| 1 Jeff Umbarger |
Big Bang Question | maandag 12 november 2001 0:36 |
| 2 V.Z.Nuri |
Re: Big Bang Question | maandag 12 november 2001 3:56 |
| 3 Jeff Umbarger |
Re: Big Bang Question | maandag 12 november 2001 6:01 |
| 4 AndroclesInFlorida |
Re: Big Bang Question | woensdag 14 november 2001 3:16 |
| 5 AndroclesInFlorida |
Re: Big Bang Question | woensdag 14 november 2001 7:09 |
| 6 Tom Roberts |
Re: Big Bang Question | woensdag 14 november 2001 19:22 |
| 7 Robert Karl Stonjek |
Re: Big Bang Question | woensdag 14 november 2001 20:34 |
Hello All, I'm sure this has been asked before, but I can't seem to find a similar posting. I'll start by stating the facts I believe to be true (and these can be refuted) and then I'll ask the questions based on those facts.
Facts:
1.) The universe is expanding - evidence by recessional redshifts and 3
degree CBR.
2.) The current *radius* of the universe is between 10 and 15 billion
light years.
3.) The farther we look in distance, the farther back in time we see.
If I look 15 billion light years to my left and see Galaxy A and then 15 billion light years to my right and see Galaxy B, then Galaxy A must be 30 billion light years from Galaxy B, right? However, because of the great distance I'm looking in to see these objects, they are very young when compared to the age of an expanding universe. Therefore these two galaxies must have been much closer together back 15 billion years ago as compared to today. However, they appear to be separated by 30 billion light years at the time I observed them.
Questions:
1.) How could two young galaxies appear on oppisite sides of the
universe when they should be right next to each other?
2.) Wouldn't observations like this indicate a steady-state universe vs.
an expanding one?
Thanks for any help on this.
- Jeff
Dear Jeff Umbarger:
| > |
Facts: 1.) The universe is expanding - evidence by recessional redshifts and 3 degree CBR. |
Which has been measured to be 9 degrees at some point in the "recent" past.
| > | 2.) The current *radius* of the universe is between 10 and 15 billion light years. |
'Visible' radius. What 'radius' is the CBR coming from?
| > |
3.) The farther we look in distance, the farther back in time we see.
If I look 15 billion light years to my left and see Galaxy A and then 15 billion light years to my right and see Galaxy B, then Galaxy A must be 30 billion light years from Galaxy B, right? However, because of the great distance I'm looking in to see these objects, they are very young when compared to the age of an expanding universe. Therefore these two galaxies must have been much closer together back 15 billion years ago as compared to today. However, they appear to be separated by 30 billion light years at the time I observed them.
Questions: |
If you live on the surface of a balloon, and you look far enough to the left, you will see the back of your head (assuming light also adheres to the balloon in its travel), similarly you can see galaxy A to your left and galaxy B to your right each at 15 billion light years. If we know the Universe popped 17 billion years ago, these two galaxies _might_ be only 4 billion light years apart, at the time the light you observed from them was emitted.
We don't know how long ago the Universe popped.
We don't know the relative velocity of these two galaxies, assuming we could even guess at the shape of the Universe, it might mean something to guess further.
| > | 2.) Wouldn't observations like this indicate a steady-state universe vs. an expanding one? |
CBR has been noted to be decreasing in energy with time. Increasing red shift with time (aka distance). Do either of those sound like there is no time variance... the definition of steady state?
Sorry if I come off being snide.
David A. Smith
Follow-up questions based on David Smith's response:
- Ok, so another assumption here, based on your response, is that space is curved and not flat, right?
- I understand how space *is* curved near massive objects, but the description of the balloon you gave below would indicate that the entire universe sits in a highly curved space. What's "curving" this space? I would not think that the universe is dense enough (that is; many massive galxies in a very compact space) to curve all of space. The effects of mass on curvature rapidly drop off with distance. Do you agree?
- Also, what if the universe is flat, Euclidian space. How, then, would we be able to explain galaxies a great distances from each other (30 billion light years) very close to the begining of the universe?
"dlzc@aol.com (formerly)" wrote:
| > | Dear Jeff Umbarger: |
| > > |
Facts: |
| > |
Which has been measured to be 9 degrees at some point in the "recent" past. |
| > > |
2.) The current *radius* of the universe is between 10 and 15 billion light years. |
| > |
'Visible' radius. What 'radius' is the CBR coming from? |
| > > |
3.) The farther we look in distance, the farther back in time we see. If I look 15 billion light years to my left and see Galaxy A and then 15 billion light years to my right and see Galaxy B, then Galaxy A must be 30 billion light years from Galaxy B, right? However, because of the great distance I'm looking in to see these objects, they are very young when compared to the age of an expanding universe. Therefore these two galaxies must have been much closer together back 15 billion years ago as compared to today. However, they appear to be separated by 30 billion light years at the time I observed them.
