SR time dilation on remote objects ?

On Tue, 06 Jul 2004 14:34:51 +0200, Bjoern Feuerbacher
wrote:

And this is still irrelevant for cosmology.

Can a galaxy moving through the cosmos at 1/2 the speed of another
galaxy claim to be older?

On Tue, 6 Jul 2004 07:13:41 -0700, "N:dlzc D:aol T:com \(dlzc\)" N:
dlzc1 D:cox wrote:

It is evidence that the Universe had a center, and where/when that center
was to be expected to be located.

David A. Smith
Where is this center? What has` when' got to do with where the center
you postulate was located. CBR seems to be rather uniform in all
directions. There are finite geographies that do not have `centers'.
If `red shift' is being correctly interpreted, everything appears to
be receding from earth's point of view.

On Tue, 6 Jul 2004 07:13:41 -0700, "N:dlzc D:aol T:com \(dlzc\)" N:
dlzc1 D:cox wrote:

It is evidence that the Universe had a center, and where/when that center
was to be expected to be located.

David A. Smith
Where is this center? What has` when' got to do with where the center
you postulate was located. CBR seems to be rather uniform in all
directions. There are finite geographies that do not have `centers'.
If `red shift' is being correctly interpreted, everything appears to
be receding from earth's point of view.

Dear vonroach:

"vonroach" wrote in message
...
On Tue, 6 Jul 2004 07:13:41 -0700, "N:dlzc D:aol T:com \(dlzc\)" N:
dlzc1 D:cox wrote:

It is evidence that the Universe had a center, and where/when that
center
was to be expected to be located.

Where is this center?

The "where" was any particular "here".

What has` when' got to do with where the center
you postulate was located.

Because any particular *now* is not at the center. Only the Big Bang is at
the center. Expansion has removed the center from the "contents" of the
Universe.

CBR seems to be rather uniform in all
directions. There are finite geographies that do not have `centers'.
If `red shift' is being correctly interpreted, everything appears to
be receding from earth's point of view.

Or from the point of view of any mass.

David A. Smith

Dear vonroach:

"vonroach" wrote in message
...
On Tue, 6 Jul 2004 07:13:41 -0700, "N:dlzc D:aol T:com \(dlzc\)" N:
dlzc1 D:cox wrote:

It is evidence that the Universe had a center, and where/when that
center
was to be expected to be located.

Where is this center?

The "where" was any particular "here".

What has` when' got to do with where the center
you postulate was located.

Because any particular *now* is not at the center. Only the Big Bang is at
the center. Expansion has removed the center from the "contents" of the
Universe.

CBR seems to be rather uniform in all
directions. There are finite geographies that do not have `centers'.
If `red shift' is being correctly interpreted, everything appears to
be receding from earth's point of view.

Or from the point of view of any mass.

David A. Smith

vonroach wrote:
On Tue, 06 Jul 2004 14:34:51 +0200, Bjoern Feuerbacher
wrote:


And this is still irrelevant for cosmology.


Can a galaxy moving through the cosmos at 1/2 the speed of another
galaxy claim to be older?

Speed relative to what?


Bye,
Bjoern

vonroach wrote:
On Tue, 06 Jul 2004 14:34:51 +0200, Bjoern Feuerbacher
wrote:


And this is still irrelevant for cosmology.


Can a galaxy moving through the cosmos at 1/2 the speed of another
galaxy claim to be older?

Speed relative to what?


Bye,
Bjoern

vonroach wrote:
On Tue, 06 Jul 2004 09:22:11 +0200, Bjoern Feuerbacher
wrote:


vonroach wrote:

On Mon, 5 Jul 2004 10:15:42 -0700, "N:dlzc D:aol T:com \(dlzc\)" N:
dlzc1 D:cox wrote:



The only evidence of the Big Bang is written at the observational the
limits of the Universe, namely the CMBR. Which indicates the Big Bang was
everywhere.

David A. Smith

But `everywhere' was hypothesized to be a `singularity'.

1) "singularity" is not necessarily the same as "point".
2) Probably there never was a singularity - at very high gravitational
fields (i.e. very high densities, close to the Big Bang) Quantum Gravity
effects should become important, and that could avoid a singularity. We
don't know yet.


Do you know what hypothesize means?

Yes. As you point out yourself, I said myself that we don't know yet.


As you state we do not know. Even
`probably' is an exaggeration.

No. We don't have a working quantum theory of gravity yet, but all
attempts in that direction have been quite consistent (AFAIK) in
saying that there should be no singularity.


Gravitational fields, quantum gravity,
are speculative which means the subject of thought, experiment, and
theorizing. Your very high densities, I interpret to mean very
concentrated matter, and very concentrated mass/energy, and any
`space' present would also be very tightly compacted.
A point has no dimension, only location.

It's not clear to me what you mean by "compacted" space, but I agree
with the rest.



Agreed.


A singularity is a vague concept

No, not at all. That is a precisely defined term. Look it up.


that implies very dense space/matter in very compact `space'.

It implies this in this special context - not in general.


Do you think a `singularity' is ever a `point'?

Yes. For example, when talking about a Black Hole.


I don't believe that
is the case. I don't recall using the term `point'.

