What is "time"

[Farsight]

An interesting observation and I think true, (but don't vouch for 30cm being enough).

It's true, see the David Wineland interview:

"But nowadays the precision of the clocks is such that we have to worry, when we compare clocks, if one clock in one lab is 30 centimeters higher than the clock in the other lab, we can see the difference in the rates they run at. And this is an extremely small effect that we haven't had to worry about before."

It like 200+ years go when the second was defined by pendulum clocks - They did not specify the gravity strength they were to run in. Do we do that now? - Tell what gravity strength is associated with the number of cycles that are a second?

No. It depends on gravitational potential. This varies with altitude, but I couldn't see any mention of sea level in the official definition. The pendulum clock is unlike other clocks in that the local slope in gravitational potential determines the clock rate.

 

[OnlyMe]

Huh? Spacetime represents space at all times. That's why there's no motion in spacetime.

We all know what a second is. It's nowadays defined as the duration of 9192631770 periods of radiation. Only it varies with altitude. If it didn't, time dilation wouldn't happen.

Ye Gods, now you're casting aspersion on gravitational time dilation?

Oh geddoutofit. What I'm telling you is legit GR gravitational time dilation. Go and do your own research.

You're the one being religious here. Not me.

This is getting surreal. You plot a worldline in spacetime. The worldline represents the motion of a body through space over time. If the worldline is straight up the body isn't moving through space. If the worldline is slanted the body is moving through space. But in either case the body isn't moving through spacetime.

Again, go and do your own research to investigate whether I've told you the correct physics. You will find that I have. And that's you've been dismissing it in favour of popscience misunderstanding.

Farsight, your whole argument is myopic.

If what you believe about Spacetime were real, there would be no change in the relationships between two gravitating bodies and gravitational fields would be static and fixed. No orbits. No apples falling on Newton's head.

Again the fact that t is a variable, allows for change and motion in space-time.

You seem to assume that because t is a variable, any equation it is found in represents all possible values of t simultaneously. That is not only wrong and not even stupid.., it is ignorance, at its worst.

 

[Farsight]

Farsight, your whole argument is myopic.

It isn't, it's simple, and it refers to Einstein and the evidence.

If what you believe about Spacetime were real, there would be no change in the relationships between two gravitating bodies and gravitational fields would be static and fixed. No orbits. No apples falling on Newton's head.

What? When you understand that there ain't no time flowing through an optical clock, you understand that an optical clock goes slower when its lower because light goes slower when its lower. Just like Einstein said. And then you understand what he was on about when he said a curvature of rays of light can only occur when the speed of light varies with position. Then you understand why apples fall down.

 

[Motor Daddy]

Then you understand why apples fall down.

Apples are being held against their will when they are being forced to be above the ground by the damn tree. When the little stick thing can't withstand the force it breaks, leaving an apple a distance away from the axis, with no force (or very little force) holding it there. It has the option to do one of three things:

1. Stay the same distance away from the axis as time elapses.
2. Get closer to the axis as time elapses.
3. Get farther away from the axis as time elapses.

Number one is perpetual motion, so that's out of the question. Indeed, if you hold an apple above the surface of the beach, and you let it go, it will not stay the same distance away from the axis as the clock ticks. That would be levitating an apple, something magicians do to entertain people. People get entertained because they know apples don't levitate, but it sure looks like it!!

Number three is out of the question, as apples can't increase potential energy by getting farther away. The only way the apple can get farther away from the axis is if the apple is forced away from the axis over a duration of time. Letting go of an apple is not forcing an apple, it is releasing the force that was being applied to the apple when you were holding it a distance away from the axis.

So, without further delay, I present to you number two, the winner. Murphy's law is not a coincidence. If something can happen, it will!

 

[OnlyMe]

It isn't, it's simple, and it refers to Einstein and the evidence.

What? When you understand that there ain't no time flowing through an optical clock, you understand that an optical clock goes slower when its lower because light goes slower when its lower. Just like Einstein said. And then you understand what he was on about when he said a curvature of rays of light can only occur when the speed of light varies with position. Then you understand why apples fall down.

Younare making less and less sense!

You are cramming sometimes unrelated ideas and speculations together and believing that you have dicovered some previously overlooked universal truth.

You are the only one I have seen use the phrase time flowing as if it hid any physical meaning or context. When someone says something like the flow of time, they are not talking about water, though occasionally the analogy is used, they are referring to an experience.., we call time and notice as change.

You know, Farsight.., if you could ever get away from your misconceptions about what Einstein, or anyone else for that matter said, there are some exciting ideas being worked on in theoretical physics today that could support genuinely legitimate speculation, about the nature of gravitation and interia, even perhaps space-time.

When I used the word tautology to describe your rant(s) it was because it really does appear that you have been telling yourself these stories for so long you cannot see, anything else. Step back from the edge of the past, just long enough to look at what is being done today, and what possibilities the advancements in physics, which have taken place in even the last 50 or so years, have opened up.

