Gravity slows down time.

[arfa brane]

Please note that you are inadvertently enabling chinglu's confusion because you too fall into the trap of not properly distinguishing between two subtle but important concepts/aspects!

I don't think so, but let's see:

I have bolded the two bits where this confusion is embodied/promulgated. The whole point I tried to explain earlier to chinglu (and now you) is that the clocks don't tick off 'years', they just tick off an absolute number of 'seconds'. And that's it. The correlations made with the number of earth-sun orbit 'years' is entirely made by the observer. The trouble comes in when the observer making the connection does not distinguish BETWEEN the 'witnessed' earth-sun years number of orbits DATA SET and the clock/biology age/tick DATA SET.

It's irrelevant that clocks measure seconds. What is relevant is that you can count how many times the earth orbits the sun.
Perhaps you haven't noticed that I've been saying that the travelling twin might be able to count earth orbits, but they can't use this in their own frame--they need a local clock.
Using the earth's orbits to count years is perfectly acceptable, as long as you're in a frame which is stationary wrt the sun. That is, you need to be "next to" a clock if you want to use it.

 

[Undefined]

My friend, let me remind you of some words of Lord Byron in regard to this ..

Let not a monument give you or me hopes
Since not a pinch of dust remains of Cheops ..

True enough, mate.

However, since truly modern times it is the 'intangible' mind of humanity and its accumulated science and knowledge base that is now 'the monument', not the tangible structures/edifices erected by humanity. While we advance in mind/knowledge we live in hope of advancing in wisdom and continuity even unto and beyond the stars.

That is me 'updating' with my own 'words' the possibilities which Lord Byron's 'words' had not encompassed because they were written at a time when the hope that humanity was capable of fulfilling all his good potential was not yet clear to him. Anyhow, that's my excuse for being more optimistic about humanity and its future!

 

[Undefined]

I don't think so, but let's see:
It's irrelevant that clocks measure seconds. What is relevant is that you can count how many times the earth orbits the sun.
Perhaps you haven't noticed that I've been saying that the travelling twin might be able to count earth orbits, but they can't use this in their own frame--they need a local clock.
Using the earth's orbits to count years is perfectly acceptable, as long as you're in a frame which is stationary wrt the sun. That is, you need to be "next to" a clock if you want to use it.

What you say is true. No problem. But I was addressing these (my bolded) bits in your own post:

The clock that measured 10 earth years isn't on the earth. The travelling twin with his travelling clock measured 12 earth orbits in 10 earth years.

See where you say in effect that the clocks measure/tick off 'years'? That is where the confusion first arose for chinglu, as I pointed out to him early on.

Now you were falling into the trap of using the same mistaken terminology and so keeping him from realizing where his confusion arises (ie, from tacitly 'connecting' two effectively disparate systems and their two disparate data sets, as explained already).

Which is why I just wanted to caution you, chinglu and everyone NOT to fall into that same conceptual/logical trap and so bringing the confusion in from the very start of any 'analysis' which does not recognize the problem which failure to distinguish between the data sets causes any further discussion between you.

 

[arfa brane]

See where you say in effect that the clocks measure/tick off 'years'? That is where the confusion first arose for chinglu, as I pointed out to him early on.

But the clocks do tick off years. The interval of time chosen is not relevant as long as it's some kind of regular periodic motion and is the same interval for the twins when they're in the same rest frame..

The travelling twin's clock measures 10 earth years (in seconds or whatever). The clock on the earth measures 12 earth years. Whatever a year is in seconds isn't really relevant. What is relevant is that the units of time change for the traveler, not how the units are measured, as long as both twins have identical clocks.
Using the earth as a clock isn't a problem.

 

[Undefined]

But the clocks do tick off years. The interval of time chosen is not relevant as long as it's some kind of regular periodic motion and is the same interval for the twins when they're in the same rest frame..

The travelling twin's clock measures 10 earth years (in seconds or whatever). The clock on the earth measures 12 earth years. Whatever a year is in seconds isn't really relevant. What is relevant is that the units of time change for the traveler, not how the units are measured, as long as both twins have identical clocks.
Using the earth as a clock isn't a problem.

