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Author Topic:   Starlight
kbertsche
Member (Idle past 2131 days)
Posts: 1427
From: San Jose, CA, USA
Joined: 05-10-2007


Message 16 of 84 (509139)
05-18-2009 11:40 PM
Reply to: Message 9 by ohnhai
05-17-2009 1:34 PM


quote:
I I remember correctly Settefield collated all historical estimations for C regardless of their age experimental methodology or accuracy of error bands. He then, almost without exception, took the upper limits of the error bands and some very old and wildly wrong guesstimates and produced a curve that suggested an exponential fall off from roughly 7 days after creation (where C remains suspiciously constant) to a steady flat state round about the time C started being measured by atomic clocks. How convenient it is that C reached a steady state round about the time we developed the tech to accurately measure it.
Basically it was the typical creationist's game of taking spurious data and bending it till it gives the desired result.
Setterfield was selective in the data which he used, he did not account for error bars when fitting his curve, and he had no physical motivation for the unusual functional form that he chose.
FYI, Setterfield's claim that the speed of light has changed was debunked long ago by Aardsma, another young-earth Creationist: Has the Speed of Light Decayed?

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cavediver
Member (Idle past 3643 days)
Posts: 4129
From: UK
Joined: 06-16-2005


Message 17 of 84 (509181)
05-19-2009 6:48 AM
Reply to: Message 11 by slevesque
05-18-2009 4:46 AM


Are these peer-reviewed journals ? They all propose a faster speed of light in the past.
Yes, PRD and PLB are two of the most important journals for Theoretical Physics - probably the most prestigious is Nuclear Physics B (NPB). PRD does tend to get filled with plenty of crap, though.
Variable speed of light theories (VSL) are nothing new. The albrecht paper is rather Mickey-Mouse in its approach - the ideas are ok but it is pure conjecture without any proposed mechanism - and the repeated use of "superluminal expansion" stinks of someone not quite getting it. Moffat is an old-timer, usually playing with fringe ideas. If you want to look at a modern paper on possible VSL (which is actually a variation in the fine structure constant, rather than c itself, as that is a fairly meaningless concept) then try this. Notice the observationally determined bounds on possible variation.

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Replies to this message:
 Message 18 by Dr Jack, posted 05-19-2009 8:28 AM cavediver has not replied
 Message 20 by riVeRraT, posted 05-20-2009 11:15 AM cavediver has replied

  
Dr Jack
Member
Posts: 3514
From: Immigrant in the land of Deutsch
Joined: 07-14-2003
Member Rating: 8.7


Message 18 of 84 (509188)
05-19-2009 8:28 AM
Reply to: Message 17 by cavediver
05-19-2009 6:48 AM


which is actually a variation in the fine structure constant, rather than c itself, as that is a fairly meaningless concept
That's interesting; if it's not too complicated to explain, why is that?

This message is a reply to:
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onifre
Member (Idle past 2951 days)
Posts: 4854
From: Dark Side of the Moon
Joined: 02-20-2008


Message 19 of 84 (509254)
05-19-2009 6:33 PM
Reply to: Message 18 by Dr Jack
05-19-2009 8:28 AM


Hi Mr. Jack,
Cavediver writes:
which is actually a variation in the fine structure constant, rather than c itself, as that is a fairly meaningless concept
Mr.Jack writes:
That's interesting; if it's not too complicated to explain, why is that?
Here's an article that can give you some basic understanding on it before Cavediver get's a chance to answer it.
The fine structure constant Alpha
quote:
The possibility that fundamental constants can change in time is predicted by some unified field theories. The detection of such a variation would be an important confirmation of these theories. The analysis of the spectra of distant quasars does indicate that the fine structure constant alpha (the constant which measures the intensity of the electromagnetic interaction) might be changing in time. Fine structure constant alpha is in fact a dimensionless combination of three other fundamental constants: alpha = e/hc (e - electron charge, h - Planck constant, c - speed of light).
Hopefully Cave can explain it better for us.
Hope the article helps, though.
- Oni

"I smoke pot. If this bothers anyone, I suggest you look around at the world in which we live and shut your mouth."--Bill Hicks
"I never knew there was another option other than to question everything"--Noam Chomsky

