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Author Topic:   Did the expansion rate of the universe exceed lightspeed?
Percy
Member
Posts: 13358
From: New Hampshire
Joined: 12-23-2000
Member Rating: 1.9


Message 76 of 86 (460384)
03-14-2008 3:50 PM


Question About Expansion Rate and Clocks
Consider two hypothetical galaxies, both receding from us at the same enormous speed of, say .9c, but one is relatively nearby and the other is on the other side of the visible universe. This means that the nearby one has an enormous velocity through space relative to ourselves, and the distant one has a small velocity through space relative to ourselves that can be ignored but an enormous velocity due to the expansion of space.

Naturally they'd both have the same amount of time Doppler effects, but wouldn't the nearby galaxy experience a large relativistic time dilation relative to ourselves and the distant one not?

If so, then this would mean that Halton Arp is not just wrong, he's nuts. I'm thinking about Arp's contention that galaxies with high red-shift values are actually relatively local objects with high recession speeds that have been ejected from galaxies. Now in addition to the incredibly unlikely coincidence that everything ejected from galaxies is ejected away from us, there's the impossibility that they're close objects because the time dilation effects are way too small.

Apologies if I'm way off the mark, be gentle, my misconceptions are hard earned. :)

--Percy


Replies to this message:
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lyx2no
Member (Idle past 1215 days)
Posts: 1277
From: A vast, undifferentiated plane.
Joined: 02-28-2008


Message 77 of 86 (460385)
03-14-2008 3:50 PM
Reply to: Message 72 by ICANT
03-14-2008 12:48 PM


Re: acceleration
Hello ICANT:

If expansion is true and expansion it taking place at light speed and is accelerating, they would never be able to collide.

The resultant expansion of space is only proceeding at the speed of light between two bodies if those two bodies are 13.7 billion ly apart.

The recession between M31 and the Milky Way due to the expansion of space is only:
3•108 m/s(2.2•106 ly/13.7•10 9 ly)=4.8•104 m/s.

A fifth of the portion of the speed at which the two are approaching and an insignificant portion of the speed of light.

Edited by lyx2no, : To comport with reality.


Kindly

******

Fractally impudent


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ICANT
Member (Idle past 99 days)
Posts: 5182
From: SSC
Joined: 03-12-2007


Message 78 of 86 (460389)
03-14-2008 4:31 PM
Reply to: Message 75 by Rahvin
03-14-2008 3:44 PM


Re: acceleration
Hi Rahvin,

Rahvin writes:

glaring mathematical mistake Percy and Cavediver pointed out.

I was quite satisfied with the answers I got from Percy and cavediver. And Percy pointing out my blunder. Too bad you had to waste a rant.

I am still waiting for information from you.
Here

God Bless,


"John 5:39 (KJS) Search the scriptures; for in them ye think ye have eternal life: and they are they which testify of me."
This message is a reply to:
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Rahvin
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Posts: 3961
Joined: 07-01-2005
Member Rating: 1.7


Message 79 of 86 (460394)
03-14-2008 4:56 PM
Reply to: Message 78 by ICANT
03-14-2008 4:31 PM


Re: acceleration
I was quite satisfied with the answers I got from Percy and cavediver. And Percy pointing out my blunder. Too bad you had to waste a rant.

Apparently you didn't actually read my post, at all. I didn't talk about your mathematical error (others had done that adequately, as I said). I talked about your continued misconception regarding the rate of expansion, which you would know if you had read the post. It was also not a "rant." The only parts that could give you that idea would be the very beginning and the last line.

I am still waiting for information from you.
Here

Which is irrelevant to this thread. Perhaps, rather than attacking me, you could try to address my argument?


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cavediver
Member (Idle past 143 days)
Posts: 4129
From: UK
Joined: 06-16-2005


Message 80 of 86 (460396)
03-14-2008 5:41 PM
Reply to: Message 76 by Percy
03-14-2008 3:50 PM


Re: Question About Expansion Rate and Clocks
Naturally they'd both have the same amount of time Doppler effects, but wouldn't the nearby galaxy experience a large relativistic time dilation relative to ourselves and the distant one not?

