Picture of galaxy from when expansion only 600 million years old

[Sisyphus]

I can go back in time (virtually) in several directions. I can go back in time and encounter galaxy UDFy-38135539 3,1 billions LY away. And I can go back in time through another galaxy, also 3,1 billions LY away, in the opposite direction. Those 2 galaxies are not close together, although they belong to the same past. And the further I go in the past, the further will be such galaxies.

 

Yes, and?

 

Are you claiming that if we could look at the "sphere" in an even further past, it was smaller and smaller?

I am claiming that the sphere gets bigger as much we go in the past.

 

The farther in the past you go, the greater the portion of the universe you are seeing. A particular portion of the universe was smaller farther in the past. The portion of the universe "inside" the CMBR has a radius of 46 billion LY. That portion at the time the CMBR was emitted had a radius of 40 million LY.

[michel123456]

Obviously, we don't understand each other.

For example, how is it possible that the CMBR has a radius in the first place?

Look back at sketch B. The past is outside. We are inside the bang (how to call it?). The past is always bigger than the present. Is that compatible with the BBT?

 

Yes, and?

 

That doesn't bother you. That galaxies were once twice the distance we are observing far away from each other. And that happened a few moments after the supposed BB. And the farther we go in observation, the more far away from each other are such galaxies. To me, it is incomprehensible. The closer we get to the BB time, the more far away are objects from each other. It should be the contrary, isn't it?

Edited October 29, 2010 by michel123456

[Sisyphus]

For example, how is it possible that the CMBR has a radius in the first place?

 

It has a radius from our perspective. It isn't actually a sphere of stuff. An observer located at some point on our sphere of CMBR would see CMBR at our location, and also be centered inside a sphere. The BB was everywhere, not in a hollow shell around us.

 

Suppose that today, simultaneously in our reference frame, every star in the universe turned green. From then on, we would observe an expanding ball of green centered on ourselves, and so would every observer in the universe. Whether the metric of space increased, decreased, or stayed constant during that time would not change that fact.

[michel123456]

It has a radius from our perspective. It isn't actually a sphere of stuff. An observer located at some point on our sphere of CMBR would see CMBR at our location, and also be centered inside a sphere. The BB was everywhere, not in a hollow shell around us.

 

 

Take a sheet of paper and draw it.

[Sisyphus]

Take a sheet of paper and draw it.

 

Here.

 

 

13.7 billion years ago, when the CMBR was emitted, the two observers were 40 million LY apart.

[imatfaal]

Why should a description of 3 spatial & one time dimensions be reducible to a 2 dimensional sketch? Sisyphus' second comment about stars turning green gave a wonderful notion of how any universal effect will appear to use to be a spherical effect with us, the observer, at the centre.

[michel123456]

Here.

 

 

13.7 billion years ago, when the CMBR was emitted, the two observers were 40 million LY apart.

 

Do it again. And again. And again.

You'll be out of range of the Big Bang. (edit: I think you are already)

I guess you ment billions, not millions.

You can also draw UDFy-38135539

And many other UDFies out of range of the BB.

Edited October 29, 2010 by michel123456

[Sisyphus]

Do it again. And again. And again.

You'll be out of range of the Big Bang.

 

The Big Bang would be a universal event. It doesn't have a range. It's everywhere at once.

 

I guess you ment billions, not millions.

 

No, I meant million. Light emitted at the time of the CMBR has traveled fro 13.7 billion years, and reached a point that was 40 million LY distant at the time of emission and 46 billion LY distant at the time of reception.

[michel123456]

The Big Bang would be a universal event. It doesn't have a range. It's everywhere at once.

 

 

 

No, I meant million. Light emitted at the time of the CMBR has traveled fro 13.7 billion years, and reached a point that was 40 million LY distant at the time of emission and 46 billion LY distant at the time of reception.

 

The Big Bang has a range of 13,7 billion years.

[Sisyphus]

The Big Bang has a range of 13,7 billion years.

