Evidence of Cosmic Backround Radiation cooling

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Discussion Overview

The discussion revolves around the cooling of Cosmic Background Radiation (CBR) over time, exploring experiments and evidence supporting this phenomenon. Participants examine the implications of CBR cooling in the context of an expanding universe and its historical measurements.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant inquires about experiments confirming the cooling of CBR and the challenges of measuring such changes over time.
  • Another participant suggests that if CBR had not been cooling, it would be detectable as visible light rather than microwaves, implying a relationship between cooling and the nature of radiation detection.
  • Multiple participants assert that evidence supports the idea that the universe was cooler in the past, consistent with predictions of an expanding universe, referencing specific studies and articles.
  • A participant corrects a previous statement regarding the terminology of 'cooler' versus 'hotter' in the context of past temperatures of the universe, introducing a mathematical expression related to temperature changes.
  • There is a mention of a broken link to a referenced article, indicating a need for accurate sourcing in the discussion.

Areas of Agreement / Disagreement

Participants generally agree that evidence exists for the universe being cooler in the past, but there is some contention regarding the terminology used to describe this phenomenon and the implications of the cooling process.

Contextual Notes

Some claims rely on specific studies and mathematical models, which may have unresolved assumptions or dependencies on definitions that are not fully explored in the discussion.

Bill Minerick
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What experiments have been conducted to confirm that the Cosmic Background Radiation (CBR) is indeed cooling over time and at any specified rate? The time requirement for obtaining separate points for measuring change seems preclusive.
 
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If it hadn't been cooling over time, then we would be detecting it now in the sky as visible light rather than microwaves.

Ratios of helium to deuterium are also sensitive to the gravitational effects of radiation in the early, radiation-dominated universe (minutes or hours after the big bang). These ratios are consistent with the rate of cooling predicted by GR:
Steigman, Ann. Rev. Nucl. Part. Sci. 57 (2007) 463.
 
Evidence the universe was cooler in the past, which is precisely what is expected in an expanding universe, has been confirmed several ways. One of the more compelling cases is reported in http://arxiv.org/abs/1012.3164, and http://www.das.uchile.cl/das_ingles/...asurements.php .
 
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Chronos said:
Evidence the universe was cooler in the past, which is precisely what is expected in an expanding universe, has been confirmed several ways. One of the more compelling cases is reported in http://arxiv.org/abs/1012.3164, and http://www.das.uchile.cl/das_ingles/...asurements.php .

Cool! The second link is broken, through.
 
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Chronos said:
Evidence the universe was cooler in the past, which is precisely what is expected in an expanding universe, has been confirmed several ways. One of the more compelling cases is reported in http://arxiv.org/abs/1012.3164, and http://www.das.uchile.cl/das_ingles/...asurements.php .

Don't you mean 'hotter in the past'?
[tex]TCMB(z)=(2.725+/-0.002) \times (1+z)^{(1-beta)}K[/tex] with beta=-0.007+/-0.027
I'm doing that all the time!

Garth
 
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Yep, another bout of dyslexia. trying to fix link to second article http://www.das.uchile.cl/das_ingles/new_temp_measurements.php
 
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