Special Relativity Andromeda galaxy Question

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Homework Help Overview

The discussion revolves around a problem in special relativity involving the Andromeda galaxy, which is two million light-years away from Earth. The original poster considers a scenario where a spaceship travels to Andromeda in 50 years as measured on the ship, and they seek to determine how long it would take for a radio message sent back to Earth to arrive, according to observers on Earth.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning, Problem interpretation, Assumption checking

Approaches and Questions Raised

  • Participants discuss the impossibility of the spaceship traveling faster than light, questioning the original poster's calculation of the spaceship's speed as 40000c. There are inquiries about the methods used to derive this speed and the implications of time dilation as described by special relativity.

Discussion Status

Participants are actively engaging with the problem, offering guidance on using Lorentz transformations and questioning the assumptions made by the original poster. Some express confusion about the equations involved and seek alternative methods to approach the problem without using Lorentz transformations. The discussion reflects a mix of interpretations and attempts to clarify the concepts involved.

Contextual Notes

There is mention of the original poster's struggle with the equations of special relativity, indicating a potential gap in their learning. The conversation also highlights the constraints of the problem, such as the requirement to consider the perspective of different observers and the implications of time dilation.

  • #31
robphy said:
Think "triangles"... legs as spatial and temporal components, hypotenuses as the invariant spacetime-intervals. You can write down an explicit algebraic answer in terms of your given quantities... without first explicitly calculating the outgoing velocity of the traveller.

Oh, of course, I see it now. I could've used that trick on the GRE ;)
 

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