No, both would exhibit time dilation. You might differentiate them and call one relativistic time dialtion, and the other cosmological time dilation, but both are caused by identical phenomena - their time directions are rotated with respect to ours. In the former, the rotation is casued by the relativie velocity; the latter, by the actual curvature of space-time tipping over the distant light-cone with respect to ours.

Edited by cavediver, : No reason given.


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 Message 76 by Percy, posted 03-14-2008 3:50 PM Percy has responded

Replies to this message:
 Message 81 by Percy, posted 03-14-2008 8:03 PM cavediver has not yet responded
 Message 82 by Percy, posted 03-14-2008 8:36 PM cavediver has responded

  
Percy
Member
Posts: 13358
From: New Hampshire
Joined: 12-23-2000
Member Rating: 1.9


Message 81 of 86 (460407)
03-14-2008 8:03 PM
Reply to: Message 80 by cavediver
03-14-2008 5:41 PM


Re: Question About Expansion Rate and Clocks
Oh. Darn. Well, Arp's still an idiot.

There was a contributor named Sylas here starting back in 2004, and he was our cosmological expert for a while. He's been gone for a while, but it was something he said that led me to my incorrect conclusion. I'll poke around for a bit and see if I can dig it out, I'd like to clear up how I picked up the wrong impression. Thanks for the info!

--Percy


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Percy
Member
Posts: 13358
From: New Hampshire
Joined: 12-23-2000
Member Rating: 1.9


Message 82 of 86 (460410)
03-14-2008 8:36 PM
Reply to: Message 80 by cavediver
03-14-2008 5:41 PM


Re: Question About Expansion Rate and Clocks
I found the Sylas post, it was Message 226. This is embarrassing because it reveals that the passage of time seems to have brought my mind back around to my earlier misunderstanding.

Anyway, that old thread was discussing a different topic but Sylas and I were touching on the same point as here. I think the discussion about the Doppler contributions must have confused me. Why did he mention them in the first paragraph, then say it's one of the lines of evidence that tells us the redshift is due to the expansion of space in the next?

Relative to ourselves, wouldn't the time dilation due to relativistic contributions be the same for a moving object regardless of the direction of its velocity vector? And then there's an additional Doppler effect that's a function of how much of the velocity vector is parallel to the distance vector? And how do we figure out which contribution is which for distant objects?

Hope you and Son Goku never get tired of answering dumb questions.

--Percy


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Replies to this message:
 Message 83 by cavediver, posted 03-15-2008 6:59 AM Percy has responded

    
cavediver
Member (Idle past 143 days)
Posts: 4129
From: UK
Joined: 06-16-2005


Message 83 of 86 (460450)
03-15-2008 6:59 AM
Reply to: Message 82 by Percy
03-14-2008 8:36 PM


Re: Question About Expansion Rate and Clocks
Sylas was addressing Tired Light, which assumes a static source,non-expanding space, and some mechanism to redden the light as it travels towards us. It cannot explain observed time dilation in observed objects, such as seen in th SN spectra that Sylas mentioned. However, it is very difficult to differentiate the relative contributions of cosmological and relativistic red-shift for a single object. That is where statistical analysis of large numbers of objects becomes valuable.

Time dilation is the same regardless of the direction. Doppler is highly direction-dependent. Blue-shifts remain blue-shifts, although lessened, after time-dilation correction. Transverse
objects experience red-shift solely from time-dilation. Red-shifts are accentuated by time-dilation. So Arp still has to explain why all his galaxy-associated high-velocity quasars are all heading away from us!!

Edited by cavediver, : No reason given.