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riVeRraT
Member (Idle past 416 days)
Posts: 5788
From: NY USA
Joined: 05-09-2004


Message 20 of 84 (509308)
05-20-2009 11:15 AM
Reply to: Message 17 by cavediver
05-19-2009 6:48 AM


I loosely studied on my own Astronomy around 10 years ago. I have an 8" Newtonian on an equatorial mount. I have seen down to 13th magnitude with it using averted vision.
I understand the Hubble concept, but I have a question. can we measure the red shift stars close to us, in our own galaxy. Do we only see their motion relative to our galaxy, or can we see the motion from the big bang?

This message is a reply to:
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Replies to this message:
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 Message 22 by onifre, posted 05-20-2009 12:09 PM riVeRraT has not replied
 Message 23 by cavediver, posted 05-20-2009 12:14 PM riVeRraT has replied

  
Taq
Member
Posts: 9972
Joined: 03-06-2009
Member Rating: 5.5


Message 21 of 84 (509310)
05-20-2009 11:21 AM
Reply to: Message 20 by riVeRraT
05-20-2009 11:15 AM


From my understanding, stars in this galaxy are gravitationally bound so there shouldn't be an observable redshift due to expansion. Redshift is seen between our galaxy and galaxies that are not gravitationally bound to our galaxy. As one example, there is an observed blueshift in the Andromeda galaxy because it is coming right for us.

This message is a reply to:
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onifre
Member (Idle past 2951 days)
Posts: 4854
From: Dark Side of the Moon
Joined: 02-20-2008


Message 22 of 84 (509317)
05-20-2009 12:09 PM
Reply to: Message 20 by riVeRraT
05-20-2009 11:15 AM


As I understand it...
can we measure the red shift stars close to us
The redshift occurs with distant galaxies, not individual stars. Especially not anything in our Local Group - which is what I'm assuming you were visibly looking at.
In fact, our Local Group, which the 2 largest galaxies are the Milky Way and Andromeda, are actually coming toward each other.
quote:
The Andromeda Galaxy is moving towards our own Milky Way Galaxy within the Local Group; thus, when observed from earth, its light is undergoing a blue shift.
Source
Furthermore, both redshift and blueshift aren't a visible phenomenon, it's is a measurment of the frequency of the emited light.
quote:
While the terms "redshifting" and "blueshifting" imply significantly redder or bluer light, only the most distant galaxies and those moving at speeds far above average emit light that arrives with perceptible red or blue tinges. For the most part, shifting is not a visible phenomenon.
Same source as above.
Do we only see their motion relative to our galaxy, or can we see the motion from the big bang?
Relative to us, and only when they are far enough from us.
Hope this helped.
- Oni

"I smoke pot. If this bothers anyone, I suggest you look around at the world in which we live and shut your mouth."--Bill Hicks
"I never knew there was another option other than to question everything"--Noam Chomsky

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cavediver
Member (Idle past 3643 days)
Posts: 4129
From: UK
Joined: 06-16-2005


Message 23 of 84 (509319)
05-20-2009 12:14 PM
Reply to: Message 20 by riVeRraT
05-20-2009 11:15 AM


Hi RR - as Taq has already explained, stars within our Galaxy are in orbit about the Galactic core, and this massively dominates any effect of the Universal expansion. Likewise, neighbouring galaxies are far more affected by local gravitational effects than the expansion. You have to look past the Local Group of galaxies to start to see real evidence of the expansion.

This message is a reply to:
 Message 20 by riVeRraT, posted 05-20-2009 11:15 AM riVeRraT has replied

Replies to this message:
 Message 24 by Taq, posted 05-20-2009 12:44 PM cavediver has replied
 Message 27 by riVeRraT, posted 05-20-2009 7:28 PM cavediver has replied

  
Taq
Member
Posts: 9972
Joined: 03-06-2009
Member Rating: 5.5


Message 24 of 84 (509326)
05-20-2009 12:44 PM
Reply to: Message 23 by cavediver
05-20-2009 12:14 PM


You have to look past the Local Group of galaxies to start to see real evidence of the expansion.
Will this always be the case? If expansion is accelerating will there be a point where expansion overpowers the gravity within a galaxy?

