# what is time?

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I agree with Eise that time and space do not deserve the place of what we would consider real physical presences. Time is only relevant when we can observe change and compare that to a set value of change from a certain physical oscillator, like a cesium clock or a pendulum, to better record or compare the phenomenon. When we say that something took a whole day to complete, we can imagine that, as we have experienced and have a set value to how long that would be. If I said that someone was very tall, you wouldn't be able to imagine a concrete and absolute view of it. Although, if I said that he was four meters tall, using this set scaling system allows me to compare and contrast with other objects that I know of to get a good grip on the reality of it.

The fact that we have these set SI units allows us to create concrete pictures of the world around us using these concepts which could be abstract, physical, or emergent of other physical phenomenon.

The meter is a length scale that is now defined as the distance light travels in a vacuum in 1/299792458 of a second. Where a second is defined as 9,192,631,770 periods of the hyperfine state of the ground state in a cesium atom which is in turn, once again, a measure of the change or movement of an object.

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Where a second is defined as 9,192,631,770 periods of the hyperfine state of the ground state in a cesium atom which is in turn, once again, a measure of the change or movement of an object.

(Change, maybe. But not movement.)

More importantly, don't confuse the way we measure time with the way we define what it is. The use of time as a dimension in relativity, for example, does not require change or movement.

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And so what is time?

Is it the measure of change or the cause of change?

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measure. time doesn't cause.

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Do you mean a dimension as in a literal sense or in a mathematical way?

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360 - 90

270 - With an x-y-z

Big bang expansion

Time is the other 90 degree's which makes a full circle and thus, time is the cycling of a circle.

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Thank you modred for some common sense.

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And so what is time?

It is what clocks measure.

Is it the measure of change or the cause of change?

It is a measure of change and no change. A radioactive atom will spontaneously decay/change at any point in time but time is still occurring in the absence of that change. Time occurs in the absence of matter; it's a part of space as well, so, no movement is needed.

Edited by StringJunky

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(Change, maybe. But not movement.)

More importantly, don't confuse the way we measure time with the way we define what it is. The use of time as a dimension in relativity, for example, does not require change or movement.

But the measurement of a second does require the counting of a number of changes in the position of a cesium atom. How else do you measure time or know the units of time without measuring it from what you consider an objective clock which changes at a set rate which you can then use to compare certain processes.

Edited by The victorious truther

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But the measurement of a second does require the counting of a number of changes in the position of a cesium atom. How else do you measure time or know the units of time without measuring it from what you consider an objective clock which changes at a set rate.

We need something with discrete units to count time but time itself is a smooth continuum.

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Do you mean a dimension as in a literal sense or in a mathematical way?

Yes. (What is the difference?)

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We need something with discrete units to count time but time itself is a smooth continuum.

So time is physical? What is it made of? A clock does not measure time it is a device that has replicable oscillatory capabilities.

Yes. (What is the difference?)

Well, one is something that can and possibly does have physical consequences in the known world. While the other is just an abstract concept used to describe or help in calculating certain variables.

Edited by The victorious truther

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So time is physical? What is it made of?

What do you mean, what is it made of?

Why should it be made of anything? What sort of answer do you expect? "Oak, with brass trimmings and inlaid mother of pearl"?

What is distance made of? What is speed made of? What is energy made of?

A clock does not measure time

Of course it does. Next you will be telling us that a ruler doesn't measure distance.

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What do you mean, what is it made of?

Why should it be made of anything? What sort of answer do you expect? "Oak, with brass trimmings and inlaid mother of pearl"?

What is distance made of? What is speed made of? What is energy made of?

Of course it does. Next you will be telling us that a ruler doesn't measure distance.

"What do you mean, what is it made of"?

So is it immaterial, is it like invisible undetectable squirrels that are causing things to decay.

Distance is just a word we use to describe the separation of two physical objects. I could say these objects are a meter apart or a few yards but these are concepts we use to relate certain distances. So as with the second which is used to distinguish a certain scale to measure the changes in the position of an object. Speed is the change in position over the change in the oscillation of a physical object which you continue to suppose some metaphysical field is causing.

When I say that time is not measured by a clock, I mean that there isn't a metaphysical presence that warps or causes it or allows it to change. We have two different views on a clock, you say it is time that is causing the change and thus a measurement of it while i'm saying that the clock is changing and thus we use this oscillatory motion to compare other changing objects to. You say it is dependent while I say it is independent.

Edited by The victorious truther

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Time isn't made up of anything. It isn't a substance. One has to be careful on the word physical.

For example color is a physical property. Yet color isn't made up of some substance. Just as physical length is a property.

Time is also a physical property as your measuring rate of change of some state or object. This doesn't mean that time is some mythical substance/force etc.

Time is simply a measurable rate of change or duration. nothing more

Edited by Mordred

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Thanks again, Mordred.

Edited by The victorious truther

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'Physical' is what physicists can measure i.e. it pertains to physics.

Edited by StringJunky

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'Physical' is what physicists can measure i.e. it pertains to physics.

Correct any measurable quantity is a physical quantity by nature.

Definitions in physics are extremely important and supply key clues into the mathematics and descriptives in physics.

(unfortunately many confuse physical with materialistic)

Edited by Mordred

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Dear mordred, if time is just a concept we use to measure duration then how would you interpret time dilation close to the speed of light or in a strong gravitational field.

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Dear mordred, if time is just a concept we use to measure duration then how would you interpret time dilation close to the speed of light or in a strong gravitational field.

The clock is still ticking normally in those frames. The time dilation is what an outside observer measuring those frames measures. It's only when you look into another frame you see a difference relative to yours.