Hi arfa.

No no no, mate! Consider: We select an atomic clock and count its natural periodic oscillation as a unit 'tick'. Then we correlate that to an Earth 'year' and set that number of ticks corresponding to a full earth orbit to represent 'one year's worth of ticks'. Yes?

Once we establish that 'standard', then its only because we use a certain 'count' of ticks to represent one 'year'. The clock has done nothing else except keep ticking at its own natural rate, and the 'count' is what it is at any stage we care to 'read off' that count!

We cannot 'claim' that the clock is 'ticking off a year'; only that it is ticking off and the count is mounting and WE relate that to another data set we originally used to 'segment the counts' into what represents 'an Earth-sun orbit cycle year'. And that's it. No more. No less.

Now if we take one of these clocks with the traveling twin as per the scenario, then that clock TOO is just ticking away and accumulating a 'count' of ticks at its new rate. And that's it. No more. No less.

See? it is the observer in each case (ie, Earth twin and traveling twin) which 'segments' the count and interprets the meaning of that segment insofar as the astronomical system 'orbit count of 'years' is concerned. That's it.

In neither case does the clock tick of a 'year'; it only ticks off a 'count' of its respective value 'tick durations', and then we make the necessary 'bridging' allowances/interpretations necessary to correlate BOTH clock 'counts' to the separate data set of Earth-sun orbit 'year' cycle count.

See? The subtle but incorrect impression that the clocks tick off 'years' is obviously a non-sequitur, as just pointed out. That is what causes the immediate misunderstanding which starts the analysis off on the wrong foot both logically and effectively. That is what needs to be understood and dropped in oder to avoid continuing the cross-purpose discussion based on a non-sequitur 'connection' which is NOT there between the clocks and the Earth-sun 'year' cycle number counts. I hope that is now made clearer as to what is or is not a valid correspondence to be made between the clocks and Earth-sun systems?

 

[BdS]

http://en.wikipedia.org/wiki/Second

Thus, the 1960 SI definition abandoned any explicit relationship between the scientific second and the length of a day, as most people understand the term. With the development of the atomic clock in the early 1960s, it was decided to use atomic time as the basis of the definition of the second, rather than the revolution of the Earth around the Sun.

Makes sense to me to do it the SI way, because we started to realise that time is not only the motion of cosmic objects, its more like the motion of atomic stuff that dictates time to the cosmic matter too.
Thats why I said things like :
post #46
post #49
When I posted those posts I had no idea how we recorded time and what chinglu was saying didnt makes sense. When I went and read up on it, it turned out we realised the problem and had corrected it with the atomic clock and SI second system.

Read the wiki link for the history of a second.

 

[arfa brane]

See? The subtle but incorrect impression that the clocks tick off 'years' is obviously a non-sequitur, as just pointed out. That is what causes the immediate misunderstanding which starts the analysis off on the wrong foot both logically and effectively.

But there is no misunderstanding. There is a clock that ticks off years, it's the earth orbiting the sun.

That is what needs to be understood and dropped in oder to avoid continuing the cross-purpose discussion based on a non-sequitur 'connection' which is NOT there between the clocks and the Earth-sun 'year' cycle number counts.

Why isn't there a connection between clocks ticking off seconds, and clocks ticking off days, months or years? Is that what you're saying? You're saying a clock that doesn't measure seconds isn't a clock?

I hope that is now made clearer as to what is or is not a valid correspondence to be made between the clocks and Earth-sun systems?

The valid connection is that both can be used to measure time, which is just like distance, so it can have any units you like. Just because the second is a well-defined interval does not mean every clock has to be based on seconds.

 

[paddoboy]

Things appear to be getting rather more complicated then necessary for this old layman......
I suppose in an effort to explain to those refusing to accept an explanation that was inevitable.

The whole debate rests on the premise of space and time, and whether they are absolute or not.

The fact that light/photons and the general transmission of any information cannot exceed "c", means that any observable situation at any particular location, is always relative to the observer, or that particular FoR. This then has profound effects on anything happening simultaneously for any two observers.
Einstein called this Special Relativity:

And it applies fully in the current situation being discussed, despite baseless fanatical opposition by some in not being able to see that fact.

