What was the width of the visible sound-horizon at the birth of the CMB ?

In article , Jeff’ĶRelf
wrote:

Hi T_Wake, You cited:

cosmocoffee.info/viewtopic.php?p=1061&

That says the Sound_Horizon has expanded to 147 Mpc today.
Multiplying by 3.262 Light_Years / Parsec, that's about .5 Giga_Light_Years,
dividing by 1,088 give me .00044 Giga_Light_Years then,
i.e. the so-called _Age_ of the universe at the birth of the CMB.

What does be width of the _Visible_ universe have to do with it's age ?


I've given you the math

http://groups.google.com/group/sci.p...4f1673f7d98696

Here t=t_0(1+z)^{-3/2}, and throwing in the redshift of about 1000 for
the cosmic microwave background and a current age of the universe t_0
\approx 13.7 Gyr gives us around 380,000 years for the age of the
universe when the CMB was emitted. T = temperature, t = Time
From google - 13.7*10^9 *(1000^(-3/2)) = 433 232.039 - roughly 4 * 10^5
years after t_0 for the CMB)


http://www.astro.ucla.edu/~wright/cosmo_03.htm

Horizon Problem
The conformal space-time diagram is a good tool use for describing the
meaning of CMB anisotropy observations. The Universe was opaque before
protons and electrons combined to form hydrogen atoms when the
temperature fell to about 3,000 K at a redshift of 1+z = 1090. After
this time the photons of the CMB have traveled freely through the
transparent Universe we see today. Thus the temperature of the CMB at a
given spot on the sky had to be determined by the time the hydrogen
atoms formed, usually called "recombination" even though it was the
first time so "combination" would be a better name. Since the
wavelengths in the CMB scale the same way that intergalaxy distances do
during the expansion of the Universe, we know that a(t) had to be
0.0009 at recombination. For the Omegao = 1 model this implies that
t/to = 0.00003 so for to about 14 Gyr the time is about 380,000 years
after the Big Bang. This is such a small fraction of the current age
that the "stretching" of the time axis when making a conformal
space-time diagram is very useful to magnify this part of the history
of the Universe.



--
The greatest enemy of science is pseudoscience.

Jaffa cakes. Sweet delicious orangey jaffa goodness, and an abject lesson why
parroting information from the web will not teach you cosmology.

Official emperor of sci.physics. Please pay no attention to my butt poking
forward, it is expanding.

Relf's Law?
"Bull**** repeated to the limit of infinity asymptotically approaches
the odour of roses."

Hi T_Wake, You showed me: www.Astro.UCLS.EDU/~wright/cosmo_03.htm

Again, why is the scale factor = a ( t ) = ( t / t_0 ) ^ .667 ?

That site is obviously not current, as they say: H_0 = 65 km/sec/Mpc
The actual value is: 70 km/sec/Mpc, see: WikiPedia.ORG/wiki/Hubble's_law
I have to do some emergency coding again today,
so I can't spend much time on this... I'll definately look at the site later.

In article , Jeff’ĶRelf
wrote:

Hi T_Wake, You showed me: www.Astro.UCLS.EDU/~wright/cosmo_03.htm

Again, why is the scale factor = a ( t ) = ( t / t_0 ) ^ .667 ?

A cosmology course would tell you why - you'd need to research on
densities and redshift - Mit's Opeb Courseware

http://ocw.mit.edu/OcwWeb/Physics/8-...Home/index.htm



That site is obviously not current, as they say: H_0 = 65 km/sec/Mpc
The actual value is: 70 km/sec/Mpc, see: WikiPedia.ORG/wiki/Hubble's_law
I have to do some emergency coding again today,
so I can't spend much time on this... I'll definately look at the site later.



The value for Hubbles constant was recently updated, but the math is
still the same.

--
The greatest enemy of science is pseudoscience.

Jaffa cakes. Sweet delicious orangey jaffa goodness, and an abject lesson why
parroting information from the web will not teach you cosmology.

Official emperor of sci.physics. Please pay no attention to my butt poking
forward, it is expanding.

Relf's Law?
"Bull**** repeated to the limit of infinity asymptotically approaches
the odour of roses."

Duckie, _Please_ email your professor this...
There's very strong evidence suggesting that
the dark energy equation of state, w = pressure over density,
is a constant -1, making the Lambda_CDM model,
with a _Known_ cosmological constant, the concordance model of cosmology.

