Einstein notion of time and the oscillation of the cesium atom

[write4u]

They are defined by basic topology. I think you need to learn what a manifold is. The Planck scale does not enter into it anywhere.

How big is the distance between spatial points that keep things apart? How do we measure the time interval between spatial points? What size is the graininess of spacetime?

 

[Fredrik]

How big is the distance between spatial points that keep things apart? How do we measure the time interval between spatial points? What size is the graininess of spacetime?

1. Depends on which two points in space we're talking about, and your choice of what to call "space".
2. We don't.
3. There's no graininess, at least not in SR or GR.

 

[azoulay]

The muon decay measurements have always been one of my favorites. High energy cosmic rays hit the atmosphere about 100 km up, giving rise to very short-lived particles called muons. These muons decay so quickly that they shouldn't be able to hit the surface of the Earth - even though they're moving at nearly the speed of light, it still takes a few hundred microseconds for them to travel 100 km, and they don't live that long.

But they do reach the surface of the earth. That's time dilation at work.

Nugatory, to explain that muons reaches Earth (if that's what's really happening but let's assume it is), time dilation (in the way you're using the term) IS NOT a rational explanation. It's for me a magical explanation. (That's the point I'm trying to make in all my posts in this thread).

If science is willing to consider "time" as being a representation of a mechanical movement, then science should try to explain why a muon reaches Earth in terms of a mechanical movement (not time dilation that's disconnected from physical/mechanical reality). The reconciliation seems hard to me but if you want to try that, I'm listening.

The Wikipedia article about time dilation (http://en.wikipedia.org/wiki/Time_dilation) is saying this:
...
An accurate clock at rest with respect to one observer may be measured to tick at a different rate when compared to a second observer's own equally accurate clocks. This effect arises neither from technical aspects of the clocks nor from the fact that signals need time to propagate, but from the nature of spacetime itself.
...

"but from nature of spacetime itself" This is NOT true science, this is magical non-sense, easy way out, I'm not sure what's going on but I have to come up with something science.

If we assume that time is always related to some kind of mechanical movement, then it is not true to say that "This effect arises neither from technical aspects of the clocks nor from the fact that signals need time to propagate, but from the nature of spacetime itself" because then you need another definition of "time", one which has nothing to do with mechanical movements.

And that's exactly the magical notion of "time" I'm fighting against in this thread.

No scientific mind can say that "time" in some situations is related to some mechanical movements and in some other situation say that if "time" shown on 2 different clocks aren't the same then " this effect arises neither from technical aspects of the clocks ..." because then you're showing that you don't understand what's really going on.

Is "time" related to a physical mechanical movement ?
OR
Is "time" an effect that's not arisen from technical aspect of the clock ?

It's one or the other.

 

[VantagePoint72]

If science is willing to consider "time" as being a representation of a mechanical movement, then science should try to explain why a muon reaches Earth in terms of a mechanical movement (not time dilation that's disconnected from physical/mechanical reality).

There is no "mechanical" explanation because there's nothing mechanical in the scenario! The muon is an elementary particle, there are no "internal workings", no ticking clock inside of it.

If we assume that time is always related to some kind of mechanical movement

No one is assuming that but you. The definition of time being used in special relativity has been given to you many times now, I see no reason to repeat it.

Everything that has been explained to you is based on rigorous mathematics and has been tested by a battery of experiments. That is science, not magic. You just don't like it. Well, tough: nature doesn't care what you like.

 

[Fredrik]

If we assume that time is always related to some kind of mechanical movement, then it is not true to say that "This effect arises neither from technical aspects of the clocks nor from the fact that signals need time to propagate, but from the nature of spacetime itself" because then you need another definition of "time", one which has nothing to do with mechanical movements.

And that's exactly the magical notion of "time" I'm fighting against in this thread.

Note that "this effect" refers to the fact that the numbers displayed by clocks agree with the proper times of their world lines. If there's something worth protesting against here, it's that this is called an "effect". It's just a description of what clocks do. It's not explained by the theory, it's one of the assumptions that defines the theory.