 

I don't know what you mean by that.

[imatfaal]

No he means millions - if I have it straight (and I thank you for starting this argument because I hope I am learning) we see a sphere centred on us (see green stars reasoning) of CMBR of radius 46billion light years. When the universe was hot enough to create the gamma (?) radiation (that has now been red-shifted down to microwaves) and forms the CMBR this same sphere was 40 Million light years. But the spheres are only from OUR perspective - the big bang was everywhere, we just see it at 46 Billion light years. All observers in the universe will see the CMBR at 46 Billion LY.

[michel123456]

I don't know what you mean by that.

 

Oh, I thought you knew everything.

It's a joke.

Of course.

 

UDFy-38135539 is 13,1 billions years away from the earth.

 

UDFy-38135539 is 0,6 billion year from the BB

 

The BB is 13,7 billions years away from the Earth.

 

That is what i call the BB range.

 

BTW when you say "It's everywhere at once." speaking about the BB: I don't know what you mean by that.

[Sisyphus]

Oh, I thought you knew everything.

It's a joke.

Of course.

 

UDFy-38135539 is 13,1 billions years away from the earth.

 

UDFy-38135539 is 0,6 billion year from the BB

 

The BB is 13,7 billions years away from the Earth.

 

That is what i call the BB range.

 

BTW when you say "It's everywhere at once." speaking about the BB: I don't know what you mean by that.

 

The BB is not 13.7 billion LY away. It happened 13.7 billion years ago, everywhere. When the universe became transparent after that, the light we call the CMBR was emitted, from everywhere. We could still see it today by looking at light that has traveled for 13.7 billion years. However, the only light that we can see that has been traveling for 13.7 billion years is from a spherical region that is currently 46 billion LY away, and was 40 million LY away at the time it was emitted.

[michel123456]

The BB is not 13.7 billion LY away. It happened 13.7 billion years ago, everywhere. When the universe became transparent after that, the light we call the CMBR was emitted, from everywhere. We could still see it today by looking at light that has traveled for 13.7 billion years. However, the only light that we can see that has been traveling for 13.7 billion years is from a spherical region that is currently 46 billion LY away, and was 40 million LY away at the time it was emitted.

 

Hm. So a single event, a singularity(???), happened "everywhere"(???) simultanitly(???), autocreating(???) itself together with space & time. That makes sense (to others, not to me). BB happened here where I sit, there where the galaxies go round, and there where you are, inside your brain. Most probably only there...

To me it is not physics anymore, there are too many question marks.

 

 

you didn't answer this one:

That galaxies were once twice the distance we are observing far away from each other. And that happened a few moments after the supposed BB. And the farther we go in observation, the more far away from each other are such galaxies. To me, it is incomprehensible. The closer we get to the BB time, the more far away are objects from each other. It should be the contrary, isn't it?

Edited October 29, 2010 by michel123456

[Sisyphus]

 

you didn't answer this one:

That galaxies were once twice the distance we are observing far away from each other. And that happened a few moments after the supposed BB. And the farther we go in observation, the more far away from each other are such galaxies. To me, it is incomprehensible. The closer we get to the BB time, the more far away are objects from each other. It should be the contrary, isn't it?

 

I still don't get why you think objects were farther apart in the past, so I'm not sure how to go about answering it.

[losfomot]

I still don't get why you think objects were farther apart in the past, so I'm not sure how to go about answering it.

 

I think he is measuring the distance between galaxies A and B and comparing it to the distance between galaxies C and D (the further back you go in time, the farther apart the objects are)... when he should be measuring the average distance between galaxies E and B and comparing it to the average distance between galaxies F and D.

 

I think.

 

 

The center represents Earth.

lol... sorry, F and D should be closer together in the diagram.

[Spyman]

What do you see?

