Understanding Time Dilation: How Fast Do You Have to Go?

[Sam Woole]

Now we're getting somewhere. Editorially, it shouldn't have required 11 pages of discussion for you to just come out and say you assume time dilation doesn't exist. All that math and case studies are utterly useless if you just simply don't accept their validity. And I do consider that to be all you - you shouldn't have been arguing the case studies if you didn't accept the basis of them them in the first place! Your arguments made it seem like you were confused about how the cases worked, not that you simply didn't accept what they were saying. And in addition, many people have posted physical evidence and you have ignored it (such as in my previous post).
So... Well, you seem to have ignored all evidence posted so far... Could you comment on some of the evidence already posted? For example, my previous post, where I mentioned the GPS system? I just asked if you are aware of how the GPS system works - we can explain it to you if you need us to.

Okay, I am really sorry for all the mess. Please forgive me as you would do some other slow students. As to the GPS, I do not know a lot. It seemed there is plenty of information available on the internet. Just tell me how time dilation is applied to GPS because I have not found any (on the internet) to this effect.

I wish to point out, my reading of other dissident scientists showed, experiments (GPS included) claimed to be verifying the time dilation idea could be interpreted in different ways. In order to silence dissent, you should be able to show, time dilation is the only mechanism to make GPS work well, no other.

 

[Sam Woole]

You say you are a "non-believer in time dilation". Why do you continue to take part in this forum? If you genuinely want to understand relativity, you will eventually have to be persuaded to become a believer. You will never understand it if you persist in your non-belief as a matter of faith.

I became a non-believer after reading a lot about SR, not as a matter of faith. The reason for my taking part here was to test my belief. So far all your arguments have not persuded me to change my stand.

It didn't "become" 25 light-minutes because of time dilation. It always was a constant 25 light-minutes (according to Bob, and Ted, but not Alice).
The figure of 20 light-minutes that you calculated was incorrect because you obtained it by subtracting a time on Bob's clock from a time on Alice's clock. As I explained in the final paragraph of post #168, that is not a valid thing to do. All time intervals must be calculated using the same clock at the start and finish.

My disbelief became stronger as I continued finding that you were contradicting yourselves. The statements above was another example of contradiction. There you said "The figure of 20 light-minutes that you calculated was incorrect because you obtained it by subtracting a time on Bob's clock from a time on Alice's clock." No, I did not do that. Intead I was just repeating your words, such as: "So Bob’s clock looks to be 5 hours 20 minutes slow from Ted’s point of view. As Bob and Ted are a constant distance apart, this delay will be constant.", post #68. The "constant delay" you described here cannot be anything else but the "5 hours 20 minutes." It works out to be 20 light-minutes, not 25. It was you who did that kind of calculation, deducting the reading on one (Bob's) clock from the reading on another (Ted's) clock. Here you assumed that the two events (12:00 on one clock and 18:00 on another) happened simultaneously.
Again, in post #91, you gave these words:"Each row of this table represents a ray of light traveling from Bob to Ted. For example in the second row, a ray of light leaves Bob, at (a), at 12:10 Bob-time, passes Alice, at (d), at 12:15 Alice-time, and arrives at Ted, at (m), at 17:30 Ted-time. If you ignore Alice’s column and just look at the rays leaving Bob and arriving at Ted, each ray arrives at Ted(m) at a Ted-time that is 5h20m later than the Bob-time that it left Bob(a)." The table you referred:
Ted’s----------Ted’s--------Ted’s
view of own--view of------view of
clock----------Alice’s-------Bob’s
----------------clock---------clock
17:20(m)---12:00(a)-----12:00(a)
17:30(m)---12:15(d)-----12:10(a)
17:40(m)---12:30(g)-----12:20(a)
17:50(m)---12:45(j)------12:30(a)
18:00(m)---13:00(m)-----12:40(a).
Hence the words and numbers you used so far explicitly told unbelievers that the distance between Bob and Ted was constantly 20 light-minutes. I never calculated in the way you alleged. As a result of Alice's experience of the G-force, Bob's clock worked faster and accumulated more minutes than Alice's; and the distance became 25 light-minutes according to Bob's clock.
The return motion of Alice, the G-force she experineced, the Doppler effect, not only have caused Bob's clock work faster, but also have added a huge distance (5 light-minutes) to the original 20, according to your latest arguments. To SR dissidents, all this was physically impossible. Many of them charged that SR was a magic, intead of science.
You said "All time intervals must be calculated using the same clock at the start and finish." In order to do this kind of calculation, we should know the actual readings on the clock. But the 14:10 reading was a fictitious number created by another kind of calculation, the 3/2 rate. It was not an actual reading. I believe when we use fictitious readings to calculate time intervals, we get fictitious results, which cannot be believed.