 

[azoulay]

Note that "this effect" refers to the fact that the numbers displayed by clocks agree with the proper times of their world lines. If there's something worth protesting against here, it's that this is called an "effect". It's just a description of what clocks do. It's not explained by the theory, it's one of the assumptions that defines the theory.

Fredrick, THANK YOU SO MUCH FOR THIS MOMENT OF LUCIDITY !

 

[azoulay]

There is no "mechanical" explanation because there's nothing mechanical in the scenario! The muon is an elementary particle, there are no "internal workings", no ticking clock inside of it.

No one is assuming that but you. The definition of time being used in special relativity has been given to you many times now, I see no reason to repeat it.

Everything that has been explained to you is based on rigorous mathematics and has been tested by a battery of experiments. That is science, not magic. You just don't like it. Well, tough: nature doesn't care what you like.

LastOneStanding, I understand that muons doesn't have a clock inside them but you missed my point. I'm trying to say that if you cannot explain the muons reaching Earth in terms of physical/mechanical movement (RATIONAL argumentation) then something is wrong in your understanding of what's really going on. To explain this phenomenon by saying that it's caused by "time dilation" because of the "nature of spacetime" is an absurd, non-logical but magical, incomprehensible for everyone, easy way out explanation.

If Science has to invent words, concepts, difficult mathematical structures, irrational thinking, new definitions that are incomprehensible for anyone expect for a science or math PhD, then for sure, science is wrong about what it has to offer. Wouldn't you think so ?

It seems to me that Science has become the witch of the middle-ages, saying things that are irrational and believing in them. It has to stop.

I respect all of you guys, I love science myself very much but let's agree on one thing: science is getting more and more difficult to understand. Doesn't that ring a bell that it's not going in the right direction ?

Also, you mentioned that the definition of time has been given to me many times but again this definition of time seems to change depending on the situation isn't that uncomfortable/unacceptable for science ?

Again:

Is "time" related to a physical mechanical movement ?
OR
Is "time" an effect that's not arisen from technical aspect of the clock ?

Which one is it ?

It has to be one or the other, do you agree with me ?

 

[Dale]

If science is willing to consider "time" as being a representation of a mechanical movement

That is your definition, not science's. However, it isn't too bad. The only real problem with it, IMO, is that it is too restrictive on what is considered a clock. I would allow clocks with no moving parts to measure time also.

, then science should try to explain why a muon reaches Earth in terms of a mechanical movement (not time dilation that's disconnected from physical/mechanical reality).

If you have a large number of muons at rest next to a good mechanical clock then you will find that with each tick of the clock the same fraction of muons decay. By YOUR definition of time, that means that the same fraction of muons decay over each interval of time. This is a law which governs the behavior of muons.

The principle of relativity requires that the same laws of physics which are valid for a system at rest are also valid for a system in inertial motion. So, since we observe that fast moving muons decay slower then we conclude that fast moving mechanical clocks also tick slower. Therefore, by YOUR definition of time, time is slower for the moving clock.

"but from nature of spacetime itself" This is NOT true science, this is magical non-sense, easy way out, I'm not sure what's going on but I have to come up with something science.

Why not? What makes this magical in any way? We have a scientific theory, in that theory we propose that spacetime has certain symmetries. We investigate the logical conclusion of those symmetries and find that if spacetime does have those symmetries then time will dilate. We hypothesize that if our theory is correct then fast moving muons will decay more slowly than stationary muons. We perform an experiment to measure the decay rate of fast moving muons. We find that it agrees with the theory. Therefore we conclude that spacetime does indeed have the symmetries. What could be more scientific than that? That is the essence of the scientific method.

Again, your arguments are purely emotional, I haven't seen you put together a single rational argument in this whole thread.

 

[VantagePoint72]

If Science has to invent words, concepts, difficult mathematical structures, irrational thinking, new definitions that are incomprehensible for anyone expect for a science or math PhD, then for sure, science is wrong about what it has to offer. Wouldn't you think so ?
...
I respect all of you guys, I love science myself very much but let's agree on one thing: science is getting more and more difficult to understand. Doesn't that ring a bell that it's not going in the right direction ?

