How do you know who is moving?

[JohnFromAus]

In the twins paradox one twin is said to move away and come back and be younger. But how can they tell which one is moving? They are moving relative to each other - sure - but surely then things would be the same from either point of view.

Is the fact that one (or both) of them must have accelerated to get some relative speed and must then decelerate/accelerate to turn around and then decelerate to stop - relevant? Ie if the speed changes that occurred happened without the application of a force (ie by magic) would things be the same?

I first read the special theory back in the 1950s when a student and have never really understood this point. It seem to me that motion of a body can only be relative to something. Lots of us have had the experience of being on a train stopped along side another stationary train. Relative motion starts and you have no idea if its your train or the other that is moving until you look for a reference.

 

I am probably missing something obvious here!!!

John

[ydoaPs]

Is the fact that one (or both) of them must have accelerated to get some relative speed and must then decelerate/accelerate to turn around and then decelerate to stop - relevant?

 

That's exactly it. The one accelerating is the one moving. But if neither accelerate, they each see the other as moving!

[Eric 5]

That's exactly it. The one accelerating is the one moving.

 

Which one is accelerating? The one moving away? Both are moving away from each other, depending on the point of veiw according to the special theory of relativity. Please explain what you are trying to say.

 

But if neither accelerate, they each see the other as moving!

 

If neither accelerate, they are either both at rest or moving at the same speed, if they are at rest then both will not see each other moving. If they are moving at the same speed then they would only see each other moving if their direction of motion were away from one another, otherwise if they are not accelerating yet moving at the same speed in the same direction, then neither one would see the other as moving. What was it that you were trying to say?

[swansont]

If two observers are moving relative to each other (at constant velocity), both can claim to be at rest and that the other observer is moving. There is no physics test you can do to confirm motion — there is no absolute reference frame. Motion like this is always relative.

 

Acceleration, OTOH, is not relative. I can do some measurement to tell if I am accelerating.

[Country Boy]

Which one is accelerating? The one moving away? Both are moving away from each other, depending on the point of veiw according to the special theory of relativity. Please explain what you are trying to say.

 

You said

In the twins paradox one twin is said to move away and come back and be younger.

 

The one that "moves away and comes back" is the one accelerating. While velocity is "relative", in special relativity, acceleration is not. In general relativity, acceleration can be interpreted as a "gravitational" force. The one accelerating feels a greater "gravitational" force which affects his clock.

 

Notice that the twin paradox depends on one of the twins coming back. That cannot be done without acceleration. If you assume that two people, with different motions, are at one point at time t= 0, then move away, each sees the other as in motion and each sees the other's time ellapsing more slowly than his own. There is no paradox in that.

[Riogho]

In Relativity anything that is not accelerating, (I.e. at a constant velocity), can make a valid claim to be at rest.

[JohnFromAus]

OK - I understand all that. What I was trying to establish was whether it was the relative motion that causes the clocks to run slower or the acceleration. No no no thats not the point Im trying to sort out. Let me try again.

1 Is the twins paradox actually true - if that happened would the one who experience the accelerations be younger?

2 What does 'be younger" mean??? Measured by whose time?

[NYSportsGuy]

OK - I understand all that. What I was trying to establish was whether it was the relative motion that causes the clocks to run slower or the acceleration. No no no thats not the point Im trying to sort out. Let me try again.

1 Is the twins paradox actually true - if that happened would the one who experience the accelerations be younger?

2 What does 'be younger" mean??? Measured by whose time?

 

 

God questions JohnfromAus. We have already established that (according to Einstein and the "special theory of relativity") when two bodies are in constant uniform motion with respect to each other or one is standing still and the other is in constant uniform motion....both can be considered either "moving" or "standing still". Why? Because in both cases, the laws of physics and gravity stay the same.

 

But in the "general theory of relativity", Einstein says that in essence, accelerating upwards or downwards in space is the same thing as standing still and having gravity pull on you....or acceleration = gravity. It is this gravity or acceleration that supposedly causes time to slow down somehow. I personally think it is the distance away frm the observer of the time that has to do with time slowing down. Still no one on this website has concretely proved me wrong.

 

But accroding to Einstein

 

I'm sorry, its BOTH the constant motion and the acceleration that supposedly leads to "being younger". Afterall, it is acceleration that LEADS to constant motion.

 

Check out this website to further understand how confusing and how "fragile" Einstein's theories on time dialtion really are:

 

http://www.geocities.com/rainforest/6039/jd2.html

 

The Doppler Effect has a lot to do with time dilation. They are apparently inter-related. As you accelerate away from a beam of light or a light wave; that light wave takes "longer" to reach you. Thus time appears slower as a result. The opposite is true if you are acclerating towards a light beam or a flash of some sort, it hit you more frequently and thus time is "speeding up". The one closest to gravity or the stronger of the two gravitational forces will see a decrease in time becasue they are accelrating away from the light source. Therefore it is the acceleration (which equals gravity) that causes time dilation or a "slowing down".

[swansont]

OK - I understand all that. What I was trying to establish was whether it was the relative motion that causes the clocks to run slower or the acceleration. No no no thats not the point Im trying to sort out. Let me try again.

