Motion

[geordief]

 

 

Atoms, nuclei and other particles decay if there is a lower energy state is available, and there is a path to get there. Those are the ones with lifetimes. But while they are sitting there, waiting for decay, there need not be any motion; it is not a requirement for the decay.

Which are the particles without lifetimes?

 

I am fairly comfortable now with the idea that no motion is required for the decay to take place.

 

On the other hand can it be said that the creation of the particle in the first place requires motion ?

 

If that is true can we say that the decay is a function of the creation and so the decay ultimately and indirectly does depend on the fact that motion is fundamental to the physicality of the universe?

 

On the " third" hand I have heard that particles can be created spontaneously but are these virtual particles? Does it matter that they are virtual ? Does it mean that particles are also created "without motion" ?

 

Btw I am not sure what you meant by "if.... there is a path to get there" . Do you just mean if circumstances permit? There is surely no actual "path" as I would think of one is there ? No "Hampton Court Maze" here ???

 

"path" has a specific meaning in this context ,does it?

[studiot]

 

In philosophical discussions there is an increased risk of misunderstandings due to a variety of possible meanings of words, but regretfully, what happened here doesn't look like an innocent misunderstanding.

The topic here as I interpreted, is not about math but about physics; and my understanding of the topic could not reasonably have been misunderstood, in view of how I defined time in the post to which you responded. Logically I had to assume that you were still talking about a physical wave of the kind that I mentioned and even you also mentioned just before:

 

 

 

Once more, such standing waves consists, according to standard physics, of propagating waves - as you seem to acknowledge yourself.

See also https://en.wikipedia.org/wiki/Wave.

 

Nevertheless, looking back at the discussion I notice a glitch in my answer to the first post, I phrased it the wrong way round (thanks Strange for pointing that out!):

In my mind it is not possible to conceive of motion without the concept of time, as time is a measure of the progress of physical processes. Thus motion implies time.

 

In other threads you have been quite vociferous about the mathematics of relativity and yet you shy away from it here and want to only discuss 'Physics' ?

 

OK so you don't want to answer my repeated question

 

 

studiot post#16

 

And also please answer my question

 

Is my stated equation a solution to the wave equation and what is its dependence on time (which does not appear in it)?

 

So how about this one one your special subject, relativity?

 

This concerns the connection between motion and time.

 

Classical mechanics forbids particles to be in two places once ( at the same time)

 

What is the (time) interval between places (points) on a lightlike path?

 

It is, of course, zero.

 

So photons are in more than one place at one time?

 

Is this a disconnect between 'motion' and time?

[swansont]

Which are the particles without lifetimes?

 

I am fairly comfortable now with the idea that no motion is required for the decay to take place.

 

On the other hand can it be said that the creation of the particle in the first place requires motion ?

 

If that is true can we say that the decay is a function of the creation and so the decay ultimately and indirectly does depend on the fact that motion is fundamental to the physicality of the universe?

 

On the " third" hand I have heard that particles can be created spontaneously but are these virtual particles? Does it matter that they are virtual ? Does it mean that particles are also created "without motion" ?

 

Btw I am not sure what you meant by "if.... there is a path to get there" . Do you just mean if circumstances permit? There is surely no actual "path" as I would think of one is there ? No "Hampton Court Maze" here ???

 

"path" has a specific meaning in this context ,does it?

 

 

 

An electron has no known lifetime. Stable atoms have no known lifetimes, though it's alway possible for some of them that their lifetimes are just so long that we would never expect to observe one decaying.

 

If a particle decays and creates other particles, motion is only required because energy is conserved, so you must have KE somewhere after the decay.

 

Virtual particle pairs can be created spontaneously. But they are not real (Cue Monty Python and the Holy Grail: It's only a model), and they are not bound by the same laws that govern real particles.

 

Path, aka channel, is a metaphor, i.e. jargon. A decay has to comply with conservation laws. A decay that would release energy but violated e.g. conservation of angular momentum would still not occur.

