Redshift: expanding space-time or galaxy moving away form each other?

[LSulayman]

I know that Hubble observed redshift which led to the conclusion that space was expanding.
But why did redshift lead to such conclusion? Why didn't they just think that galaxy were "flying" away from each other instead of thinking that it was the space that was actually expanding? What made Hubble believe that?

PS: I know that now there is other evidenc for expanding universe but I want to know about then.

 

[LSulayman]

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[Radrook]

Red Shift Anomalies
http://universalcurrents.wordpress.com/



The red shift itself as indicator of distance remains suspect until a convincing explanation concerning closer objects interacting with supposedly far more distant ones as indicated by their different red shifts is provided.

 

[Calimero]

Are you serious?

Both galaxies that constitute Arp 87, are approx 300 millon light years from us.

Halton Arp may have been great observational astronomer, but for some reason, he rejects obvious. Technology has come long way since his days.

 

[marcus]

I know that Hubble observed redshift which led to the conclusion that space was expanding.
But why did redshift lead to such conclusion? Why didn't they just think that galaxy were "flying" away from each other instead of thinking that it was the space that was actually expanding? What made Hubble believe that?
...

Lula didn't the idea of space expanding come long before Hubble's observation? You had better check the dates.

You already mentioned deSitter, your fellow Dutch. But more importantly I think there was the Russian Alex Friedmann who wrote a paper in 1922 which estimated the age of the universe at around 10-12 billion years, based on the idea that space was expanding.

By "space expanding" I mean spatial distances increasing according to the Friedmann metric (which we still use in cosmology.)

Friedmann's paper was in German, titled "Über die Krümmung des Raumes". That is "about the curvature of space." To say that spatial distance increases is just another way of describing a kind of spacetime curvature.

Friedmann simply gave a solution of Einstein 1915 GR equation which had this curvature feature, this expansion. It was a natural theory step to take if you believed GR equation could be right.

And that was 1922---Friedmann had no "Hubble" data. Hubble did not publish results until 1929, I think.
You ask "why did Hubble think so and so?" I don't know what Hubble thought. Maybe he did not think distance expansion! Maybe he thought "flying" as you said, or something else. It does not matter what theoretical interpretation that one observationalist made. Other people looked at his results and recognized what Friedmann had guessed much earlier---a possible solution to the Einstein equation involving the curvature that we perceive as distance expansion.

If my view of history is wrong, I hope someone will correct this account. And perhaps provide some online source. I don't have a source handy.
================

Edit: http://en.wikipedia.org/wiki/Edwin_Hubble
http://en.wikipedia.org/wiki/Vesto_Slipher (who noticed the redshift earlier)
http://en.wikipedia.org/wiki/Alexander_Friedmann

I think that although Slipher noticed redshifts of galaxies earlier, he did not relate it to the estimated distance. So it remained for Hubble to plot the approximately linear relation between distance and redshift.

 

[Radrook]

Here is a more detailed explanation of the opposing view.

Redshift
http://www.electric-cosmos.org/arp.htm

 

[Calimero]

Radrook, you have the right to believe what you want, but please stop posting crackpot links. It is not opposing view, it is nonsense. Stephan's quintet is one of the most watched objects in the sky, and NGC 7320 is foreground galaxy. You can even see individual stars in it, because of its proximity.

 

[daumphys]

The far away Universe what we have seen through telescope is old Universe scenery, and the near Universe what we have seen is recent Universe scenery. We know far away Universe moves fast cause of geometric effect. Than, do we solve model equations which contains geometric effects and time delay effects together about expanding Universe?

 

[Radrook]

Radrook, you have the right to believe what you want, but please stop posting crackpot links. It is not opposing view, it is nonsense. Stephan's quintet is one of the most watched objects in the sky, and NGC 7320 is foreground galaxy. You can even see individual stars in it, because of its proximity.

But he believes otherwise for the following reasons.

Exzcerpt:

Stephan's Quintet

In "Quasars, Redshifts, and Controversies" (p. 96-101) Halton Arp discusses the five interacting galaxies NGC 7317, 7318A, 7318B, 7319, and 7320 that constitute Stephan's Quintet. The last one, NGC 7320, has a redshift value of 800 km/sec. The other four have redshifts of either 5700 km/sec or 6700 km/sec. Mainstream astronomers therefore claim those last four are about eight times farther away from us than NGC 7320. Therefore, they say, there cannot be any interaction between 7320 and the others.


Arp states "The deepest 200 inch (Mt. Palomar) plates that I have been able to obtain clearly show a 'tail' coming out of the southeast end of NGC 7320." He points out, "A tail like this from NGC 7320... must be an interaction tail - which could arise only from physical interaction with the adjacent high-redshift members of the Quintet."


He then states that at least one amateur has been able to see the tail but, "it is amazing that so many professionals have difficulty seeing it." NASA routinely crops their images of Stephan's Quintet to exclude the area where this tail would be seen.
However, my good friend, amateur astronomer John Smith acquired a full image of the Quintet.


The large, dark galaxy on the left is the low redshift NGC 7320. Then going counter-clockwise we have 7317, 7318A, 7318B, and 7319. At the top of the image is the small galaxy NGC 7320C. After some digital image processing (which only increased contrast), the result shown below was obtained.


It is apparent that a 'tail' does indeed extend out from NGC 7320 toward the left. In fact it appears to curve around and connect to the small galaxy NGC 7320C. The redshift of this small companion galaxy is z = 0.02 which is about 10 times that of NGC 7320.

So, once again we have evidence of a physical connection between two objects that have vastly different redshift values.

http://www.electric-cosmos.org/arp.htm

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>


Excerpt



Stephan’s Quintet

...It is possibly the single best example of visibly connected extragalactic objects with discordant redshifts in existence today. The physical connection between the objects is so plainly visible and their associated redshifts so disparate that one would think I would not hesitate to feature them on this website. Ironically, despite the overwhelmingly visible proof the following images provide, they also serve as stark reminders of just how stubborn and incredibly biased the current scientific community is in regards to discordant redshifts or any evidence that might throw the Big Bang Theory into question.



http://www.discordancyreport.com/stephans-quintet/

 

[matt.o]

It is worth noting (for anyone reading without a background in astrophysics/cosmology) that Arp's ideas are not taken seriously by mainstream cosmologists/astrophysicists.