Questions: |
| > |
If you live on the surface of a balloon, and you look far enough to the left, you will see the back of your head (assuming light also adheres to the balloon in its travel), similarly you can see galaxy A to your left and galaxy B to your right each at 15 billion light years. If we know the Universe popped 17 billion years ago, these two galaxies _might_ be only 4 billion light years apart, at the time the light you observed from them was emitted. We don't know how long ago the Universe popped. We don't know the relative velocity of these two galaxies, assuming we could even guess at the shape of the Universe, it might mean something to guess further. |
| > > |
2.) Wouldn't observations like this indicate a steady-state universe vs. an expanding one? |
| > |
CBR has been noted to be decreasing in energy with time. Increasing red shift with time (aka distance). Do either of those sound like there is no time variance... the definition of steady state? Sorry if I come off being snide. David A. Smith |
"Jeff Umbarger"
Facts:
Questions:
Thanks for any help on this.
see http://members.home.net/androcles/tiredlight
"dlzc@aol.com (formerly)"
Facts:
Which has been measured to be 9 degrees at some point in the "recent" past.
'Visible' radius. What 'radius' is the CBR coming from?
If I look 15 billion light years to my left and see Galaxy A and then 15
billion light years to my right and see Galaxy B, then Galaxy A must be
30 billion light years from Galaxy B, right? However, because of the
great distance I'm looking in to see these objects, they are very young
when compared to the age of an expanding universe. Therefore these two
galaxies must have been much closer together back 15 billion years ago
as compared to today. However, they appear to be separated by 30 billion
light years at the time I observed them.
Questions:
1.) How could two young galaxies appear on oppisite sides of the
universe when they should be right next to each other?
If you live on the surface of a balloon, and you look far enough to the
left, you will see the back of your head (assuming light also adheres to the
balloon in its travel),
We don't know how long ago the Universe popped.
We don't know the relative velocity of these two galaxies, assuming we could
even guess at the shape of the Universe, it might mean something to guess
further.
2.) Wouldn't observations like this indicate a steady-state universe vs.
an expanding one?
CBR has been noted to be decreasing in energy with time.
Jeff Umbarger wrote:
You need to keep more careful track of the distinction between facts
and conclusions. The redshifts and CMBR observations are facts; that
the universe is expanding is a conclusion. But that is the best conclusion
presented so far which is in agreement with all the facts....
Here's your crucial mistake -- the radius of the _VISIBLE_ universe
be between 10 and 15 billion lightyears. We don't know what the
radius of the entire universe is....
Yes, as long as one uses the preferred "cosmological time" of the FRW
manifolds.
Yes.
They are on opposite sides of the _VISIBLE_ universe, _TODAY_. Back when
the light we see today was emitted from them, they were _THEN_ also on
opposite sides of the _VISIBLE_ universe _BACK_THEN_. Back then they were
much closer to earth (and to each other), but between emission and
detection the expansion of the universe has caused the light to travel
much longer paths. They were never "right next to each other" -- earth
was always between them.
Note I am using the usual "cosmological" coordinates in FRW
manifolds: time is measured everywhere along the geodesic paths
of the dust particles (galaxies), and distance is measured
along surfaces of constant time.
No. How can it be "steady state" if space is expanding?
Tom Roberts tjroberts@lucent.com
"Tom Roberts"
You need to keep more careful track of the distinction between facts
and conclusions. The redshifts and CMBR observations are facts; that
the universe is expanding is a conclusion. But that is the best conclusion
presented so far which is in agreement with all the facts....
2.) The current *radius* of the universe is between 10 and 15 billion
light years.
Here's your crucial mistake -- the radius of the _VISIBLE_ universe
be between 10 and 15 billion lightyears. We don't know what the
radius of the entire universe is....
3.) The farther we look in distance, the farther back in time we see.
Yes, as long as one uses the preferred "cosmological time" of the FRW
manifolds.
If I look 15 billion light years to my left and see Galaxy A and then 15
billion light years to my right and see Galaxy B, then Galaxy A must be
30 billion light years from Galaxy B, right? However, because of the
great distance I'm looking in to see these objects, they are very young
when compared to the age of an expanding universe. Therefore these two
galaxies must have been much closer together back 15 billion years ago
as compared to today. However, they appear to be separated by 30 billion
light years at the time I observed them.
Yes.
1.) How could two young galaxies appear on oppisite sides of the
universe when they should be right next to each other?
They are on opposite sides of the _VISIBLE_ universe, _TODAY_. Back when
the light we see today was emitted from them, they were _THEN_ also on
opposite sides of the _VISIBLE_ universe _BACK_THEN_. Back then they were
much closer to earth (and to each other), but between emission and
detection the expansion of the universe has caused the light to travel
much longer paths. They were never "right next to each other" -- earth
was always between them.
Note I am using the usual "cosmological" coordinates in FRW
manifolds: time is measured everywhere along the geodesic paths
of the dust particles (galaxies), and distance is measured
along surfaces of constant time.
2.) Wouldn't observations like this indicate a steady-state universe vs.
an expanding one?
