[JustinW]

I have recently watched a talk given by Strauss called "universe from nothing". It was pretty insightfull but brought a question to mind about the expansion of the universe. In the talk he layed out a scenario of what hubble observed with a grid of dots. Every dot represented a galaxy. When overlapping a grid that was observed at a later time with a grid previously observed you could see that the dots expanded outward from our galaxy, and that the further out the galaxy, the greater the rate of expansion. He showed that this was true, not just from our galaxy's stand point but with observing from any galaxy. Giving the effect that whatever galaxy the observer stood on would seem as though it were the center of the universe.



Since the outer galaxies are expanding at a faster rate, by his explanation, one standing on one of the outer galaxies would observe our galaxy expanding at this same greater rate. This doesn't add up. Because if someone were standing on one of the outer galaxies looking toward earth we would look like we were moving outward at more than the SOL and the galaxies around us would be also. But this isn't the case. The galaxies around us are not moving away from us at that speed, are they? If not then why would an observer at the outer point of our observable looking in observe this? So is the expansion rate the same throughout the universe? Or is it greater for galaxies on the outer edge of our observation cone? I don't see how it can be both and was hoping someone might be able to explain.


Also, if the speed IS greater the farther out the observation we could pin point the location of the center of the universe? Which by Krausses explanation would be our galaxy.

http://www.youtube.c...h?v=7ImvlS8PLIo This is the talk by Krauss. It is a long video but the grid and explanation is in the first ten minutes I think.

I hope I didn't confuse anyone too much. The picture in my head was a lot simpler than when I tried to put it in words.

[PaulWDent]

A nice thing happens when the rekative velocity (due to expansion) between two galaxies is proportional to the distance between them. That is, you will observe exactly the same rate of expansion wherever you are, and every other galaxy appears to be moving away from you. Wherever you are seems to be the center!

Reduce it to one dimension to make things easy: Consider a stream cars accelerating away from a stop light. The car 1000 meters ahead is already doing 100km/hr
The car 800 meters ahead has only reached 80km/hr. The car 600 meters ahead is only doing 60km/hr, and on on.

The car 800 meters ahead sees the car 1000 meters ahead, that is 200 meters ahead of him, doing 20km/hr faster than he is going. It's 200m away from him and receding from him at the rate of 20km/hr. That's the same relative-velocity-versus-distance law of 10km/hr per 100m of separation. He also sees the car 600 meters ahead of the stop light but 200 meters behind him, which is going 20km/hr slower than him, getting further behind him at the rate of 20km/hr.

So cars both in front and behind seem to be receding from him at a rate of 10km/hr per 100m of distance away from him.

He therefore thinks he is the center of expansion! (But every car sees the same thing)

[michel123456]

PaulWDent, on 3 January 2012 - 04:31 AM, said:

A nice thing happens when the rekative velocity (due to expansion) between two galaxies is proportional to the distance between them. That is, you will observe exactly the same rate of expansion wherever you are, and every other galaxy appears to be moving away from you. Wherever you are seems to be the center!

Reduce it to one dimension to make things easy: Consider a stream cars accelerating away from a stop light. The car 1000 meters ahead is already doing 100km/hr
The car 800 meters ahead has only reached 80km/hr. The car 600 meters ahead is only doing 60km/hr, and on on.

The car 800 meters ahead sees the car 1000 meters ahead, that is 200 meters ahead of him, doing 20km/hr faster than he is going. It's 200m away from him and receding from him at the rate of 20km/hr. That's the same relative-velocity-versus-distance law of 10km/hr per 100m of separation. He also sees the car 600 meters ahead of the stop light but 200 meters behind him, which is going 20km/hr slower than him, getting further behind him at the rate of 20km/hr.

So cars both in front and behind seem to be receding from him at a rate of 10km/hr per 100m of distance away from him.