1 Is the twins paradox actually true - if that happened would the one who experience the accelerations be younger?

2 What does 'be younger" mean??? Measured by whose time?

 

1. Yes

2. As measured by the clock in your own reference frame. That's the only one that has any relevance to you.

 

But accroding to Einstein

 

I'm sorry, its BOTH the constant motion and the acceleration that supposedly leads to "being younger". Afterall, it is acceleration that LEADS to constant motion.

 

No, according to Einstein the accumulated dilation is (ignoring higher-order terms) [math]\frac{1}{2}\frac{tv^2}{c^2}[/math]

 

The duration of the acceleration doesn't enter into the equation. Further, for constant acceleration you can account for differences in v with the above equation, i.e. you can account for acceleration with simple kinematics.

 

Check out this website to further understand how confusing and how "fragile" Einstein's theories on time dialtion really are:

 

http://www.geocities.com/rainforest/6039/jd2.html

 

Bwahahahaha! Somebody who writes up an "interview" with Einstein that reflects his own misunderstandings of relativity, proves absolutely nothing. He contradicts things Einstein published, and shows that he does not understand the Hafele-Keating experiment. A load of rubbish. Take the time to bring up the points here and they will be demolished.

[Eric 5]

Swansont, you say that the twin paradox is a real occurance. The twin paradox is a thought experiment based on time dilation. Time dilation according to the Special Theory of Relativity is a term that refers to the loss of time of a moving clock as observed by a stationary observer, time APPEARS to move slower on a moving object from the viewpoint of a stationary observer. Many people today think that this thing called time actually slows down. Well, these people have a misunderstanding of the Special Theory of Relativity, it states that time APPEARS to move slower to a stationary observer.

 

Besides, this time thing that slows down, slows down in what way? Velocity? Vibration? Exactly in what way does this thing slow down?

In other words, in what physical way does this time move, what are the mechanics behind the motion of time that are being altered by motion?

 

Most examples of this phenomenon that appear in books covering this topic use an analogy of a space ship traveling at near the speed of light. What these examples show is that time APPEARS to slow down in a ship that is traveling at or near the speed of light to an observer that is traveling much slower or is at rest relative to the ship. It APPEARS to slow down, but time does not actually slow down.

[ydoaPs]

Eric5, what do you make of REAL experiments with REAL clocks?

[Riogho]

Swansont, you say that the twin paradox is a real occurance. The twin paradox is a thought experiment based on time dilation. Time dilation according to the Special Theory of Relativity is a term that refers to the loss of time of a moving clock as observed by a stationary observer, time APPEARS to move slower on a moving object from the viewpoint of a stationary observer. Many people today think that this thing called time actually slows down. Well, these people have a misunderstanding of the Special Theory of Relativity, it states that time APPEARS to move slower to a stationary observer.

 

Besides, this time thing that slows down, slows down in what way? Velocity? Vibration? Exactly in what way does this thing slow down?

In other words, in what physical way does this time move, what are the mechanics behind the motion of time that are being altered by motion?

 

Most examples of this phenomenon that appear in books covering this topic use an analogy of a space ship traveling at near the speed of light. What these examples show is that time APPEARS to slow down in a ship that is traveling at or near the speed of light to an observer that is traveling much slower or is at rest relative to the ship. It APPEARS to slow down, but time does not actually slow down.

 

We have experimental evidence of Time Dilation.

[Eric 5]

It will help you understand this whole time dilation concept if you go to your reference books and define the terms: Time, Clocks, Special Relativity, Appears.

 

If you can find any verifiable step by step clear concise scientific research that was written about these experiments that shows exactly how these experiments were carried out to the point of being able to recreate the experiment, please let me know. Otherwise, all of these experiments that were done to "prove" time dilation are all as true as they can be recreated and verified by anyone interested in doing so. Believe what you will.

[Cap'n Refsmmat]

http://hyperphysics.phy-astr.gsu.edu/hbase/relativ/airtim.html#c2

 

http://blogs.scienceforums.net/swansont/archives/6

[swansont]

Eric5, it appears that you are still assuming there is a universal time; that's the only way the use of "appears" makes any sense. An observer can only measure the time relative to their own reference frame, but it is a measurement. It's not an illusion or appearance.

 

And, as far as recreating the time dilation experiments, it's been done, and is done continually. GPS satellites' clocks run at a different rate as compared to how they run on the earth, in a repeatable way.

[JohnFromAus]

This is all very interesting and helpful to me although I am still puzzled. Is it that perhaps somethings need a "better" language than english to express them - mathematics perhaps. I am always boggled by the human races sense of its own importance and the belief that we can and will one day understand everything!

Anyway back to the topic.

My reference for Special Relativity is a 1968 book "Introduction to Special Relativity" by Robert Resnick. Plenty of maths and physics - not a general interest level. Anyone have a different undergrad level text to recommend? I am always a bit suspicious of stuff on the net unless I know who wrote it or am recommended to it by some trusted authority - after all I could easily put up some articles of what I think!

 

1 yes you can detect acceleration but you cannot distinguish this from the effect of gravity

2 What still puzzles me (among a mass of other things) is ... well a thought experiment....

 

Twins are anaethatized(? cant spell well either) and one is then accelerated. When the acceleration stops they are both aroused. They now have relative motion and presumably would see each others clock running slower than their own. ( I hope!) . They are then KO ed again and brought back together by appropriate accelerations and then woken up. Who is the younger - I suppose its the one who was accelerated BUT he saw his brothers clock running slowly so would expect he would be the elder not the younger! Or would their be two of each of them! So that A could see a younger B and B a younger A!