No. How can it be "steady state" if space is expanding?
Tom, I've had my toes roasted several times for referring to 'expanding
space'. As has been pointed out to me, it is not space that expands but
*spacetime*. If you are telling me something different, ie expanding space,
then I will have to comb through previous posts and challenge those who
corrected me to explain why you say expanding space and they say expanding
spacetime!!
Philosophically, expanding spacetime requires only a physics account, but
expanding space is quite different because for space to expand, we must
either know or make assumptions about the nature of free space. No
assumptions of that kind are required for expanding spacetime which is
really an expansion of a coordinate system.
Further, the ether has no effect (its existence or non existence) except
when space expands. If space expands then the ether expands (becomes
thinner) and may have real and measurable consequences (though I'm not an
etherist and have not thought what these consequences/measurements might
be).
Kind Regards,
Back to my home page Contents of This Document
Not a fact. The recession is interpretation by theory, the redshift alone is
real. The CBR just is. Thus redshift and CBR are empircal data. How that is
interpreted depends upon theory.
>
Hello All,
I'm sure this has been asked before, but I can't seem to find a similar
posting. I'll start by stating the facts I believe to be true (and these
can be refuted) and then I'll ask the questions based on those facts.
1.) The universe is expanding - evidence by recessional redshifts and 3
degree CBR.
Not true. While it may be the limit to how far we can see, since redshift is
a function of distance, that doesn't mean there are not galaxies beyond this
radius that we cannot see.
>
2.) The current *radius* of the universe is between 10 and 15 billion
light years.
You see things as they were, yes, since the speed of light is quite slow,
cosmologically speaking.
>
3.) The farther we look in distance, the farther back in time we see.
Sure..(shrug).
>
If I look 15 billion light years to my left and see Galaxy A and then 15
billion light years to my right and see Galaxy B, then Galaxy A must be
30 billion light years from Galaxy B, right?
>
However, because of the
great distance I'm looking in to see these objects, they are very young
when compared to the age of an expanding universe. Therefore these two
galaxies must have been much closer together back 15 billion years ago
as compared to today. However, they appear to be separated by 30 billion
light years at the time I observed them.
1.) How could two young galaxies appear on oppisite sides of the
universe when they should be right next to each other?
2.) Wouldn't observations like this indicate a steady-state universe vs.
an expanding one?
and
http://members.home.net/androcles/dark2
5 Big Bang Question
Van: AndroclesInFlorida
Onderwerp: Re: Big Bang Question
Datum: woensdag 14 november 2001 7:09
>
Dear Jeff Umbarger:
> >
1.) The universe is expanding - evidence by recessional redshifts and 3
degree CBR.
That can be put down to experimental error.
>
> >
2.) The current *radius* of the universe is between 10 and 15 billion
light years.
That cannot be determined, and therefore provides no information :)
>
> >
3.) The farther we look in distance, the farther back in time we see.
A bold assumption. If you look in a mirror, you'll see your face... but so
what?
>
>
similarly you can see galaxy A to your left and
galaxy B to your right each at 15 billion light years. If we know the
Universe popped 17 billion years ago, these two galaxies _might_ be only 4
billion light years apart, at the time the light you observed from them was
emitted.
> >
WHAT? It hasn't been discovered for long enough to make that determination!
Where did you get that piece of tripe from?
>
Yep... see
http://members.home.net/androcles/dark2
>
Increasing red
shift with time (aka distance). Do either of those sound like there is no
time variance... the definition of steady state?
That's ok.. Some of us are used to relativists being snide.
>
Sorry if I come off being snide.
6 Big Bang Question
Van: Tom Roberts tjroberts@lucent.com
Onderwerp: Re: Big Bang Question
Datum: woensdag 14 november 2001 19:22
>
Facts:
1.) The universe is expanding - evidence by recessional redshifts and 3
degree CBR.
>
2.) The current *radius* of the universe is between 10 and 15 billion
light years.
>
3.) The farther we look in distance, the farther back in time we see.
>
If I look 15 billion light years to my left and see Galaxy A and then 15
billion light years to my right and see Galaxy B, then Galaxy A must be
30 billion light years from Galaxy B, right? However, because of the
great distance I'm looking in to see these objects, they are very young
when compared to the age of an expanding universe. Therefore these two
galaxies must have been much closer together back 15 billion years ago
as compared to today. However, they appear to be separated by 30 billion
light years at the time I observed them.
>
1.) How could two young galaxies appear on oppisite sides of the
universe when they should be right next to each other?
>
2.) Wouldn't observations like this indicate a steady-state universe vs.
an expanding one?
7 Big Bang Question
Van: Robert Karl Stonjek
Onderwerp: Re: Big Bang Question
Datum: woensdag 14 november 2001 20:34
>
Jeff Umbarger wrote:
> >
Facts:
1.) The universe is expanding - evidence by recessional redshifts and 3
degree CBR.
>
> >
>
> >
>
> >
>
> >
>
> >
>
Robert Karl Stonjek.
Created: 16 November 2001