He therefore thinks he is the center of expansion! (But every car sees the same thing)

Wonderful example!
It was beaten down to death when I presented it some time ago. I'll have to dig to find it. (edit: found it here)

(parenthesis)
the following is not an answer to the OP:
there are 2 combined effects here, acceleration & delay. The example works because the cars didn't start at the same time at the stop light: the first car started, then the second say 1 sec. later, the third 2 sec. later and so on.

Following the Big-Bang Theory, all "cars" started at the same time. The delay is only observational caused by the fact that Speed of Light is finite: we observe the "car" behind us as if it had started in the past.
Then to explain expansion, the only thing you need is acceleration. There is no need for direction: all the "cars" may be moving "in a stream", in the same direction.
(parenthesis closed)

I'd like to hear the mainstream answer to the OP.
Taking into account that
_the receding galaxies we observe far away are galaxies in the past: they were receding from us. The objects near to us, that are in closest time, are not receding so much.
_an observer placed upon a far away galaxy is also an observer in the past: he is supposed observing another universe closer to the CMBR and he cannot observe us because we are in his future.

This post has been edited by michel123456: 3 January 2012 - 08:20 AM

[JustinW]

Alright I can get the jest of what you're saying. When someone says that the outer galaxies that we observe are receding at twice the SOL, how do they know that they are moving that fast and not us moving that fast relative to their past observable location? It was a nice example and it is probably something very simple, I'm just trying to wrap my head around it. How can an outer observer see that our galaxy and the one next to us move apart at the same rate as we observe his galaxy and the one next to him if they're moving faster than us? It would seem that if an outside observer were moving that much faster than us, he would be able to tell by observing the relation to things around him compared to the relation to things around us. Is that how we know how fast the expansion is at the outer part of our light cone?

[guenter]

JustinW, on 3 January 2012 - 02:10 PM, said:

How can an outer observer see that our galaxy and the one next to us move apart at the same rate as we observe his galaxy and the one next to him if they're moving faster than us?

That is plausible, provided both, we and our outer colleague, agree on the current standard cosmology, based on the cosmological principle. It is also helpful to think of the expanding dotted balloon.

[Arch2008]

Galaxies move according to the laws of gravity. So galaxies in our Virgo Super Galaxy Cluster orbit around a common center of gravity. Thus, the Milky Way and Andromeda are moving toward each other, while others are moving away from us.

However, the space itself between every galaxy is inflating. This is caused by Dark Energy. A given megaparsec (mps) of so-called empty space inflates according to Hubble’s constant. The more megaparsec’s you have between any two galaxies, the greater the effect of inflation. So two galaxies separated by a thousand mps will have the distance between them increase faster than two galaxies separated by only one mps by a factor of a thousand. An observer on any particular galaxy will see the distance between their galaxy and all others increase and conclude that the galaxy they are on is “at the center”, which is a misconception. The actual space between is inflating.

Dark Energy (DE) may be the energy of space itself. At current levels, gravity is stronger than DE. This is why the effect is not noticed inside galaxies. However, the more space inflates the more DE you get. If the rate continues, then in about fifty billion years, DE will overcome the Strong nuclear force and all of the hadrons will fly apart.

[derek w]

PaulWDent.Your analogy with the stream of cars accelerating is wrong.The cars would not move,the road would be like a giant elastic band that is being stretched,and the cars would move away from each other because the road is expanding,and the rate at which the road expands would be accelerating.

[JustinW]

I always confuse myself when trying to explain things like this. I think the expanding dotted balloon analogy is a good one, except there is always a dot on the balloon that stays in the same place. Esspecially if you concider the universe to be flat. And the fact that the outer dots from the static dot move faster.

[zapatos]

Arch2008, on 3 January 2012 - 05:58 PM, said:

Galaxies move according to the laws of gravity. So galaxies in our Virgo Super Galaxy Cluster orbit around a common center of gravity. Thus, the Milky Way and Andromeda are moving toward each other, while others are moving away from us.