 

[jackle]

...my reading of other dissident scientists showed, experiments (GPS included) claimed to be verifying the time dilation idea could be interpreted in different ways...

Do any of these "dissident scientists" have any credability at all in the scientific community? What is the reason for their status?

In order to silence dissent, you should be able to show, time dilation is the only mechanism to make GPS work well, no other.

You can't show that there is only one explanation for anything. It could be the fairies interferring. How can you show that it isn't Father Christmas behind it all? The point is that the other explanations are not good science.

My disbelief became stronger as I continued finding that you were contradicting yourselves...

I think you were finding contradictions that aren't there. When they are explained, you just find another. Do you think the established scientific community haven't thought about it properly?

The statements above was another example of contradiction.

I can see the pattern here. This will be explained to you in meticulous detail and you will find something else, or refuse to accept the answer.

<edit: Wrote this when I was a bit annoyed. No need to take it personally>

 

[robphy]

I became a non-believer after reading a lot about SR, not as a matter of faith.

An obvious follow-up question to your statement is
"What specifically have you been reading (title and author, please)?"

 

[JesseM]

I became a non-believer after reading a lot about SR, not as a matter of faith. The reason for my taking part here was to test my belief. So far all your arguments have not persuded me to change my stand.
My disbelief became stronger as I continued finding that you were contradicting yourselves. The statements above was another example of contradiction. There you said "The figure of 20 light-minutes that you calculated was incorrect because you obtained it by subtracting a time on Bob's clock from a time on Alice's clock." No, I did not do that. Intead I was just repeating your words, such as: "So Bob’s clock looks to be 5 hours 20 minutes slow from Ted’s point of view. As Bob and Ted are a constant distance apart, this delay will be constant.", post #68. The "constant delay" you described here cannot be anything else but the "5 hours 20 minutes." It works out to be 20 light-minutes, not 25. It was you who did that kind of calculation, deducting the reading on one (Bob's) clock from the reading on another (Ted's) clock. Here you assumed that the two events (12:00 on one clock and 18:00 on another) happened simultaneously.
Again, in post #91, you gave these words:"Each row of this table represents a ray of light traveling from Bob to Ted. For example in the second row, a ray of light leaves Bob, at (a), at 12:10 Bob-time, passes Alice, at (d), at 12:15 Alice-time, and arrives at Ted, at (m), at 17:30 Ted-time. If you ignore Alice’s column and just look at the rays leaving Bob and arriving at Ted, each ray arrives at Ted(m) at a Ted-time that is 5h20m later than the Bob-time that it left Bob(a)." The table you referred:
Ted’s----------Ted’s--------Ted’s
view of own--view of------view of
clock----------Alice’s-------Bob’s
----------------clock---------clock
17:20(m)---12:00(a)-----12:00(a)
17:30(m)---12:15(d)-----12:10(a)
17:40(m)---12:30(g)-----12:20(a)
17:50(m)---12:45(j)------12:30(a)
18:00(m)---13:00(m)-----12:40(a).
Hence the words and numbers you used so far explicitly told unbelievers that the distance between Bob and Ted was constantly 20 light-minutes. I never calculated in the way you alleged. As a result of Alice's experience of the G-force, Bob's clock worked faster and accumulated more minutes than Alice's; and the distance became 25 light-minutes according to Bob's clock.
The return motion of Alice, the G-force she experineced, the Doppler effect, not only have caused Bob's clock work faster, but also have added a huge distance (5 light-minutes) to the original 20, according to your latest arguments. To SR dissidents, all this was physically impossible. Many of them charged that SR was a magic, intead of science.
You said "All time intervals must be calculated using the same clock at the start and finish." In order to do this kind of calculation, we should know the actual readings on the clock. But the 14:10 reading was a fictitious number created by another kind of calculation, the 3/2 rate. It was not an actual reading. I believe when we use fictitious readings to calculate time intervals, we get fictitious results, which cannot be believed.

