Gravitational red shift question

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Homework Help Overview

The discussion revolves around the concept of gravitational redshift, specifically addressing why the frequency of a photon decreases as it moves away from a star. Participants are exploring the implications of gravitational potential and energy conservation in this context.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants are attempting to understand the relationship between the frequency of photons and gravitational effects, questioning the implications of the equation provided and the conservation of energy in a gravitational field.

Discussion Status

The discussion is ongoing, with participants expressing uncertainty about the mathematical representation of the phenomenon and seeking clarification on the underlying concepts. There is no explicit consensus yet, but some productive lines of reasoning are being explored.

Contextual Notes

Some participants note confusion regarding the equation's implications and the relationship between kinetic and potential energy as the photon escapes the gravitational field of the star.

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Why does the frequency of a photon emitted from the surface of a star decrease as it moves away from the star?
if hf`=hf(1-GM/(R*c^2)
then as the distance becomes larger, R becomes larger, so f`becomes smaller?
 
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We use the fact that the total energy must remain constant.
I'm not 100% sure, but I think t hat when leaving the star, the photon has to get out of the gravitation-field of the star, therefore its kinetic energy has to decrease since the potential energy is rising.
 
hmm... that makes sense, but the mathematical equation looks weird...
it seems to say otherwise~
 
still a little weird~
 

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