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Author Topic: What is the significance of the cosmic background radiation?  (Read 4123 times)

Offline thedoc

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Andy M  asked the Naked Scientists:
   
Penzias & Wilson are hailed as heroes for their discovery of background radiation. I really don't get it. Why? What does it tell us and how does the discovery advance science?

Thanks
Andy, Liverpool

What do you think?
« Last Edit: 23/08/2012 04:30:01 by _system »


 

Offline yor_on

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Take a look at http://www.physicsoftheuniverse.com/topics_bigbang_background.html
It was like a puzzle where the CBR became a pivot defining a Big Bang as more likely than a 'steady universe' although there is a ongoing discussion still. The idea of a very 'hot' beginning for the universe seems to be in question.

"It has frequently been asserted that the discovery of the Cosmic Microwave Background Radiation (CMB) by Penzias and Wilson is proof of the validity of the Hot Big Bang Theory of the origin of the Universe. In reality this is not the case because the expansion of the Universe at the time of the supposed "Fireball'' would not produce the perfect black-body radiation which is actually observed. This problem with the CMB has been pointed out before by Mitchell (1994) but the present study establishes the argument by means of rigorous thermodynamic calculations. The CMB is said to have been produced at the time of"de-coupling'' when the electron density in the primeval Universe was very small. The radiation generated at that epoch would have had a black-body spectrum. Three cases are analysed when the electron density approached zero; three appropriate temperatures are taken and then the thermodynamic properties — including density — are calculated for the three cases. These provide a measure of the expansion to the present day. Wien's law is applied to calculate the fall in temperature of the radiation for each case — assuming that the black-body spectrum is maintained. According to the Hot Big Bang Theory the three cases should all arrive at 2.72 K, but they do not. The conclusion is that the CMB spectrum ought to be "smeared" and not the almost perfect black-body curve, which is actually observed. Therefore the Hot Big Bang Theory fails this test. "  By Bligh, B. R.
 

Offline Emc2

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Offline yor_on

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Agreed, makes sense 'if' we have 'indivisible blocks' creating a universe. Then what we see would be a symmetry breaking, as one might assume this 'liquid universe' pre existing to have a perfect symmetry, maybe :)
 

Offline imatfaal

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At present the CMBR is seen as pretty good evidence for the Big Bang theory - and whilst there will always be discussion, refinement, and testing of any important theory, to describe this area as unsettled is not correct.  Yoron's link and first sentence I would agree with - it's the rest and the quote that is against current thought. 

Here is a quote from the excellent page in Y's link

Quote
The Ukrainian-American physicist George Gamow was the first to realize that, because the universe is all there is, the huge heat from a hot Big Bang could not dissipate in the same way as the heat from a regular explosion and therefore it must still be around today.

Gamow's research students, Ralph Alpher and Robert Herman, moreover, argued in 1948 that, because the Big Bang effectively happened everywhere simultaneously, that energy should be equally spread as cosmic microwave background radiation (or CMB for short) throughout the universe.


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In 1965, Arno Penzias and Robert Wilson, two young employees of Bell Telephone Laboratories in New Jersey, discovered, although totally by accident, exactly that. The mysterious microwave static they picked up on their microwave antenna seemed to be coming equally from every direction in the sky, and eventually they realized that this microwave radiation (which has a temperature of about -270°C, marginally above absolute zero, and the coldest thing found in nature) must indeed be the “afterglow” of the Big Bang


So in other words - many years ago the CMBR was predicted as a necessary remnant of the big bang - years later it was discovered.  This adds weight to the big bang theory. 
 

Offline imatfaal

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Side debate from EMC2 on Eternal Universes and calling into doubt validity of the big bang moved to New theories

Please try to keep to the topic and keep speculation non-mainstream ideas to New Theories
 

Offline Emc2

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ok, sounds good..

   
 

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