I think what Im asking is ...is time dilation an effect of gravity (acceleration) or of relative motion?

But its really like what I used to tell my students - If I knew the right question to ask I would also know the answer!

I really must find that book and have another read!!

John

[Eric 5]

Eric5, it appears that you are still assuming there is a universal time; that's the only way the use of "appears" makes any sense. An observer can only measure the time relative to their own reference frame, but it is a measurement. It's not an illusion or appearance.

 

A measurement of what exactly?

 

 

And, as far as recreating the time dilation experiments, it's been done, and is done continually. GPS satellites' clocks run at a different rate as compared to how they run on the earth, in a repeatable way.

 

We are told that these experiments have been done. The way that these experiments are portrayed to us is more in a story form reporting that says the experiments got the desired results, but they are not portrayed in a manner to the public in a way that anyone could recreate these tests themselves. Where is the proof beyond a reasonable doubt? The special theory of relativity basically states “that there is a loss of time of a moving clock as observed by a stationary observer.”

 

Without this observer there is no loss of time in a moving clock. If time dilation were a real effect then it would happen with or without a stationary observer. This time dilation idea depends on an observer that is not moving with the clock. Again, without this observer, no time dilation.

 

 

Taken from Wikipedia.

“The Hafele–Keating experiment was a test of the theory of relativity. In October of 1971, J. C. Hafele and Richard E. Keating took four cesium-beam atomic clocks aboard commercial airliners and flew twice around the world, first eastward, then westward, and compared the clocks against those of the United States Naval Observatory.”

 

 

In order to do the test correctly the clocks on the air liners would have to be observed by a stationary observer. No mention of how this was done. When they compared the clocks, how did they do this? This reference and all other references I have found on these time dilation experiments are vague. No step by step account of the test from beginning to end. Have you seen any report that tells in detail how these tests were done? They all seem to leave out pertinent data regarding the tests, leaving us to assume how they were done or just take their word for it. What kind of scientific research reporting is that? Again, in what way were these clocks compared? The test results that can be found are so vague that you can see in many science forums like this, people who have their own take on how this was done. Some even say that the planes landed and then the clocks were compared. There would not be a debate on these experiments if there was undeniable readily available to the public, data that shows step by step the process of the experiments. But as it stands, we are left to take their word for it. That is not how science should be done.

 

Now lets look at the item that is supposed to be effected by this time dilation. The clock.

 

The idea of time dilation is centered around a moving clock counting off time slower than a clock that is a rest.

 

Clocks are a man made device operating as man designed it, counting off man made increments that man gave a numeric significance to, that results in a man made concept called time. Clocks are designed to give numbers, to which man assigns a significance or importance to. A clock could be considered to be a device or machine that generates a number or numbers in a regulated manner that was pre-determined by man. A clock is akin to a regulated number generator that converts mechanical, electrical, or the motion of an object to a number through pre-determined engineering of the device, and these numbers are delivered at a rate that follows the set standards that man has agreed to be universal in all such machines. How would this device be considered a proper tool in the time dilation experiments, when it is not built to react to changes in its environment?

 

 

Please share with me your definition of a clock that shows that clocks actually measure anything outside of its immediate construction. What outside influence is a clock measuring?

[swansont]

A measurement of what exactly?

 

Time. Which is measured by counting the oscillations of an oscillator.

 

(have I repeated this enough that you'll stop asking?)

 

We are told that these experiments have been done. The way that these experiments are portrayed to us is more in a story form reporting that says the experiments got the desired results, but they are not portrayed in a manner to the public in a way that anyone could recreate these tests themselves. Where is the proof beyond a reasonable doubt? The special theory of relativity basically states “that there is a loss of time of a moving clock as observed by a stationary observer.”

 

Have you read the paper?

 

It's not assumed that just anyone can recreate the experiment. Someone with some training in the field, and with the proper equipment, could. (even an amateur like this guy)

 

Without this observer there is no loss of time in a moving clock. If time dilation were a real effect then it would happen with or without a stationary observer. This time dilation idea depends on an observer that is not moving with the clock. Again, without this observer, no time dilation.

 

You misunderstand what is meant by observer. Anything that is present to experience the dilation counts anything that can make a measurement. The clock counts as an observer.

 

Taken from Wikipedia.

“The Hafele–Keating experiment was a test of the theory of relativity. In October of 1971, J. C. Hafele and Richard E. Keating took four cesium-beam atomic clocks aboard commercial airliners and flew twice around the world, first eastward, then westward, and compared the clocks against those of the United States Naval Observatory.”

 

 

In order to do the test correctly the clocks on the air liners would have to be observed by a stationary observer. No mention of how this was done. When they compared the clocks, how did they do this? This reference and all other references I have found on these time dilation experiments are vague. No step by step account of the test from beginning to end. Have you seen any report that tells in detail how these tests were done? They all seem to leave out pertinent data regarding the tests, leaving us to assume how they were done or just take their word for it. What kind of scientific research reporting is that? Again, in what way were these clocks compared? The test results that can be found are so vague that you can see in many science forums like this, people who have their own take on how this was done. Some even say that the planes landed and then the clocks were compared. There would not be a debate on these experiments if there was undeniable readily available to the public, data that shows step by step the process of the experiments. But as it stands, we are left to take their word for it. That is not how science should be done.

