Special Relativity: Time dilation

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Homework Help Overview

The discussion revolves around conceptual questions related to time dilation in the context of special relativity, specifically examining the perspectives of observers on a spaceship and on Earth as the spaceship travels to a distant star.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants explore the reasoning behind the differences in perceived travel time between the spaceship observer and the Earth observer, questioning how time dilation and length contraction affect their observations.

Discussion Status

Some participants have offered hints regarding the relativity of simultaneity and suggested analyzing the journey from the spaceship's reference frame, indicating a productive direction in the discussion. There is an acknowledgment of the need for clarity on the concept of proper time.

Contextual Notes

Participants reference the need for multiple clocks to analyze the situation accurately, highlighting the complexity of simultaneity in different reference frames.

ntknow
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Hello. This is not a concrete problem, rather conceptual question.

Homework Statement


2. Homework Equations
3. The Attempt at a Solution [/B]
Spaceship with speed v with respect to the Earth is traveling from the Earth to say some distant star, which is distant L apart from the Earth looking by observer who is in the Earth frame. Analysis from both observers point of view:
Earth observer:
observes that spaceship travels the distance in time T1 = L/v. In addition to that, he observes that clock in the spaceship during the travel advances by T0=T1/ ɣ, i.e. less than his clock.

Spaceship observer:
by relativity he sees that the Earth observer's clock is ticking slower than his clock, however, by above argument total travel time in his frame is smaller than in the Earth frame. Additional facts are that he observes length, L, contracted and time reading difference between clock in the Earth and clock, for example, in the star.

Problem for me:
Could someone summarise / make me clear / point out flaws in the reasoning why total travel time is still smaller as observed by spaceship observer than by the Earth observer if spaceship observer during all the time then Earth gets farther from him sees the Earth observer's clock running slower?
 
Last edited:
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ntknow said:
Hello. This is not a concrete problem, rather conceptual question.

Homework Statement


2. Homework Equations
3. The Attempt at a Solution [/B]
Spaceship with speed v with respect to the Earth is traveling from the Earth to say some distant star, which is distant L apart from the Earth looking by observer who is in the Earth frame. Analysis from both observers point of view:
Earth observer:
observes that spaceship travels the distance in time T1 = L/v. In addition to that, he observes that clock in the spaceship during the travel advances by T0=T1/ ɣ, i.e. less than his clock.

Spaceship observer:
by relativity he sees that the Earth observer's clock is ticking slower than his clock, however, by above argument total travel time in his frame is smaller than in the Earth frame. Additional facts are that he observes length, L, contracted and time reading difference between clock in the Earth and clock, for example, in the star.

Problem for me:
Could someone summarise / make me clear / point out flaws in the reasoning why total travel time is still smaller as observed by spaceship observer than by the Earth observer if spaceship observer during all the time then Earth gets farther from him sees the Earth observer's clock running slower?

Have you covered the "relativity of simultaneity" or the "leading clocks lag" concept yet?
 
PeroK said:
Have you covered the "relativity of simultaneity" or the "leading clocks lag" concept yet?

Yes, I am familiar with these concepts.
 
ntknow said:
Yes, I am familiar with these concepts.

Can you analyse the journey from the ship's RF? Hint: you need three clocks. Two "rest" clocks: one on Earth and one at the distant star. And one clock moving with the ship.
 
.
 
Last edited:
Restating PeroK's comment: Proper time is measured by a single clock in a single place.
Only the clock on the spaceship (in the frame of) meets this requirement.
 

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