However, the space itself between every galaxy is inflating. This is caused by Dark Energy. A given megaparsec (mps) of so-called empty space inflates according to Hubble’s constant. The more megaparsec’s you have between any two galaxies, the greater the effect of inflation. So two galaxies separated by a thousand mps will have the distance between them increase faster than two galaxies separated by only one mps by a factor of a thousand. An observer on any particular galaxy will see the distance between their galaxy and all others increase and conclude that the galaxy they are on is “at the center”, which is a misconception. The actual space between is inflating.

Dark Energy (DE) may be the energy of space itself. At current levels, gravity is stronger than DE. This is why the effect is not noticed inside galaxies. However, the more space inflates the more DE you get. If the rate continues, then in about fifty billion years, DE will overcome the Strong nuclear force and all of the hadrons will fly apart.

If I understand you correctly, it sounds as if you are saying the space between galaxies in a supercluster is expanding. That is not so, as gravity is stronger than the effects of DE. It is between superclusters that you see space expanding.

JustinW, on 3 January 2012 - 06:30 PM, said:

I always confuse myself when trying to explain things like this. I think the expanding dotted balloon analogy is a good one, except there is always a dot on the balloon that stays in the same place. Esspecially if you concider the universe to be flat. And the fact that the outer dots from the static dot move faster.

But with the baloon analogy, you can pick ANY dot to be the one that stays in the same place. The rest move away relative to it. Just as the view is from anywhere in the universe. We all look like we are the one dot not moving.

Quote

Since the outer galaxies are expanding at a faster rate, by his explanation, one standing on one of the outer galaxies would observe our galaxy expanding at this same greater rate. This doesn't add up. Because if someone were standing on one of the outer galaxies looking toward earth we would look like we were moving outward at more than the SOL and the galaxies around us would be also. But this isn't the case. The galaxies around us are not moving away from us at that speed, are they? If not then why would an observer at the outer point of our observable looking in observe this?

I think the confusion here is when you said "if someone were standing on one of the outer galaxies looking toward earth we would look like we were moving outward at more than the SOL and the galaxies around us would be also. But this isn't the case. The galaxies around us are not moving away from us at that speed, are they?" The person standing on one of the outer galaxies looking toward earth would see us moving outward FROM THEM at greater than SOL, and the galaxies around us would also be moving outward FROM THEM at greater the SOL. That is, the galaxies around us are not moving away FROM US at greater than SOL, they are moving away FROM THEM at greater than SOL.

[JustinW]

Right, so the expansion is at the same rate all around. It's just that galaxies closer to us are moving at a speed more relative to ours?

[zapatos]

JustinW, on 3 January 2012 - 07:05 PM, said:

Right, so the expansion is at the same rate all around. It's just that galaxies closer to us are moving at a speed more relative to ours?

The expansion rate is the same everywhere. Imaging the G's below represent galaxies, and each 's' is one unit of space. You will notice that G7 is one unit from G6, and G8 is two units from G6, and G9 is three units from G6, etc.

G1 s G2 s G3 s G4 s G5 s G6 s G7 s G8 s G9 s G10 s G11 s G12

Now picture space expanding. There will be a new unit of space between each galaxy, so now the picture looks like the following, with two units of space between each galaxy:


G1 ss G2 ss G3 ss G4 ss G5 ss G6 ss G7 ss G8 ss G9 ss G10 ss G11 ss G12


The result being that now, G7 is two units from G6, and G8 is four units from G6, and G9 is six units from G6, etc.

So the further away a galaxy is, the faster is seems to be receding from you. And this holds true for any galaxy you choose to start at. Start from any one and you see that the further away a galaxy is from you, the faster it seems to be receding from you.

If I'm at G1, G2 seems to be receding FROM ME slowly, and G11 and G12 seems to be receding FROM ME quickly.
If I'm at G12, G11 seems to be receding FROM ME slowly, and G1 seems to be receding FROM ME quickly.

EDIT for fat fingers.