[Tim88]

[edit: removed other answer that I'll rephrase later]

 

 

In other threads you have been quite vociferous about the mathematics of relativity and yet you shy away from it here and want to only discuss 'Physics' ?

 

[..]

 

I'm pretty sure that the topic here concerns the physics of motion; it may be useful if geordief clarifies this point. I can imagine that you were not aware of hijacking and strawmanning; thus my negative impression may have been unwarranted.

 

 

What is the (time) interval between places (points) on a lightlike path?

 

It is, of course, zero.

 

So photons are in more than one place at one time?

 

Is this a disconnect between 'motion' and time?

 

A limit is not a disconnect. Time on a light-like path corresponds to the progress of physical processes in a physical entity going at the speed of light. We all know that no massive clock can go at the speed of light and no valid reference frame can be set up at that speed. I could stop there and simply conclude that your reasoning is therefore invalid:

http://math.ucr.edu/home/baez/physics/Relativity/SpeedOfLight/headlights.html

 

Nevertheless in my opinion Gibbs made it too easy on himself, so I'll join you in your Einsteinian ride on a light wave, without fear of paradoxes. Clock rate is indeed zero in the limit: the wavefront of a light wave in vacuum is unaltered over its trajectory, just like a "frozen" clock. But contrary to what you suggested, a photon "experiences" no time nor distance. However from our perspective it can travel a great distance in a short time and in zero proper time, or as first phrased by Einstein (who was a physicist, not a mathematician):

 

For v=c all moving objects—viewed from the “stationary” system—shrivel up into plane figures. For velocities greater than that of light our deliberations become meaningless; we shall, however, find in what follows, that the velocity of light in our theory plays the part, physically, of an infinitely great velocity.

PS §4 of http://fourmilab.ch/etexts/einstein/specrel/www/

Edited September 21, 2016 by Tim88

[geordief]

 

So we both read the question upside down!

 

In other words, is motion logically dependent on time, or can motion exist without time? The point of contention is thus if motion implies time.

 

In logical deduction it often helps to test with less abstract examples, such as:

Can a bicycle exist without wheels? => Do wheels imply the existence of bicycles? Do bicycles imply the existence of wheels?

I may have been ill advised to use the word "conceive". I would not personally be interested in a deductive/logical answer to the question (I did make an apology for posting under philosophy)

 

I am more interested in the practicalities such as they can be to the question . What do current physical observations tell us about this connection?

 

I was taken aback to learn recently that atomic decay which is used to measure time does this without what I would call movement or motion.

 

In post#3 Strange said "I don't think it is possible to have motion without time. But there can be time without motion." and that seems to sum up what I have learned or think I know so far.

 

It is a bit inconvenient as the two phenomena do not thus seem to be symmetrically /mutually interdependent as I might have expected before I learned about atomic decay.

 

I have been familiar with the expression Time is what we measure with clocks" but I never imagined these clocks might not rely on movement (as apparently they have been doing behind my back all the while )

Edited September 21, 2016 by geordief

[studiot]

 

geordief post#30

I have been familiar with the expression Time is what we measure with clocks" but I never imagined these clocks might not rely on movement (as apparently they have been doing behind my back all the while

 

Capacitors are used as timing devices in electrical circuits.

Without special circuitry they are inherently non linear.

In act they are exponential in operation.

 

Now this use of capacitors does involve motion.

 

But you could use a row of radioactive atoms as a perfectly satisfactory timing device with the same exponential law as of the capacitor, but no motion would be involved.

Any instant you want the time for you simply count the remaining atoms and would be able to convert this number to the time.

 

In fact I do believe that the countdown timer to the end-of-life warning in my smoke alarm works this way.

 

[Tim88]

I may have been ill advised to use the word "conceive". I would not personally be interested in a deductive/logical answer to the question (I did make an apology for posting under philosophy)

 

I am more interested in the practicalities such as they can be to the question . What do current physical observations tell us about this connection?

 

I was taken aback to learn recently that atomic decay which is used to measure time does this without what I would call movement or motion.

 

In post#3 Strange said "I don't think it is possible to have motion without time. But there can be time without motion." and that seems to sum up what I have learned or think I know so far.