The situation is described in the following link rather simply [even for me! ] so it should be understandable to others.
It takes the form of a question and answer:


AT....
http://van.physics.illinois.edu/qa/listing.php?id=16276

QUESTION:
Well, according to the twins paradox, Mary is suppose to age slower than John because shes moving near C relative to John. But if relative to Mary John is travelling near c and relative to Mary John's clock ticks slower as you previously stated, isn't John suppose to age slower than Mary? So in the end, who does age slower???


ANSWER:
So long as they continue in fixed relative motion, there's no objective way to say. Say at time t=0 they started at the same age and the same place. Later on, each wants to see how much the other has aged. They get a picture of the other sent to them. The picture looks young, but they have to make some allowance for the time it took to send the picture, since it was taken a while ago. After making that allowance, each concludes that the other was still not aging as fast as they themselves were. However, each says that the other did not make a big enough allowance, since according to them the relative speed of the light and the other observer was less than c. they each have a consistent account, equally good.

In order to make a comparison that everyone will have to agree on, we have to get John and Mary back to the same place at the same time. Then we can take a picture and everyone in any frame can look and see who aged more. That means that one or both of John and Mary have to change their motion, i.e. accelerate. Say that it's John who fires his rocket engines and accelerates back toward Mary. He no longer is using a non-accelerating frame, so our old rules describing how things look from his point of view don't apply. Mary's frame is ok. She says John isn't aging fast enough, so she must be right. We conclude that John's acceleration back toward Mary must make him see her as aging faster. We can get quantitative about this, figuring out how things look from accelerating frames.

If we then add one more principle, that one can't distinguish between the effects of gravity and acceleration, then we have the ingredients for General Relativity

 

[chinglu]

Hi chinglu!

Please read my above post to arfa brane, wherein I point out again where both of you are making 'claims' that the clock's are ticking off 'years'. Which is obviously incorrect, as I have already explained, because clocks only tick off their respective value 'second' counts, and not anything else connected with astronomical data. It is the observer (you) who is making claims and connections between two totally disconnected/independent data sets, and getting the 'paradox' because you haven't made the correct bridging allowances/interpretations necessary, as also explained previously. Bye, and good luck!

No one is disputing your analysis of the number of seconds ticked off by the clocks at the respective frames.

But, the number of ticked seconds in the earth frame matches the earth orbits.

The number of seconds in the moving frame does not match the number of seconds for earth orbits.

Who cares?

Both twins lived 12 earth orbits.

Now, because the moving twin's clock registered a different number of seconds that does not match the number of earth orbits, does that mean he did not live the same number of earth orbits as the stay at home twin?

So, you are claiming the two twins lived the same number of earth orbits but the moving twin is younger.

How do you work that out?

 

[Undefined]

But there is no misunderstanding. There is a clock that ticks off years, it's the earth orbiting the sun.

Hi arfa.

The clocks tick off INTERNAL (or if you like, INHERENT) oscillations. No more than that. Any further connection we make from the cumulative tick 'counts' with any other EXTERNAL system dynamics/cycle is all OUR (the observers') doing. See? There is no actual causal connection between the astronomical cycle and the clock tick/count, as can be readily seen when the TRAVELING twin clock ticks at a DIFFERENT RATE of ticks and accumulates a DIFFERENT absolute cumulative tick 'count' number than the stay-put twin's clock. That is the subtlety which is at the center of the confusion right from the start of this discussion/analysis.

Why isn't there a connection between clocks ticking off seconds, and clocks ticking off days, months or years? Is that what you're saying? You're saying a clock that doesn't measure seconds isn't a clock?

Not saying that at all, mate.

Just that once the initial 'standard' agreed to by both twins' clocks at the starting state (Earth-sun related 'year' equalling a certain number of cumulative 'tick counts), then all further 'connections' are automatically and effectively causally 'broken', especially so by the traveling twin taking his clock with him to a different 'state'.

The valid connection is that both can be used to measure time, which is just like distance, so it can have any units you like. Just because the second is a well-defined interval does not mean every clock has to be based on seconds.