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 Message 82 by Percy, posted 03-14-2008 8:36 PM Percy has responded

Replies to this message:
 Message 84 by Percy, posted 03-15-2008 4:36 PM cavediver has responded

  
Percy
Member
Posts: 13358
From: New Hampshire
Joined: 12-23-2000
Member Rating: 1.9


Message 84 of 86 (460489)
03-15-2008 4:36 PM
Reply to: Message 83 by cavediver
03-15-2008 6:59 AM


Re: Question About Expansion Rate and Clocks
cavediver writes:

So Arp still has to explain why all his galaxy-associated high-velocity quasars are all heading away from us!!

This has puzzled me for a long time, how someone so obviously brilliant could be so wrong, so I just looked into this a little bit more. Information is sparse, but it appears that a survey of the local group reveals that all eleven companion galaxies have a redshift relative to their parent galaxies (is this true?), when it should be roughly 50%.

From this Arp concludes that the observed red-shift of galaxies is intrinsic. Intrinsically red-shifted objects have lower mass than local matter because they're made up of particles with lower mass. They have low mass because they are new matter forged in the center of galaxies, and matter increases in mass over time.

But ferreting out these details doesn't diminish in the slightest how incredibly far fetched this all is. You'd think he would long ago have tired of his work never finding any additional observational or experimental support. Indeed the opposite occurs, as each year improving astronomical tools disprove more and more of his supposed anomalies, and more weight is added to the evidence against his ideas. He must be a very odd bird.

--Percy


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Replies to this message:
 Message 85 by cavediver, posted 03-15-2008 7:30 PM Percy has responded

    
cavediver
Member (Idle past 143 days)
Posts: 4129
From: UK
Joined: 06-16-2005


Message 85 of 86 (460506)
03-15-2008 7:30 PM
Reply to: Message 84 by Percy
03-15-2008 4:36 PM


Re: Question About Expansion Rate and Clocks
Information is sparse, but it appears that a survey of the local group reveals that all eleven companion galaxies have a redshift relative to their parent galaxies (is this true?), when it should be roughly 50%.

I've just perused the fourteen companions of M31 listed on Wiki - seven are higher z than M31, five on lower (more negative z), and there is no data for two. Hmmm...


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 Message 84 by Percy, posted 03-15-2008 4:36 PM Percy has responded

Replies to this message:
 Message 86 by Percy, posted 03-15-2008 9:03 PM cavediver has not yet responded

  
Percy
Member
Posts: 13358
From: New Hampshire
Joined: 12-23-2000
Member Rating: 1.9


Message 86 of 86 (460516)
03-15-2008 9:03 PM
Reply to: Message 85 by cavediver
03-15-2008 7:30 PM


Re: Question About Expansion Rate and Clocks
cavediver writes:

I've just perused the fourteen companions of M31 listed on Wiki - seven are higher z than M31, five on lower (more negative z), and there is no data for two. Hmmm...

But is Arp so perverse, so taken with his own theories, so nuts, as to make up data?

The source of the claim that all eleven companion galaxies in the local group have redshifts greater than their parent galaxies comes from reviews of Arp's 1998 book Seeing Red. For example, this is from a review by Tom Van Flandern:

Companion galaxies in general seem to have net redshifts that exceed that of their parents. All eleven companion galaxies in the Local Group have redshifts with respect to their parent, the Andromeda galaxy in the center of the group. Likewise, all eleven companion galaxies of the neighboring M81 group have redshifts relative to M81. Yet, if these companions were orbiting their parent galaxy, roughly 50% of them ought to have been blue-shifted. Although the evidence for companion redshifts is less definitive for more distant galaxy groups, it is still statistically significant. Excess redshifts over blueshifts for companion galaxies relative to their parents is apparently a verifiable feature of the local universe. And that means the redshift must have some cause other than velocity.

This is really just made up? I mean, sure Arp is wrong and all that, but is he a liar? Delusional? What?

Sorry, rhetorical questions, I know, but what an unfathomable mystery and waste of an incredibly promising career, plus there's all the ammunition he provides to kooks.

--Percy


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