# Standard SRT problem need a standard SRT solution.

Discussion in 'Physics & Math' started by Quantum Quack, Mar 26, 2005.

1. ### Quantum QuackLife's a tease...Valued Senior Member

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The first thing I would Like to do in this thread is clarify the question that needs the provision of an answer.

It, I believe is a common question about SRT especially regards time dilations and RF that seem to end up with more than one tick rate.

Standard SRT puzzle:

Clock A see's clock B fly away at velocity and return showing an accumulated elapsed time of 8 units. A's clock shows 10 units.

A = 10
B= 8

Simultaneously
Clock B see's clock A fly away at velocity and return showing an accumulated time of 8 units. B's clock shows 10 units.

B= 10
A= 8

Regardless of who did the flying when we compare clocks as a single RF [relative v=0] we have
Clock A = 10 and 8 units of accumulated time.
Clock B = 8 and 10 units of accumulated time.

1] How is this question best described in the proper lingo?
2] What is the best way of solving this question?

To answer by saying that the question is invalid is not a valid answer....

N.B. I am not arguing issues of SRT validity. I simply wish to know how SRT would answer the question. So that in future when this question comes up again [and I am sure it will] there is a straight forward answer to provide.

Last edited: Mar 26, 2005

3. ### 2inquisitiveThe Devil is in the detailsRegistered Senior Member

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"How is this question best described in the proper lingo?"

It's called the Twin Paradox. I think it has been discussed a time or two before in

5. ### superluminalI am MalcomRValued Senior Member

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It all depends on who shifts between frames. Who accelerated away from who? It's very simple. He who takes action to shift from one frame to the other shows net time loss.

A sees B running slow. B sees A running equally slow. Either A or B must accelerate/decelerate to "get back together" in the same frame. If A accelerates, he is transforming frames and will show 8 while B shows 10. If B accelerates, B shows 8, A shows 10. If both accelerate equally, both show 10.

And yes, this "so called" paradox has been explained a million times. It's only a paradox to those who haven't seen the correct resolution yet.

7. ### Quantum QuackLife's a tease...Valued Senior Member

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by 2inq.
by SL,
.

Ok, OK I see, it is the Twin Paradox afterall.

So you would say SL that if a novice came up to you and started going on about the scenario I posed above that mentioning accel and de-accell would way lay the initial concerns and at least point the quester in useful direction?

Would it be far to state that in all situation that require accel and de-accel the symmetry of the problem is broken?

8. ### superluminalI am MalcomRValued Senior Member

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Yes. Of course symmetrical accel/decel results in no time difference. Acceleration in itself does not affect the degree of dilation. Numerous experiments show this. However, in this universe, it requires acceleration to shift frames.

9. ### Quantum QuackLife's a tease...Valued Senior Member

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Now I have my son sitting next to me as I type this and his question as a novice is an obvious one.

Why wouldn't acceleration be seen by both frames? Why does accel break symmetry? and so on.

this obviously comes down to the question:
If A see's B accelerate away shouldn't B see A as doing the same thing?

Why is accel treated differently to ordinary constant velocity in regared to symmetry?

10. ### superluminalI am MalcomRValued Senior Member

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Yes, both see each other move away. But one has to fire the engines, batten down the hatches, and gets smushed into their seats by G forces. HE has shifted his spacetime/frame context. The other guy just relaxes and watches.

11. ### superluminalI am MalcomRValued Senior Member

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As to why? It's the nature of the universe. People who add speed to themselves are shifting in spacetime, asymetrically to observers who don't.

Nothing in SRT says you can't or don't know who changes frames.

Last edited: Mar 26, 2005
12. ### Quantum QuackLife's a tease...Valued Senior Member

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Ahhh...now we are getting to the nitty gritty......ha...thanks

"shifting in space time asymmetrically"

So for now my son has much to ponder on......and rest assured he says "I'll be back" [in his fav Arney accent]

13. ### superluminalI am MalcomRValued Senior Member

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Cool. The whole problem here, as I see it QQ, is that something happens when an object gains speed. What that is, is a fundamental part of the behavior of the universe. The results are proven (despite claims to the contrary). But it really irks some folks that the "thing that happens" is not intuitively obvious.

14. ### Quantum QuackLife's a tease...Valued Senior Member

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SL, as you know form my other threads on space time and gravitational paradoxs and ....and....and.....so on.....that I believe it will all come down to our understadning of the nature of that space time and most importantly the relationship between time and energy, with in that volume of space.

I might add that I don't use the word paradox in a sense of conflict but in a sense of a lack of understanding. As I see paradoxes as being just that. Something that we have yet to learn.

When an object is accelerated it is in some way changed with regards to the space time it existed in prior.

My current thoughts on the subject are that because we change at the rate of 'c' acceleration requires dilation so that this change rate is maintained as 'c'
Even though the velocity has appeared to increase the overall net velocity is in fact the same. The space time state is all that has changed thus the illusion of movement [velocity] is given.

Any way this is off topic and still the subject of rigourous scrutiny.

SL, I get the impression that it takes GR to deal with this asymmetrical change in space time. Is this impression correct? [ I know so little about GR so please excuse the naivety of the question.]

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16. ### Quantum QuackLife's a tease...Valued Senior Member

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the answer is yes, It takes GR to deal with accel and deaccel....phases of the twin paradox......hmmmmm...thanks for the link.

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18. ### Quantum QuackLife's a tease...Valued Senior Member

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Philosophically I see no distinction between spacetime and mass. Hence my thoughts on the subject appear at odds.....ohhh...well......

19. ### superluminalI am MalcomRValued Senior Member

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OK. It appears there are two ways to approach it...

20. ### Quantum QuackLife's a tease...Valued Senior Member

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[quoted from the later link provided]

Ha...I see we have a paradox between two resources. One is "ney" the other is "yey".....to me it isn't an importance as I understand niether at the depth required.

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Right.

22. ### superluminalI am MalcomRValued Senior Member

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You know what's missing in all of this? Our own fleet of private sports-spacecraft that can accelerate up to near c. We could fly off and make all the measurements we want...

23. ### Quantum QuackLife's a tease...Valued Senior Member

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what you have to do SL is not accelerate your self but deaccelerate the universe, that way you stay at 'c' and everything else slows down.....ha...

Actually there is an element of seriousness in the above comment....