This post has been edited by zapatos: 4 January 2012 - 12:52 AM

[JustinW]

Once explained it seems so simple. I don't know why I didn't understand in the first place. Maybe I was in an argumentative mood when I watched the video. Just out of curiousity, does anyone happen to know if the vacuum pressure of space is changing with the rate of expansion? And if not, why not? I'm sure someone has heard me ask this before, but I don't think I've ever gotten a clear answer.

This post has been edited by JustinW: 3 January 2012 - 08:30 PM

[michel123456]

zapatos, on 3 January 2012 - 07:31 PM, said:

The expansion rate is the same everywhere. Imaging the G's below represent galaxies, and each 's' is one unit of space. You will notice that G7 is one unit from G6, and G8 is two units from G6, and G9 is three units from G6, etc.

G1 s G2 s G3 s G4 s G5 s G6 s G7 s G8 s G9 s G10 s G11 s G12

Now picture space expanding. There will be a new unit of space between each galaxy, so now the picture looks like the following, with two units of space between each galaxy:


G1 ss G2 ss G3 ss G4 ss G5 ss G6 ss G7 ss G8 ss G9 ss G10 ss G11 ss G12


The result being that now, G7 is two units from G6, and G8 is four units from G6, and G9 is six units from G6, etc.

So the further away a galaxy is, the faster is seems to be receding from you. And this holds true for any galaxy you choose to start at. Start from any one and you see that the further away a galaxy is from you, the faster it seems to be receding from you.

If I'm at G1, G2 seems to be receding FROM ME slowly, and G11 and G12 seems to be receding FROM ME quickly.
If I'm at G12, G11 seems to be receding FROM ME slowly, and G1 seems to be receding FROM ME quickly.

EDIT for fat fingers.

Is this correct?
At the risk of being stupid I thought (accelerating) expansion was
G1 s G2 ss G3 sss G4 ssss G5 sssss G6 ssssss G7 sssssss G8 ssssssss G9 sssssssss G10 ssssssssss G11 sssssssssss G12
With G12 a galaxy cluster in the very long past.

[zapatos]

michel123456, on 4 January 2012 - 08:15 AM, said:

Is this correct?
At the risk of being stupid I thought (accelerating) expansion was
G1 s G2 ss G3 sss G4 ssss G5 sssss G6 ssssss G7 sssssss G8 ssssssss G9 sssssssss G10 ssssssssss G11 sssssssssss G12
With G12 a galaxy cluster in the very long past.

Disclaimer: I am not an expert.

Because the expansion of space is the same everywhere, you get my example:
G1 ss G2 ss G3 ss G4 ss G5 ss G6 ss G7 ss G8 ss G9 ss G10 ss G11 ss G12
There is no preferred position in space. No matter where you are, the further the galaxy from you, the faster it seems to move.

In your example:
G1 s G2 ss G3 sss G4 ssss G5 sssss G6 ssssss G7 sssssss G8 ssssssss G9 sssssssss G10 ssssssssss G11 sssssssssss G12
If you were sitting at G8, space would be acting differently looking toward G12 than if you were looking toward G1.

I may be mistaken but you seem to be mixing space and velocity.

If you were to illustrate the apparant velocity from your location at G1 as you looked into the very long past, you would see:
G1 v G2 vv G3 vvv G4 vvvv G5 vvvvv G6 vvvvvv G7 vvvvvvv G8 vvvvvvvv G9 vvvvvvvvv G10 vvvvvvvvvv G11 vvvvvvvvvvv G12

[Arch2008]

If the distance between hypothetical galaxies G were v=one megaparsec, then:

G1 v G2 v G3 v G4

would change over time to:

G1 v+h G2 v+h G3 v+h G4

Where h is the Hubble constant, 70 km per second per mps.