So that's what all this sturm und drang is about? You're upset because science is hard? Give me a break. No, I don't believe that the fact the our investigation into basic physics has required the development of new ideas that exceed our basic intuition suggests it's "not going in the right direction". I see absolutely nothing unreasonable about the fact that it takes many years of hard work to understand modern physics. The suggestion that that has anything to do with its validity is absurd.

Your objections are fundamentally unscientific. They are driven purely by emotion and an entirely unreasonable expectation that the fundamental workings of the universe in all their mathematical glory should be easily accessible to any Joe Schmo who picks up a popular science book.

I wish you'd been up front from the beginning that this was the basis of your objection (or perhaps I should have just listened to DaleSpam, who's had you pinned from the beginning). I would never have wasted my time trying to explain things to someone whose fundamental position is, apparently, that if it has to be explained then its not worth understanding.

 

[Nugatory]

If Science has to invent words, concepts, difficult mathematical structures, irrational thinking, new definitions that are incomprehensible for anyone except for a science or math PhD, then for sure, science is wrong about what it has to offer. Wouldn't you think so

It's not quite that bad... There are perfectly reasonable treatments (Einstein wrote one himself) of special relativity that can be understood using only algebra, not even elementary calculus - and elementary calculus is high school or first-year undergraduate level math.

You won't be able to come up with new discoveries that advance our current understanding without doing enough study to get that science or math PhD, but here we aren't talking about new scientific advances. We're talking about stuff that was discovered and became part of the mainstream of science more than a century ago. That's three whole generations of physics students who have gone through the same cycle: "Holy s**t, that can't be right, it makes no sense! Let's look at the math again! Hmmm... Wait a moment... Lemme think about it... Let's try working through the math again... Hey, now I get it - that's really cool!". It takes some work, as does just about anything worthwhile, but it's well within the reach of a non-specialist. And it really is cool to really understand this stuff - well worth the effort.

 

[Fredrik]

If Science has to invent words, concepts, difficult mathematical structures, irrational thinking, new definitions that are incomprehensible for anyone expect for a science or math PhD, then for sure, science is wrong about what it has to offer. Wouldn't you think so ?

It seems to me that Science has become the witch of the middle-ages, saying things that are irrational and believing in them. It has to stop.

There's nothing irrational in SR. The vector space version of the math can be understood by anyone who has completed one year at the university. And of course science has to invent mathematical structures. It's not rational to complain about that.

science is getting more and more difficult to understand. Doesn't that ring a bell that it's not going in the right direction ?

It's getting more difficult to understand because the things that are easy to understand were the first things to be discovered.

Is "time" related to a physical mechanical movement ?
OR
Is "time" an effect that's not arisen from technical aspect of the clock ?

Which one is it ?

I don't know what ether of those statements means. Fortunately science (and even some non-science like what I'm about to mention) makes more precise statements than that. You may be interested in something that's been discussed in several other threads recently.

1. It's possible that the reason for the final ages of the twins in the twin paradox scenario is that there's simply less time along the path through spacetime that the astronaut twin takes from the departure event to the return event.

2. It's also possible that the reason is that there's a preferred rest frame, such that clocks at rest in it are ticking at their maximum rates, while clocks that have velocity v in that frame are slow by a factor of $\gamma$. The speed of light is still measured to be c, because physical objects (like meter sticks) are contracted by a factor of gamma when they have a non-zero velocity in the preferred rest frame.

These statements are two attempts to guess what is "actually happening" to clocks and stuff. That's all they are, guesses. However, the former is a straightforward interpretation of the mathematics, and the latter is the interpretation that has fallen out of favor because it seems to require the existence of an undetectable substance (the ether) that fills up all of space, and is such that it slows down clocks and shortens meter sticks that move through it.

So there's no question about which one of these interpretations is a physicist's preferred way to think. The reason I'm mentioning this is that it makes it easier to explain why questions about whether something should be considered an "effect" or not can't always be considered scientific. In the twin paradox, the theory tells us how to calculate the final ages of the twins. It doesn't tell us why they age the way they do. This makes the two interpretations above indistinguishable by experiment. They are interpretations, not theories. They are not science.

