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CraigS
04-08-2010, 11:52 AM
Interesting papers, relatively recent, quite readable, by the same person (Southampton University), and using SN1A data (see attachments, if interested):

"Alternative cosmology fits supernovae redshifts with no dark energy" - March 2009.

His conclusion:
"Supernovae and radio galaxy redshift data are fitted in an alternative cosmology. The galaxies are assumed to recede with unchanging velocities in a static Robertson-Walker metric with a(t) = 1. An exact fit is obtained with no adjustable parameters. There is no indication that the recession velocities are changing with time, so no call for ”dark energy”."

Second paper:
"Does gravity operate between galaxies? Observational evidence re-examined" - May 2010.
His conclusion:
"On the largest scale, the net force accelerating or decelerating the galaxies is apparently zero. Each recedes with unchanging velocity following Newton’s first law."

Please note I'm not trying to push any particular personal views or opinions here (there's always more scientific debate for and against - and it seems this one isn't fully settled), but I thought it was interesting because the conclusion seems to differ from other papers based on Supernova Type 1a data.

In his words:
"This model may be incompatible with other cosmological data, such as the cosmic microwave back-ground and the distribution of galaxies. Most phenomena, however, depend on the distribution and movement of matter, not on the expansion of space itself. These questions remain to be examined."

Interesting.
Cheers.
PS: He's also saying that Martin Rees' (& others) provided comments during the study. ;)

renormalised
04-08-2010, 01:36 PM
I'll have to read these...sounds interesting:)

If he's saying what I think he is, then there'll be no acceleration or contraction and the Universe will just coast along on into infinity. Pretty much in line with previous expectations and values derived for matter and energy density within the universe. That means no CC...that'll make a lot of physicists happy:)

Hmmm...what needs to be done is the SNIA model needs to be refined and more observations of the supernovae need to be done. Going to need a dedicated, worldwide supernova search program with both small and large scopes to figure out what's happening. In order to tie down the theory from the obs, they'll need to find 20-50 Type IA Sn's every year till they get a large enough sample to make this, at least, relative statistically significant...iron out any selection bias.

You watch what will be said by you know who;):P

bojan
04-08-2010, 02:39 PM
Interesting..

So, he is saying that distant galaxies are there where they are simply because their velocity (after BB explosion?) was highest.
I think this was one of the first simple explanations offered, after expansion was detected (by redshift).

renormalised
04-08-2010, 03:20 PM
Yes, but that explanation would imply a zero point in spacetime...i.e. a point of origin which would be observable. Given our point of reference, it would mean that the Earth (or where the Earth is in relation to the rest of the universe) would be the centre. That would make the geocentrists and the creationists extremely happy:rolleyes::screwy:

That would also mean the CMB would appear to have a different temp at different positions within the universe....something we don't see from observation. Despite our position, the anisotropy would be detectable in the light coming from these distant objects, which it isn't.

Steffen
04-08-2010, 03:51 PM
Or more precisely, St Peter's Basilica in Rome.
;)

Cheers
Steffen.

sjastro
04-08-2010, 04:00 PM
It also makes a mess of Hubbles Law. The recession velocity of the galaxies will be same for all observers (in the line of sight) irrespective of the distance between observer and galaxy.

Steven

bojan
04-08-2010, 04:09 PM
How is that?

xelasnave
04-08-2010, 04:27 PM
Would not all the galaxies be in more or less the same place now as they were after the initial inflation period...(that short period of say up to 30 seconds that is attributed to inflation when the universe grew from the size of a basket ball to near all it is today) ... and really after inflation how far have galaxies really moved if you dont take into account inflation or "current" expansion... very little I expect when compared to the great distances created by the inflation period.

I dont think galaxies can be thought of as accelerating due to some explosive force as some may imagine the big bang may produce.

Galaxy movement in relation to each other and not in relation to the inflation would be relatively insignificant and any movement to or away from each other will be mere fractions of c.

alex

sjastro
04-08-2010, 04:44 PM
Hubbles law states that in a metrically expanding Universe, the recession velocity is proportional to the distance between the observer and the object. So doubling the distance doubles the recession velocity.

The model presented here is that galaxies are moving in space at a constant velocity rather than space expanding. A galaxy moving away from an observer in space will travel at that velocity irrespective of how far the galaxy is from the observer.

Steven

bojan
04-08-2010, 04:47 PM
Yes, but more distant galaxies had higher initial velocity (and still have), so they are further away at present.
So, something like Hubble law could still be observed...

xelasnave
04-08-2010, 04:53 PM
Does the expansion of space mean that galaxies will have any velocity?
alex

bojan
04-08-2010, 05:03 PM
I don't think the papers from Craig's post are talking about metrically expanding Universe.