This is how I interpret the movie:

 

We are not moving through time towards the Big Bang, instead we are moving through our observable universe, from its center at Earth and outward through the boundary of our cosmic horizon. At time 3:36 the movie shows our cosmic horizon in space from the outside and yet unknown part of the Universe and then we start to move back inside towards Earth again.

 

Nowhere in the movie am I able to see any inconsistency at all with the Big Bang theory and especially I am not able to see galaxies to be generally more spread out at distances further away from Earth or any claims that the remote past of the Universe should have been wider or that anything is "getting bigger & bigger as much we go back in time".

 

-----

 

If you throw a rock into a lake and observe the waves moving outward like rings, the outermost rings have the greatest radius and are the oldest and yet they were smaller the further back in time we go, closer towards the impact time of the rock.

 

I am not able to understand why you think that because the rings we see are bigger and older the further away we are looking, it then somehow implies that the rings themselves would grow or be bigger if we should go back in time.

 

-----

 

[EDIT]

This is how the Known Universe looks from our viewpoint:

"In more recent studies the universe appears as a collection of giant bubble-like voids separated by sheets and filaments of galaxies, with the superclusters appearing as occasional relatively dense nodes. This network is clearly visible in the 2dF Galaxy Redshift Survey. In the figure a 3-D reconstruction of the inner parts of the survey is shown, revealing an impressive view on the cosmic structures in the nearby universe. Several superclusters stand out, such as the Sloan Great Wall, the largest structure in the universe known to date."

http://en.wikipedia.org/wiki/Observable_universe

Edited October 29, 2010 by Spyman

[IM Egdall]

Yes. In your link also under "If the Universe is only 14 billion years old, why isn't the most distant object we can see 7 billion light years away?"

 

We can read : "This question makes some hidden assumptions about space and time which are not consistent with all definitions of distance and time. One assumes that all the galaxies left from a single point at the Big Bang, and the most distant one traveled away from us for half the age of the Universe at almost the speed of light, and then emitted light which came back to us at the speed of light." emphasis mine.

 

This is something similar, where it seems to me that people believe that we are at the center of the Universe, or that we were once upon a time. Or i understand very badly.

 

In the OP, I think it is understandable that the Big Bang, if it were visible (we know it is not) should be BEHIND the UDFy-38135539 galaxy, and not in front of it.

 

 

The big bang, if it were visible, would be both behind and in front of this galaxy. As I understand it, cosmological models tell us that the big bang is not at a specific location. It occurred here, there and everywhere in the universe. Wild, huh! Think of the expanding balloon analogy. The SURFACE of the balloon represents our universe. So where is the center of this surface? There is no center.

[michel123456]

I think he is measuring the distance between galaxies A and B and comparing it to the distance between galaxies C and D (the further back you go in time, the farther apart the objects are)... when he should be measuring the average distance between galaxies E and B and comparing it to the average distance between galaxies F and D.

 

I think.

 

 

The center represents Earth.

lol... sorry, F and D should be closer together in the diagram.

 

1.Right. I am measuring the distance between A & B. Because as much as I can understand, A & B were close together at the time of the BB. (And C and E and Earth were together)

 

2. In all space-time diagrams I have seen, following the BB hypothesis, the Universe is smaller in the past: Galaxies A & B were closer together, and I think it is not what we are observing.

 

3.Hubble's Law says that the further are the galaxies, the more distanced they are. Right. So I am asking, how come that this observation (in which I agree) drives to a theory that says exactly the contrary, that galaxies were together in the past?

 

4. the average distance between E & B is an interesting feature, but I am not aware of such information, it does not come out of Spyman's diagram for example, and IIRC the Universe is considered homogeneous and isotropic at large scale. It has nothing to do with my objections on the BBT.

 

Here we are. We do not see the same thing.

 

This is how I interpret the movie:

 

We are not moving through time towards the Big Bang, instead we are moving through our observable universe, from its center at Earth and outward through the boundary of our cosmic horizon. At time 3:36 the movie shows our cosmic horizon in space from the outside and yet unknown part of the Universe and then we start to move back inside towards Earth again.