Once the clocks counts are examined, and their respective number is correlated to the original count value equalling an Earth-sun 'year', then obviously the two twins will need to make the necessary correction for the traveling twin's clock count value to bring it UP to equal what the Earth twin's clock counted. OR they can just RECOGNIZE that the raveling twin's clock countd at different rate for the same common 'standard' from which both started, and so realize that any TICKING/BIOLOGICAL PROCESSES INHERENT to the traveling clock/twin will result in that clock/twin having 'counted/aged' at a different rate EVEN THOUGH the original common standard clock and the original common 'year' cycles ticked/aged at their own starting standard rate!

That's all. Anything else is subjective connection overlays which mask the subtle but important 'diconnect' that leads to the confusion if not recognized from the start and allowed for when comparing notes upon return. See? There is a difference between the OBJECTIVE AGING rate INHERENT to the OBJECTIVE motional states of the clocks, and the SUBJECTIVE 'correlations' made between VARYING RATE clock counts and an agreed CONSTANT STARTING STANDARD astronomical cycle count.

If we can separate the two from the start, thn there is no paradox and no disagreement to discuss, because both twins will have 'lived through' 12 astonomical cycle Earth-years, BUT only ONE will have AGED DIFFERENTLY from that standard agreed 'year count' which is EXTERNAL TO BOTH CLOCK/TWIN's tick/age processes. Yes?

 

[paddoboy]

Both twins lived 12 earth orbits.

Now, because the moving twin's clock registered a different number of seconds that does not match the number of earth orbits, does that mean he did not live the same number of earth orbits as the stay at home twin?

So, you are claiming the two twins lived the same number of earth orbits but the moving twin is younger.

How do you work that out?

Because you deliberately are misinterpreting and shoving obtuse meanings into other people's post.
Anyway for your enjoyment here we go again.

The Earth orbits the travelling twin observed were in another FoR.
His own FoR both mechanical and biological moved through a lesser period compared to the other FoR

Now read the links I have given.....one quite illustrative and should be able to explain the concept at any level.
If you chose not to watch, well keep living in ignorance, but your ignorance and invalid interpretation of SR/GR will not change the world we live in, or the accepted standards one iota.

 

[Undefined]

Hi chinglu.

No one is disputing your analysis of the number of seconds ticked off by the clocks at the respective frames.

That wasn't the point I was trying to make. But ok, it's good that this aspect is agreed upon.

But, the number of ticked seconds in the earth frame matches the earth orbits.

That is immaterial, since the clock ticks off a certain number of INHERENT TICKS. The fact that it was initially agreed that a CERTAIN NUMBER of such ticks in the Earth motional state is SET to EQUAL one Earth-sun astronomical 'Earth year' orbit/cycle' is just a starting standard FOR that Earth state and NO OTHER state. Do you agree on that?

The number of seconds in the moving frame does not match the number of seconds for earth orbits.

That is, like I already said, because the clock tick and the twin biology PROCESSES are INHERENT to them and not to anything EXTERNAL, including whatever 'standard year' astronomical cycles you want to relate them to 'according to any agreed standard' conversion between clock counts and astronomical cycle from Earth state initializing standard.

Regardless of any 'logical/numerical' ADJUSTMENTS made to reach a correlation between clock counts and astronomical counts, the BIOLOGY PROCESS has also SLOWED DOWN for the traveling twin, as it did for the traveling clock. This is OBVIOUSLY causally disconnected from any 'agreed logical correspondence' which the twins make regarding 'counts'. The BIOLOGY has IMPRINTED WITHIN ITS CURRENT STATE something called "AGING" RATE/CONDITION, which remains INHERENT regardless what further 'correlations' are made 'mathematically/abstractly' between the clock counts and astronomical counts. Just as the clock will have that IMPRINT of its own 'lesser aging' reflected in its own LESSER ABSOLUTE TICK NUMBER 'count'. Get that subtle but important 'disconnect' aspect, mate?

Both twins lived 12 earth orbits.