 

Again, there's more detail in the paper — Wikipedia is not a substitute for that. It assumes some experience and basic level of competence in the field. Just like all journal articles do.

 

 

Now lets look at the item that is supposed to be effected by this time dilation. The clock.

 

The idea of time dilation is centered around a moving clock counting off time slower than a clock that is a rest.

 

Clocks are a man made device operating as man designed it, counting off man made increments that man gave a numeric significance to, that results in a man made concept called time. Clocks are designed to give numbers, to which man assigns a significance or importance to. A clock could be considered to be a device or machine that generates a number or numbers in a regulated manner that was pre-determined by man. A clock is akin to a regulated number generator that converts mechanical, electrical, or the motion of an object to a number through pre-determined engineering of the device, and these numbers are delivered at a rate that follows the set standards that man has agreed to be universal in all such machines. How would this device be considered a proper tool in the time dilation experiments, when it is not built to react to changes in its environment?

 

Great care is taken in the building and operation of atomic clocks to assure that temperature, humidity, magnetic fields, vibration, etc. do not cause any effects.

[JohnFromAus]

Hey - I have thought a bit more and come to realize that my problem with the twins paradox was really a problem I had accepting time dilation as a reality. Once you can accept that the paradox is understandable. I have to do some more reading/study to get this all straight in my mind but I am getting there.

It seems to be that the Newtonian view assumed that the speed of all movement was relative to something or other and that time and space were fixed. It turned out that this was a workable assumption in the everyday world but is really only an approximation to reality. The MM experiment showed that c is constant for all observers which then leads to time and space having to be relative. - something like that anyway.

So Im back to my books for a while. Thanks to everyone for the discussion.

John

[raf]

You misunderstand what is meant by observer. Anything that is present to experience the dilation counts anything that can make a measurement. The clock counts as an observer.

 

so the clock stays the same, its just that time appears(perception) to be slower for the observer?

 

if c is constant then distance would be a factor and time would be altered in the sense that the light would take longer to reach us so we might see the same event at different times if we were at different distances! but the man made clock should be the same its just that both people would record a different time of the event.

[Eric 5]

I have to tell you that I was going to commend you on your ability to “stick to your guns” and your strong commitment to your understanding of this topic. I was going to tell you that I enjoy having a discussion with someone who is so dedicated as you to proving his point, and staying on topic. That was until I saw your last post. I hope that this last post was done in haste, and not actually what you meant to communicate. I still look forward to discussing more on this topic with you. The discussions with you have caused me to do more research on time dilation, which is always a benefit to my ability to understand the topic and discuss it with others.

 

So here is my response:

 

Originally Posted by Eric 5

A measurement of what exactly?

 

Time. Which is measured by counting the oscillations of an oscillator.

 

(have I repeated this enough that you'll stop asking?)

 

 

 

Time is not being measured, oscillations are. Not all machines that are built to “measure” time use an oscillator. You have not stated what this physical thing that is being measured is made of. If time is a physical thing that causes a clock to move in a regulated manner, then in what form is this thing that you call time. Are you saying that the form that time exists as, is an oscillation?

 

If time is something more that a mere human consideration, then it must exist as some sort of energy , either energy that is flowing or moving, or energy that is condensed, as in the case of matter.

 

There are only two ways in which something can exist or be real for anyone. Either they perceived this something through any of their body's senses, or they imagined or conceived this something. Time has to fall into one of these two categories. From our conversations, you seem to think that time is more than a consideration. I would just like you to explain in what way time is not just a consideration, but exists as an actual physical thing.

 

 

 

Originally Posted by Eric 5

We are told that these experiments have been done. The way that these experiments are portrayed to us is more in a story form reporting that says the experiments got the desired results, but they are not portrayed in a manner to the public in a way that anyone could recreate these tests themselves. Where is the proof beyond a reasonable doubt? The special theory of relativity basically states “that there is a loss of time of a moving clock as observed by a stationary observer.”

 

 

Have you read the paper?

 

 

I have read much on the topic, I can not say if I have read THE paper. Be more specific.

 

 

It's not assumed that just anyone can recreate the experiment. Someone with some training in the field, and with the proper equipment, could. (even an amateur like this guy).

 

I never said that just anyone can recreate the experiment. I said that the experiments that were done do not give specifics so that anyone who wanted to, could recreate the experiment. There are no exact details on how these experiments were carried out.

 

Now comes the best part. You refered me to an article to show that someone can indeed recreate the experiment of time dilation as done with the air planes. The experiment with the planes was to prove time dilation per the theory of Special Relativity, you know moving clocks. The article you refered me to is time dilation per the theory of General Relativity, gravitational time dilation. So the article does not apply to what I originally was asking. But it does not matter, because the article that you offered up as evidence of time dilation, contradicts itself, and proves the point that clocks do not measure a thing called time. The information in this article states that there is no way to know what time it really is. Thanks for the article, I am going to use it in future discussions of time dilation.

 

 

The following is from the article.

 

"If you have one clock ... you are peaceful and have no worries," says Van Baak, fingering a length of cable connecting two of his machines. "If you have two clocks ... you start asking, 'What time is it, really?'"