A person who adheres to the second interpretation would have to consider the twins final ages an "effect", a result of the interactions between measuring devices and the undetectable ether. But a person who adheres to the former interpretation would not consider it an effect. It's just a property of spacetime.

If your two alternatives are similar to these, it's not a simple matter of "which one is it?". Such questions are not answered by the theory, and are therefore not science.

 

[azoulay]

...

It is an experimental fact that if you set up a coordinate system according to Einstein's convention, then any clock's proper time is slow compared to the coordinate time if that clock is moving in that coordinate system. It is also an experimental fact that if two different clocks take different paths through spacetime between the same pair of events that the amount of proper time they experience may be different.

DaleSpam, is there any experiment that have ever been done that proves that the speed of Oscillation of the Cesium atom is NOT affected when it travels at high speed, let's say in an air plane jet ?

This is, I think, a crucial question because when supposedly "two different clocks taking different paths through spacetime between the same pair of events shows different value of time why would someone prefer the interpretation that it is the "proper time" they experience that are different instead of my above assumption (that the speed of Oscillation of the Cesium atom varies at high velocities) ?

LastOneStanding says that the speed of Oscillation of the Cesium atom varying while traveling at high velocity is "not what happens":

That is not what happens. According to either reference frame, time is running slowly in the other frame. This is possible precisely because of the difference between coordinate and proper time. However, when all the clocks are brought back together for comparison, it is found that different amounts of proper time elapsed for each.

But how can he be sure that's not what's happening ? I think he believes so deeply the actual theory that he is not willing to open up for other possibilities, possibly I'm wrong

If no experiment has been done to disprove the varying speed of the Oscillation of the Cesium atom (which is most probably the case) why would we throw this possibility out to explain why two clocks are showing different values?

 

[Dale]

DaleSpam, is there any experiment that have ever been done that proves that the speed of Oscillation of the Cesium atom is NOT affected when it travels at high speed, let's say in an air plane jet ?

What kind of experiment are you envisioning here? I.e. How would you propose to test this question?

 

[azoulay]

What kind of experiment are you envisioning here? I.e. How would you propose to test this question?

What about putting an atomic clock in some sort of high speed centrifuge?

Would Einstein theory predict any "time dilation" in this kind of scenario ?

regards, jonathan

 

[Nugatory]

DaleSpam, is there any experiment that have ever been done that proves that the speed of Oscillation of the Cesium atom is NOT affected when it travels at high speed, let's say in an air plane jet ?

Yes.

Every cesium atom (and everything else on the surface of the earth) that is at rest in June is moving at a speed of about 37 miles per second by December, every year (they spend December to next June slowing back down again). No one has ever observed a change in the oscillation frequency of cesium atoms across this change of speed, which is far greater than the speed of any aircraft.

 

[Nugatory]

What about putting an atomic clock in some sort of high speed centrifuge?

Would Einstein theory predict any "time dilation" in this kind of scenario ?

It does, but that's not an effect of the movement, but rather the acceleration.
In fact this is a variant of the twin paradox problem.

 

[Dale]

What about putting an atomic clock in some sort of high speed centrifuge ?

Yes, this experiment was done using muons instead of cesium atoms.

Bailey et al., “Measurements of relativistic time dilation for positive and negative muons in a circular orbit,” Nature 268 (July 28, 1977) pg 301.
Bailey et al., Nuclear Physics B 150 pg 1–79 (1979).

Would Einstein theory predict any "time dilation" in this kind of scenario ?

Yes, and the time dilation predicted was observed.

 

[write4u]

Question:
Does time dilation affect time only or could one also say 'spacetime dilation' and be correct?

 

[azoulay]

Yes, this experiment was done using muons instead of cesium atoms.

Bailey et al., “Measurements of relativistic time dilation for positive and negative muons in a circular orbit,” Nature 268 (July 28, 1977) pg 301.
Bailey et al., Nuclear Physics B 150 pg 1–79 (1979).

Yes, and the time dilation predicted was observed.

What was observed ? Probably two clocks showing different value in time ? And that's being interpreted as time dilation. Time dilation is, for what I understand of it, only an interpretation.

