On Jun 10, 10:50*pm, Jacko wrote:
On 9 June, 22:49, Chalky wrote:



On Jun 7, 10:19 am, Chalky wrote:

I have just been boning up on primordial nucleosynthesis, and the
following statement in Wiki (admittedly not always the most reliable
source), *struck me as incredible:-

"there are about seven protons for every neutron at the beginning of
nucleogenesis....... This fraction is in favour of protons initially
primarily because because lower mass of the proton favors their
production."

Why my astonishment?

1) The masses of protons and neutrons are almost identical.

On closer examination of the soup, the following statement needs
revision:

2) Two ups and one down seems as likely a bundle to me as two downs
and one up when my quark soup starts to cool enough.

Actually, I find two downs and one up is the preferred option because
they are electrically neutral. Under charge conservation, every
instance of two ups and one down, must have the associated generation
of one free electron at the big bang.

Generating free electrons? Seem to be charge consevation bounds why
this does not happen.

Two ups and one down quark make a total charge of +e so there must be
an electron of charge -e generated to achieve charge conservation.
These electrons must be free because it is far too hot for atom
formation. At quark soup time, it is even too hot for for nucleon
formation.

OK?

Chalky wrote:
On Jun 10, 8:32 am, Uncle Al Uncle...hate.spam.net wrote:
Chalky wrote:

What is the density at inception?

Dunno but it should be pretty simple to work out approximately. (Mean
density now multiplied by the cube of 13.7 billion years / 3 minutes)

this assumes the universe mass is the same now and 13.7 billion years
ago.

Is that valid?

Richard D. Saam

On Jun 12, 7:11*am, "Richard D. Saam" wrote:
Chalky wrote:
On Jun 10, 8:32 am, Uncle Al Uncle...hate.spam.net wrote:
Chalky wrote:

What is the density at inception?
Dunno but it should be pretty simple to work out approximately. *(Mean
density now multiplied by the cube of 13.7 billion years / 3 minutes)

this assumes the universe mass is the same now and 13.7 billion years
ago.

No it doesn't. It assumes that the mass now is approximately the same
as it was 3 minutes after the big bang

Is that valid?

You are welcome to supply a more rigorous analysis if you so wish.

Chalky wrote:
On Jun 12, 7:11 am, "Richard D. Saam" wrote:
Chalky wrote:
On Jun 10, 8:32 am, Uncle Al Uncle...hate.spam.net wrote:
Chalky wrote:
What is the density at inception?
Dunno but it should be pretty simple to work out approximately. (Mean
density now multiplied by the cube of 13.7 billion years / 3 minutes)
this assumes the universe mass is the same now and 13.7 billion years
ago.

No it doesn't. It assumes that the mass now is approximately the same
as it was 3 minutes after the big bang

Is that valid?

You are welcome to supply a more rigorous analysis if you so wish.


According to Harrison eqn 18.48

density*Universe Radius^(3*gamma)

If lambda is other that 1
then mass has to change.

The expression 'matter is created during expansion' is used
for gamma = 0

On Jun 12, 11:22*pm, "Richard D. Saam" wrote:
Chalky wrote:
On Jun 12, 7:11 am, "Richard D. Saam" wrote:
Chalky wrote:
On Jun 10, 8:32 am, Uncle Al Uncle...hate.spam.net wrote:
Chalky wrote:
What is the density at inception?
Dunno but it should be pretty simple to work out approximately. *(Mean
density now multiplied by the cube of 13.7 billion years / 3 minutes)
this assumes the universe mass is the same now and 13.7 billion years
ago.

No it doesn't. It assumes that the mass now is approximately the same
as it was 3 minutes after the big bang

Is that valid?

You are welcome to supply a more rigorous analysis if you so wish.

According to Harrison eqn 18.48

Presumably you mean

density*Universe Radius^(3*gamma)

=Mass?

and gamma = sqrt(1-v^2/c^2)?
If so, v is the velocity of what relative to what?