Sam, I just looked over the post mentioning Ted and I see that you are correct that Ted should be 25 light-minutes away from Bob, since he was supposed to be at the same position where Alice turned around. But what I don't understand is why you think there is a 20-minute light delay. Remember that Ted's clock was not synchronized with Bob's in the first place. So if Ted sees Bob's clock to be 5 hours 20 minutes behind his own, and he knows the light takes 25 minutes to pass between them, then he knows Bob's clock is really only 4 hours 55 minutes behind his own in their mutual rest frame. This has nothing to do with time dilation or relativity, it's just two clocks which are running at the same speed but which are out-of-sync, just like if I came from another time zone to visit you and forgot to reset my watch, we'd see that are watches displayed different times when we held them up next to each other. And there's nothing that says Bob and Ted's clocks must be out-of-sync by an exact hour amount.

Where in DrGreg's posts do you think he indicates that the light-delay between Bob and Ted is 20 minutes? Or if he doesn't say so explicitly, what lead you to infer this?

 

[DrGreg]

I became a non-believer after reading a lot about SR, not as a matter of faith. The reason for my taking part here was to test my belief. So far all your arguments have not persuded me to change my stand.

Logically there are 3 views of time dilation you can take:

1. You can take the positive view that it is true
2. You can take the negative view that it is false
3. You can take the neutral view that it might be true or false

The logic of my argument in this thread has been to show that if you begin with the neutral view, the demonstration should convince you, by the end, to take the positive view.

However, if you begin by taking the negative view, then, frankly, nothing is going to change your mind. Yes, you will find contradictions, but the contradictions are not between the parts of my argument. The contradictions are between my argument and your assumptions.

If time dilation is true, it must mean that clocks that were once synchronised do not remain synchronised. Your attacks on my argument rely (whether you realize it or not) on an implicit assumption that clocks do remain synchronised.

As this argument has been going round in circles for a long time, I see no point in continuing along this road. I think it would be good for you to follow the advice in post 175 and look at this from another angle.

As for GPS, I just searched this forum for “GPS dilation” and found https://www.physicsforums.com/showthread.php?t=87010", for example, and many more. I’m sure other readers may be able to quote better references.

For a whole list of various experimental evidence look at this thread: Experimental support for SR & GR.

 

[EngineeredVision]

Potential Solution

I first want to apologize that I have not yet read all the posts throughout this thread. However, I believe that I may be able to provide a way to add a visualized approach to this subject. Until just today, I myself was having difficulty entirely grasping relativity, especially SR and how simultaneity and time dilation occured.

Being a technical artist and animator with access to advanced 3d modeling and animation programs I decided to create some visual simulations that would help illustrate how simultaneity and time dilation operate. I've had many intelligent individuals attempt to explain how SR works in the past, yet never fully understood it. Words and even mathematical expressions and equations aren't enough sometimes. A picture is worth a thousand words, and an animaiton is worth even more. Upon viewing the animations that I created the relationships jumped out at me eliminating my previous doubts about the concepts of relativity.

Anyway, if members here believed that there would be enough of a use for animations such as these then I might be willing to improve them and make them presentable in a pre-rendered avi or mov format. Unfortunately, I'm currently without webspace so I don't have anywhere where I could upload the animations, but if there is a significant demand for these type of visual tools/simulations then I'll try to make something happen.

Sometimes, seeing really is believing.

 

[russ_watters]

Okay, I am really sorry for all the mess. Please forgive me as you would do some other slow students. As to the GPS, I do not know a lot. It seemed there is plenty of information available on the internet. Just tell me how time dilation is applied to GPS because I have not found any (on the internet) to this effect.

Then you must not have looked, because there is tons of material out there (some already linked). The gist of it is that the clocks on GPS satellites are adjusted prior to launch to run at a different rate than identical clocks on earth. After launch, they stay in sync with clocks on the ground, to within a very high degree of precision.

I wish to point out, my reading of other dissident scientists showed, experiments (GPS included) claimed to be verifying the time dilation idea could be interpreted in different ways. In order to silence dissent, you should be able to show, time dilation is the only mechanism to make GPS work well, no other.

This absurd request highlights that you really do have a strong faith-based belief that time dilation isn't real. Unless you start taking an honest and open-minded view of the subject, you will never understand it.

Sam, try this on: using the assumption that you are wrong, prove to us that you are right!