CraigS
04-08-2010, 05:12 PM
These guys seem to be enquiring into the nature of "the metrically expanding universe" and I think they're saying that the observation data doesn't seem to support a "metrically accelerating universe".

The definition which Steven quotes seem to be critically dependent on the definition of "metrically expanding". In my naivity, I thought Hubble's Law was Earth-centric. There again, I guess there's nothing special about Earth's frame of reference ?

Cheers

CraigS
04-08-2010, 05:18 PM
G'Day Alex;
What caused the velocity is outside the scope of the paper's investigation area.
Cheers

renormalised
04-08-2010, 05:24 PM
Well, if you want to be really precise:):P

CraigS
04-08-2010, 05:27 PM
Oh ... unless it's St Peter's Basilica in Rome !

sjastro
04-08-2010, 05:41 PM
The paper uses terminology familiar to the concept of metric expansion.
For example Z is a cosmological redshift not a doppler shift.

Getting back to my original comment if two observers in different locations measure different velocities for an object moving away in space then acceleration (or deceleration) is occurring which contradicts the point of the article.

I find it difficult how one can fit Hubble's recession velocities into this picture for a doppler shift mechanism.

Even considering a "localized" version where the Z is interpreted as a Doppler shift in our patch of the Universe doesn't help either.

Steven

renormalised
04-08-2010, 06:07 PM
I still haven't read the paper yet, but I can gather that they think the universe, from their observation of the supernovae, seems to employ more of a constant expansion. They're saying that the galaxies are moving apart at a constant rate relative to their position in the initial expansion , no matter where or how far away you look. So, if a galaxy is 12 billion light years away and is moving away at 0.9c, then even after traveling a further 2 billion light years, it will still be traveling at 0.9c...and so forth. As Steven has reiterated, that throws redshift-distance determination right out the door, unless you can find a factor which when added to or multiplied by z, gives you the correct distance. That is, providing they're assumptions as to the metric for the expansion are correct to begin with.

renormalised
04-08-2010, 06:11 PM
These following pages should help to enlighten everyone...

http://www.jb.man.ac.uk/~jpl/cosmo/RW.html (http://www.jb.man.ac.uk/%7Ejpl/cosmo/RW.html)

http://en.wikipedia.org/wiki/Friedmann%E2%80%93Lema%C3%AEtre%E2% 80%93Robertson%E2%80%93Walker_metri c

http://en.wikipedia.org/wiki/Scale_factor_%28universe%29

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

bojan
04-08-2010, 07:18 PM
OK, this makes sense..

Robh
04-08-2010, 08:24 PM
Most interesting!
I find the idea of static space quite believable, more so than the invention of dark energy. One must note that even if all galaxies are receding from a common point, then at any point in the observable Universe we will still measure recession of galaxies in every direction from that point.

Regards, Rob.

CraigS
04-08-2010, 08:46 PM
Hmm;
I'm on a learning curve here folks. Looks like I've got more reading to do.
:)

Steven;
Thanks for the insights. I'm not quite into the right perspective/understanding yet. I'll chase it until I get it, though. I appreciate your comments - thanks.

Carl - thanks for the links. I'm going to chase up the references at the bottom of 'Metric Expansion of Space' link tomorrow (I'm about brain-dead tonight).

Bojan - Cool - glad you got it. Cheers.

Robh: It is interesting, huh ?

Cheers to all,
Craig

renormalised
04-08-2010, 09:22 PM
It's not so much static as it's neither decelerating or accelerating. However, if you measure recessional velocities from an origin point, then you immediately violate the cosmological principle.

renormalised
04-08-2010, 10:03 PM
Here's some books you might like to purchase, if you want to...

http://www.fishpond.com.au/Books/Science/Astronomy_Space/9780521126533/?cf=3&rid=1310969512&i=121&keywords=Astrophysics

http://www.fishpond.com.au/Books/Science/Astronomy_Space/9780735406148/?cf=3&rid=1310969512&i=146&keywords=Astrophysics

http://www.fishpond.com.au/Books/Science/Astrophysics/9780521358088/?cf=3&rid=1310969512&i=219&keywords=Astrophysics

http://www.fishpond.com.au/Books/Science/Astronomy_Space/9783540329244/?cf=3&rid=1310969512&i=305&keywords=Astrophysics
(http://www.fishpond.com.au/Books/Science/Astronomy_Space/9783540329244/?cf=3&rid=1310969512&i=305&keywords=Astrophysics)
http://www.fishpond.com.au/Books/Science/Physics2/9780521887052/?cf=3&rid=1310969512&i=309&keywords=Astrophysics

http://www.fishpond.com.au/Books/Science/Astronomy_Space/9783540419273/?cf=3&rid=1310969512&i=350&keywords=Astrophysics
(http://www.fishpond.com.au/Books/Science/Astronomy_Space/9783540419273/?cf=3&rid=1310969512&i=350&keywords=Astrophysics)
http://www.fishpond.com.au/Books/Science/Applied_Sciences/9780521516006/?cf=3&rid=1310969512&i=431&keywords=Astrophysics
(http://www.fishpond.com.au/Books/Science/Applied_Sciences/9780521516006/?cf=3&rid=1310969512&i=431&keywords=Astrophysics)
That should be enough to keep you busy, if you're interested in learning some more:)

