One of the most recent papers on the issue is Phil Fraundorf's paper, [1206.2877] A traveler-centered intro to kinematics he essentially has a choice between what he calls "inertially floating free frames" and "Radar Time and Radar Distance" He chooses Radar Time and Radar Distance for his analysis, in large part, because most people believe that the universe consists of a globally curved space, in which small regions of Minkowski space-time are embedded. The paper about [gr-qc/0104077] On Radar Time and the Twin `Paradox' has been criticized by Antony Eagle, [physics/0411008] A note on Dolby and Gull on radar time and the twin "paradox" because it seems to be rejecting the notion that "distant objects go forward and backward in time, every time you go dancing." This idea that distant objects go forward and backward in time every time you go dancing implies that the universe is globally, a Minkowski space, in which the local curvature of spacetime is embedded. If you go look in another paper by Mike Fontenot, 3. Michael L. Fontenot, Accelerated Observers in Special Relativity you can find another writer who says, far more emphatically, that we must be FORCED to conclude that distant objects go forward and backward in time, every time you go dancing.
This idea has been animated by WWoods here: File:Lorentz transform of world line.gif and myself, recently, here: Talk:Twin paradox

But if Michael Fontenot's ideas were correct, I'm not at all sure these ideas are consistent with the leading modern notions of relativity theory. For instance... There is a statement called the cosmological principle which says that "The distribution of matter in the universe is isotropic and homogeneous"

But if you are forced to accept that distant objects go forward and backward in time depending on your temporal facing, and you assume that all matter in the universe exploded outward from a single point, then the universe would be isotropic from any non-accelerated  point-of-view, but not homogeneous.  It would have a well-defined distribution, similar to these: hyperbolic circle - Google Search

If distant planets actually do go forward and backward in time, every time you go dancing, then that would mean the universe really does consist of locally curved spacetime embedded in a globally flat Minkowski Spacetime, then a great deal of modern cosmology would have to be re-worked, and the science of cosmology would have to go back to square one... Starting with Edward Arthur Milne's kinematic cosmology: Relativity Gravitation and World Structure : E.A. Milne : Free Download & Streaming : Internet Archive

Direction isn't important IF the assumption of Hubble's Law Holds

Supernova

Stars (astronomical objects)

Outer Space

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What is a Supernova?

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Charlie Kilpatrick, I've authored refereed publications on supernovae and supernova remnants

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A supernova is a transient astronomical object whose intrinsic brightness is several (~seven to nine) magnitudes brighter than a classical nova.

Where supernovae lie in luminosity-timescale space.

That's it.  The definition is purely in terms of observational characteristics with no physical interpretation overlaid to confuse the issue. 

This point is one that's underappreciated by the public and especially astrophysicists.  You should never, ever mix classification with physical mechanisms.  The former always informs the latter.  If you start working physical mechanisms into your definitions (e.g., a supernova is the explosion of a high-mass star), then you'll start biasing the interpretation of your observations and have a much harder time dealing with new trends in your data.

In addition to the above definition of supernovae, several other classifications have been developed, such as "Type I" (supernovae without hydrogen in their spectra) and "Type II" (supernovae with hydrogen in their spectra).  Only through continued observation of trends in the lightcurves (variation in brightness with time) and spectra of supernovae were astrophysicists able to predict that a particular subclass of supernovae come from white dwarfs (so-called "Type Ia supernovae") while the remainder come from high-mass stars. 

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Jonathan Doolin

Do they have a global standard for reporting information on supernova data?

I have seen reports of "redshift" and "magnitude" but to measure a redshift, one must first be sure that they have properly identified the colors that have been redshift.  That's fine.

But then I see reports of "magnitude" being listed through locally defined colors... Red, Green, Blue filters that exist on the telescope itself.

Astronomers are very smart, so they surely take into account that if the colors have shifted, then surely whatever they measure as magnitude should shift, too. 