 

“He wanted his children to see that relativity is proportional. So he loaded the family's blue minivan with portable power supplies, monitoring equipment, and three HP 5071 cesium clocks. Three, because time is always marked relative to other clocks: More clocks mean more accurate time.”

 

The same guy contradicts himself.

 

“They hiked the trails, and the kids relaxed with board games and books, while in the imperceptibly lessened gravity, time moved a little bit faster than at home.”

 

I have to ask, how was he comparing the clocks in the mountains to the clocks at home while he was in the mountains? He would need to observe both the clocks near him in the mountains and the clocks at his house simultaneously in order to conduct the test properly. This guy Van Baak even stated that if you have more than one accurate clock, you would be asking yourself, “what time is it really.” So if this guy brought his clocks down from the mountain and compared them to the clocks in his house, he will be in the position of comparing four very accurate clocks, and asking himself what time is it really?

 

 

Then there is this guy named John Ackerman who has four very accurate clocks, and even when they are in the same reference frame, are not in synch. Now imagine if you were to subject these machines to a road trip up and back from the mountains.

 

From the article:

 

“It's a hobby that feeds on itself: A good clock always needs a better clock to set it. "You always have to have a reference frequency," says Ackerman. "If you get the next new good thing ... you have to measure it against something even better." It's a source of pride to Ackerman that his four machines keep time within 100 nanoseconds of each other.”

 

 

I say, just think, all the tests that were done in the past to prove time dilation were not that reliable because a better more accurate clock was yet to be made.

 

These clock are off by 100 nanoseconds, and they are at rest, and experiencing the same amount of gravity. How can any two clocks be reliably used in time dilation tests.

 

 

 

From the article:

 

“That fastidiousness is typical in both the amateur and professional timekeeping communities, where people are drawn first to the idea of finding precision in the physical world. Consistently, they tell stories of an early fascination with looking ever closer at something, trying to understand its exact boundaries. Fundamental to the field of precise time is that it will never be perfect. With every new level of accuracy comes a new frame of reference for error. Time has an intractable precision -- you can spend your days always moving closer to the ever-unreachable now.”

 

 

 

 

 

 

You misunderstand what is meant by observer. Anything that is present to experience the dilation counts anything that can make a measurement. The clock counts as an observer.

 

 

This statement that you made has no merit. If you look up the word observer you will find that I have not misunderstood the term. Where did you get the idea that in the theory of Special Relativity, anything that is present and can make a measurement is considered an observer? The last sentence is what did it for me, how does a clock observe? Clocks are not alive and do not have the ability to observe, or perceive. Clocks, like the dead, cannot observe.

 

Your statement basically says that Special Relativity can work with nobody around. Seriously, did you mean to say this?

 

I am sure that you read this article all the way through, so I do not see how you could have read all of these inconsistencies, and considered this article to be an accurate claim to the idea of time dilation. I would say that you read the article and wanted to believe that time dilation is true.

 

There is a quote that I have posted on this thread before that eloquently states how people will accept data without much scrutiny or skepticism if that data hints at what they what to believe is true.

 

I will post it again for the benefit of anyone who has not seen it.

 

“What a man believes upon grossly insufficient evidence is an index into his desires -- desires of which he himself is often unconscious. If a man is offered a fact which goes against his instincts, he will scrutinize it closely, and unless the evidence is overwhelming, he will refuse to believe it. If, on the other hand, he is offered something which affords a reason for acting in accordance to his instincts, he will accept it even on the slightest evidence. The origin of myths is explained in this way.”

Bertrand Russell

 

 

Anyways, my point is still this:

 

1. Time is not a real physical thing, time is a consideration.

2. Clocks do not measure an energy called time. Clocks are a man-made device that work in such a way that man has designed them to operate.

 

3. Time dilation is the appearance of clocks moving slower, time dilation does not in reality occur.

 

 

So far in our discussion of this topic you have not stated how time is a real physical thing. You have not stated how a clock is anything more then a machine designed to assign a number to a pre-engineered motion, or the or preexisting activity of an object. You have not shown any evidence of how in any time dilation tests, both clocks were observed simultaneously, as stated in the Special Theory of Relativity.

 

 

 

 

Please do not take any of this personally, I would like to continue this discussion with someone like you who has put so much time and research into stating his view. You have provided me with a worthy adversary in this on going debate. Please continue to do so.

[swansont]

Time is not being measured, oscillations are. Not all machines that are built to “measure” time use an oscillator. You have not stated what this physical thing that is being measured is made of. If time is a physical thing that causes a clock to move in a regulated manner, then in what form is this thing that you call time. Are you saying that the form that time exists as, is an oscillation?

 

I'm saying that [math]\omega = \frac{d\theta}{dt}[/math], which means that [math]\theta = \omega t[/math]

 

The amount of phase an oscillator accumulates is proportional to how much time has passed. IOW, time (from a measurement aspect) is the phase of an oscillation. If you count oscillations, you measure time. By definition.

 

The metaphysical question, "what form is this thing that you call time" is something else, and I'm not addressing that. It's a separate issue.

 

 

If time is something more that a mere human consideration, then it must exist as some sort of energy , either energy that is flowing or moving, or energy that is condensed, as in the case of matter.