Understanding physics did not end with Einstein! ... And not everything we have learned since, can be explained by what Einstein said nearing 100 years ago!

 

[Trippy]

No. The overshoot is still there even no matter how many terms...

Correct, because no matter how many terms are included, it is still only a finite approximation of an infinite series.

...infinity included.

Show me a circuit capable of producing a pure square wave. You can't, they don't exist. Every circuit that (currently) produces square waves has a finite, non-zero rise time, therefore no circuit is capable of producing a pure square-wave, therefore we expect every square-wave to ring because every square wave is a finite approximation of an infinite series.

.- The drawing I showed had 125 terms. All terms for the square wave have a odd number of half cycles.

I'm 99% sure this is wrong - the square wave is made up of the sum of the oddly numbered harmonics (2n+1), the number of half cycles has nothing to do with it.

.The first, a single half cycle, by its self overshoot in the middle, then the next has a pair of over shoot with the two peaks closer to the edges and its dip in the middle removes the first term's central over shoot. The next with five peaks kills the second's two overshoot and brings the center back up, but never mind that. - As the point is every higher odd frequency term removes the prior term's two near the edges and replaces them with two new overshoots still closer to the edge etc. I.e. the 100,001 frequency term has two very near the edges over shoots but it did remove the two near edges over shoots made by the 99,999 term etc to infininity. Never is the Gibbs over shoot removed or even made zero. - it just keeps moving nearer to the edges. As you can see in the 125 terms it actually grow taller for each of the most recent terms but it is bounded as all the highest terms are with less amplitude than earlier ones.

Everything you've said is true for a finite approximation of the infinite series, none of it is true for the infinite series.

.You and also understand this from a slope point of view because at the edges, the square wave slope is infinite. Consider the edge at x = o (part of the vertical line x = 0.) No matter how high the frequency of the sin wave component are, as the leave the x -axis, they curve toward positive x (away from the line x = 0). To come closer to the line x = 0, the amplitude of the highest frequency is ALWAYS GREATER than the flat top of the square wave and ALL the lower frequency components add a little more to that highest frequency component's over shoot. but this positive sum of contributions does converge to a well known limit. That is forever true no mater how many terms are in the Fourier sum. I.e. for some very small x the first peak of the highest frequency sin wave it closer to the edge but its amplitude is always greater than the top of the square wave in amplitude.

Again, this is true for finite approcximations, not the infinite series.

 

[Trippy]

Exactly. And we can call that truncation an error similar to computational roundoff. In practice, as with signals, the presence of reactances in transmission lines or circuits inexactly matched will produce errors so many decimal places to the right - effectively the same as truncation or roundoff error, even though not exactly the same same value of error. In other words any error will produce some variation of the Gibbs effect.

And then the point is that as you extend the series out to infinity, the ringing and overshoot from Gibbs converges to zero and the edge squares up. In a practical system this amounts to carefully matching impedances which today is helped by design simulators. Otherwise high speed CPUs would not be feasible as the Gibbs effect would cause all kinds of false triggers. Pretty amazing when you realize the fundamental (first term in the series) is zipping along in the radar band!

All very true. Every circuit has impedance and capacitance, however, we can tune them to the fundamental frequency of the square wave they need to carry.

 

[OnlyMe]

I could be wrong here, this has been a long discussion, that I have not been following closely... But didn't this begin by Billy admitting a mistake, in comparrison with James, and then beginning to try and explain the mistake? If so, it sounds like Billy is trying to describe the mistake and others are explaining the correction....

But like I said I have not been following this discussion closely.

 

[Aqueous Id]

I could be wrong here, this has been a long discussion, that I have not been following closely... But didn't this begin by Billy admitting a mistake, in comparrison with James, and then beginning to try and explain the mistake? If so, it sounds like Billy is trying to describe the mistake and others are explaining the correction....

But like I said I have not been following this discussion closely.

Billy T was praising James R for his accuracy, but then mentioned one thing he said James R was wrong about, that an infinite Fourier series cannot converge to an ideal waveform with a discontinuity (such as a square wave) . Billy elaborated on the Gibbs effect, which produces perturbations around the edges due to truncating the series. Trippy pointed out that this is a separate case, for the finite series only.

I'm of the opinion that the Fourier Transform is relevant to the discussion of time, since it provides a mapping between time and frequency domains. So, rather than rely on the idea that time corresponds to change, which I think is inaccurate, we can introduce the ways time corresponds to frequency (a variant transform is said to map time to "sequency".)

Note that a gradient measures change but not time. So a temperature gradient in a metal bar that's heated on one end and cooled on the other describes dT/dx but has no bearing on time. Yet if we map the spectrum over the length of the bar as df/dx then we can take the inverse Fourier transform and arrive at d(sin 2pi f t)/dx thus demonstrating the passage of time, even though the observation is static, and the observed change is across space, not time.

