How does relativity define time (as a constant or not?)

[PeterDonis]

"A detector at the end of the tube gives an output according to the number of cesium atoms striking it and peaks when the frequency is absolutely correct. This peak is then used to make slight corrections to the crystal oscillator that controls the clocking mechanism, locking in the frequency. This locked frequency is then divided by 9,192,631,770 which results in the familiar one pulse per second."

You're shifting your ground here. Originally you were claiming that the cesium clock worked by measuring the motion of the light. Now you are claiming that it works by measuring the motion of the crystal oscillator, which doesn't involve any motion of the light itself, or any wave phenomenon associated with the light, only of the oscillator. (The cesium atoms themselves move, and are filtered according to their energy, but that also has nothing to do with the motion of the light, and the motion of the cesium atoms is not periodic and has nothing to do with defining the unit of time.) Which is it?

 

[ghwellsjr]

You gave the value of frequency in post #8 as 9,192,631,770 Hz. Since c is 299,792,458 m/s, the wavelength is 0.0326 m or 3.26 cm which is over an inch. You have stated that there is an oscillation that covers a distance of over an inch. As PeterDonis asked, what is oscillating back on forth over a distance of 3.26 cm?...


I don't believe there is any crystal that is oscillating at 9,192,631,770 Hz.

http://www3.nd.edu/~techrev/Archive/Winter2002/a4.html

"A detector at the end of the tube gives an output according to the number of cesium atoms striking it and peaks when the frequency is absolutely correct. This peak is then used to make slight corrections to the crystal oscillator that controls the clocking mechanism, locking in the frequency. This locked frequency is then divided by 9,192,631,770 which results in the familiar one pulse per second."

The wikipedia article on crystal oscillators states that the highest frequency is "hundreds of megahertz". You're an order of magnitude beyond that.

Your linked article also says:

These clocks do not keep time according to atomic decay, but rather by the oscillation of the nucleus of an atom and its surrounding electrons. The mass of the nucleus and the gravity and electrostatic “spring” between the positively charged nucleus and the electrons set the oscillation frequencies.

If you think this article is authoritative, then I can see why you might believe that the Cesium atomic clock is based on some part of it oscillating over some distance like a pendulum or a balance clock.

As for the other part I KNOW you are smart enough that if you cared too, you could look at the references I've linked and re-read what was said carefully; by applying an objective scientific methodology you'd uncover the mistaken assumptions in saying:

Did it ever occur to you that if there is a back and forth motion of something over a distance of 3.26 cm then the total distance will be 6.52 cm and at 9,192,631,770 Hz, that something will be traveling at twice the speed of light. Are you sure you want to continue with this claim?

Because I doubt your sincerity, and ability to be objective, I am not going to repeat what I've already shown and said to correct the obvious mistaken assumptions above. (Hint: The frequency of the Earth's rotation is the same at the Equator, Arctic circle, or any other latitude, even though it's rotational speed and the distance traveled are not.)

You are not being an effective teacher if you refuse to explain your position in a way that someone who doesn't know what you are talking about can understand. You are the one who is claiming that the distance involved in the oscillation is 3.26 cm but you still have not said what part of the Cesium clock is doing that. Your hint does not mean that no part of the Cesium clock is oscillating over a distance of 3.26 cm, just not all the parts are oscillating over that distance, correct? What part is it?

 

[TrickyDicky]

There is some semantics confusion here and both sides in this discussion are partly right.

Wiki: "Motion (physics), any movement or change in position or time"

It all comes down to what one understands as motion,classical change of position in time or simply change in time if one concludes from the basics of QM that the HUP prevents the absence of motion microscopically, or from the basics of relativity that there is no such thing as absolute rest.
In this last case a hyperfine transition frequency would imply motion, and in any case this transition is used as the frequency standard, and the atoms obviously move(one would need absolute zero temperature to detain their motion completely) in any of the senses referred above, both elements are needed to be able to measure time in practice.

 

[ghwellsjr]

There is some semantics confusion here and both sides in this discussion are partly right.

Wiki: "Motion (physics), any movement or change in position or time"

That is what wikipedia says when you type "motion" into the search window. But when you click on that particular option, the article says nothing about motion being a change in time. I think the above quote is a mistake and probably should say "change in position with respect to time".

It all comes down to what one understands as motion,classical change of position in time or simply change in time if one concludes from the basics of QM that the HUP prevents the absence of motion microscopically, or from the basics of relativity that there is no such thing as absolute rest.
In this last case a hyperfine transition frequency would imply motion, and in any case this transition is used as the frequency standard, and the atoms obviously move(one would need absolute zero temperature to detain their motion completely) in any of the senses referred above, both elements are needed to be able to measure time in practice.

The motion of the atoms as a whole has nothing to do with the physics of the hyperfine transition frequency. Each atom is emitting one particular precise frequency, which would not be useful to make an atomic clock. You need a large number of them doing it at the same time and their motion with respect to themselves increases the inaccuracy of the timing.

Motion is not a change in time. What does that mean? A change with respect to what?

Here's what the body of the wikipedia article says regarding motion in subatomic particles:

Within each atom, electrons exist in an area around the nucleus. This area is called the electron cloud. According to Bohr's model of the atom, electrons have a high velocity, and the larger the nucleus they are orbiting the faster they would need to move. If electrons 'move' about the electron cloud in strict paths the same way planets orbit the sun, then electrons would be required to do so at speeds which far exceed the speed of light. However, there is no reason that one must confine one's self to this strict conceptualization, that electrons move in paths the same way macroscopic objects do. Rather one can conceptualize electrons to be 'particles' that capriciously exist within the bounds of the electron cloud.

As I said earlier, if you try to determine the motion of a subatomic particle you get a value higher than the speed of light.

 

[PeterDonis]

It all comes down to what one understands as motion

Maxila can speak for himself, of course, but I have understood him to consistently mean "change in position with respect to time", which is, as ghwellsjr noted, the standard definition.

the atoms obviously move

But the motion of the atoms is different, physically, from the energy level transition of their electrons that are being used to define the time standard (by way of the frequency of the photons associated with the transition). So even if we are going to monkey with the definition of "motion" to mean "any change with time", we still have to be careful not to confuse one change with another.

 

[TrickyDicky]

Maxila can speak for himself, of course, but I have understood him to consistently mean "change in position with respect to time", which is, as ghwellsjr noted, the standard definition.

That is why I explained how a frequency, or change in time can be understood as a change in position wrt time, if you want to question it go ahead.

But the motion of the atoms is different, physically, from the energy level transition of their electrons that are being used to define the time standard (by way of the frequency of the photons associated with the transition). So even if we are going to monkey with the definition of "motion" to mean "any change with time", we still have to be careful not to confuse one change with another.

I didn't confuse it, just mentioned it just in case you didn't admit(with argumenents) the "monkeying".

 

[Dale]

Maxila,you may have started with a correct core idea, but you have taken it too far. You are correct that we cannot measure t, only some df/dt. The place where you go too far is asserting that the only possible f is x.

Because I doubt your sincerity, and ability to be objective

This ad hominem response is completely inappropriate and unwarranted.

Thread closed.