The galaxies themselves are not responsible for this. The expansion is related to a property of space itself between the galaxies, called Dark Energy. So, as already stated, the moving car analogy is incorrect.




http://xxx.lanl.gov/...2/9812133v1.pdf

http://en.wikipedia....go_Supercluster

Also, the hubble constant is the rate at which the velocity of recession of the galaxies increases with distance; the value is about 70 kilometers per second per megaparsec with a relative uncertainty of about ± 10%. Since the Virgo Super Galaxy Cluster is 33 mps in diameter, the space between the galaxies is inflating, not just the space between SGC's. Also, Purlmutter’s paper was based on SN observations from galaxies inside the Virgo SGC.

This post has been edited by Arch2008: 4 January 2012 - 04:26 PM

[Spyman]

michel123456, on 4 January 2012 - 08:15 AM, said:

Is this correct?
At the risk of being stupid I thought (accelerating) expansion was
G1 s G2 ss G3 sss G4 ssss G5 sssss G6 ssssss G7 sssssss G8 ssssssss G9 sssssssss G10 ssssssssss G11 sssssssssss G12
With G12 a galaxy cluster in the very long past.

The expansion rate is thought to be the same everywhere on very large scales, in zapatos's example we only see one duration of time so we can't determine if there is an shift in rate or not, and it is supposed to show the real distances between galaxies and not how distant they appear to be from our viewpoint. AFAIK cosmological expansion is imagined like how far distant galaxies are located as if we could measure their true distance instantly over time and the rate of expansion changes over time and is constant relative distance.

Further more according to current Big Bang theory the expansion was very fast at the initial beginning and then rapidly decreased, later on and roughly during the first half of our Universe's life time the expansion was slowly deccelerating and then the rate turned sign and the Universe's expansion started to slowly accelerate, so the full picture can't be viewed as easily as you wish.

Following standard models we have never seen any object emitting light from a distance further than ~6 billion lightyears from us, any object we see that it took light less than ~10 billion years to travel to us, was farther and farther away from us but still closer than 6 billion lightyears when it emitted the light reaching us now, and any object we see that it took light more than ~10 billion years to travel to us, was closer and closer to us from 6 billion lightyears when it emitted the light reaching us now. The most distant objects we have ever recieved light from is now thought to be ~45 billion lightyears away, but it was only 0.04 billion lightyears from us when it emitted the light we see today.

The G12 galaxy cluster in the very long past might seem to be 12 billion lightyears away but it was only ~4.8 billion lightyears distant when it emitted the light we see now and it is currently located ~23.4 billion lightyears from us.



Trying to extend on zapatos's example including timestamps and for different expansions:


Simple Expansion non accelerating s +s +s +s (rate=1)

T1 - G1 s G2 s G3 s G4 s G5 s G6 s G7 s G8 s G9 s G10 s G11 s G12
T2 - G1 ss G2 ss G3 ss G4 ss G5 ss G6 ss G7 ss G8 ss G9 ss G10 ss G11 ss G12
T3 - G1 sss G2 sss G3 sss G4 sss G5 sss G6 sss G7 sss G8 sss G9 sss G10 sss G11 sss G12
T4 - G1 ssss G2 ssss G3 ssss G4 ssss G5 ssss G6 ssss G7 ssss G8 ssss G9 ssss G10 ssss G11 ssss G12


Accelerating Expansion at constant rate s +s +ss +sss (rate=+1)

T1 - G1 s G2 s G3 s G4 s G5 s G6 s G7 s G8 s G9 s G10 s G11 s G12
T2 - G1 ss G2 ss G3 ss G4 ss G5 ss G6 ss G7 ss G8 ss G9 ss G10 ss G11 ss G12
T3 - G1 ssss G2 ssss G3 ssss G4 ssss G5 ssss G6 ssss G7 ssss G8 ssss G9 ssss G10 ssss G11 ssss G12
T4 - G1 sssssss G2 sssssss G3 sssssss G4 sssssss G5 sssssss G6 sssssss G7 sssssss G8 sssssss G9 sssssss G10 sssssss G11 sssssss G12


Accelerating Expansion at accelerating rate s +s +sss +ssssss (rate=+1 +2 +3)

T1 - G1 s G2 s G3 s G4 s G5 s G6 s G7 s G8 s G9 s G10 s G11 s G12
T2 - G1 ss G2 ss G3 ss G4 ss G5 ss G6 ss G7 ss G8 ss G9 ss G10 ss G11 ss G12
T3 - G1 sssss G2 sssss G3 sssss G4 sssss G5 sssss G6 sssss G7 sssss G8 sssss G9 sssss G10 sssss G11 sssss G12
T4 - G1 sssssssssss G2 sssssssssss G3 sssssssssss G4 sssssssssss G5 sssssssssss G6 sssssssssss G7 sssssssssss G8 sssssssssss G9 ...