 

There are only two ways in which something can exist or be real for anyone. Either they perceived this something through any of their body's senses, or they imagined or conceived this something. Time has to fall into one of these two categories. From our conversations, you seem to think that time is more than a consideration. I would just like you to explain in what way time is not just a consideration, but exists as an actual physical thing.

 

I can perceive time. Can't you?

 

 

Originally Posted by Eric 5

We are told that these experiments have been done. The way that these experiments are portrayed to us is more in a story form reporting that says the experiments got the desired results, but they are not portrayed in a manner to the public in a way that anyone could recreate these tests themselves. Where is the proof beyond a reasonable doubt? The special theory of relativity basically states “that there is a loss of time of a moving clock as observed by a stationary observer.”

 

 

I have read much on the topic, I can not say if I have read THE paper. Be more specific.

 

I was more specific. The Hafele-Keating paper, since we're discussing the Hafele-Keating experiment.

 

http://www.scienceforums.net/forum/showpost.php?p=393400&postcount=47

 

Hafele and Keating, Science 177 (#4404), pp. 168-170

 

(there are actually two papers there; this one discusses the experiment, since you wanted to know how the analysis was done and how to recreate it. The theory is discussed in the paper preceding this one.

 

 

I never said that just anyone can recreate the experiment. I said that the experiments that were done do not give specifics so that anyone who wanted to, could recreate the experiment. There are no exact details on how these experiments were carried out.

 

And this is how I know you haven't read the paper. But I'll summarize: take two sets of clocks and compare them to each other. Move one set of clocks in a controlled fashion. Then, compare the clocks again. If they agreed in the beginning, they will disagree afterwards by a predictable amount.

 

Now comes the best part. You refered me to an article to show that someone can indeed recreate the experiment of time dilation as done with the air planes. The experiment with the planes was to prove time dilation per the theory of Special Relativity, you know moving clocks. The article you refered me to is time dilation per the theory of General Relativity, gravitational time dilation. So the article does not apply to what I originally was asking. But it does not matter, because the article that you offered up as evidence of time dilation, contradicts itself, and proves the point that clocks do not measure a thing called time. The information in this article states that there is no way to know what time it really is. Thanks for the article, I am going to use it in future discussions of time dilation.

 

And I never said he was recreating the experiment. I said he could if he wanted to. And he's right that nobody know what time it really is, but that's a perhaps subtle point that's not particularly relevant to this discussion. (i.e. what the starting point for the phase is, and what the best way to measure the time is, are things that are not a given — they are by agreement, not dictated by physics. But in measuring time differences, the original phase does not matter, and the best way of realizing a timescale is at a much smaller level of precision than these experiments)

 

The following is from the article.

 

"If you have one clock ... you are peaceful and have no worries," says Van Baak, fingering a length of cable connecting two of his machines. "If you have two clocks ... you start asking, 'What time is it, really?'"

 

“He wanted his children to see that relativity is proportional. So he loaded the family's blue minivan with portable power supplies, monitoring equipment, and three HP 5071 cesium clocks. Three, because time is always marked relative to other clocks: More clocks mean more accurate time.”

 

The same guy contradicts himself.

 

Not at all. More clocks will give you a more accurate measurement.

 

“They hiked the trails, and the kids relaxed with board games and books, while in the imperceptibly lessened gravity, time moved a little bit faster than at home.”

 

I have to ask, how was he comparing the clocks in the mountains to the clocks at home while he was in the mountains? He would need to observe both the clocks near him in the mountains and the clocks at his house simultaneously in order to conduct the test properly. This guy Van Baak even stated that if you have more than one accurate clock, you would be asking yourself, “what time is it really.” So if this guy brought his clocks down from the mountain and compared them to the clocks in his house, he will be in the position of comparing four very accurate clocks, and asking himself what time is it really?

 

He compared them after they got back. A clock that runs slow will display a number that lags another clock.

 

 

Then there is this guy named John Ackerman who has four very accurate clocks, and even when they are in the same reference frame, are not in synch. Now imagine if you were to subject these machines to a road trip up and back from the mountains.

 

From the article:

 

“It's a hobby that feeds on itself: A good clock always needs a better clock to set it. "You always have to have a reference frequency," says Ackerman. "If you get the next new good thing ... you have to measure it against something even better." It's a source of pride to Ackerman that his four machines keep time within 100 nanoseconds of each other.”

 

 

I say, just think, all the tests that were done in the past to prove time dilation were not that reliable because a better more accurate clock was yet to be made.

 

These clock are off by 100 nanoseconds, and they are at rest, and experiencing the same amount of gravity. How can any two clocks be reliably used in time dilation tests.

 

If you paid attention, you would have noticed that his four machines are NTP servers, not clocks. (only one of them has a cesium clock in it). His synchronization has to account for internet time delays. Keeping the differences to 100 nanoseconds is quite an accomplishment, but has nothing to do with the reliability of time dilation experiments.

 

 

From the article:

 

“That fastidiousness is typical in both the amateur and professional timekeeping communities, where people are drawn first to the idea of finding precision in the physical world. Consistently, they tell stories of an early fascination with looking ever closer at something, trying to understand its exact boundaries. Fundamental to the field of precise time is that it will never be perfect. With every new level of accuracy comes a new frame of reference for error. Time has an intractable precision -- you can spend your days always moving closer to the ever-unreachable now.”