I quote:

Detection of a deviation of w from w = -1, or for a time evolution of w,
or a sound speed in the dark energy, would raise challenging questions
for fundamental physics, e.g., what fixes the the energy
and mass scales associated with a quintessence field ?
....
Fig 2.22 [ www.Cotse.NET/users/jeffrelf/W.PNG ]
The left panel shows forecasts of constraints on
the dark energy equation of state parameter w and Omega_m
for various experiments including Planck.
The right panel shows forecasts of constraints on the time evolution of w,
parameterised through w = w_0 + w_1(z),
[ w_1(z) is the variance with z, the redshift ] for Planck
combined with various redshift surveys and SNe observations from SNAP.
__ www.RSSD.ESA.INT/SA/PLANCK/docs/Bluebook-ESA-SCI(2005)1_V2.pdf

Now... using this model, with an ever-constant lambda,
it's possible to express the so-called age of the _Visible_ universe
in units of length, temperature, entropy ( dissipation, Joules per Kelvin ),
and time.

No place is perfectly without entropy, ever,
so it can be modeled as a fifth _Spatial_ dimension: Entropy_Time_Space
Let me know if your professor has any trouble with the word _Modeled_.

In article , Jeff’ĶRelf
wrote:

Duckie, _Please_ email your professor this...

No place is perfectly without entropy, ever,
so it can be modeled as a fifth _Spatial_ dimension: Entropy_Time_Space
Let me know if your professor has any trouble with the word _Modeled_.


I've shown my professors your stuff. I've already told you what they
think. You have no grounding in physics, and its bull**** of the
highest order.

Is there any limits to your ignorance.





--
The greatest enemy of science is pseudoscience.

Jaffa cakes. Sweet delicious orangey jaffa goodness, and an abject lesson why
parroting information from the web will not teach you cosmology.

Official emperor of sci.physics. Please pay no attention to my butt poking
forward, it is expanding.

Relf's Law?
"Bull**** repeated to the limit of infinity asymptotically approaches
the odour of roses."

Hi T_Puddleduck, I take it you won't email your professor my explanation.
You probably sent her a bunch or out-of-context ramblings then.

Hi T_Puddleduck, scale factor = a ( t ) = ( t / t_0 ) ^ .667 ?

That's wrong. ( Gy = Giga_Year, Gly = Giga_Light_Year, 1 Gpc = 3.262 Gly )
According to WMAP's models, it's 13.7 Gy to the peak in the power spectrum,
margin of error near one percent.

The Hubble_Parameter, H_0 is:

H_0 = ( 70,000 / 3.262 km / s == Gly / Gy ) / Gly
H_0 = ( .07158 Gly / Gy ) / Gly
H_0 = .07158 Gy

Ignoring lambda:

Scale_Factor / .07158 Gy = 13.7 Gy
Scale_Factor = .07158 Gy * 13.7 Gy = .98 Gy ^ 2

I don't know why it's not exactly 1,
it might have something to do with the lambda WMAP used.

Hi T_Wake, I wrote:

I read:

[ Planck_Surveyor ] will lead to more accurate estimates of
the distance to the last scattering surface
and of the size of the sound-horizon at last scattering.
www.RSSD.ESA.INT/SA/PLANCK/docs/Bluebook-ESA-SCI(2005)1_V2.pdf

What are the current estimates ?

and you replied:

Quote taken out of context in a serious way.
Can you please rephrase it in a more sensible manner ?

Because the early universe was in thermal equilibrium,
the radiation from this time had a blackbody spectrum.
Only one part in 10 ^ -5 deviates from the 3,000 K, .25 eV, norm.
Using models of the pre-CMB acoustics/fluid,
and given the location of the first ( most powerful ) acoustic peak,
it's possible to get a length, a wavelength.
The peaks correspond, roughly, to resonances in which
the photons decouple when a particular mode is at its peak amplitude/power.
This then tells you the size of the _Visible_ decoupling surface
at the birth of the CMB.

To give you any more detail, I'd have to look into the models used.
Once I figure out the length ( .00038 Giga_Light_Years ? )
I'll see if I can figure out how they came up with
the .00038 Giga_Years number.

Jeff...Relf wrote:
Hi T_Puddleduck, scale factor = a ( t ) = ( t / t_0 ) ^ .667 ?

That's wrong. ( Gy = Giga_Year, Gly = Giga_Light_Year, 1 Gpc = 3.262 Gly )
According to WMAP's models, it's 13.7 Gy to the peak in the power spectrum,
margin of error near one percent.

The Hubble_Parameter, H_0 is:

H_0 = ( 70,000 / 3.262 km / s == Gly / Gy ) / Gly
H_0 = ( .07158 Gly / Gy ) / Gly
H_0 = .07158 Gy

Ignoring lambda:

Scale_Factor / .07158 Gy = 13.7 Gy
Scale_Factor = .07158 Gy * 13.7 Gy = .98 Gy ^ 2

I don't know why it's not exactly 1,
it might have something to do with the lambda WMAP used.

You have no idea how the WMAP folks found a model that was consistant
with observation, ****wit. I could point you to a PDF where the details
of why that specific lambda was used, but you wouldn't understand.

Hi Eric_Gisse, If you know how to wipe your ass then go ahead and tell us.
Otherwise shut the **** up.