How Far Are the Cosmic Ray and Photon at t=0s According to the Observer?

AI Thread Summary
The discussion centers on calculating the distance between a cosmic ray and a photon at t=0s as observed from a specific point in the Milky Way. It is noted that the cosmic ray has a gamma factor of 10^10, and the photon passes the observer at t2=1.33x10^-8 seconds. Participants express confusion about the application of special relativity, suggesting that the distance can simply be calculated as ct2, given the observer's perspective. However, it is acknowledged that while relativity may not be necessary for this specific calculation, subsequent parts of the problem may involve relativistic effects due to the galaxy's movement. The conversation highlights the importance of understanding both classical and relativistic concepts in astrophysical scenarios.
roman15
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Homework Statement


A cosmic ray of gamma=10^10 is chased across the Milky Way by a photon. The cosmic ray passes an Observer at one edge of the galaxy and t=0s then the photon passes at t2=1.33x10^-8. These times are recorded by the Observer
How far away are the cosmic ray and photon at t=0s according to the observer?


Homework Equations





The Attempt at a Solution


Im not really seeing how to apply special relativity to this, wouldn't the distance between them just be ct2, because its asking according to the observer and from t=0 to t2, the distance traveled by the photon in that time would be the distance between them right?
 
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roman15 said:
Im not really seeing how to apply special relativity to this, wouldn't the distance between them just be ct2, because its asking according to the observer and from t=0 to t2, the distance traveled by the photon in that time would be the distance between them right?
Right. Relativity is not needed to answer this question. (I suspect that there are followup questions that might require special relativity.)
 
Doc Al said:
Right. Relativity is not needed to answer this question. (I suspect that there are followup questions that might require special relativity.)

haha you there are, the next couple of parts of the question deal with the galaxy moving relative to the cosmic ray
 

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