I thought you meant this. Sorry for the misunderstanding.



[snip]

Bye,
Bjoern

vonroach wrote:
On Tue, 06 Jul 2004 09:22:11 +0200, Bjoern Feuerbacher
wrote:


vonroach wrote:

On Mon, 5 Jul 2004 10:15:42 -0700, "N:dlzc D:aol T:com \(dlzc\)" N:
dlzc1 D:cox wrote:



The only evidence of the Big Bang is written at the observational the
limits of the Universe, namely the CMBR. Which indicates the Big Bang was
everywhere.

David A. Smith

But `everywhere' was hypothesized to be a `singularity'.

1) "singularity" is not necessarily the same as "point".
2) Probably there never was a singularity - at very high gravitational
fields (i.e. very high densities, close to the Big Bang) Quantum Gravity
effects should become important, and that could avoid a singularity. We
don't know yet.


Do you know what hypothesize means?

Yes. As you point out yourself, I said myself that we don't know yet.


As you state we do not know. Even
`probably' is an exaggeration.

No. We don't have a working quantum theory of gravity yet, but all
attempts in that direction have been quite consistent (AFAIK) in
saying that there should be no singularity.


Gravitational fields, quantum gravity,
are speculative which means the subject of thought, experiment, and
theorizing. Your very high densities, I interpret to mean very
concentrated matter, and very concentrated mass/energy, and any
`space' present would also be very tightly compacted.
A point has no dimension, only location.

It's not clear to me what you mean by "compacted" space, but I agree
with the rest.



Agreed.


A singularity is a vague concept

No, not at all. That is a precisely defined term. Look it up.


that implies very dense space/matter in very compact `space'.

It implies this in this special context - not in general.


Do you think a `singularity' is ever a `point'?

Yes. For example, when talking about a Black Hole.


I don't believe that
is the case. I don't recall using the term `point'.

I thought you meant this. Sorry for the misunderstanding.



[snip]

Bye,
Bjoern

Bjoern Feuerbacher wrote in message ...
Marcel Luttgens wrote:
Bjoern Feuerbacher wrote in message ...

Marcel Luttgens wrote:

SR time dilation on remote objects ?


A remark to all GRists:

Instead of quibbling about formulae incorporating the "assumed"
space expansion, (pseudo-)cosmologists should better give their opinion
about

The "Triplets" thought experiment (Adapted from the "Twin paradox")

Why? It is irrelevant for the cosmological time dilation.

Why is it irrelevant? Are not remote galaxies receeding from
Earth with some velocity, which is a function of their distance?
Is such velocity only "apparent", Iow not real? If it is a mere
illusion, how do you explain the Doppler shift?
And if it is real (for those believing in expansion of course,
I have to dot the i's), and some galaxy at distance d from Earth
moves at v wrt the Earth, does not the Earth moves at the same
velocity wrt the galaxy? For an Earth observer, is not the time
on the galaxy slowed down by some factor wrt the time on Earth?
And for the galactic observer, is not time on Earth slowed
down by the same factor wrt its own time? Does this not logically
mean that the Earth clock and the galactic clock tick at the same
rate, as confirmed by Terence in the "Triplets thought experiment"?
As both clocks tick at the same rate, how can the contemporary
cosmologists claim that a time dilation factor of (1 + z) works
on supernovae to lessen the delay in the rest frame?
I am looking forward to reading your comments.



_________________________________

"Terence sits at home on Earth. Galaxy (yes, it's her name)
flies off in a space ship at a velocity v/2. Simultaneously,
Terra (also a name) flies off in the opposite direction at -v/2.
After a while, Terra, who considers that Galaxy flies away
from her at a velocity v,

Why should Terra consider that? Does she not know how to
add velocities in SR?


You don't seem to grasp the spirit of Terra's claim, which
is that Galaxy is flying away from her at some velocity.


claims that Galaxy is now younger
than her, exactly like GRists claim that time goes slower on
SN because of space expansion.

That is in no way "exactly like".


Don't GRists make such claim? Remove "exactly" if you prefer.


According to Terence, both Terra and the GRists are wrong,

There *is* no "right" or "wrong" here. Who is younger depends
on the frame of reference. There is no "absolute time".


This is trivial.


because Terra's clock and Galaxy's clock tick at the same
rate."

Right. And still irrelevant for cosmology.


Right, what a nice and honest concession!

But *not* irrelevant for cosmology: both clocks tick at the same
rate, not only according to Terence, but also, logically, to
Terra and Galaxy, who both should apply the Cosmological Principle.
Iow, they should know that the time slowing effect due to expansion
is symmetrical, and therefore conclude, contrary to the claims by
illogical relativistic cosmologists, to the absence of any observable
time dilation effect on remote objects like supernovae.



Till now, none of them dared to comment.
They should at least try to demonstrate that Terence is wrong.

No. In his frame of reference, he is perfectly right.


Fine.

In their frames of references, both Galaxy and Terra are also
perfectly right to claim that the other one is younger.

And this is still irrelevant for cosmology.


Could you elaborate, not forgetting elementary logic?
This also would be fine.

[Ad hominem comments snipped]



Bye,
Bjoern

Marcel Luttgens