Here again is where the terminology used sets you up for confusion. Remmber what I said about the term "lived through" and "aged through" being TWO SEPARATE things, both logically and effectively? This goes to the heart of realizing WHICH is an EXTERNALITY and WHICH is an INTERNALITY, as I tried to explain about two different 'data sets' which arise because of this internal/external nature of what the data represents.

Ie: One can 'live' through and 'witness' an EXTERNAL PROCES cycle count situation, BUT one MUST ALSO be 'counting' off and 'aging' though' an INTERNAL PROCESS cycle/count which is totally disconnected from the externality UNLESS and UNTIL one makes the 'correlation' PROPERLY. Which means recognizing the differences already explained, and their effects on any 'analysis' if they are not allowed for properly via 'bridging' allowances and interpretations which 'correct' for the EXTERNALITIES-INTERNALITIES comparisons during the analysis.

Now, because the moving twin's clock registered a different number of seconds that does not match the number of earth orbits, does that mean he did not live the same number of earth orbits as the stay at home twin?

No no no, mate! They didn't register the number of 'seconds', only the number of their respective-length value TICKS. Period. Any connection between number of ticks with 'second' or 'year' or etc is purely a CONVENTION 'standard' established when starting out from same state Earth-sun correlated 'standard' for that 'convention' initially agreed to. BUT when the clocks move away from the same state, the ticks/counts have NO FURTHER correspondence to 'second' OR 'year' etc, as I already explained, since both the clocks are thereafter THEIR OWN INHERENT ARBITERS of the meaning/value of the counts. It just so happens that the stay-put clock is still happily agreeing with the starting standard CONVENTION correlation. BUT if that clock TOO was also started traveling, IT TOO would no longer be in happy agreement with the starting standard convention as to 'second' or 'year' etc. Unless I can get you to see thsi DISCONNECT, and the CONFLATION you make regarding 'lived through' (an EXTERNALITY data set) and 'aged through' (an INTERNALITY) data set, then you will continue to have the confusion problem.

So, you are claiming the two twins lived the same number of earth orbits but the moving twin is younger.

How do you work that out?

Exactly! You got it, mate! That is...

The EXTERNALITY data set (ie, they both LIVED/WITNESSED) is readily AGREED to be 12 Earth-sun orbit 'years'; while their RESPECTIVE INTERNALITIES data set (ie, they/clocks AGED/TICKED) is DISAGREED upon because their respective cumulative counts/aging is DIFFERENT even though their externalities agree! Hence they will make the necessary adjustments to their RESPECTIVE INTERNALITIES data sets, and so come up with the conclusions/interpretations which make sense when compared to their COMMON EXTERNALITY data set (ie, 12 Earth 'years' elapsed externally while internally a certain amount of ticking/aging went on which is causally disconnected and only connected when the two observers make the necessary bridging insights/allowances which recognize the INTERNAL/EXTERNAL differences built into the data sets in the 'experiment/analysis'.


Back tomorrow if I can. Meanwhile I hope the subtle aspects causing the problems are now clearer to both arfa and you, chinglu? Bye all.

 

[arfa brane]

There is no actual causal connection between the astronomical cycle and the clock tick/count, as can be readily seen when the TRAVELING twin clock ticks at a DIFFERENT RATE of ticks and accumulates a DIFFERENT absolute cumulative tick 'count' number than the stay-put twin's clock. That is the subtlety which is at the center of the confusion right from the start of this discussion/analysis.

No, look, you seem to have misunderstood what I've been saying to chinglu.

You are correct that there is no causal connection between any astronomical cycle and a clock tick rate, the connection is that both are clocks. The only requirement for a system to be a clock is that it exhibit regular periodic motion. To be relevant to the twin paradox, it will need a period that is sufficiently small, such that two values can be compared when the traveling twin returns.

In fact, if the traveling twin can observe the earth's motion, then he has a clock which is identical to the stationary twin's clock, which is the periodic motion of the earth. That's all they need to compare.
The traveler will report that they measured the same number of orbits, but that the earth wasn't orbiting at a constant rate, assuming they can determine the earth's velocity, which isn't too far away from determining its position, which is required so that you can count the number of orbits.

