Evidence of Cosmic Backround Radiation cooling

[Bill Minerick]

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.

 

[bcrowell]

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.

 

[Chronos]

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 .

 

[bcrowell]

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.

 

[Garth]

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'?

$$TCMB(z)=(2.725+/-0.002) \times (1+z)^{(1-beta)}K$$ with beta=-0.007+/-0.027

I'm doing that all the time!

Garth

 

[Chronos]

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