Discussion Overview
The discussion revolves around the behavior of photon energy in the context of an expanding Universe, particularly focusing on the implications of redshift and energy conservation. Participants explore the relationship between photon energy, frequency, and wavelength as the Universe expands, raising questions about where the energy of individual photons goes during this process.
Discussion Character
- Exploratory
- Debate/contested
- Conceptual clarification
Main Points Raised
- Some participants note that as the Universe expands, the temperature decreases, leading to the cooling of the microwave background radiation.
- It is proposed that the energy of a photon, defined by E=hf, decreases due to an increase in wavelength caused by the expansion of spacetime, which reduces its frequency.
- One participant questions where the energy of the photon goes as it redshifts, suggesting that the overall amount of energy decreases without the creation of new photons.
- Another participant mentions a concept that the momentum and energy of photons decay into wavelength and wavetime, seeking a simpler explanation for this phenomenon.
- A later reply attempts to clarify that the redshift is a result of the expanding metric of spacetime and does not imply that the photon itself does anything to spacetime.
- One participant draws an analogy with a rubber band to illustrate how energy can appear to change without actually being lost, suggesting a parallel to the behavior of photons in an expanding Universe.
Areas of Agreement / Disagreement
Participants express uncertainty regarding the fate of photon energy during redshift, with no consensus reached on the mechanisms involved or the implications for energy conservation in the context of the expanding Universe.
Contextual Notes
Some discussions involve assumptions about energy conservation and the nature of spacetime, which remain unresolved. The complexity of the topic may pose challenges for non-physicists in grasping the underlying physics.