[..]

 

I was just in the process of rephrasing my clarification to swansont which you already cited, I'll make sure to keep it practical.

In fact you simplify my rephrasing.

 

 

But that's not the issue. The point of contention was whether time implied motion.

 

 

Apparently we both read the question upside down! Thanks, that's reassuring to me. I will elaborate my corrected reply.

 

 

Is it possible to conceive of have motion without the concept of time (either time per se or time as measured by a clock and a signal)?

Thus, can there be motion without time? The point of contention is if motion implies time.

 

In logical deduction it often helps to test with less abstract examples, such as:

Can there be a bicycle without wheels? -> The claim for discussion: a bicycle implies wheels.

The contention is NOT if wheels imply a bicycle!

 

Similarly:

Can there be motion without time? -> The claim for discussion: motion implies time.

[..]

I was taken aback to learn recently that atomic decay which is used to measure time does this without what I would call movement or motion.

 

In post#3 Strange said "I don't think it is possible to have motion without time. But there can be time without motion." and that seems to sum up what I have learned or think I know so far.

 

It is a bit inconvenient as they the two phenomena do not thus seem to be symmetrically /mutually interdependent as I might have expected before I learned about atomic decay.

 

I have been familiar with the expression Time is what we measure with clocks" but I never imagined these clocks might not rely on movement (as apparently they have been doing behind my back all the while )

 

I now think that you meant it the way I first understood it, which is the inverse of what you actually said (or else I'm too tired now). Maybe you managed to confuse everyone.

 

Atomic transitions can be understood as a kind of movement, as it relates to the creation of an EM wave by means of an electron jump.

- https://en.wikipedia.org/wiki/Atomic_clock

 

[edit: slight rephrasing; better link]

Edited September 21, 2016 by Tim88

[swansont]

Atomic transitions can be understood as a kind of movement, as it relates to the creation of an EM wave by means of an electron jump.

- https://en.wikipedia.org/wiki/Atomic_clock

 

No, not really. The electron jump refers to its energy. Position is not a variable in these equations. As I stated before, the phase of the clock's operation where it's "ticking" is a superposition of states. No transition is occurring while that happens.

[Tim88]

No, not really. The electron jump refers to its energy. Position is not a variable in these equations. As I stated before, the phase of the clock's operation where it's "ticking" is a superposition of states. No transition is occurring while that happens.

 

It's unclear to me if your "not really" refers to the subject matter or to an imperfection in my phrasing... and "superposition of states" is agnostic about the physical mechanism.

 

While we cannot know (yet) the internal mechanism of the creation of EM waves inside atomic clock atoms, we can find plausible explanations on the web, such for example http://science.howstuffworks.com/atomic-clock1.htm

As a matter of fact, we understand the creation of EM waves at radio frequencies rather well - and that works by means of electron acceleration (e.g. https://en.wikipedia.org/wiki/Electromagnetic_radiation ).

 

So, if with your remark you meant that you know how to create EM waves without electron motion then please explain. I'm looking forward to hear it.

Edited September 22, 2016 by Tim88

[swansont]

It's unclear to me if your "not really" refers to the subject matter or to an imperfection in my phrasing... and "superposition of states" is agnostic about the physical mechanism.

 

While we cannot know (yet) the internal mechanism of the creation of EM waves inside atomic clock atoms,

"Not really" means no, you're wrong.

 

Where did I mention anything about EM waves? I was talking about the oscillation in an atomic clock and atomic transitions. Motion isn't a concept that is used in describing the state of an atom in any way other than an analogy.

 

we can find plausible explanations on the web, such for example http://science.howstuffworks.com/atomic-clock1.htm

No, atomic clocks do not physically have an oscillating mass and spring. Other than that, I don't know what, specifically, you're referring to.

 

As a matter of fact, we understand the creation of EM waves at radio frequencies rather well - and that works by means of electron acceleration (e.g. https://en.wikipedia.org/wiki/Electromagnetic_radiation ).

