Cosmic background radiation, what does it mean?

[six_strings]

Does the cosmic background radiation data suggest there couldn't be vast amounts of matter outside our observational range? Or is this just the farthest as we can observe or detect? I guess more to the point, my question would be, could there be matter out there causing acceleration of expansion? Or would the cosmic background radiation data suggest it would be to far away to have this gravatational effect? <div class="Discussion_UserSignature"> </div>

 

[six_strings]

Hmm... Or is it that the CBR wouldn't even detect matter, since its detection is directed at finding radiation? <div class="Discussion_UserSignature"> </div>

 

[search]

<font color="yellow">Does the cosmic background radiation data suggest there couldn't be vast amounts of matter outside our observational range?</font><br /><br />According with Standard Cosmology around 400 000 years after the Big Bang the temperature dropped enough to allow electrons and protons to form hydrogen atoms. <br /><br />This is called the recombination period or decoupling during which electrons became bound to nuclei. After the decoupling of matter and radiation, which happened at about the same time as recombination, ambient photons could travel freely, and are visible today as the Cosmic Microwave Background Radiation. Universe became transparent.<br /><br />So matter cannot be seen or detected from CMBR because that is the moment matter starts to form.<br /><br /><font color="yellow">Or is this just the farthest as we can observe or detect?</font><br /><br />Pretty much because before CMBR the universe was opaque.<br /><br /><font color="yellow">I guess more to the point, my question would be, could there be matter out there causing acceleration of expansion?</font><br /><br />Acceleration is believed to be cause by "dark energy"(cosmological constant, quintessence, phantom energy you name it and everyone as a theory). The problem is that no one knows what is dark energy. We just know there is a repulsive force sending everything appart (exceptions made to local clusters). This acceleration is believed to have start 5 billion years ago when the universe. Before it was deccelerating due to the attractive influence of matter and baryons. Then dark energy became the dominant force and the acceleration started.<br /><br /><font color="yellow"> Or would the cosmic background radiation data suggest it would be to far away to have this gravatational effect?</font><br /><br />Very far indeed and gravity is the weakest of the 4 forces in the universe. But in quantum mechanics "imagine two particles which interact then distance thems

 

[brellis]

I am to cosmology what a grain of sand is to the people that designed the pyramids. That said, I think the Big Bang Theory runs into trouble when we start being able to sense 'structure' in the Cosmic Background Radiation, and likewise when we establish varying degrees of acceleration at great distances.<br /><br />I ask questions similar to yours: do the variances indicate that the universe is not only finite, but is being affected by some greater unseen 'universe'? Is our universe like a bubble in a pond, feeling the effects of a 'wave' every 5 billion years or so?<br /><br />speedfreek has a sensible answer to such a question: (paraphrasing here) we develop theories about what we can see, and the BB theory allows our universe to exist inside something else. oh heck, speedy had better come to the rescue again! my head is spinning too fast!<br /><br />There was an excellent discussion recently in this thread on red shift discrepancy. Check it out. I've 'thumbed' through it several times now, it's a fascinating read. <div class="Discussion_UserSignature"> <p><font size="2" color="#ff0000"><em><strong>I'm a recovering optimist - things could be better.</strong></em></font> </p> </div>

 

[alokmohan]

What you think of the dark energy?Does it really exist?Has CMB helped us anyway?

 

[brellis]

I don't know much about dark energy. It sounds more like a plausible explanation for acceleration rather than a theory. My gut tells me that our precious little bubble we call universe is not alone in the greater scheme of things. Perhaps humanity will survive long enough to look back on the present day the way we look at medieval flat-earth thinking of a thousand years ago. <div class="Discussion_UserSignature"> <p><font size="2" color="#ff0000"><em><strong>I'm a recovering optimist - things could be better.</strong></em></font> </p> </div>