If lambda is other that 1
then mass has to change.

The expression 'matter is created during expansion' is used
for gamma = 0

Chalky wrote:
On Jun 12, 11:22 pm, "Richard D. Saam" wrote:
Chalky wrote:
On Jun 12, 7:11 am, "Richard D. Saam" wrote:
Chalky wrote:
On Jun 10, 8:32 am, Uncle Al Uncle...hate.spam.net wrote:
Chalky wrote:
What is the density at inception?
Dunno but it should be pretty simple to work out approximately. (Mean
density now multiplied by the cube of 13.7 billion years / 3 minutes)
this assumes the universe mass is the same now and 13.7 billion years
ago.
No it doesn't. It assumes that the mass now is approximately the same
as it was 3 minutes after the big bang
Is that valid?
You are welcome to supply a more rigorous analysis if you so wish.
According to Harrison, Cosmology eqn 18.48

Presumably you mean

density*Universe Radius^(3*gamma)

=Mass?

No, density*Universe Radius^(3*gamma) = constant
density = Mass/volume
analogous to adiabatic expression:

Pressure*Volume^gamma1 = constant1

and gamma = sqrt(1-v^2/c^2)?
No, gamma is not the Lorentz transform.
gamma is another dimensionless constant
presented by Harrison,
defined in terms of the relativistic equation of state:
Pressure = (gamma - 1) density*c^2
in conjunction with the Friedmann-Lemaitre equations result in universe
conditions:
gamma = 4/3 for radiation dominated universe
gamma = 2/3 for static universe
gamma = 0 for constant density universe
gamma = 1 for a zero pressure universe

If gamma is other that 1
then mass has to change.

The expression 'matter is created during expansion' is used
for gamma = 0

These are theoretical constructs,
but in this context,
change
'matter is created during expansion'
to
'available energy during expansion'

Looks like the possible making of a Carnot cycle in there somewhere.
Has anyone theoretically constructed such a thing?

Richard D. Saam

On Jun 17, 7:34 pm, "Richard D. Saam" wrote:
Chalky wrote:
On Jun 12, 11:22 pm, "Richard D. Saam" wrote:
Chalky wrote:
On Jun 12, 7:11 am, "Richard D. Saam" wrote:
Chalky wrote:
On Jun 10, 8:32 am, Uncle Al Uncle...hate.spam.net wrote:
Chalky wrote:
What is the density at inception?
Dunno but it should be pretty simple to work out approximately. (Mean
density now multiplied by the cube of 13.7 billion years / 3 minutes)
this assumes the universe mass is the same now and 13.7 billion years
ago.
No it doesn't. It assumes that the mass now is approximately the same
as it was 3 minutes after the big bang
Is that valid?
You are welcome to supply a more rigorous analysis if you so wish.
According to Harrison, Cosmology eqn 18.48

Presumably you mean

density*Universe Radius^(3*gamma)

=Mass?

No, density*Universe Radius^(3*gamma) = constant
density = Mass/volume
analogous to adiabatic expression:

Perhaps you should have said that initially

Pressure*Volume^gamma1 = constant1

and gamma = sqrt(1-v^2/c^2)?

No, gamma is not the Lorentz transform.
gamma is another dimensionless constant
presented by Harrison,

Perhaps you should have also said that initially.

Please note;-I still don't know which Harrison you are quoting, or
what book.

(The most popular Harrison comes up as Harry Harrison, the SF
writer)

defined in terms of the relativistic equation of state:
Pressure = (gamma - 1) density*c^2
in conjunction with the Friedmann-Lemaitre equations result in universe
conditions:
gamma = 4/3 for radiation dominated universe

Hmm. This suggests it is not constant. The early universe was
radiation dominated whereas the current universe is matter dominated.
I note you do not even cover that option, below.

gamma = 2/3 for static universe
gamma = 0 for constant density universe
gamma = 1 for a zero pressure universe

These assertions strike me as highly cosmology dependent.

If gamma is other that 1
then mass has to change.