Robh
05-08-2010, 12:46 PM
From my reading of the proposed model it is in fact static space i.e. not expanding. But galaxies are receding from each other with unchanging velocities.
The paper talks of a common point of divergence. However, an observer at any point, not necessarily the point of origin, will still see other galaxies moving away from each other. The cosmological principle, as anything else in Science, is not immutable. However, I see no reason why the cosmological principle can't be applied to the current state of the universe. As all galaxies have moved away from the point of origin, it is no longer part of our observed universe. If galaxies extend beyond the event horizon in every direction, then our universe is what we see - seemingly the same in every direction.

CraigS
05-08-2010, 01:37 PM
Thus restoring a homogeneous, isotropic universe ? I think I'm starting to get the hang of this ..!...?

But .. I think Carl's point is that, by definition, the concept of a 'point of origin' automatically 'violates' the cosmological principle. It's cool that science allows thinking outside of things like this principle. It seems that whenever something comes hard up against it, (or violates it), something really interesting comes out of it.

renormalised
05-08-2010, 05:04 PM
The only time there can be a common point of origin and all the galaxies experience moving away from each other is if that point of origin lies outside the universe, completely. This is including the observable universe and the universe as a whole. Otherwise, you have a preferred frame of reference and this immediately violates the cosmological principle. All the observation that have been made point to the universe being isotropic and homogeneous on the largest of scales. For that to be the case, there cannot be a preferred frame of reference to the matter-energy density within the universe, otherwise it would've been detected.

The first premise of a static universe in which all the galaxies are moving away from one another makes no sense. You have a finite sized container with all its contents racing away to...where??. Eventually the galaxies will crowd to a point, or several points near the edge of the universe because at some stage, they will have to change their direction of motion tangential to their original motion vector....there's no more space to move in even if the universe is finite but unbound. This would already be occurring for the farthest galaxies, yet we see no evidence for this type of motion in the observations. Occam's Razor, ergo, it's not occurring. It would also mean that the redshift being detected is solely a Doppler shift and not a Hubble redshift....then you would have to explain those galaxies which exhibit a blueshift to their spectrum.

Then you have the problem that not all galaxies are, in fact, moving away from one another in the way that's been observed. If you have a preferred frame of reference because of a defined point of origin within the universe, you cannot have all the galaxies moving away from one another in all directions because some will have to be moving at a tangent to your motion. There's no way around it. Yes, you may be able to say that all the galaxies are in fact moving away from one another, with careful observation, but you would also be detecting galaxies whose motion would have a partial vector of movement across your line of sight. It would be akin to proper motion. This hasn't been observed.

renormalised
05-08-2010, 05:22 PM
But, it doesn't. There's no isotropy or homogeneity...you always have that preferred reference frame, the origin point (which is observable). Not only that, explosions (or a conflagration, which this would be better described as) don't happen in the manner of having everything moving away from the point of origin in a nice orderly manner. The physics just doesn't work like that. In order to have all the galaxies move away at constant velocities dependent on distance (which is not what is seen), you would have to have such a ridiculously smooth and ordered explosion, the chances of it ever happening would be even less than for a BB style of expansion. There would have to be zero turbulence to the explosion and the matter distribution would have to be even smoother than what we do find. It doesn't add up. Explosions are turbulent and lumpy affairs at the best of times. Anything that mixed up would show up in the CMB even now, after all this time. It would also show up in the distribution of matter and energy across the universe. It'd be incredibly lumpy, even on the largest of scales, but that's not what we find.

CraigS
05-08-2010, 05:38 PM
I was just reading your previous response to Rob. I think I understand.

It seems to be the same reasoning as to why the big bang origin is defined as "that point of infinite density and zero size occurred everywhere. All of space and time expanded out of that condition, so in effect everywhere was experiencing that condition. There was nothing outside of that "everywhere" which could be defined as a destination point and no vector to define a trajectory." (Your words). Is the Cosmo principle one of the reasons why the origin in BBTs is defined in such a way ?