 

So, if with your remark you meant that you know how to create EM waves without electron motion then please explain. I'm looking forward to hear it.

Again, where did I mention anything about EM waves?

[michel123456]

 

+1 on both counts.

 

 

A wave is a solution to the wave equation.

 

Are you suggesting that the following equation

 

y = A sin(bx)

 

does not satisfy the wave equation?

The equation gives a single solution. If you want many solutions to describe the entire wave, you must make several inputs the one after the other, no?

[Strange]

The equation gives a single solution. If you want many solutions to describe the entire wave, you must make several inputs the one after the other, no?

 

 

No. You have had a thread on your misunderstanding of mathematics already. The equation describes how one set of values maps on to another. There is nothing sequential about it.

[studiot]

Hello Michel,

 

An equation of a travelling wave is y = Asin (bx-ct), (there are others) A, b and c are constants t is time.

 

Note that it contains both x and t.

 

so if you choose some value for x, the value for y will also depend on t.

That is the value of y will be different for different values of t at the same x.

 

The equation I gave before does not contain t

 

y = Asin(bx)

 

So for any given value of x, the value of y will always be the same, whether t is 1 femtosecond, 1 year or 1 millenium.

 

This is the difference I meant.

[michel123456]

 

 

No. You have had a thread on your misunderstanding of mathematics already. The equation describes how one set of values maps on to another. There is nothing sequential about it.

Set of values, yes. That is what I was trying to say.

If you have a set of values, how do you insert this set? All at once? Only the fact that you must insert this set means time.

Hello Michel,

 

An equation of a travelling wave is y = Asin (bx-ct), (there are others) A, b and c are constants t is time.

 

Note that it contains both x and t.

 

so if you choose some value for x, the value for y will also depend on t.

That is the value of y will be different for different values of t at the same x.

 

The equation I gave before does not contain t

 

y = Asin(bx)

 

So for any given value of x, the value of y will always be the same, whether t is 1 femtosecond, 1 year or 1 millenium.

 

This is the difference I meant.

 

"for any given value", what does it mean for you? That you give all the values at the same time?

Or that you insert a value, take the result, then insert another one, take the result & etc ad nauseam then draw the result.

For example you can at t=0 insert a single value and at t=1 get the result, and at t=3 draw a single dot. I don't think it is conceptually acceptable to make those 3 steps in δτ=0

[Strange]

Set of values, yes. That is what I was trying to say.

If you have a set of values, how do you insert this set? All at once? Only the fact that you must insert this set means time.

 

 

There is no "inserting".

"for any given value", what does it mean for you? That you give all the values at the same time?

Or that you insert a value, take the result, then insert another one, take the result & etc ad nauseam then draw the result.

For example you can at t=0 insert a single value and at t=1 get the result, and at t=3 draw a single dot. I don't think it is conceptually acceptable to make those 3 steps in δτ=0

 

You are confusing the definition of a function with you calculating individual values. The former does not involve time. The latter obviously does (but is irrelevant).

[studiot]

Good morning Michel.

 

 

 

For example you can at t=0 insert a single value and at t=1 get the result, and at t=3 draw a single dot. I don't think it is conceptually acceptable to make those 3 steps in δτ=0

 

I don't quite follow this. You seem to have your insertion process the wrong way round.

 

But to answer the rest of your question,

 

The equation y = Asin(bx) means that if you assign any value to x you can calculate a value for y.

 

That is what is meant by 'for any given value of x'.

 

Now the rest of my point means that your calculation of y will result in the same number whatever time you perform or plot this calculation, because the result does not change with time.

 

You cannot insert a value for time into an equation where it does not explicitly appear.

 

This is true of any equation so that for instance in the equation

 

x² + y² + z² = r²

 

you cannot insert values for say v or w since they do not appear in the equation.

 

 

 

FYI I need to prepare a few sketches to answer your query about gravity in the other thread today, so look there again later.

 

Edited September 23, 2016 by studiot

[michel123456]

Good morning Michel.

 

 

I don't quite follow this. You seem to have your insertion process the wrong way round.

