CMBR and the expansion history of the Universe

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SUMMARY

The Cosmic Microwave Background Radiation (CMBR) provides a snapshot of the universe at the time of last scattering, capturing the state of the universe but not the specifics of its expansion history. While the redshift of the CMBR contains information about the total amount of expansion since that time, it does not detail how that expansion occurred. This understanding parallels the observation of redshifted galaxies, where the emitted light reflects the state of the universe at emission, modified by subsequent expansion. The Planck Survey's findings on the flatness of space pertain to the universe's state at last scattering rather than its current flatness.

PREREQUISITES
  • Understanding of Cosmic Microwave Background Radiation (CMBR)
  • Familiarity with redshift and its implications in cosmology
  • Knowledge of the expansion history of the universe
  • Basic concepts of cosmological models and their applications
NEXT STEPS
  • Research the implications of redshift in cosmology
  • Study the Planck Survey data and its significance in cosmology
  • Explore models of cosmic expansion and their historical context
  • Investigate the relationship between CMBR and the large-scale structure of the universe
USEFUL FOR

Astronomers, cosmologists, and physics students interested in the early universe, cosmic expansion, and the implications of CMBR observations.

Ranku
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Does the CMBR contain the imprint of the entire expansion history of the universe or only of the last scattering ?
 
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It's a snapshot of the state of the universe at last scattering. Its redshift contains information about the total amount of expansion over the remaining history of the universe, but not the details of how that expansion has happened.
The two can be combined into a model that tracks the entire expansion history, but that information isn't there in the light itself.
This is similar to observing a particular redshifted galaxy - the image is of the state at emission, modified (redshifted) by the amount of expansion undergone until reception.
 
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Bandersnatch said:
It's a snapshot of the state of the universe at last scattering. Its redshift contains information about the total amount of expansion over the remaining history of the universe, but not the details of how that expansion has happened.
The two can be combined into a model that tracks the entire expansion history, but that information isn't there in the light itself.
This is similar to observing a particular redshifted galaxy - the image is of the state at emission, modified (redshifted) by the amount of expansion undergone until reception.
So when the Planck Survey of CMBR observed that space is flat, is that a measure of flatness of the present universe or during last scattering?
 

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