 

 

All measurements have errors in them.

 

This statement that you made has no merit. If you look up the word observer you will find that I have not misunderstood the term. Where did you get the idea that in the theory of Special Relativity, anything that is present and can make a measurement is considered an observer? The last sentence is what did it for me, how does a clock observe? Clocks are not alive and do not have the ability to observe, or perceive. Clocks, like the dead, cannot observe.

 

An observer is anything that can make a measurement. You are misunderstanding the term as it is used in scientific papers.

 

Your statement basically says that Special Relativity can work with nobody around. Seriously, did you mean to say this?

 

Yes. Absolutely. Dilation is an effect on time, not on people. Anything that measures time, or is in any way affected by the rate at which it passes, will be affected. A plant can be an observer, as the term is used, if you had sufficient dilation to use plant growth to measure time passage. Since there actually needs to be an object on order to have motion, dilation will always be present for the object.

 

I am sure that you read this article all the way through, so I do not see how you could have read all of these inconsistencies, and considered this article to be an accurate claim to the idea of time dilation. I would say that you read the article and wanted to believe that time dilation is true.

 

 

And you would be wrong to say that. I concluded, based on evidence, that relativity was a valid theory long before that article came out.

 

Anyways, my point is still this:

 

1. Time is not a real physical thing, time is a consideration.

2. Clocks do not measure an energy called time. Clocks are a man-made device that work in such a way that man has designed them to operate.

 

3. Time dilation is the appearance of clocks moving slower, time dilation does not in reality occur.

 

And that makes you oh-for-three. I'll give you a foul-tip on the first one, since I am not claiming time is physical.

 

So far in our discussion of this topic you have not stated how time is a real physical thing. You have not stated how a clock is anything more then a machine designed to assign a number to a pre-engineered motion, or the or preexisting activity of an object. You have not shown any evidence of how in any time dilation tests, both clocks were observed simultaneously, as stated in the Special Theory of Relativity.

 

Where in the theory of special relativity does it state that the clocks have to be observed simultaneously?

[Eric 5]

Alright, having this discussion with you has been quite a research journey, much is being uncovered because of you. We are both making long posts that are saturated with information. I appreciate all that you wrote in your most recent post, and am willing to respond to each point that you mentioned if required, but I am going to try and keep my post short and to the point. I want to stick to the basics of this topic. Your answers to the last two comments hit at the core of this debate.

 

Originally Posted by Eric 5 

Anyways, my point is still this:

 

1. Time is not a real physical thing, time is a consideration.

2. Clocks do not measure an energy called time. Clocks are a man-made device that work in such a way that man has designed them to operate.

 

3. Time dilation is the appearance of clocks moving slower, time dilation does not in reality occur.

 

 

Your reply to this was, “And that makes you oh-for-three. I'll give you a foul-tip on the first one, since I am not claiming time is physical.”

 

 

You say time is not physical, so what is it? It is either a real physical thing, or imagined, a concept. If time is not a physical thing, then what are these man made machines called clocks, measuring?

 

 

 

Originally Posted by Eric 5 

So far in our discussion of this topic you have not stated how time is a real physical thing. You have not stated how a clock is anything more then a machine designed to assign a number to a pre-engineered motion, or the or preexisting activity of an object. You have not shown any evidence of how in any time dilation tests, both clocks were observed simultaneously, as stated in the Special Theory of Relativity.

 

 

 

 

Your response, “Where in the theory of special relativity does it state that the clocks have to be observed simultaneously?”

 

 

I am not going to transcribe the book that Einstein wrote, but I will tell you to read it. Anyone familiar with Special Relativity will tell you that it is based on events that occur simultaneously and how they appear to an observer. After coming this far in our dialog, only to find out that you do not have a firm grasp on what the concept of time dilation is, I can see why you have the belief in time dilation as an actual physical occurrence. It is too bad that I am now just finding this out, I would have spent more time pointing you to the book that started this concept. I have mentioned this book previously in this thread, I will do this again since I would like you to get the proper understanding of what Special Theory of Relativity says about time dilation.The book: RELATIVITY. THE SPECIAL AND THE GENERAL THEORY.

 

ISBN 0-517-025302

 

 

Definition per the: DICTIONARY OF SCIENTIFIC LITERACY.

 

ISBN 0-471-53214-2

 

 

Space-Time--- “Einstein’s SPECIAL THEORY OF RELATIVITY states that space and time are interrelated. For example, the rate of the flow of time depends on the state of motion of the observer. A clock on a moving laboratory appears to be ticking more slowly than a set of identical clocks distributed throughout a stationary laboratory.

Another example: Two events or occurrences at two different locations can be seen to be occurring simultaneously by one observer but will not be seen as not occurring simultaneously by a moving observer.”

 

This is why I kept asking how were the clocks observed in these time dilation tests. According to Special Relativity, both the moving clock and the stationary clock need to be compared simultaneously. One of the clocks have to be moving relative to a stationary clock, and both clocks have to be observed simultaneously. You can’t look at one clock and then later look at a different clock and say there was a time dilation. Comparing two clocks, each comparison done at different times, to prove time dilation would make no sense.