Maybe

But to answer the rest of your question,

 

The equation y = Asin(bx) means that if you assign any value to x you can calculate a value for y.

 

That is what is meant by 'for any given value of x'.

 

Now the rest of my point means that your calculation of y will result in the same number whatever time you perform or plot this calculation, because the result does not change with time.

 

You cannot insert a value for time into an equation where it does not explicitly appear.

 

This is true of any equation so that for instance in the equation

 

x² + y² + z² = r²

 

you cannot insert values for say v or w since they do not appear in the equation.

That is sensible, i cannot argue against anything you said above.

FYI I need to prepare a few sketches to answer your query about gravity in the other thread today, so look there again later.

 

Than you. Much appreciated.

Wait... what other thread? (Alzheimer* striking again)

 

*joking. I hope

Edited September 23, 2016 by michel123456

[Tim88]

"Not really" means no, you're wrong.

 

Where did I mention anything about EM waves? I was talking about the oscillation in an atomic clock and atomic transitions. Motion isn't a concept that is used in describing the state of an atom in any way other than an analogy.

 

No, atomic clocks do not physically have an oscillating mass and spring. Other than that, I don't know what, specifically, you're referring to.

 

Again, where did I mention anything about EM waves?

 

It appears that you claim that the explanations in the references that I know and rely on, are wrong. According to the cited references, atomic clocks are based on electromagnetic radiation. As I did not personally built such a clock, it is possible that I misunderstood something, basing myself on those explanations; however it is for me a self contradiction to speak of "oscillations" that do not involve "motion"!

 

Maybe you overlooked the clarification that the word "conceive" in the OP could be misunderstood; it appears that is exactly what is happening here.

[edit: precision:] the question was rephrased as: "What do current physical observations tell us about this connection?"

 

PS. modern definition of second: "The second is the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of cesium 133". In other words, I'm not mistaken about this. Observations involve EM radiation.

Edited September 24, 2016 by Tim88

[swansont]

It appears that you claim that the explanations in the references that I know and rely on, are wrong. According to the cited references, atomic clocks are based on electromagnetic radiation. As I did not personally built such a clock, it is possible that I misunderstood something, basing myself on those explanations; however it is for me a self contradiction to speak of "oscillations" that do not involve "motion"!

 

Maybe you overlooked the clarification that the word "conceive" in the OP could be misunderstood; it appears that is exactly what is happening here.

[edit: precision:] the question was rephrased as: "What do current physical observations tell us about this connection?"

 

PS. modern definition of second: "The second is the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of cesium 133". In other words, I'm not mistaken about this. Observations involve EM radiation.

You're citing a pop-sci website. I build atomic clocks for a living.

 

Your definition of the second is correct. What I'm talking about is how many clocks actually work. We don't detect the radiation. We detect the number of atoms in each of the states. The atoms don't emit the radiation at 9.2 GHz (or 6.8 GHz for Rb). The transition is very long-lived, so it's much better to measure the state populations. In a beam clock, it's by hot-wire ionization, and measuring the current.

[studiot]

You're citing a pop-sci website. I build atomic clocks for a living.

 

Your definition of the second is correct. What I'm talking about is how many clocks actually work. We don't detect the radiation. We detect the number of atoms in each of the states. The atoms don't emit the radiation at 9.2 GHz (or 6.8 GHz for Rb). The transition is very long-lived, so it's much better to measure the state populations. In a beam clock, it's by hot-wire ionization, and measuring the current.

 

Thank you swansont for telling us this, I didn't realise my theoretical heath-robinson atom counting clock had been developed and was actually in service. +1

[Endy0816]

Do atomic clocks still use the formula:

 

seconds = # of cycles / (cycles/second)

 

or something else?

[Tim88]

[..] I build atomic clocks for a living.

 

Your definition of the second is correct. What I'm talking about is how many clocks actually work. We don't detect the radiation. We detect the number of atoms in each of the states. The atoms don't emit the radiation at 9.2 GHz (or 6.8 GHz for Rb). The transition is very long-lived, so it's much better to measure the state populations. In a beam clock, it's by hot-wire ionization, and measuring the current.

