Relative distances and speed

If most matter(maybe superclusters) have been separating at
an ever faster rate for 13+ billion years, what is the minimum
percent of the speed of light the furthest group is now
traveling relative to our speed? How does this relate to the
initial inflation speed? Have there been slow downs? Or, how
close were clusters when they were first formed? I am looking
for absolute distances w/o gravitational distortion. Thank you.

kjakja wrote:
If most matter(maybe superclusters) have been separating at
an ever faster rate for 13+ billion years, what is the minimum
percent of the speed of light the furthest group is now
traveling relative to our speed?

We still do not know if the volume if the universe is finite
or infinite. If it's the latter, there is no "furthest group".

Additionally, what do you mean with "our speed" here? Our speed
relative to what?

I suppose you simply mean the speed of the furthest group of galaxies
with respect to us. If the universe really is finite, then,
according to current knowledge (IIRC), it has a size of at
least 70 billion light years. So we can make a (very rough!)
estimate by using Hubble's law (which is *not* valid for
such large distances!):
v = H*d,
where v is speed, H is the Hubble parameter, which is,
according to current knowledge, around 22 km/s/(million light
years), and arrive at
v = 154 000 km/s,
which would be about half of the speed of light.

But anyway - the (apparent) recession speeds of galaxies
due to the expansion of the universe should not be confused
with real motions through space. Read this, please:
http://www.astronomycafe.net/cosm/expan.html

How does this relate to the initial inflation speed?

What do you mean with "inflation speed"? How fast the parts of space
where today this galaxy group is located moved away from us during
inflation, or what? There is no one single answer for this - during
inflation, the expansion rate of the universe was *accelerating*,
so this "apparent recession speed" was increasing all the time
during inflation.


Have there been slow downs?

After inflation, the expansion rate of the universe slowed
down for some billion years, but began to accelerate again
a few billion years ago.


Or, how
close were clusters when they were first formed?

Don't know.


I am looking
for absolute distances w/o gravitational distortion. Thank you.

What do you mean with "gravitational distortion" here?



Bye,
Bjoern

In article , Bjoern
Feuerbacher writes:

I suppose you simply mean the speed of the furthest group of galaxies
with respect to us. If the universe really is finite, then,
according to current knowledge (IIRC), it has a size of at
least 70 billion light years. So we can make a (very rough!)
estimate by using Hubble's law (which is *not* valid for
such large distances!):
v = H*d,
where v is speed, H is the Hubble parameter, which is,
according to current knowledge, around 22 km/s/(million light
years), and arrive at
v = 154 000 km/s,
which would be about half of the speed of light.

The v = H*d equation is valid for all distances, provided that the
distance is the proper distance and v its derivative. This is actually
quite simple to see: if a homogeneous and isotropic universe is to
remain that way, this is the only possible expansion law. Pure
kinematics; we don't even need any physics!

This is sometimes known as Hubble's Law.

At low redshifts, there is a linear relation between the redshift and
the luminosity distance. This is what Hubble actually discovered. AT
LOW REDSHIFTS, all distances are approximately equivalent, and the
velocity can be deduced from the redshift via the Doppler formula (even
though the redshift is not caused by the Doppler effect). This relation
becomes non-linear at higher redshifts.

Don't even think about trying to use the relativistic Doppler formula
for large redshifts. This is "not even wrong".

Recommended reading:

@ARTICLE {EHarrison93a,
AUTHOR = "Edward R. Harrison",
TITLE = "The Redshift-Distance and Velocity-Distance
Laws",
JOURNAL = APJ,
YEAR = "1993",
VOLUME = "403",
NUMBER = "1",
PAGES = "28",
MONTH = jan
}

@BOOK {EHarrison81a,
AUTHOR = "Edward R. Harrison",
EDITOR = "",
TITLE = "Cosmology, the Science of the Universe",
PUBLISHER = "Cambridge University Press",
YEAR = "1981",
ADDRESS = "Cambridge"
}

Bjoern Feuerbacher wrote:
kjakja wrote:
If most matter(maybe superclusters) have been separating at
an ever faster rate for 13+ billion years, what is the minimum
percent of the speed of light the furthest group is now
traveling relative to our speed?

We still do not know if the volume if the universe is finite
or infinite. If it's the latter, there is no "furthest group".

Additionally, what do you mean with "our speed" here? Our speed
relative to what?