This message is a reply to:
 Message 23 by cavediver, posted 05-20-2009 12:14 PM cavediver has replied

Replies to this message:
 Message 25 by onifre, posted 05-20-2009 6:40 PM Taq has not replied
 Message 26 by cavediver, posted 05-20-2009 7:02 PM Taq has not replied

  
onifre
Member (Idle past 2951 days)
Posts: 4854
From: Dark Side of the Moon
Joined: 02-20-2008


Message 25 of 84 (509354)
05-20-2009 6:40 PM
Reply to: Message 24 by Taq
05-20-2009 12:44 PM


Hi Taq,
If expansion is accelerating will there be a point where expansion overpowers the gravity within a galaxy?
According to the Big Rip hypothesis that's exactly what will happen.
quote:
First, the galaxies would be separated from each other. About 60 million years before the end, gravity would be too weak to hold the Milky Way and other individual galaxies together. Approximately three months before the end, the Solar system will be gravitationally unbound. In the last minutes, stars and planets will be torn apart, and an instant before the end, atoms will be destroyed.
The authors of this hypothesis, led by Robert Caldwell of Dartmouth College, calculate that the end of the universe as we now know it would be in approximately 50 billion years.
Hope this helped.
- Oni
Edited by onifre, : No reason given.
Edited by onifre, : No reason given.

"I smoke pot. If this bothers anyone, I suggest you look around at the world in which we live and shut your mouth."--Bill Hicks
"I never knew there was another option other than to question everything"--Noam Chomsky

This message is a reply to:
 Message 24 by Taq, posted 05-20-2009 12:44 PM Taq has not replied

  
cavediver
Member (Idle past 3643 days)
Posts: 4129
From: UK
Joined: 06-16-2005


Message 26 of 84 (509355)
05-20-2009 7:02 PM
Reply to: Message 24 by Taq
05-20-2009 12:44 PM


If expansion is accelerating will there be a point where expansion overpowers the gravity within a galaxy?
Not under normal accelerative expansion - the gravitationally bound elements will stay gravitationally bound. This will probably extend as far as our own supercluster.
The Big Rip scenario described by Oni is a "what if" scenario, where the dark energy component actually grows as the Universe expands, creating a divergent expansion. This would tear apart not just galaxies but eventually even nucleons! Interesting but pure speculation at this stage. The dark energy component could well decrease with expansion, such that gravitational attraction once again dominates, and the Universe could well collapse (given sufficient density.)

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 Message 24 by Taq, posted 05-20-2009 12:44 PM Taq has not replied

  
riVeRraT
Member (Idle past 416 days)
Posts: 5788
From: NY USA
Joined: 05-09-2004


Message 27 of 84 (509356)
05-20-2009 7:28 PM
Reply to: Message 23 by cavediver
05-20-2009 12:14 PM


onfire writes:
The redshift occurs with distant galaxies, not individual stars. Especially not anything in our Local Group - which is what I'm assuming you were visibly looking at.
I could find my old log, but I believe I looked at a few galaxies through my scope. I remember, m-101, m-31, m81 and 82, I think m-105.
onfire writes:
Furthermore, both redshift and blueshift aren't a visible phenomenon, it's is a measurment of the frequency of the emited light.
Yes, that I knew. Like measuring Doppler with sound equipment.
cavediver writes:
Hi RR - as Taq has already explained, stars within our Galaxy are in orbit about the Galactic core, and this massively dominates any effect of the Universal expansion.
I think that is wrong? Objects we measure using Hubble's law are only measured relative to us. Everything in our galaxy is moving with us, so universal expansion is undetectable. (I just realized/remembered this)
cavediver writes:
Likewise, neighbouring galaxies are far more affected by local gravitational effects than the expansion. You have to look past the Local Group of galaxies to start to see real evidence of the expansion.
I think galaxies close to us, are also moving with us, so we can't detect their expansion relative to the universe. If M-33/31 are only 2 million light years away, then it has only separated from us very little compared to the 14 billion light years we have traveled from the center. So it is moving too slowly away from us to measure using Hubble's law.

