What is Time?

[oxmixmudd]

But an operational definition of a clock does not have that problem (assuming you did read post #181 [operational definition]).



But timekeepers do use statistics continuously to maintain their cutting-edge clocks.

I see only a very superficial correlation between you comments and my post. That is, your comments don't indicate to me you understand the point I was making. Could you elaborate?

Thanks,

Jim

[little_monkey]

LM uses the definition, 'time is what we measure with clocks', which is to me also a bit circular, or perhaps just not sufficient.

Clarification: it's not circular - what is done is a mapping between the motion of a particle and the motion of the internal parts of a clock. It's a definition of motion that is very precise, objective and doable. And there isn't any other way of measuring motion. So one can philosophize about the meaning of "time", but it won't change one iota as to what is done in our physical theories, as all scientific theories developed since Galileo, we've be doing this - a mapping. It's the old saying: call a spade a spade.

[oxmixmudd]

Clarification: it's not circular - what is done is a mapping between the motion of a particle and the motion of the internal parts of a clock. It's a definition of motion that is very precise, objective and doable. And there isn't any other way of measuring motion. So one can philosophize about the meaning of "time", but it won't change one iota as to what is done in our physical theories, as all scientific theories developed since Galileo, we've be doing this - a mapping. It's the old saying: call a spade a spade.

Understood, and I'm not trying to say physics is wrong to do so. It works for all the things that physics does with it. It is sufficient. But it doesn't capture all that time is either. Because any change of any sort is impossible without time. Yet your definition doesn't capture that. And a clock depends on a 'regular motion' to measure time, yet time is evidenced by any sort of motion or change. And I think it clear that even if there is no measurable motion, if the possibility of/potential for motion exists, then there is time. So a clock measures time, but it doesn't explain or give us a handle on what time is, except in the circular sense that time is what a clock measures. And that is why I called the definition circular. It was not meant as an insult in the way it typically gets used around here.

So the definition you use tells us time is what a clock measures, but it doesn't help us understand the essence of time itself. And perhaps I'm being unfair, because it may also well be true we don't understand what the essence of 'space' is either - but I think we come closer to that than we do time. Or perhaps another observation, there are legitimate theorists that want to say time is an illusion, yet they don't want to say space is an illusion - and that to me implies the physicists definition of time then captures less of what time is than the physicists definition of space, because we don't have theories that try to claim space is an illusion as well - or do we? And It would seem to me if time is an illusion, then there is no reason not to assume space may not also be an illusion, because it is quite clear the two are intimately related things (ToR).

BTW - Have you ever thought about the fact that even though motion is used to measure time, and motion is evidence of time, the fastest possible motion in its (unreachable) limit itself removes time AND one spatial dimension in the direction of motion? That is, even though it is unreachable because the energy requirement is infinite, a physical object moving through space at exactly the speed of light is time dilated to time's 'rate' being 0 (no time experienced for any distance travelled) and Lorentz contracted to a length in the direction of motion of 0.

Just sort of odd in terms of it's implications from a 'thought experiment' perspective.


Jim

[little_monkey]

Understood, and I'm not trying to say physics is wrong to do so. It works for all the things that physics does with it. It is sufficient. But it doesn't capture all that time is either. Because any change of any sort is impossible without time. Yet your definition doesn't capture that.

You seem to think that what I'm saying is that time is some sort of illusion. Far from me to think so. What I'm pointed out, among many things, is that what we see is motion. And the way we go about measuring motion is through a clock.

And a clock depends on a 'regular motion' to measure time, yet time is evidenced by any sort of motion or change.

Of course, but how do we know that there are different types of motion? By comparing these different types of motion to the regular motion inside a box we call a clock. With no clocks, how can you measure these different types of motion??? It's not a fault that the universe contains situations that produce regular motion. And it took millennia to take advantage of that. Big thanks to Galileo.

And I think it clear that even if there is no measurable motion, if the possibility of/potential for motion exists, then there is time.

You can't know that until that potential actually produces motion. Otherwise, it is just speculation.

So a clock measures time, but it doesn't explain or give us a handle on what time is, except in the circular sense that time is what a clock measures. And that is why I called the definition circular.

I'm aware that on a philosophical basis, you can speculate on the nature of "time", but in what ways will that affect physical theories?

It was not meant as an insult in the way it typically gets used around here.

No offense taken. And I hope I didn't insult you.

BTW - Have you ever thought about the fact that even though motion is used to measure time, and motion is evidence of time, the fastest possible motion in its (unreachable) limit itself removes time AND one spatial dimension in the direction of motion? That is, even though it is unreachable because the energy requirement is infinite, a physical object moving through space at exactly the speed of light is time dilated to time's 'rate' being 0 (no time experienced for any distance travelled) and Lorentz contracted to a length in the direction of motion of 0.

Just sort of odd in terms of it's implications from a 'thought experiment' perspective.


Jim

There are two major problems:

(1) As you've indicated, you would need an infinite force, but more closely to what the equations in SR are saying: you would need to have zero mass, so photons qualify but you don't...;-)

(2) At c, from the photon's pov, time is meaningless. In terms of what I'm saying: your clock ceases to function - the regular motion of your clock goes to zero - it's a useless apparatus.

[Truthseeker]

Understood, and I'm not trying to say physics is wrong to do so. It works for all the things that physics does with it. It is sufficient. But it doesn't capture all that time is either. Because any change of any sort is impossible without time. Yet your definition doesn't capture that. And a clock depends on a 'regular motion' to measure time, yet time is evidenced by any sort of motion or change. And I think it clear that even if there is no measurable motion, if the possibility of/potential for motion exists, then there is time. So a clock measures time, but it doesn't explain or give us a handle on what time is, except in the circular sense that time is what a clock measures. And that is why I called the definition circular. It was not meant as an insult in the way it typically gets used around here.

