Energy Change Due to Doppler Shift

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Discussion Overview

The discussion revolves around the energy change of a photon due to gravitational redshift or blueshift, specifically questioning the source of this energy change within the context of gravitational fields.

Discussion Character

  • Exploratory, Conceptual clarification

Main Points Raised

  • One participant questions the origin of energy change in a photon that is gravitationally red or blue shifted.
  • Another participant proposes that the energy change comes from the potential energy of the system involving the photon and the object attracting it, suggesting a conservation of energy perspective.
  • A third participant draws an analogy with a ball dropped in a gravitational field, asking where the energy change comes from in that scenario as well.

Areas of Agreement / Disagreement

Participants express differing views on the source of energy change, with no consensus reached on the explanation for the energy dynamics involved.

Contextual Notes

The discussion does not resolve the assumptions regarding energy conservation principles or the specific definitions of energy in the context of gravitational interactions.

deadscientist
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Hello all, so let's suppose a photon is being gravitationally red or blue shifted changing its frequency which ultimately changes its energy, where does this energy change come from?
 
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I believe it's from the potential energy of the system. (Photon + object attracting it)
The photon gains energy and the system loses an equal amount of potential energy or vice versa.
 
Suppose a drop a ball in a gravitational field and it gains kinetic energy. Where does this energy change come from?
 
Thankyou all, answers were very helpful
 

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