However, looking through the IAUC (International Astronomical Union Circulars) data on supernova, many report different magnitudes based on filters, but when I read papers supporting the lambda Cold Dark Matter universe based on Type I supernova data, they do not get into the nitty gritty of how the actual magnitude of the supernova is calculated.  In fact, if I recall, correctly, these papers often don't report the magnitude at all; but rather simply report the redshift and distances to the supernova. (And they tend to ignore right-ascension and declination)

To assign the supernova a "distance" is a physical interpretation of the observational characteristics... The observational characteristics are just the Right ascension, Declination, and the spectral analysis. 

Do amateur astronomers sending in International Astronomical Union Circulars have sufficient equipment and training to provide an accurate measurement of magnitude, and be sure they are all measuring and communicating the same quantity?

Or does the information about magnitude through two or three filters give all that is needed to reconstruct the spectral analysis?

Also, when they make a measure of redshift, how confident are they that they have found, for instance, the hydrogen alpha line?  Many IAUC cirucluars report precisely what line they are using to find the redshift, but many just say z=2.1 or whatever, without giving any indication of how it was calculated.

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Charlie Kilpatrick

There's no formal standard, but it's generally expected that you should report the magnitude of the observation for photometry and the redshift, magnitude, and a guess at the spectral type and epoch (i.e., how many days relative to the supernova reaching maximum brightness) for spectroscopy.

Redshifts are exact.  They're based on comparison to known spectroscopic lines in supernova spectra - usually hydrogen or helium features, although silicon features are used for Type Ia supernovae (which lack hydrogen and helium).

Magnitudes are measured in a specific filter (V, R, B are commonly used filters for visible, red, and blue) or sometimes in unfiltered light for faint objects.  These filters have been very precisely engineered and measured so we know exactly how much light at each wavelength can pass through.  There are also hundreds of standard stars measured in each filter for comparison, which sets a magnitude scale.  Whenever you see a supernova with a magnitude measurement, that's based on comparison to a bright, photometric standard star.

Astronomers who study Type Ia supernovae for cosmology don't much care about the intrinsic brightness of their supernovae.  They only want an object with a distance and redshift they can measure simultaneously so they can put it on the Hubble diagram.  If you're reading papers about cosmology, you'll also need to read the papers cited within to get a better understanding on how the actual supernova photometry is performed.  Also, Hubble's law is assumed to be isotropic based on the Cosmological principle , so it doesn't really matter where in the sky a supernova is located (as in RA and dec) - as long as it has a distance and redshift you can measure then you should be able to model Hubble's law.

Assigning Type Ia supernova distances is also based on an assumption.  The peak, bolometric, intrinsic magnitude of Type Ia supernovae has been observed to be roughly the same to within a couple tenths of a magnitude.  Therefore, if you can measure the relative magnitude (at peak) of a Type Ia supernova and assume it's similar to all other Type Ia supernovae you've observed (ymmv), you'll have a rough idea of the distance to that supernova.

I've never been on an IAU Circular (I generally use Astronomer's Telegrams, for example: http://adsabs.harvard.edu/abs/20... , Spectroscopic Classification of ASASSN-15rw as a Type Ia ).  As I understand it from reading their guidelines on submissions (How to Submit Scientific Items for Publication in the IAUCs), they prefer submissions with CCD-quality data.  Most amateurs don't own that kind of equipment as it can run into the tens or hundreds of thousands of dollars.  But there aren't any rules or prejudice against amateur submissions.

It would be very difficult to reconstruct spectral analysis based on photometry, especially in terms of resolving lines such as H-alpha.  IAUCs that report spectral lines to two or more degrees of precision are fitting a spectral line profile to the error bars in their data in order to measure the uncertainty in their redshift measurement.  It's a form of non-linear error propagation.  Usually, specific codes are used to perform the spectral fitting, such as SuperNova IDentification (SNID) by Blondin and Tonry.  That code has extensive documentation on how redshifts, magnitudes, types, etc. are evaluated:http://fr.arxiv.org/pdf/0709.4488v1

Doubts about Type Ia supernovae data and the Lambda CDM model

Do they have a global standard for reporting information on supernova data?