 

[BdS]

There is a clock that ticks off years, it's the earth orbiting the sun.

You are correct that there is no causal connection between any astronomical cycle and a clock tick rate, the connection is that both are clocks. The only requirement for a system to be a clock is that it exhibit regular periodic motion.

In fact, if the traveling twin can observe the earth's motion, then he has a clock which is identical to the stationary twin's clock, which is the periodic motion of the earth. That's all they need to compare.

If the earth was orbiting and spinning in the opposite direction then time would be going backwards? obviously time is not going backwards in that case... If the planet was traveling in the opposite direction we would still be getting older not younger. Can you see why cosmic cycles/motion is not a valid clock yet? Things moving in the universe do show time is progressing, but if time was only motion on the cosmic scale then you need to explain why the direction of motion on the cosmic scale doesn't make time go backwards and forwards. Why dont I get younger if I travel in the opposite direction to the earth? IMO thats exactly the type of logic used and why the the SI system was invented and preferred...

 

[arfa brane]

Can you see why cosmic cycles/motion is not a valid clock yet?

If it is a cycle then it can be a clock. The orbit of our sun around the galactic centre is an example of periodic motion, so that means it's a clock. A clock is just a device that we use to count the periods in periodic motion. An atomic clock does that too.
And, you know, you use a period or interval of time so it's relevant to the system of interest. The second is an anthropocentric unit of time, that's all it is.

Otherwise your argument about time not going backwards seems a bit irrelevant.

 

[BdS]

If it is a cycle then it can be a clock. The orbit of our sun around the galactic centre is an example of periodic motion, so that means it's a clock. A clock is just a device that we use to count the periods in periodic motion.

The problem is that you are only considering time on the cosmic scaled motion and not taking into account the motion on the atomic scale. You saying the earth motion clock is ticking at distance, but what about the motion of things in the matter? Because things can move at a constant speed in the cosmic scale, but at the same time vary on the atomic scale.

An atomic clock does that too.

Yes, but its based off atomic events not on cosmic events.

The second is an anthropocentric unit of time, that's all it is.

Yes your cosmic motion is just that, but the atomic clocks isnt.

And, you know, you use a period or interval of time so it's relevant to the system of interest.

Your cosmic motion clock isnt taking into account whats going on at the atomic scale and thats why its flawed and an archaic way of measuring time.

Otherwise your argument about time not going backwards seems a bit irrelevant.

No its not! if you say time is only motion or can be measured accurately by motions/cycles on only the cosmic scale then its very relevant.

 

[arfa brane]

The problem is that you are only considering time on the cosmic scaled motion and not taking into account the motion on the atomic scale.

No, the problem is that you've completely misunderstood what I've said to you.

 

[origin]

No one is disputing your analysis of the number of seconds ticked off by the clocks at the respective frames.

But, the number of ticked seconds in the earth frame matches the earth orbits.

The number of seconds in the moving frame does not match the number of seconds for earth orbits.

Almost! The number of seconds in the moving frame does not match the number of seconds [as measured on earth] for earth orbits.

Who cares?

Both twins lived 12 earth orbits.

Correct.

Now, because the moving twin's clock registered a different number of seconds that does not match the number of earth orbits, does that mean he did not live the same number of earth orbits as the stay at home twin?

No, you were right in the previous sentence - both twins lived 12 earth orbits.

So, you are claiming the two twins lived the same number of earth orbits but the moving twin is younger.

Yes! Hooray you get it!!

How do you work that out?

With RELATIVITY! You should try learning a little bit about it.

 

[(Q)]

What truth are you trying to claim?

Are you claiming the traveling twin witnessed 12 earth years and his clock contradicts him and claimed he only witnessed 10 years?

That is crackpottery.

Has anyone noticed chinglu is simply repeating the same thing over and over and over? Is there any reason to continue responding?

 

[paddoboy]

____________________________________________________________________________________________________________________________________
Otherwise your argument about time not going backwards seems a bit irrelevant.
___________________________________________________________________________________________________________________________________

No its not! if you say time is only motion or can be measured accurately by motions/cycles on only the cosmic scale then its very relevant.

I totally agree...great analogy!