(Disclaimer: I don't qualify as an expert either.)

[michel123456]

Arch2008, on 4 January 2012 - 03:50 PM, said:

If the distance between hypothetical galaxies G were v=one megaparsec, then:

G1 v G2 v G3 v G4

would change over time to:

G1 v+h G2 v+h G3 v+h G4

Where h is the Hubble constant, 70 km per second per mps.
(...)

You are confusing me more: you cannot add a distance to a velocity. The formula is Velocity = Hubbleconstant times Distance.

zapatos, on 4 January 2012 - 03:12 PM, said:

Disclaimer: I am not an expert.

Because the expansion of space is the same everywhere, you get my example:
G1 ss G2 ss G3 ss G4 ss G5 ss G6 ss G7 ss G8 ss G9 ss G10 ss G11 ss G12
There is no preferred position in space. No matter where you are, the further the galaxy from you, the faster it seems to move.

In your example:
G1 s G2 ss G3 sss G4 ssss G5 sssss G6 ssssss G7 sssssss G8 ssssssss G9 sssssssss G10 ssssssssss G11 sssssssssss G12
If you were sitting at G8, space would be acting differently looking toward G12 than if you were looking toward G1.(...)

Bolded mine
Ha.
No. Because G8 cannot observe G1: he cannot observe anything in its future. The sequence G1 to G12 is also a time sequence, no one can observe to the left, everybody observe to the right, in the past.
So G8 is observing
G8 ssssssss G9 sssssssss G10 ssssssssss G11 sssssssssss G12
or
G8 s G9 ss G10 sss G11 ssss G12
With another value for s.

zapatos, on 4 January 2012 - 03:12 PM, said:

I may be mistaken but you seem to be mixing space and velocity.

Sure I am. Since velocity is space (distance) divided by time and time is a direct function of distance, if velocity increases so does space.

[Arch2008]

Nonetheless, the distance between the galaxies in the example starts at one mps. After one second the new distance is one mps + 70 km. After two seconds it would be one mps + 140km. The distance increases by the Hubble constant.

Also, your confusion may be over what a velocity is. Velocity is distance over time (miles per hour). The Hubble constant is a rate of change in distance, 70 km per second per mps. The distance increases at the rate of change equal to the Hubble constant.

This post has been edited by Arch2008: 4 January 2012 - 06:11 PM

[michel123456]

Spyman, on 4 January 2012 - 03:51 PM, said:

The expansion rate is thought to be the same everywhere on very large scales, in zapatos's example we only see one duration of time so we can't determine if there is an shift in rate or not, and it is supposed to show the real distances between galaxies and not how distant they appear to be from our viewpoint. AFAIK cosmological expansion is imagined like how far distant galaxies are located as if we could measure their true distance instantly over time and the rate of expansion changes over time and is constant relative distance.

Further more according to current Big Bang theory the expansion was very fast at the initial beginning and then rapidly decreased, later on and roughly during the first half of our Universe's life time the expansion was slowly deccelerating and then the rate turned sign and the Universe's expansion started to slowly accelerate, so the full picture can't be viewed as easily as you wish.

Following standard models we have never seen any object emitting light from a distance further than ~6 billion lightyears from us, any object we see that it took light less than ~10 billion years to travel to us, was farther and farther away from us but still closer than 6 billion lightyears when it emitted the light reaching us now, and any object we see that it took light more than ~10 billion years to travel to us, was closer and closer to us from 6 billion lightyears when it emitted the light reaching us now. The most distant objects we have ever recieved light from is now thought to be ~45 billion lightyears away, but it was only 0.04 billion lightyears from us when it emitted the light we see today.