How is Einstein theory falsifiable ?

 

[ghwellsjr]

Previously I asked you:

Do you consider a light clock to be another example of MECHANICAL MOVEMENT? I'm asking about a pair of mirrors rigidly separated by a fixed distance and with a flash of light bouncing between the two mirrors and a counter that increments each time the reflection bounces off one of the mirrors?

Do you have an answer?

 

[azoulay]

What kind of experiment are you envisioning here? I.e. How would you propose to test this question?

Maybe we could redo the Hafele–Keating experiment and monitor the speed of Oscillation of the Cesium atoms.

I bet that during that famous experiment, no one thought of monitoring the speed of Oscillation of the Cesium atoms.

Is anyone an expert on the subject ?

regards, jonathan

 

[Dale]

What was observed ?

The muons in the centrifuge decayed slower than muons at rest in the lab, as predicted by relativity.

Probably two clocks showing different value in time ? And that's being interpreted as time dilation. Time dilation is, for what I understand of it, only an interpretation.

It is an observed experimental fact: clocks of any construction slow down in an inertial frame where they are moving.

How is Einstein theory falsifiable ?

There are an enormous number of ways that SR is falsifiable. In the Bailey experiment, if no time dilation had been observed or if a different amount of time dilation than predicted by SR had been observed, then SR would have been falsified.

 

[ghwellsjr]

Maybe we could redo the Hafele–Keating experiment and monitor the speed of Oscillation of the Cesium atoms.

What do you mean by "the speed of Oscillation"?

 

[Dale]

Maybe we could redo the Hafele–Keating experiment and monitor the speed of Oscillation of the Cesium atoms.

This a typical "move the goalposts" argument which is very typical of crackpots. When you propose an experiment and find that it has been done and confirmed relativity then propose another experiment and another and another and another until finally you blindly stumble on one which has not been exactly done.

You already asked "is there any experiment that have ever been done that proves that the speed of Oscillation of the Cesium atom is NOT affected when it travels at high speed", and when asked what kind of experiment would prove that you mentioned an atomic clock in a centrifuge. It has been done and confirmed relativity. So why are you going back and asking the same question again?

 

[azoulay]

What do you mean by "the speed of Oscillation"?

For Cesium: 9,192,631,770 periods per second.

At high speed, if we could monitor the number of periods (speed of Oscillation) of the Cesium atom it would decrease.

 

[ghwellsjr]

What do you mean by "the speed of Oscillation"?

For Cesium: 9,192,631,770 periods per second.

At high speed, if we could monitor the number of periods (speed of Oscillation) of the Cesium atom it would decrease.

If the Hafele–Keating experiment didn't monitor the number of periods, then what was the experiment all about?

 

[azoulay]

The muons in the centrifuge decayed slower than muons at rest in the lab, as predicted by relativity.

What does that have to do with time dilation ? I see no connection at all.

I don't know the details but that experiment seems to me to show that movement is slowing down at high speed. Am I missing something ?

 

[Dale]

At high speed, if we could monitor the number of periods (speed of Oscillation) of the Cesium atom it would decrease.

What would you use as a reference standard? Atomic clocks make such good clocks because they are very stable, so what could you use where, if a variation were detected, you could attribute the variation to the Cesium and not your reference?

The simple fact is that there are only 4 mechanisms available, EM, strong, weak, and gravity. All 4 exhibit time dilation, as predicted by relativity.

 

[azoulay]

If the Hafele–Keating experiment didn't monitor the number of periods, then what was the experiment all about?

Are you serious with this question ?

Are you saying that the Hafele–Keating experiment was monitoring exactly that: the number of periods of the Cesium atom ?

Because if that's the case, you just proved my point.

 

[Dale]

What does that have to do with time dilation ? I see no connection at all.

A constant fraction of a population muons decay every unit of time, so their rate of decay is a clock. Less decay means less time as measured by the muon clock.

The nice thing about this type of clock is that it has no internal parts to be squished or jostled or otherwise damaged by any motion or acceleration. It is completely insensitive to any type of disruptive effect that might damage macroscopic clocks. It is an ideal clock.