Calculating Arrival Time Difference for Particles Produced in a Distant Galaxy

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Discussion Overview

The discussion revolves around calculating the difference in arrival time between a photon and a particle with mass produced simultaneously in a distant galaxy, specifically focusing on the implications of their energies and relativistic effects. The scope includes theoretical considerations and mathematical reasoning related to special relativity.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant questions whether the energy of the photon is relevant, suggesting it may be a distraction since it travels at the speed of light.
  • Another participant asserts that the photon will arrive in exactly 150,000 years, implying that the mass of the particle affects its travel time.
  • A different participant emphasizes the need for the relativistic energy formula and clarifies that the rest mass of the particle must be considered.
  • One participant mentions the gamma factor, suggesting it can be used to determine the velocity of the particle, which is necessary for calculating its arrival time.
  • A later reply seeks clarification on how the gamma factor of 1000 was determined, indicating a need for further explanation of the calculations involved.

Areas of Agreement / Disagreement

Participants express differing views on the relevance of the photon's energy and the necessary calculations for the massive particle's arrival time. The discussion remains unresolved regarding the exact implications of these factors.

Contextual Notes

There is uncertainty regarding whether the mass provided is rest mass or another form, which may affect the calculations. Additionally, the discussion does not resolve how the gamma factor was derived or its implications for the particle's velocity.

babtridge
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Maybe its because my exams are close and I'm starting to panic but there is a question that has been bustin' my balls all day and was hoping any of you could help...

A particle with mass 10eV and a photon are produced simultaneously in a galaxy 150,000 light yrs away. The energy for both particles is 10MeV. Estimate the difference in arrival time between the particles.

My question really is: Is the energy for the photon a red herring because surely this travels at speed c and you don't need this info?!

Thanks in advance people cleverer than me
 
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So the photon has 10MeV (ignoring GR effects),and that is not a useful piece of information.It should arrive in exactly 150,000 years.

What about the electron...?The time that is needed is in the Earth's reference frame...

Daniel.
 
you are going to need the relativistic formula for energy. you know, the Einstein-formula(E² =p²c² + m²c^4). Also be sure to know wether the given mass is restmass or not...

For a photon E =pc since the restmass is ZERO

marlon
 
You needn't momentum & stuff.

The gamma factor is 1000.That should give you the velocity,which is all u need.

Daniel.
 
cheers for your help guys.
Once again much appreciated
 
dextercioby said: "The gamma factor is 1000."

How do you get that?
 

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