The expression 'matter is created during expansion' is used
for gamma = 0

These are theoretical constructs,
but in this context,
change
'matter is created during expansion'
to
'available energy during expansion'

That seems somewhat more credible

Looks like the possible making of a Carnot cycle in there somewhere.
Has anyone theoretically constructed such a thing?

Dunno (as in my original response that you objected to).

To cut to the chase, I suggested, in that response, a simple approach
to determining density as a function of time, to a first
approximation, and invited you to provide a more rigorous analysis.
AFAICT you have not yet done so. I still don't know what your approach
is supposed to predict at 1 second, or 3 minutes, or any other time,
for that matter.

On Jun 12, 7:11*am, "Richard D. Saam" wrote:
Chalky wrote:
On Jun 10, 8:32 am, Uncle Al Uncle...hate.spam.net wrote:
Chalky wrote:

What is the density at inception?
Dunno but it should be pretty simple to work out approximately. *(Mean
density now multiplied by the cube of 13.7 billion years / 3 minutes)

this assumes the universe mass is the same now and 13.7 billion years
ago.

Is that valid?

I note from line 15 of page 87 of "The accidental universe"# that
density (of particles) is actually supposed to be inversely
proportional to time squared.

This should make things nice and simple. (Not least because
temperature is also inversely proportional to time squared, in the
early [radiation dominated] universe.]

#
http://books.google.co.uk/books?id=s...ult&resnum =5

Chalky wrote:
Please note;-I still don't know which Harrison you are quoting, or
what book.

(The most popular Harrison comes up as Harry Harrison, the SF
writer)

In the context of cosmology, the default meaning of "Harrison" can
reasonably be taken to be the (superb) book

Edward R Harrison
"Cosmology: The Science of the Universe"
Cambridge U.P., 1981

(I believe there is a 2nd edition of available, but I don't have
publication info for it.)

If it doesn't mean this, then it might mean the classic paper by the
same author
http://adsabs.harvard.edu/abs/1993ApJ...403...28H
Title: The redshift-distance and velocity-distance laws
Authors: Harrison, Edward
Publication: Astrophysical Journal, Part 1 (ISSN 0004-637X),
vol. 403, no. 1, p. 28-31.
Publication Date: 01/1993

ciao,

--
-- "Jonathan Thornburg [remove -animal to reply]"
Dept of Astronomy, Indiana University, Bloomington, Indiana, USA
"Washing one's hands of the conflict between the powerful and the
powerless means to side with the powerful, not to be neutral."
-- quote by Freire / poster by Oxfam

On Jun 22, 5:22 pm, "John Bell (Change John to Liberty for email)"
wrote:

I note from line 15 of page 87 of "The accidental universe"# that
density (of particles) is actually supposed to be inversely
proportional to time squared.

Does this apply for time after recombination as well as before?

This should make things nice and simple. (Not least because
temperature is also inversely proportional to time squared, in the
early [radiation dominated] universe.]

#http://books.google.co.uk/books?id=s...&lpg=PA87&dq=d...

On Jun 22, 5:23 pm, Ian Parker wrote:
On 22 June, 10:41, "Chalky (OR)"
wrote:

What formula?

I am afraid I must eat a little humble pie here. Plotting the curve
from the present to 3min gives T = t^(-2/3).

Interesting. This does seem to give the correct result from the
present to the surface of last scattering (matter dominated era).

T is proportional to Density. (Assuming no other degrees of freedom)

Can this be confirmed, Temperature is proportional to density, now
too, not just in the early radiation dominated era? (I don't really
understand your degrees of freedom argument)

Speed of recession (km/s per MPs) = sqrt(Density)

Is left hand side supposed to have dimensions of 1/time, or distance/
time ?
if 1/time, we have time is proportional to Temperature^-1/2
This is the formula which seems to work for the peeriod before
recombination

This on integration gives T^(-3/2) prop t. or T prop 1/(t^(2/3))

Now you have lost me again. Integrating what WRT what?