This message is a reply to:
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Replies to this message:
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 Message 31 by lyx2no, posted 05-20-2009 11:05 PM riVeRraT has replied
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onifre
Member (Idle past 2951 days)
Posts: 4854
From: Dark Side of the Moon
Joined: 02-20-2008


Message 28 of 84 (509359)
05-20-2009 7:50 PM
Reply to: Message 27 by riVeRraT
05-20-2009 7:28 PM


I could find my old log, but I believe I looked at a few galaxies through my scope. I remember, m-101, m-31, m81 and 82, I think m-105.
No need, I'm sure you did as there are many within our Local Group.
Everything in our galaxy is moving with us, so universal expansion is undetectable.
I believe you are getting a few facts confused here, RR. The galaxies within our Local Group are measurable, they show a Blue Shift indicating that they are coming toward us. This is the affect that Cave was talking about due to the Galactic core's gravitational attraction.
The Blue Shifting of the galaxies within our Local Group is a measured fact.
So it is moving too slowly away from us to measure using Hubble's law.
The galaxies within our Local Group have been measured and are Blue Shifting rather than Red Shifting.
PS. If you don't mind could you split the posts and not put both me and cavediver on the same post. He knows a shit load more than I do and I'd hate for him to miss a question that can help both you and I because he may not notice that you replied to him on the post for me, thanks.
- Oni
Edited by onifre, : No reason given.

"I smoke pot. If this bothers anyone, I suggest you look around at the world in which we live and shut your mouth."--Bill Hicks
"I never knew there was another option other than to question everything"--Noam Chomsky

This message is a reply to:
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Replies to this message:
 Message 29 by Coragyps, posted 05-20-2009 8:42 PM onifre has replied

  
Coragyps
Member (Idle past 734 days)
Posts: 5553
From: Snyder, Texas, USA
Joined: 11-12-2002


Message 29 of 84 (509362)
05-20-2009 8:42 PM
Reply to: Message 28 by onifre
05-20-2009 7:50 PM


The galaxies within are Local Group are measurable, they show a Blue Shift indicating that they are coming toward us.
Some of the local group galaxies are blueshifted, but some are redshifted. Since the three big ones, the Milky Way, Andromeda, and Triangulum, are in mutual orbits of some complicated sort, and the little ones are in orbits around the big ones, any particular galaxy can be heading toward us or away in any particular megamillenium.
I made that last word up, I think.
Local Group - Wikipedia lists 'em - the Leo Dwarf is one that is redshifted.

This message is a reply to:
 Message 28 by onifre, posted 05-20-2009 7:50 PM onifre has replied

Replies to this message:
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onifre
Member (Idle past 2951 days)
Posts: 4854
From: Dark Side of the Moon
Joined: 02-20-2008


Message 30 of 84 (509369)
05-20-2009 10:16 PM
Reply to: Message 29 by Coragyps
05-20-2009 8:42 PM


Some of the local group galaxies are blueshifted, but some are redshifted. Since the three big ones, the Milky Way, Andromeda, and Triangulum, are in mutual orbits of some complicated sort, and the little ones are in orbits around the big ones, any particular galaxy can be heading toward us or away in any particular megamillenium.
Thanks for the correction, Coragyps. I knew I should have looked that up to make sure, but I also knew if I was wrong someone would catch it.
So question, is the megamillenial shifting to and from caused by Dark Energy - versus - gravity of the Galactic center/core?
As I was reading up I noticed they mentioned Leo I was one of the furthest.
quote:
At about 820,000 light-years distant, it is a member of the Local Group of galaxies and is thought to be one of the most distant satellites of the Milky Way galaxy.
Does it's distance have anything to do with it's red shifting?
I made that last word up, I think.
Apparently some Russian (I'm guesing by the letters and movies I've seen) gaming website has the name. Games is the only english word I saw. So it looks like the Russian gaming nerds beat you to that word.
- Oni
Edited by onifre, : No reason given.

"I smoke pot. If this bothers anyone, I suggest you look around at the world in which we live and shut your mouth."--Bill Hicks
"I never knew there was another option other than to question everything"--Noam Chomsky

This message is a reply to:
 Message 29 by Coragyps, posted 05-20-2009 8:42 PM Coragyps has not replied

  
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