The G12 galaxy cluster in the very long past might seem to be 12 billion lightyears away but it was only ~4.8 billion lightyears distant when it emitted the light we see now and it is currently located ~23.4 billion lightyears from us.

That's all O.K.

Quote

Trying to extend on zapatos's example including timestamps and for different expansions:


Simple Expansion non accelerating s +s +s +s (rate=1)

T1 - G1 s G2 s G3 s G4 s G5 s G6 s G7 s G8 s G9 s G10 s G11 s G12
T2 - G1 ss G2 ss G3 ss G4 ss G5 ss G6 ss G7 ss G8 ss G9 ss G10 ss G11 ss G12
T3 - G1 sss G2 sss G3 sss G4 sss G5 sss G6 sss G7 sss G8 sss G9 sss G10 sss G11 sss G12
T4 - G1 ssss G2 ssss G3 ssss G4 ssss G5 ssss G6 ssss G7 ssss G8 ssss G9 ssss G10 ssss G11 ssss G12


Accelerating Expansion at constant rate s +s +ss +sss (rate=+1)

T1 - G1 s G2 s G3 s G4 s G5 s G6 s G7 s G8 s G9 s G10 s G11 s G12
T2 - G1 ss G2 ss G3 ss G4 ss G5 ss G6 ss G7 ss G8 ss G9 ss G10 ss G11 ss G12
T3 - G1 ssss G2 ssss G3 ssss G4 ssss G5 ssss G6 ssss G7 ssss G8 ssss G9 ssss G10 ssss G11 ssss G12
T4 - G1 sssssss G2 sssssss G3 sssssss G4 sssssss G5 sssssss G6 sssssss G7 sssssss G8 sssssss G9 sssssss G10 sssssss G11 sssssss G12


Accelerating Expansion at accelerating rate s +s +sss +ssssss (rate=+1 +2 +3)

T1 - G1 s G2 s G3 s G4 s G5 s G6 s G7 s G8 s G9 s G10 s G11 s G12
T2 - G1 ss G2 ss G3 ss G4 ss G5 ss G6 ss G7 ss G8 ss G9 ss G10 ss G11 ss G12
T3 - G1 sssss G2 sssss G3 sssss G4 sssss G5 sssss G6 sssss G7 sssss G8 sssss G9 sssss G10 sssss G11 sssss G12
T4 - G1 sssssssssss G2 sssssssssss G3 sssssssssss G4 sssssssssss G5 sssssssssss G6 sssssssssss G7 sssssssssss G8 sssssssssss G9 ...

Where are we supposed to be today? At G1 & T4 I suppose. Anyway I would prefer to focus on what we are observing, not on any theorization or prediction.

Here below I included the time stamp to make it clearer
What we are observing is:

T0.-T1.--T3.---T6.----T10.-----T15.------T21.-------T28.--------T36.---------T45
G1 s G2 ss G3 sss G4 ssss G5 sssss G6 ssssss G7 sssssss G8 ssssssss G9 sssssssss G10

Where T is directly linked to the amount of "s": time of observation in the past is a direct function of the distance through the constancy of Speed Of Light.

Disclaimer: we need an expert urgently.
--------------
The editor is not WYSIWYG, it is difficult to make T & G correspond vertically, I hope the result appears the same on everyone's screen.

This post has been edited by michel123456: 4 January 2012 - 06:03 PM

[guenter]

Arch2008, on 4 January 2012 - 05:43 PM, said:

Nonetheless, the distance between the galaxies in the example starts at one mps. After one second the new distance is one mps + 70 km. After two seconds it would be one mps + 140km. The distance increases by the Hubble constant.

Yes, according to the Hubble law, the receding velocity v is proportional to the distance d, v = d*H.