In the course of evolution of universe new matter is continuously being
created. Whatever we see is not the current stat of matter. It is
always a few years back in time. Then how do we calcuate the density of
the universe when it is defined as "current" matter/"current" volume.

Dear suchita.kulkarni:

wrote in message
oups.com...
In the course of evolution of universe new matter is
continuously being created.

And destroyed.

Whatever we see is not the current stat of matter.
It is always a few years back in time. Then how
do we calcuate the density of the universe when
it is defined as "current" matter/"current" volume.

We could reference a "current" time-rate to that of the past.
This would be a simple "local" measure. The higher the average
universal curvature (a function of universal density), the slower
the time rate compared to a lower average universal curvature.
Were we to need such a "silly" measurement.

David A. Smith

wrote in message
oups.com...
In the course of evolution of universe new matter is continuously being
created.

Where do you get that idea from?

Bill

Whatever we see is not the current stat of matter. It is
always a few years back in time. Then how do we calcuate the density of
the universe when it is defined as "current" matter/"current" volume.

Dear Bill Hobba:

"Bill Hobba" wrote in message
...

wrote in message
oups.com...
In the course of evolution of universe new
matter is continuously being created.

Where do you get that idea from?

Pair creation I had assumed. He may be from the "constant
creation" or "static universe" camps though.

David A. Smith

If the universe is expanding and the matter is not being created then
we should see voids but the observed size of voids do not match with
the expected, so we should say that matter is being created.

If we don't need such a kind of measurement then how do we deine the
density of universe and estimate the same?

Dear suchita.kulkarni:

wrote in message
ups.com...
If we don't need such a kind of measurement
then how do we deine the density of universe
and estimate the same?

It would be really good if you could leave some attribution to
whom you were responding...

"deine" =?= "derive"?
"deine" =?= "define"?

We have 1+z from astronomical observation. This equates to
"gravitational time dilation" around a black hole, I would think.
At least as a first pass...
URL:http://encyclopedia.laborlawtalk.com/Time_dilation
t1 * sqrt( 1 - r_h / r_1 ) = t2 * sqrt( 1 - r_h / r_2 )
.... assuming no mass is added to this Universe...
r_h would be the initial size of the Universe (unknown, but
likely tens of million light years)
t1/t2 could be 1+z. Solve for r_1/r_2. I don't know if this is
useful or not... it is getting late.

You might be interested in this:
URL:http://www.astro.ucla.edu/~wright/cosmo_01.htm

David A. Smith

Dear suchita.kulkarni:

wrote in message
ups.com...
If the universe is expanding and the matter is
not being created then we should see voids

*Lot's* of void. The CMBR was tens of million light years thick,
was supposedly optically opaque, and filled the Universe. No
such dense gas cloud remains.

but the observed size of voids do not match
with the expected, so we should say that
matter is being created.

We should say since Universal expansion is accelerating, that
mass is lost. But we know that the law of Conservation of Energy
forbids the change of net energy (inclusive of matter). So I
don't see any basis for your assumption of matter *addition*.

Yes, matter is created and destroyed all the time. But the
expectation is (and is in agreement with what little we can see)
that no matter/energy has been added to this Universe since the
arrival of Dark Matter and Dark Energy.

David A. Smith

"N:dlzc D:aol T:com (dlzc)" N: dlzc1 D:cox wrote in
message news:ctBge.5779$eU.5709@fed1read07...
| Dear suchita.kulkarni:
|
| wrote in message
| ups.com...
| If the universe is expanding and the matter is
| not being created then we should see voids
|
| *Lot's* of void. The CMBR was tens of million light years thick,
| was supposedly optically opaque, and filled the Universe. No
| such dense gas cloud remains.
|
| but the observed size of voids do not match
| with the expected, so we should say that
| matter is being created.
|
| We should say since Universal expansion is accelerating, that
| mass is lost. But we know that the law of Conservation of Energy
| forbids the change of net energy (inclusive of matter). So I
| don't see any basis for your assumption of matter *addition*.
|
| Yes, matter is created and destroyed all the time. But the
| expectation is (and is in agreement with what little we can see)
| that no matter/energy has been added to this Universe since the
| arrival of Dark Matter and Dark Energy.

Hmm... Do you think a hundred years of observation is enough to be
able to tell if new matter was coming into our "local bubble" Universe
from a bigger one? The mass-energy flow rate for the entire Universe
might not be very noticable at all in "our neck of the 'hood".
Something on the order of the Pioneer anomaly maybe? That is a pretty
small effect.

FrediFizzx

http://www.vacuum-physics.com/QVC/qu...uum_charge.pdf
or postscript
http://www.vacuum-physics.com/QVC/qu...cuum_charge.ps

Dear FrediFizzx:

"FrediFizzx" wrote in message
...
"N:dlzc D:aol T:com (dlzc)" N: dlzc1 D:cox
wrote in
message news:ctBge.5779$eU.5709@fed1read07...
| Dear suchita.kulkarni:
|
| wrote in message
| ups.com...
| If the universe is expanding and the matter is
| not being created then we should see voids
|
| *Lot's* of void. The CMBR was tens of million
| light years thick, was supposedly optically
| opaque, and filled the Universe. No such
| dense gas cloud remains.
|
| but the observed size of voids do not match
| with the expected, so we should say that
| matter is being created.
|
| We should say since Universal expansion is
| accelerating, that mass is lost. But we
| know that the law of Conservation of Energy
| forbids the change of net energy (inclusive
| of matter). So I don't see any basis for your
| assumption of matter *addition*.
|
| Yes, matter is created and destroyed all
| the time. But the expectation is (and is in
| agreement with what little we can see) that
| no matter/energy has been added to this
| Universe since the arrival of Dark Matter
| and Dark Energy.

Hmm... Do you think a hundred years of
observation is enough to be able to tell if
new matter was coming into our "local
bubble" Universe from a bigger one?

We've got 13 Gy displayed. In that time we have the "intrusion"
of Dark Matter and Dark Energy (assuming...). Beyond that
(closer to us), we have fully formed objects that seem to bear
out distance-equals-age. Additionally, acceleration of
expansion, and the continuity of expansion, hint at a constancy
in the mass/energy contained in this Universe (assuming local
properties derive from the Universe et al). Not much room for
the arrival of "new stuff".

The mass-energy flow rate for the entire
Universe might not be very noticable at
all in "our neck of the 'hood". Something
on the order of the Pioneer anomaly
maybe? That is a pretty small effect.

Roughly equal to the Hubble coefficient. Roughly equal to the
recession rate of the Moon from Earth. Three orders of magnitude
less than the expansion of the PtIr "meter rod" in Paris. Three
orders of magnitude greater than the mass loss of our Sun due to
irradiation. We can measure small effects, if we know where to
look.

We are limited by our light cone. But if objects are being
added, they would eventually cross it. If "dust" is being added,
it isn't showing up in inter-supercluster space. Such "noise"
would be a place to look.

One wonders why matter "infalling" from a container Universe
wouldn't enter through the event horizon?

David A. Smith