I am inclined to agree that someone who invents many ways to measure the passage of time does not necessarily know what time really is. Furthermore, perhaps time measurement is as far as we can go to know the real nature of time.




One's conscious travels through spacetime and in so doing he perceives the things in space and what he would call, "time is passing." Just a laughable notion.

[JimL]

(2) At c, from the photon's pov, time is meaningless. In terms of what I'm saying: your clock ceases to function - the regular motion of your clock goes to zero - it's a useless apparatus.

What does it mean that for a photon "time is meaningless"? Does time "cease to exist" for the photon, or in what other sense do you mean "meaningless?"

[little_monkey]

What does it mean that for a photon "time is meaningless"? Does time "cease to exist" for the photon, or in what other sense do you mean "meaningless?"

In post #64, I said, Imagine a universe in which there is no motion.... I was describing the world from the perspective of a photon. In that frame of reference, a clock would be frozen, you would not be able to distinguish one moment to the next. If I would tap you on the shoulder and ask you, what time is it? Assume you always lived on that photon and that you could respond: you would shrug as you would not understand what I'm asking you. In that sense, for the photon and you, time would be meaningless.

[Truthseeker]

Just a note to say I am not in agreement with LM's last post but will not explain.

[X6]

'Photon' doesn't have motion defined in 3D. Special relativity can be applied only where it is tested to give us appropriate results (e.g., if the result differs from experimant by 2 factor or by 0.5 factor it can be called appropriate, as in QM).

I think, we, as all living creatures around the Universe, are equipped with devices that can do much more than any other man-made devices. Some can see in 5D, some in 7D, some are tied to this world tighter than others... I think you shouldn't overestimate physics. Physics is good, but it is not good if you speculate with theories, the only purpose of which is to make calculations for a small set of events.

[JimL]

In post #64, I said, Imagine a universe in which there is no motion.... I was describing the world from the perspective of a photon. In that frame of reference, a clock would be frozen, you would not be able to distinguish one moment to the next. If I would tap you on the shoulder and ask you, what time is it? Assume you always lived on that photon and that you could respond: you would shrug as you would not understand what I'm asking you. In that sense, for the photon and you, time would be meaningless.

So, if time is meaningless with regards to the photon, in what sense does time exist for the photon. If time is just a dimension that an object moves through then what does the objects velocity have to do with its effect on time? Why does velocity determine time, make time meaningless?

[little_monkey]

So, if time is meaningless with regards to the photon, in what sense does time exist for the photon.

The first part of your sentence ( time is meaningless with regards to the photon) is the answer to the second part of your sentence (what sense does time exist for the photon)...

If time is just a dimension that an object moves through then what does the objects velocity have to do with its effect on time?

For the observer, his clock slows down, But he doesn't notice that. He thinks his clock still ticks at the same rate, It's only when he compares his clock to the clock of an observer in a different frame that he will realize his was ticking at a different rate.

Why does velocity determine time, make time meaningless?

Only for particles moving at c will time be meaningless - the clock is frozen, it no longer works. To such an observer, nothing moves, nothing changes. How could you differentiate one "moment" of time from another "moment" of time when nothing changes?

[Truthseeker]

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'Photon' doesn't have motion defined in 3D.

Our binoculars and telescopes are designed based on the assumption that photon trajectories are wholly in space-time (3 spatial and 1 temporal coordinates in Minkowski's model. Do the telescopes and binoculars not work well?

[Truthseeker]

If time is just a dimension that an object moves through . . .

No, every object moves through space-time.

then what does the objects velocity have to do with its effect on time?

We don't understand time yet. It seems better to say, though, that velocity effects the observer's perception of spacetime or measurements made in it.

Do you know about the Doppler Effect? It is very much related to time dilation. If you don't know, you should read up on it.

Why does velocity determine time, make time meaningless?

No, that's probably not the right way to view the evolution of space-time. Common sense says that photons do not think.

[JimL]

The first part of your sentence ( time is meaningless with regards to the photon) is the answer to the second part of your sentence (what sense does time exist for the photon)...

Yes I understand what you mean by its being meaningless, but if it is meaningless, then in what sense can it even be said to exist. I believe I read somewhere that the photon only moves through time, not through space, but what does it mean to move through time, if time is meaningless? It seems more as though it is moving through no time?

For the observer, his clock slows down, But he doesn't notice that. He thinks his clock still ticks at the same rate, It's only when he compares his clock to the clock of an observer in a different frame that he will realize his was ticking at a different rate.

I understand, but why? Why does velocity make time meaningless? Why does motion only through time, make time stand still?

Only for particles moving at c will time be meaningless - the clock is frozen, it no longer works. To such an observer, nothing moves, nothing changes. How could you differentiate one "moment" of time from another "moment" of time when nothing changes?

Yes i understand that, but why? How do you make sense of the contradiction of frozen velocity?

[little_monkey]

Yes I understand what you mean by its being meaningless, but if it is meaningless, then in what sense can it even be said to exist. I believe I read somewhere that the photon only moves through time, not through space, but what does it mean to move through time, if time is meaningless? It seems more as though it is moving through no time?

It's meaningless to a photon but not to massive particles.

I understand, but why? Why does velocity make time meaningless? Why does motion only through time, make time stand still?

Not sure what you have in mind.

Yes i understand that, but why? How do you make sense of the contradiction of frozen velocity?

Which velocity is frozen?