of a CD or some radioactive halftime. The other way round is easy. That's why I am saying that time is an abstraction of change, and that it is definitely not the other way round.

 

So we're arguing about unfalsifiable nonsense?

No. We are not talking empirical science. If you think that everything that is not empirical is nonsense, then you are right.

 

It's generally a good idea to learn physics before you try to make arguments based on physics. For any unit system, you need a basis set of quantities which spans the entire set. Sometimes, those basis quantities are chosen to be [time], [length], [mass], and [charge]. However, there's no particular reason to choose them. You could equally well use [acceleration], [density], [current], and [energy], for example. In that choice energy has fundamental dimensionality. The choice is completely arbitrary.

 

You could not better show me my points that definitions are circular, and that for an empirical science it is necessary to have operational definitions for enough of its concepts, so that it can assign values to all of its concepts.

 

So I guess we've established that you're incapable of reading.

 

The discussion started with me saying that all definitions are tautological. Then somehow on the way you started me of accusing me of using rhetorical tautologies, pasting a Wikipedia article that does not apply, and that is vague as it can be. Its only reference shows many examples that are not propositions ('free gift', 'new innovation') and that in fact are pleonasms. But definitions are propositions, and given my definition, they are tautologies. Not because of their propositional form (A or (not A)), but because its truth is independent of empirical circumstances: its truth follows from the meanings of their words.

 

So now please explain me where I am supposed to misread you.

 

I want to get a better understanding of time. Your definition has not done that for me. I also want to know why you're clinging to misleading, overtly circular, and useless metaphysical definitions. I can't wrap my brain around what you could possibly gain from thinking about time in this way.

 

In my opinion just this: that time is not something we can tell about, but that we need to tell about anything else.

Edited December 20, 2014 by Eise