I suppose you simply mean the speed of the furthest group of galaxies
with respect to us. If the universe really is finite, then,
according to current knowledge (IIRC), it has a size of at
least 70 billion light years. So we can make a (very rough!)
estimate by using Hubble's law (which is *not* valid for
such large distances!):
v = H*d,
where v is speed, H is the Hubble parameter, which is,
according to current knowledge, around 22 km/s/(million light
years), and arrive at
v = 154 000 km/s,
which would be about half of the speed of light.

But anyway - the (apparent) recession speeds of galaxies
due to the expansion of the universe should not be confused
with real motions through space. Read this, please:
http://www.astronomycafe.net/cosm/expan.html


From the website you cited -

"Two galaxies permanently located at positions (x1 , y1 , z1 ) and ( x2
, y2 , z2 ) at one time find themselves one billion light years apart.
Then a few billion years later while located at the same coordinates,
they find themselves 3 billion light years apart. The galaxies have not
'moved', nevertheless, their separations have increased."

It is unfortunate that astronomers who take their cue from the early
20th century concepts,give themselves an observational luxury that is
not present in actual observations and certainly not in large scale
cosmological modelling.

Foreground motion of the local Milky Way stars against any two galaxies
such as M81 and M82 emerges from acknowledging a center of rotation
around the Milky Way axis.

http://www.ast.cam.ac.uk/~ipswich/Ob...Ursa_Major.jpg

If a supernovae occured simultaneously in each parent galaxy and is
observed from Earth from a line drawn through the center of our Sun's
galactic orbital motion*,due to finite light distance,the actual
positions of each galaxy will NOT remain constant wrt the local stars.


* our astronomical ancestors used this method for heliocentric orbital
modelling from a line drawn through the center of the planet's orbit)


How does this relate to the initial inflation speed?

What do you mean with "inflation speed"? How fast the parts of space
where today this galaxy group is located moved away from us during
inflation, or what? There is no one single answer for this - during
inflation, the expansion rate of the universe was *accelerating*,
so this "apparent recession speed" was increasing all the time
during inflation.


Have there been slow downs?

After inflation, the expansion rate of the universe slowed
down for some billion years, but began to accelerate again
a few billion years ago.


Astronomers can model the positions of galaxies wrt to each other and
subsequently their collective structure and motions.Because "expansion
rate" is an unqualified notion which ignores the foreground motion of
Milky Way stars as a tool to model the galactic position and motion in
tandem with Roemer's insight on the illusion created by finite light
distance.

http://dibinst.mit.edu/BURNDY/Online...mer/index.html

If you have difficulties I suggest you review the M81/M82 image taken
from the perspective of the celestial sphere.Newton ,in creating the
geocentric/heliocentric orbital equivalency via Flamsteed's 1676
erroneous proof for isochronical rotation unwittingly shuts off the
ability to incorporate a greater axis of morion such as the solar
system's motion about the Milky Way axis along with the rest of the
local stars.See for yourself -

"Cor. 2. And since these stars are liable to no sensible parallax from
the annual motion of the earth, they can have no force, because of
their immense distance, to produce any sensible effect in our system.
Not to mention that the fixed stars, every where promiscuously
dispersed in the heavens, by their contrary actions destroy their
mutual actions, by Prop. LXX, Book I."







Or, how
close were clusters when they were first formed?

Don't know.


I am looking
for absolute distances w/o gravitational distortion. Thank you.

What do you mean with "gravitational distortion" here?



Bye,
Bjoern

In message ,
writes

If you have difficulties I suggest you review the M81/M82 image taken
from the perspective of the celestial sphere.Newton ,in creating the
geocentric/heliocentric orbital equivalency via Flamsteed's 1676
erroneous proof for isochronical rotation unwittingly shuts off the
ability to incorporate a greater axis of morion such as the solar
system's motion about the Milky Way axis along with the rest of the
local stars.See for yourself -

"Cor. 2. And since these stars are liable to no sensible parallax from
the annual motion of the earth, they can have no force, because of
their immense distance, to produce any sensible effect in our system.
Not to mention that the fixed stars, every where promiscuously
dispersed in the heavens, by their contrary actions destroy their
mutual actions, by Prop. LXX, Book I."

And just what is wrong with that? Sir Isaac did know about the inverse
square law, you know :-)
--
Support the DEC Tsunami Appeal http://www.dec.org.uk/.
Mail to jsilverlight AT merseia DOT fsnet DOT co DOT uk is welcome.


--
No virus found in this outgoing message.
Checked by AVG Anti-Virus.
Version: 7.0.300 / Virus Database: 265.6.13 - Release Date: 16/01/2005