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#73
Dec310, 02:12 PM

Astronomy
Sci Advisor
PF Gold
P: 23,108

You probably know the StefanBoltzmann law for black body radiation. Find the watts/square meter power density of a surface at 2.725 K. Then divide by c/4. Dividing watts/m^{2} by c/4 should give joules/m^{3}. The overall mass energy density of the universe is in fractions of a nanojoule per cubic meter and the CMB energy density is a small part, so it should come out femtojoules per cubic meter, I guess. Or fractions of a pico. You can find it with StefBoltz. 


#74
Dec310, 02:28 PM

P: 26

i wonder if your able to use this energy.....maybe not yet becouse of the entropy



#75
Dec310, 09:53 PM

P: 33

I found it is 6*10**(5) of the density of the Universe!
This means is 6*10**(5) of the mass of the Universe ( 10^53 kg) 


#76
Dec410, 02:52 PM

P: 380




#77
Dec610, 05:24 AM

P: 33

The new model, developed by Paul Steinhardt of Princeton University in the US and Neil Turok at Cambridge University in the UK, will be controversial. It requires that time existed before the Big Bang, assumes that the universe is older than the 14 billion years we think it is, and says that the universe regularly undergoes repeating "cycles" of big bangs and big crunches (Sciencexpress 1126231).
http://physicsworld.com/cws/article/news/24844 How were explained the Big Crunches? 


#78
Dec910, 12:52 PM

P: 26

that's the one! thanks



#79
Dec1710, 06:41 PM

P: 186

Before the Big Bang, time and space did not exist. Trying to ask what happened before the Big Band is like trying to ask what’s north of the North Pole?



#80
Dec1710, 10:42 PM

Astronomy
Sci Advisor
PF Gold
P: 23,108

You might like to listen to his talk at Cambridge in fall of 2005. Anyway, fashions change. Cosmologists no longer think that (what you said) on the whole. There are a number of newer models that go back prebang. At least one is approaching the test stage (assuming NASA can get its next microwave background mapping mission funded.) Say if you would like some links to professional research papers or any help navigating the literature. The main overview you can get by scanning the list of recent papers in "quantum cosmology". Here's a keyword search. They are almost all about cosmology that goes back prebang and has no singularity. At least the first 50100. I haven't looked at the whole list. http://www.slac.stanford.edu/spires/...tecount%28d%29 I defined the search to find all "quantum cosmology" that appeared after 2006 and to order them with the most highly cited first. So you get the papers first which other researchers have most often referred to in their papersa rough measure of how valuable/important the paper is. The first 50 or 100 in some sense defines the field. 


#81
Dec1810, 09:57 AM

P: 81

marcus seems to be right about "quantum cosmology".
See this fascinating article: The Birth of Time: Quantum Loops Describe the Evolution of the Universe ScienceDaily (Dec. 17, 2010) http://www.sciencedaily.com/releases...1216095014.htm ... a new theoretical model of quantum gravity describing the emergence of spacetime from the structures of quantum theory. ... loop quantum gravity (LQG). The theory holds that space is weaved from onedimensional threads. ... The starting points for the model are two fields, one of which is a gravitational field, the other a scalar field. ... time emerges as the relation between the gravitational field (space) and the scalar field  a moment in time is given by the value of the scalar field. ... the passage of time emerges as the property of the state of the gravitational and scalar fields and the appearance of such a state corresponds to the birth of the wellknown spacetime. 


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