Another example our musically inclined science guy exchem could demonstrate is a motif from the old chants and motets from Europe. Take, for example, two singers at a fermata (holding the note a long time) an octave apart. Suppose they are at 440 and 880 Hz (the pitch "A" and the interval an octave higher). Take the IFT and it yields two waves (complex due to the nature of the vocal tract, therefore not simple sine waves) . The two singers are not exactly alike in spectral content and yet there is very high correlation such that the blend is quite beautiful. Our perception is that nothing is changing, because we perceive the spectrum, whereas time domain perception (of the two pitches) is subliminal. So in fact we "measure time" without perceiving change. For example, a person with perfect pitch can hear this octave being sustained at the fermata, and plot, as a function of time, the wave produced -- with reasonable accuracy. A logging recorder in another room can be plotting the time domain signal, and the two plots will be remarkably similar. Also, these tones are held indefinitely thus the listener "showed the passage of time" (one of Farsight's numbnuts complaints) without "a clock". Elapsed time doesn't even occur to her since the fermata conveys a suspension of time.

 

[paddoboy]

You are making less and less sense!

You are cramming sometimes unrelated ideas and speculations together and believing that you have dicovered some previously overlooked universal truth.

I wonder if all these ideas and newly discovered universal truths have anything to do with his claim of having a ToE....Which he has not commented on for a while now, despite me mentioning it at least half a dozen times.

Show me a world, realm or Universe, where time does not exist:
Time exists emotionally, mentally, consciously, and unconsiously.
It is a property of the Universe we belong to, just as space is.

 

[quantum_wave]

I believe in a previous comment I said i don't believe time dilation has anything to do with the question, What is time?

When I said, ...

... I'm just saying that there are mechanics in the nature of the universe that govern the "how" of the observable of time dilation. Generally accepted science has yet to establish a consensus on the mechanics, but threads like this establish the opinion that there is more to time than the mathematics of spacetime explains; a view which I see you might agree with. ...

I was referring to your previous response to me, where you said, ...

...
Still I do believe gravitation does have an underlying fundamental kinetic origin, yet to be understood. And I don't believe the modern interpretation of GR that suggests that the curvature of space-time causes gravitation... From where I sit today, GR and space-time is just our best descriptive tool/model for describing the dynamics involved. How things happen as a result of gravitation. ...

Clearly I see where you said ...

...
This is way far from the OP even from much of the relevant side discussion(s) and should be thread of its own, that I am not prepared to start.

Don't worry, I understand from your posts over time that you don't participate in alternative ideas, and I guess it was a surprised to see you don't believe in the modern interpretation of GR re. the cause of gravitation. My view is that the math is nearly perfect, but there are energy density mechanics at work to explain the "how". Since curved spacetime is the GR explanation of how gravity works, and the EFEs quantify the curvature to predict the geodesics that objects follow through spacetime, gravitational energy and the curvature might be interchangeable.

 

[river]

It seems to me that TIME is about and based on MOVEMENT

This is what you guys are arguing about

The definition of movement and not really about time

 

[paddoboy]

It seems to me that TIME is about and based on MOVEMENT

This is what you guys are arguing about

The definition of movement and not really about time

Show me a world, realm or Universe, where time does not exist:
Time exists emotionally, mentally, consciously, and unconsiously.
It is a property of the Universe we belong to, just as space is.

 

[river]

river said: ↑
It seems to me that TIME is about and based on MOVEMENT

This is what you guys are arguing about

The definition of movement and not really about time

Show me a world, realm or Universe, where time does not exist:
Time exists emotionally, mentally, consciously, and unconsiously.
It is a property of the Universe we belong to, just as space is.

All that you have mentioned is on an intelligent beings qualities

But to objects , time does not matter

To objects , what matters is the qualities that make up the manifestation of matter , such as spin , volume , magnetic fields , structure etc.

And then the interactions between these qualities within themselves and then of course between other matter

 

[paddoboy]

All that you have mentioned is on an intelligent beings qualities
But to objects , time does not matter
To objects , what matters is the qualities that make up the manifestation of matter , such as spin , volume , magnetic fields , structure etc.
And then the interactions between these qualities within themselves and then of course between other matter

Can't disagree with any of that...But it all happens in time.
They would not happen if we had no time.

 

[river]

river said: ↑
All that you have mentioned is on an intelligent beings qualities
But to objects , time does not matter
To objects , what matters is the qualities that make up the manifestation of matter , such as spin , volume , magnetic fields , structure etc.
And then the interactions between these qualities within themselves and then of course between other matter

Can't disagree with any of that...But it all happens in time.
They would not happen if we had no time.

You understood nothing of my post

 

[paddoboy]

You understood nothing of my post

Actually its you who does not understand.
Answer my question.
Give me an example of any realm, universe, or world where time does not exist.
I'm waiting.

 

[river]

Actually its you who does not understand.
Answer my question.
Give me an example of any realm, universe, or world where time does not exist.
I'm waiting.

micro-world

 

[paddoboy]

micro-world

Time is essential.......sorry, try again.

 

[river]

Time is essential.......sorry, try again.

Maybe to the BB theory , but nothing else in this Universe