 

 

I tried to find the exact paper that you wanted me to read on the Hafele-Keating experiment. I found a web site that contained the paper, but getting access to the paper required an access number that I do not have. You could post the web site address if you want me to read what you read, but… In looking for this paper I did find a research site that states that the Hafele-Keating experiment is invalid. So now who are we to believe?

 

Here is what the web site said.

 

 

The REAL result of the Hafele-Keating experiment

[ Follow Ups ] [ Post Followup ] [ Relativity XVIII ] [ FAQ ]

 

“Posted by alen on June 01, 2003 at 07:25:38:

The website linked below indicates that the result of the Hafele-Keating experiment was severely flawed. An engineer, A.G. Kelly, obtained the original 1971 test report from the United States Naval Observatory, on which the 1972 paper was based, and discovered that the original results actually did not support the result computed in the 1972 paper.

The great problem with the experiment was the drift rates of the caesium clocks. They were anything from 2 to 9ns per hour, and the rates could vary by as much as 4ns. This could mean an uncertainty of as much as 300ns in a test supposed to produce a result of only 40 to under 300ns. The clocks were not all equally stable, and averaging could not make the test more reliable. One clock, serial no 120, was so poor that A.G. Kelly says "That erratic clock had contributed all of the alteration in time on the Eastward test and 83% on the Westward test, as given in the 1971 report". He says that, if this clock had been ignored, the East and West results would have been "within 5ns and 28ns of zero". Even more clearly, the most stable of the four clocks, no 447, by itself constituting a better experiment than all the clocks together, indicated, as an overall result of the test, zero kinematic time accumulation.

For what it is worth, if the experiment indicated anything, it indicated, via clock 447, that accelerated clocks, moving between events by different spacetime paths, do not accumulate any time difference when they are brought together again. Such a result, if it were dependable, would rather indicate that the proper times in all reference frames accumulate at the same rate, independently of space-time paths, and thus support a view that the SR 'proper time' is a universal time rate that is the same for all reference frames.”

 

Here is the web address. http://www.superstringtheory.com/forum/relboard/messages18/88.html

 

 

 

 

 

 

I have to thank you for helping me find another nail to put in the coffin to the myth of time dilation being a real physical occurrence.

[swansont]

 

I am not going to transcribe the book that Einstein wrote, but I will tell you to read it. Anyone familiar with Special Relativity will tell you that it is based on events that occur simultaneously and how they appear to an observer. After coming this far in our dialog, only to find out that you do not have a firm grasp on what the concept of time dilation is, I can see why you have the belief in time dilation as an actual physical occurrence. It is too bad that I am now just finding this out, I would have spent more time pointing you to the book that started this concept. I have mentioned this book previously in this thread, I will do this again since I would like you to get the proper understanding of what Special Theory of Relativity says about time dilation.

 

Oh, please. I do have the proper understanding of what SR says about time dilation. Simultaneity for an observer is presented as a concept of SR, but there is nothing that states that measurements have to continually occur at the same time. The measurements that occur at the beginning and end of the experiment happen simultaneously.

 

Space-Time--- “Einstein’s SPECIAL THEORY OF RELATIVITY states that space and time are interrelated. For example, the rate of the flow of time depends on the state of motion of the observer. A clock on a moving laboratory appears to be ticking more slowly than a set of identical clocks distributed throughout a stationary laboratory.

Another example: Two events or occurrences at two different locations can be seen to be occurring simultaneously by one observer but will not be seen as not occurring simultaneously by a moving observer.”

 

This is why I kept asking how were the clocks observed in these time dilation tests. According to Special Relativity, both the moving clock and the stationary clock need to be compared simultaneously. One of the clocks have to be moving relative to a stationary clock, and both clocks have to be observed simultaneously. You can’t look at one clock and then later look at a different clock and say there was a time dilation. Comparing two clocks, each comparison done at different times, to prove time dilation would make no sense.

 

Makes no sense to you, perhaps. Simultaneous measurement, yes (there's no way to not compare them simultaneously). Simultaneous while the clocks are in motion, no.

 

It's not that complicated. If you have a clock that runs slow (compared to some other clock), and loses 1 sec in an hour, but then stops running slow after the hour is up, it will be 1 sec slow. It will continue to be 1 sec behind the other one. You can compare them at your leisure.

 

Remember [math]\theta = \omega t[/math]? Use that for two clocks.

 

"Run slow" means the frequency is smaller. If you have a period where the frequency is different, the phase won't match up. But if the frequency is the same, the phase difference will remain the same. The amount of phase difference depends on how long you have different frequencies. You can ignore the times that the frequencies are the same, because no phase difference accumulates then.

 

I tried to find the exact paper that you wanted me to read on the Hafele-Keating experiment. I found a web site that contained the paper, but getting access to the paper required an access number that I do not have. You could post the web site address if you want me to read what you read, but… In looking for this paper I did find a research site that states that the Hafele-Keating experiment is invalid. So now who are we to believe?

 

Umm, the peer-reviewed one? The one that has be re-confirmed over and over again?

 

I've read the stuff from Kelly. He was/is free to write it up and submit it for acceptance in a peer-reviewed journal. But given that the results have been reconfirmed, over and over again, I don't think there's much traction there.

[Reaper]

I kinda find it funny that Eric 5 is trying to tell a physicist (and one who works with atomic clocks no less) that he doesn't understand relativity.