 

That's a somewhat different clock operation principle than the ones that I read and heard about - interesting! Please reference a paper that discusses its operation.

[swansont]

 

That's a somewhat different clock operation principle than the ones that I read and heard about - interesting! Please reference a paper that discusses its operation.

 

 

 

http://geodesy.unr.edu/hanspeterplag/library/geodesy/time/met5_3_S10.pdf

 

Fig 2 shows the hot-wire ionizer after the inhomogeneous magnetic field used to separate the states.

 

http://www.leapsecond.com/history/1965-Metrologia-v1-n3-Cesium.pdf

 

page 118

"By means of the well-known surface-ionization process (ZANDBERG and IoNov, 1959; DATZ and TAYLOR, 1956) the atoms are converted into positively-charged ions with nearly 100% efficiency and can then be collected and measured. "

 

There are two categories of clock: active and passive. Active devices (some, but not all, hydrogen masers) emit radiation at the clock frequency. Passive devices do not. Cesium beam clocks and atomic fountains (the kind I've built) are passive devices.

[Tim88]

 

 

 

http://geodesy.unr.edu/hanspeterplag/library/geodesy/time/met5_3_S10.pdf

 

Fig 2 shows the hot-wire ionizer after the inhomogeneous magnetic field used to separate the states.

 

http://www.leapsecond.com/history/1965-Metrologia-v1-n3-Cesium.pdf

 

page 118

"By means of the well-known surface-ionization process (ZANDBERG and IoNov, 1959; DATZ and TAYLOR, 1956) the atoms are converted into positively-charged ions with nearly 100% efficiency and can then be collected and measured. "

 

There are two categories of clock: active and passive. Active devices (some, but not all, hydrogen masers) emit radiation at the clock frequency. Passive devices do not. Cesium beam clocks and atomic fountains (the kind I've built) are passive devices.

 

Thanks for the precision! The next sentence clarifies:

 

"The resulting detected beam current goes through a maximum when the frequency of the radiation field is swept through the resonant frequency of the cesium transition".

 

I can understand that someone who builds Ferrari's may be annoyed when an average car user states that of course cars use roads to drive on, because the engine turns the front wheels which in turn push on the road; he may say no "not at all", high performance cars don't do that, "you are totally wrong". However that doesn't matter for the question if cars use roads to drive on.

[swansont]

 

Thanks for the precision! The next sentence clarifies:

 

"The resulting detected beam current goes through a maximum when the frequency of the radiation field is swept through the resonant frequency of the cesium transition".

 

I can understand that someone who builds Ferrari's may be annoyed when an average car user states that of course cars use roads to drive on, because the engine turns the front wheels which in turn push on the road; he may say no "not at all", high performance cars don't do that, "you are totally wrong". However that doesn't matter for the question if cars use roads to drive on.

 

 

That's radiation from the frequency synthesizer that is absorbed by the atoms. Not emitted. You had posited "the creation of EM waves inside atomic clock atoms" based on "the creation of an EM wave by means of an electron jump" These clocks are not detecting EM waves created by (or in) the clock atoms. Furthermore, the oscillations that are measured are not based on motion.

 

Recall the definition of the second you cited: "The second is the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of cesium 133"

 

Transotions can be emission, but they can also be absorption.

 

As I said before, the atoms are put into a superposition — that's from absorbing a "π/2" pulse of microwaves from an external source. You have half of the atoms in each state. If you look at the Bloch sphere, the state vector oscillates, so you let the atoms remain in this superposition for some duration. They act like they're ticking, but there's nothing moving— they're just in whatever state they're in. If the external microwave frequency is on resonance, a subsequent "π/2" pulse puts all the atoms into one state. If the frequency is off, some go to the other state, which is why you can tune the frequency to maximize the signal. That tells you your external synthesizer is on resonance, and if it stays there, that's ticking at a stable and possibly accurate rate. And that's what gets measured: the external frequency synthesizer. Not radiation from the atoms. The atoms are used as a discriminator, not a source.