Where did the energy of red shifted CMB go?

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SUMMARY

The discussion centers on the conservation of energy in the context of the Cosmic Microwave Background (CMB) and its redshift from gamma radiation to microwave radiation. Participants highlight that energy is not conserved in General Relativity, referencing Sean Carroll's blog post which explains that energy can be lost in dynamic spacetimes. The redshift phenomenon does not imply that energy is merely transformed; rather, it indicates that energy can dissipate without a corresponding increase elsewhere. This challenges traditional notions of energy conservation in cosmological contexts.

PREREQUISITES
  • Understanding of General Relativity principles
  • Familiarity with the Cosmic Microwave Background (CMB)
  • Knowledge of redshift and its implications in cosmology
  • Basic grasp of energy conservation laws in physics
NEXT STEPS
  • Read Sean Carroll's blog post on energy conservation in General Relativity
  • Explore the implications of redshift on cosmic expansion
  • Investigate the relationship between energy and spacetime dynamics
  • Study the properties and significance of the Cosmic Microwave Background
USEFUL FOR

Astronomers, physicists, cosmologists, and students interested in the implications of General Relativity on energy conservation and the behavior of the universe.

1832vin
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i know it sounds stupid, but i can't seem to find an answer to it

where did the energy went? you can't just just destroy energy, but when you red shift a gamma CMB into a microwave CMB, the energy has go to go somewhere...?
it's not like one gamma photo spitted into many microwave, cause that would make CMB not very smooth

i mean, I've just got no clue, normally, when red shift is from an object, you can say that momenta is given to the object receding or something, but you can't really give energy to space and expect it to do nothing...?
and according to my very rudimentary calculations with a lot of assumptions, the amount of energy lost would still, be not enough to expand space at all, so if it's not expanding space, where did the energy go?

thankyou
 
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In general energy is not conserved in General Relativity. So the energy is simply lost.
 

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