A problem regarding time dilation

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Discussion Overview

The discussion revolves around a problem involving time dilation as experienced by two spacecraft, one moving with simple harmonic motion and the other at constant speed. Participants explore the implications of their respective motions on the aging of individuals aboard the spacecraft when they meet after a certain time.

Discussion Character

  • Exploratory
  • Mathematical reasoning

Main Points Raised

  • One participant describes the scenario involving two spacecraft and poses questions about the differences in aging between individuals aboard them after a specified time.
  • Another participant suggests using a space-time diagram to visualize the world lines of the spacecraft and rockets, indicating that the aging difference can be calculated using the spacetime distance along their worldlines.
  • A later reply reiterates the importance of the space-time diagram and mentions a specific formula for calculating age differences along straight segments of the worldlines.
  • One participant inquires whether the age of a person in spacecraft 2 would differ from that of a person in the rocket if both have the same velocity, asking for clarification on the factor by which their ages would differ.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the specific outcomes of the aging differences, and multiple viewpoints regarding the calculations and implications of the scenario remain present.

Contextual Notes

Participants mention the need for visual aids and mathematical calculations, but the discussion does not resolve the assumptions or conditions under which the aging differences would be calculated.

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two spacecraft s travel parallel to each other along straight lines AB and CD as shown in the picture here ...
while s1 moves with a simple harmonic motion , s2 moves with a constant speed and only at points A and B it gets enough thrust within a very negligible time to reverse its direction of velocity ...
s1 and s2 travel the same AB=CD distance after a same amount of time ..
now both of the spacecraft s fire rockets R1 and R2 at the same time from points D and B respectively and they come back after time t .
now if S1,R1, S2,R2 carry 4 persons of the same age then after time t when they meet
1. what will be the difference between their ages ?
2. on what condition it is possible for all of them to have the same age when they meet ?
[ note: you can take v of S2 and f of S1 arbitrarily ]
answers with proper visualizing power will be appreciated ... mathematical analysis is also appreciated but not needed ...

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Draw a space-time diagram. Spaceship A's world line will be a sinusoidal curve, except oriented vertically instead of horizontally because the t axis is vertical. Spacecraft B's world line will be a zigzag line. The worldlines of the two rockets will be straight line segments, starting at the event where they're launched. The change of age of each person is given by the spacetime distance along their worldline between the starting point and the end point.

That's your visualization tool. To actually calculate the changes in age, you'll need to do a (straightforward) line integral to calculate the change of age along the sinusoidal world line. For the straight segments, we don't need the calculus - ##\Delta{\tau}=\sqrt{\Delta{t}^2-\Delta{x}^2}## will do the trick.
 
Nugatory said:
Draw a space-time diagram. Spaceship A's world line will be a sinusoidal curve, except oriented vertically instead of horizontally because the t axis is vertical. Spacecraft B's world line will be a zigzag line. The worldlines of the two rockets will be straight line segments, starting at the event where they're launched. The change of age of each person is given by the spacetime distance along their worldline between the starting point and the end point.

That's your visualization tool. To actually calculate the changes in age, you'll need to do a (straightforward) line integral to calculate the change of age along the sinusoidal world line. For the straight segments, we don't need the calculus - ##\Delta{\tau}=\sqrt{\Delta{t}^2-\Delta{x}^2}## will do the trick.
thanks .. that was helpful ... i also want to know if the spacecraft 2 has the same velocity as the rocket will the age of the man in in the spacecraft and the man in the rocket differ ? if it does then by what factor ?
 
Draw your spacetime diagram, label the end points of the relevant line segments, calculate the amount of aging on each path... And let us know what you find.
 

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