Edited by StringJunky

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Distance is just a word we use to describe the [physical] separation of two physical objects.

And time is just a word we use to describe their temporal separation.

When I say that time is not measured by a clock, I mean that there isn't a metaphysical presence that warps or causes it or allows it to change

That is a bizarre straw man argument. You have invented this "metaphysical field" and then say that is not what clocks measure. Well, obviously not, as it doesn't appear to exist.

We can use regular events to measure time in the same way we use regular marks (or footsteps) to measure distance. That doesn't make distance a "metaphysical field".

Dear mordred, if time is just a concept we use to measure duration then how would you interpret time dilation close to the speed of light or in a strong gravitational field.

The same way you interpret changes in length in those circumstance: a change in the measurements from another frame of reference. You can consider this as a transformation (e.g. rotation) of the coordinate system used.

Edited by Strange

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It is what clocks measure.

This is pretty useless, don't you think? "What is a photon?" "It is what a photomultipier measures." Would you be satisfied by such an answer?

A radioactive atom will spontaneously decay/change at any point in time but time is still occurring in the absence of that change. Time occurs in the absence of matter; it's a part of space as well, so, no movement is needed.

There is no way you can know it. And what is the meaning of 'time is occurring'? I would say that events occur. In my opinion it is impossible to say what time is, or even measure it, in the absence of events.

We need something with discrete units to count time but time itself is a smooth continuum.

Again, you can't know. All clocks or based on cycles or ticks: we only know that until now we can treat time as continuous.

Of course it does. Next you will be telling us that a ruler doesn't measure distance.

The comparison is not quite apt: a ruler measures length, or distance, as you say. But the time-equivalent of length is duration, not time: a fixed time interval between two ticks. The equivalent of time is space. And I have really no idea what space would be when there were no distances and lengths at all.

measure. time doesn't cause.

Yes. This makes time's existence something different from physical things, or better events, that can cause something. I somehow agree that time exists, but it exists not in the same way as physical objects and events. (Yes, that would be materialistic.)

(Change, maybe. But not movement.)

More importantly, don't confuse the way we measure time with the way we define what it is. The use of time as a dimension in relativity, for example, does not require change or movement.

Well, Einstein explicitly referred to clocks and rods in his 'On the Electrodynamics of Moving Bodies'. I think he did because without reference to concrete clocks and rods, by using operational definitions, he could clarify what he meant. He had to go back to the most basic points of what it means to measure time and space. Comparison with standard durations and lengths is such an operational definition.

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But the measurement of a second does require the counting of a number of changes in the position of a cesium atom. How else do you measure time or know the units of time without measuring it from what you consider an objective clock which changes at a set rate which you can then use to compare certain processes.

You measure a quantum state. Not position.

So time is physical? What is it made of?

The same thing length is made of, just rotated 90º

When I say that time is not measured by a clock, I mean that there isn't a metaphysical presence that warps or causes it or allows it to change. We have two different views on a clock, you say it is time that is causing the change and thus a measurement of it while i'm saying that the clock is changing and thus we use this oscillatory motion to compare other changing objects to. You say it is dependent while I say it is independent.

I don't think anyone here has side that time causes anything, as if it was a physical force.

This is pretty useless, don't you think? "What is a photon?" "It is what a photomultipier measures." Would you be satisfied by such an answer?

On the one hand, yes, but consider that you can't define all the words you use using other words, without becoming circular. Some things have to be understood on basic principles. Also, that the function of investigating the nature of things is not physics but metaphysics, as you know. Physics doesn't tell you what it is. It tells you how it behaves.

Try to define distance or length without referring to synonyms for those words, or terms that would be defined with those synonyms. Having an implicit understanding of length is probably easier to do because we can literally visualize it.

So "it's what clocks measure", from a physics aspect, has to suffice.

The comparison is not quite apt: a ruler measures length, or distance, as you say. But the time-equivalent of length is duration, not time: a fixed time interval between two ticks. The equivalent of time is space. And I have really no idea what space would be when there were no distances and lengths at all.

A distinction without a difference. You can call it a time interval; it's a matter of defining what the starting point is. In many cases the choice of zero is implied.

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On the one hand, yes, but consider that you can't define all the words you use using other words, without becoming circular. Some things have to be understood on basic principles. Also, that the function of investigating the nature of things is not physics but metaphysics, as you know. Physics doesn't tell you what it is. It tells you how it behaves.

I think I agree: definitions must be circular in the end (per definition ). I said the same elsewhere. And it is impossible to define time without referring to change, and one has a hard task defining what change is without referring to time. But the operational definition of time is always attached to a 'standard changer'. And one refers to the duration of other processes by comparing them with the standard changer. And as you can use different kinds of changes to define a standard duration, it seems to me that time is the abstract notion, which we can only access by referring to change.

So "it's what clocks measure", from a physics aspect, has to suffice.

I know, but in my opinion it is not enough. Where e.g. an electrical current can have effects, we can use these effects to measure the current. So we measure by means of causal effects of the current. This is definitely not the case with time. The cause of the moving pendulum is gravity and inertia, not time. We cannot remove time, and then the clock stops.

A distinction without a difference. You can call it a time interval; it's a matter of defining what the starting point is. In many cases the choice of zero is implied.

I do not think so. In the first place, it is a consistent use of language: space is to time, what length is to duration. Or if you want: space is to length, what time is to duration. We can use lengths and durations to make operational definitions of space and time. But not the other way round.

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We cannot remove time, and then the clock stops.

But we can move the clock through space and it's measured time will change.

Edited.

Edited by StringJunky

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