 

[Sam Woole]

As this argument has been going round in circles for a long time, I see no point in continuing along this road. I think it would be good for you to follow the advice in post 175 and look at this from another angle.
As for GPS, I just searched this forum for “GPS dilation” and found https://www.physicsforums.com/showthread.php?t=87010", for example, and many more. I’m sure other readers may be able to quote better references.
For a whole list of various experimental evidence look at this thread: Experimental support for SR & GR.

Thank you DrGreg for the links to the GPS and other evidence material. I shall take a good look at them and see whether I can be convinced. Regardless whatever may be the outcome, my scope of view will no doubt become wider.

My thanks also go to everybody else who have taken part in this thread such as Doc Al, JesseM and russ-waters, etc.

Wishing to see you again after I have digest all the material.

Sam.

 

[jackle]

...if members here believed that there would be enough of a use for animations such as these then I might be willing to improve them and make them presentable in a pre-rendered avi or mov format...

I'd be very interested to view your work. Unfortunately, I don't have any free time to contribute to your project.

 

[FX89]

I don't know how you got that conclusion from my words. What I said was: "The two twins don't disagree about what the other twin's clock reads--the traveling twin agrees that 3.944 years have passed on the earth-twin's clock, and the earth-twin agrees that 1 year has passed on the traveling twin's clock." So if they departed at the age of n, this sentence tells you that the traveling twin would agree that the earth-twin was n+3.944, and the earth-twin would agree that the traveling twin was n+1.

I can see this post is more than an year old and probably abandoned, but if by any chance the people that were posting here managed to travel forth through time and see this reply, i was wondering:

1) why do they have to be tweens?

2) (more serious mather) can anyone explain why this phenomena is occurring? Or is it just measured in clock ticks?


I'd be greateful to anyone who answered this post. (preferable during this lifetime as i don't yet understand what makes time travel possible)

 

[pervect]

How about starting a new thread with a self-contained question? This thread is too long (and too argumentative) for me to want to wade through it - at least that's my opinion.

 

[owenhbrown]

I have a problem more related to GR.

I read that if you have a stop-watch on the ground and another on a very high tower the one at the top, from the perspective of an observer on the ground, would move slower.

I can deal with that.

But then I read, I think, that if the stopwatch was brought down from the tower the two stop-watches would be in unision, reading the same time...

Now did I read this wrong? That just doesn't make sense to me... Is this example true?

I would imagine that the stop-watch on the tower, when brought back to Earth, should be BEHIND the time of the stop-watch at the bottom.

Please clarify...

 

[Ich]

I read that if you have a stop-watch on the ground and another on a very high tower the one at the top, from the perspective of an observer on the ground, would move slower.

It would tick faster.

But then I read, I think, that if the stopwatch was brought down from the tower the two stop-watches would be in unision, reading the same time...

Now did I read this wrong?

You probably read this wrong.

I would imagine that the stop-watch on the tower, when brought back to Earth, should be BEHIND the time of the stop-watch at the bottom.

Yes, but it would be ahead, not behind.

 

[owenhbrown]

Ok thanks... that all makes sense to me... Now I feel like reading more =)

 

[bydavies]

With all the material I have read about time dialatiion, I have learned that the only effect is the illusion the observer sees and there is no physical time difference once the object traveling and the observer are brought together.

There's a nice demonstration here http://uk.youtube.com/watch?v=KHjpBjgIMVk, which explains the theory in ways that even I could understand.

 

[Doc Al]

With all the material I have read about time dialatiion, I have learned that the only effect is the illusion the observer sees and there is no physical time difference once the object traveling and the observer are brought together.

Read up on the "Twin Paradox"; the time difference when the twins reunite is quite real.

There's a nice demonstration here http://uk.youtube.com/watch?v=KHjpBjgIMVk, which explains the theory in ways that even I could understand.

That's just an illustration of time dilation. Note that the ship and the Earth observers never get to reunite and compare clocks.

 

[owenhbrown]

You see what I mean now? ByDavies brought up the exact point that made me want to never try to understand time dilation - the suggestion that the clock moving faster at the top of the tower is only an illusion and no difference would be observable when the clocks are brought together again.

How does the act of bringing the clock back to Earth suddenly make the time go back to normal, Earth time?

 

[JesseM]

You see what I mean now? ByDavies brought up the exact point that made me want to never try to understand time dilation - the suggestion that the clock moving faster at the top of the tower is only an illusion and no difference would be observable when the clocks are brought together again.

But as pervect pointed out, bydavies was wrong--"the time difference when the twins reunite is quite real."