Also, the paper which started this thread did point out that:

"This model may be incompatible with other cosmological data, such as the cosmic microwave back-ground and the distribution of galaxies. Most phenomena, however, depend on the distribution and movement of matter, not on the expansion of space itself. These questions remain to be examined."

Interrrressting !!!

Cheers

renormalised
05-08-2010, 05:45 PM
Yes, for the observations we see in the present universe's physical conditions to be upheld, then the BB must be defined as an isotropic and homogeneous expansion on the largest of scales. It's what we see. The universe can be as lumpy as it likes on smaller scales, which it is, but when you average out the matter-energy density of the universe over it's entire volume, the answer come extremely close to zero. Therefore it is isotropic (everything looks the same no matter where you look) and homogeneous (there's no areas which have any more matter-energy than any of the others).

CraigS
05-08-2010, 05:57 PM
Cool !!

Man, the guy that wrote this paper has a lifetime of digging himself out of this pile ie: => against the Cosmo principle, against the CMBR evidence, against Hubble's Law, against SNIA analysis, ...

I look forward to his next chapter !!!
:P

cheers

sjastro
05-08-2010, 06:01 PM
:P

It's also informative that you can publish such material and not be burnt at the stake as suggested by some psuedoscientists.

Steven

renormalised
05-08-2010, 06:03 PM
Shades of the Inquisition even:):P

renormalised
05-08-2010, 06:14 PM
There's nothing wrong with questioning the prevailing paradigm. Where it does become wrong is when you take your line of reasoning from wholly unsubstantiated and entirely speculative premises. You should at least know what you're on about (that means, knowing the prevailing school of thought well enough to be able to comment on it) and then come at it from a well reasoned direction. Not from some fantasy crazed ego trip just because you like the sound of something or it's your belief it's right and everyone else has it wrong. If you have something to say and are questioning the results or interpretations of another thing, then make sure it makes sense and doesn't just dismiss or ignore everyone else offhand.

That makes for good science.

CraigS
05-08-2010, 06:18 PM
Ahh ..ah dunno 'bout that one ..
He's gotta be pretty singed - if this forum is a micro-cosm of his world.

Love to tap into the feedback loop .. maybe Ned might be in it ??
:)

sjastro
05-08-2010, 07:43 PM
I'm sure Ned would have a few comments. Afterall a theory that would invalidate his work with COBE and WMAP............

Steven

sjastro
05-08-2010, 08:04 PM
Or as practiced by pseudoscience.

(1) If you can't refute mainstream science directly then create a fictionalized version and refute that.
(2) Argue the science is wrong because it is dogmatic.
(3) Conspiracy theories of pseudoscientists mysteriously disappearing after challenging mainstream science.
(4) Accuse theoretical scientists (mathematicians in particular) of being in league with the devil.
(5) Suggest that scientists such as Einstein or Feynman were closet supporters of the pseudoscience in question.
(6) Claiming the pseudoscience is testable in the laboratory despite the fact the technology as yet is unavailable and possibly won't be for the next 2 or 3 centuries.

Etc, Etc ,etc.........

Steven

renormalised
05-08-2010, 08:13 PM
You forgot #7...Cherry pick as many articles you can find and use everything you do find completely out of context...and #8 Accusing others of being dogmatic and critical, when they themselves are being exactly the same. Although "etc etc etc" just about covers it anyway:)

CraigS
05-08-2010, 08:49 PM
I would happily defer to you to write the questions ...
;)
:)

Rgds.

astroron
05-08-2010, 08:54 PM
I have been following this thread with interest:)
But now I am going to ask a maybe stupid question, who is Ned:shrug:

CraigS
05-08-2010, 09:02 PM
Prof Edward (Ned) Wright ..

http://www.astro.ucla.edu/~wright/intro.html

Cheers

renormalised
05-08-2010, 09:02 PM
Ned = Edward Wright, cosmologist at UCLA. Pretty cool guy. Did much of the ground work for COBE and WMAP.

Very informative pages...Ned Wright's Cosmology Tutorials (http://www.astro.ucla.edu/%7Ewright/cosmolog.htm)

astroron
05-08-2010, 10:49 PM
:thanx: both of you:thumbsup:

Steffen
05-08-2010, 11:57 PM
I guess I'll stick to my own pet theory - giant intergalactic eddy currents. It rolls off the tongue so nicely it must be profound.

Cheers
Steffen.

renormalised
06-08-2010, 12:30 AM
Let it be known, then let it be so!!:)

(i.e. give us a run down on the low down:P)

Steffen
06-08-2010, 02:42 PM
I haven't really worked out the details but you've got to admit, it sounds enticing :)

Cheers
Steffen.

renormalised
06-08-2010, 02:46 PM
GIEC....another acronym!!!!:P