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Before-Big Bang

by Parbat
Tags: bang, beforebig
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marcus
#73
Dec3-10, 02:12 PM
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Quote Quote by universe11 View Post
Most of the radiation energy in the universe is in the cosmic microwave background...

Do you know the value of this energy?
I've calculated it several times but don't know it by heart. You can calculate it if you want.

You probably know the Stefan-Boltzmann 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/m2 by c/4 should give joules/m3.

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 Stef-Boltz.
robsharp14
#74
Dec3-10, 02:28 PM
P: 26
i wonder if your able to use this energy.....maybe not yet becouse of the entropy
universe11
#75
Dec3-10, 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)
yoda jedi
#76
Dec4-10, 02:52 PM
P: 380
Quote Quote by familia View Post
i think u r referring to quantum theory
me two.
universe11
#77
Dec6-10, 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?
robsharp14
#78
Dec9-10, 12:52 PM
P: 26
that's the one! thanks
Imax
#79
Dec17-10, 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 whatís north of the North Pole?
marcus
#80
Dec17-10, 10:42 PM
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Quote Quote by Imax View Post
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?
Penrose says that this was precisely the prevailing expert view before 2005.
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 pre-bang. 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 pre-bang and has no singularity. At least the first 50-100. 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 papers---a rough measure of how valuable/important the paper is.
The first 50 or 100 in some sense defines the field.
alphachapmtl
#81
Dec18-10, 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 space-time from the structures of quantum theory.
... loop quantum gravity (LQG). The theory holds that space is weaved from one-dimensional 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 well-known space-time.
jtbell
#82
Mar25-11, 04:57 PM
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I see no science in this discussion since it was revived in March. Thread closed.


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