Discussion Overview
The discussion revolves around the cooling rate of the Cosmic Microwave Background Radiation (CMBR) and attempts to estimate its temperature at different points in the universe's history, particularly around 800 million years ago. Participants explore theoretical and mathematical aspects related to the CMBR's cooling and its relationship with the expansion of the universe.
Discussion Character
- Exploratory
- Technical explanation
- Conceptual clarification
- Debate/contested
- Mathematical reasoning
Main Points Raised
- One participant notes that the CMB temperature was approximately 9 K 11 billion years ago, compared to about 3 K currently, indicating a cooling of around 6-7 K over that time.
- Another participant questions whether the cooling has occurred at a constant rate over the past 11 billion years.
- A response suggests that while the cooling rate is not constant, a referenced paper provides an interesting method for measuring temperature.
- A specific cooling rate formula is presented: \dot T = H_0 \cdot T = 6.27 \cdot 10^{ - 18} {\textstyle{K \over s}}.
- One participant provides a method to estimate the CMBR temperature 800 million years ago using redshift calculations, concluding that the temperature would have been 1.061 times the current temperature.
- Another participant raises a question about the presence of plasma emitting in the gigahertz range in the local system, suggesting it could explain the isotropic nature of the CMBR outside the standard model.
Areas of Agreement / Disagreement
Participants express differing views on whether the cooling rate of the CMBR has been constant, and the discussion includes multiple approaches to estimating historical temperatures, indicating that no consensus has been reached.
Contextual Notes
Some limitations include the dependence on specific assumptions regarding redshift calculations and the interpretation of cooling rates, which remain unresolved in the discussion.