Emphasis mine (counts for the followings too).

I completely disagree with you. The movie do not show the Universe TODAY. It shows the universe that we are observing today from the Earth, as it was some time ago. The "time-ago" feature expands in the past as much we go far away in distance. When we reach the limits of our observable universe, at time 3,36 in the movie, we are closer to the Big Bang than we are today. It is a travel in the past, not only a travel in space.

 

 

Nowhere in the movie am I able to see any inconsistency at all with the Big Bang theory and especially I am not able to see galaxies to be generally more spread out at distances further away from Earth or any claims that the remote past of the Universe should have been wider or that anything is "getting bigger & bigger as much we go back in time".

Or you have your eyes closed, or I cannot explain what I am seeing. In a single question, which is bigger, the Earth, or the entire Universe?

-----

 

If you throw a rock into a lake and observe the waves moving outward like rings, the outermost rings have the greatest radius and are the oldest and yet they were smaller the further back in time we go, closer towards the impact time of the rock.

Exactly. Here we agree.

 

I am not able to understand why you think that because the rings we see are bigger and older the further away we are looking, it then somehow implies that the rings themselves would grow or be bigger if we should go back in time.

(..)

And here I understand that I cannot make myself clear. What you don't understand is exactly the same as my objection upon the BBT. I am claiming that observation is that the rings grow when we go back in time, and that the analogy of the rock throwned into a lake is exactly the contrary of observation.

 

How to say it otherways?

 

in the rock-in-the-lake analogy, the waves moving outwards are going forward in time, of course. Well, our observation don't go like that. Our observation go backward in time.

 

I hope here below a simple way to explain my point of vue:

 

in the rock-in-the-lake analogy, the outer wave is the oldest. In our observation of the Universe, the outer wave is the youngest.

Edited October 30, 2010 by michel123456

[between3and26characterslon]

For no other reason than to add to the confusion, if the universe is 14bn years old and the light from the most distant was emitted 14bn years ago then the light would not have had any distance to travel becasue at that time objects were close together. So if we are observing light that is 14bn years old it must have been at least 14bn LY away when it was emitted???

 

Hope that helps

[Sisyphus]

 

Here. In the early universe, light has only had time to travel from A to Earth (making that the perceived location of the CMBR), and everything is close together. In the present universe, light has had time to travel from D to Earth, and everything is farther apart. Where is the problem?

[michel123456]

 

Here. In the early universe, light has only had time to travel from A to Earth (making that the perceived location of the CMBR), and everything is close together. In the present universe, light has had time to travel from D to Earth, and everything is farther apart. Where is the problem?

 

No. We have no representation of the "present universe". What we observe is the universe in the past.

[Sisyphus]

No. We have no representation of the "present universe". What we observe is the universe in the past.

 

In a way. Hence why the CMBR is visible in both diagrams, despite being in the past of both. What part of the drawing do you object to?

[michel123456]

In a way. Hence why the CMBR is visible in both diagrams, despite being in the past of both. What part of the drawing do you object to?

 

The succession of the 2 diagrams suggests that in some sort CMBR grew from one situation to the other as in the stone-in-the-lake analogy. This is not the way it goes. If CMBR was small (left side) 13,7 billion years ago, we should observe it that way today, because we observe today what was going on 13,7 billion years ago. And we are not observing a small CMBR ring.

 

 

As I said above, the outer ring is younger than the inside ring. In Universe's history, the larger ring comes before the smaller ones. The story goes from the outside to the inside. The story goes from the larger ring to the smaller ring. Not from the small to the big.

Edited October 31, 2010 by michel123456

[Sisyphus]

The CMBR does not grow. The red rings in the drawings are not actual objects, but the view from Earth. Think of it as an event, that occurred simultaneously throughout the universe. As you move farther into the future from that event, you will have to look a farther distance in order to see it, because the light emitted from the nearby parts of it will have already passed.