I have seen reports of "redshift" and "magnitude" but to measure a redshift, one must first be sure that they have properly identified the colors that have been redshift.  That's fine.

But then I see reports of "magnitude" being listed through locally defined colors... Red, Green, Blue filters that exist on the telescope itself.

Astronomers are very smart, so they surely take into account that if the colors have shifted, then surely whatever they measure as magnitude should shift, too. 

However, looking through the IAUC (International Astronomical Union Circulars) data on supernova, many report different magnitudes based on filters, but when I read papers supporting the lambda Cold Dark Matter universe based on Type I supernova data, they do not get into the nitty gritty of how the actual magnitude of the supernova is calculated.  In fact, if I recall, correctly, these papers often don't report the magnitude at all; but rather simply report the redshift and distances to the supernova. (And they tend to ignore right-ascension and declination)

To assign the supernova a "distance" is a physical interpretation of the observational characteristics... The observational characteristics are just the Right ascension, Declination, and the spectral analysis. 

Do amateur astronomers sending in International Astronomical Union Circulars have sufficient equipment and training to provide an accurate measurement of magnitude, and be sure they are all measuring and communicating the same quantity?

Or does the information about magnitude through two or three filters give all that is needed to reconstruct the spectral analysis?

Also, when they make a measure of redshift, how confident are they that they have found, for instance, the hydrogen alpha line?  Many IAUC cirucluars report precisely what line they are using to find the redshift, but many just say z=2.1 or whatever, without giving any indication of how it was calculated.

Twelve Views on Quora... Long argument.

Can we propose that there is center (point of symmetry) for the universe describable by 4 dimensional geometry? Or that takes in the assumption of taking the universe to be finite with positive curvature?

When we have an expanding balloon, there exists a point of symmetry (center) for the balloon's 2D dimensional universe, which is the center of the sphere which can only be described using an additional dimension of length. 

Can we say that our universe could also have a center (a point of symmet... (more)

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Jonathan Doolin, Colllege Math and Physics Instructor

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Asked-to-Answer, thanks, 
... and also a topic of great interest to me for many years.

It largely depends on whether your conceptualization of the universe claims that the domain and range of the Lorentz Transformation equations are all events, future and past, or if you put some arbitrary limit on the Lorentz Transformation equations--saying, for instance, they cannot affect events in the distant past, or that they cannot affect events billions of light-years away.

The Cosmological Principle states that the universe must be both homogeneous and isotropic.  In such a case, then there cannot be a single center point of the universe.  There is only one structure that meets these two criteria--one that has distant parts of the universe moving faster than the speed of light, but at any given moment, it is perfectly homogeneous.  This model of the universe renders the Lorentz Transformations irrelevant, by adding another variable to the distance measurement... a cosmological scale factor, usually denoted as a(t)... saying that distant objects are not moving away according to their velocities, but rather because of this universal scale factor.  Scale factor (cosmology). 

However, if you permit some modification on the Cosmological Principle, and permit the Lorentz Transformations.  You can have a universe that appears, from all locations LOCALLY to be homogeneous (within the nearest 3 or 4 billion light years) but actually does come from a single point in space and time,  Generally at or near the (x,y,z) coordinates of any given observer.

This idea was first presented by E. A. Milne (See Relativity Gravitation and World Structure : E.A. Milne : Free Download & Streaming : Internet Archive )

You can see a second-hand article about Milne and his model here Cosmology: Methodological Debates in the 1930s and 1940s.  The description here of Milne's model bears only the most  tangential resemblence to what is in the actual book.  In Milne's book, for instance, he gives the clear definition of homogeneity, only to dispel the concept by reductio ab adsurdam.  However, if you read the second-hand-article, you get the impression that Milne invented the idea of homogeneity in order to make it a part of his own model!

And it is interesting to note, that references to the actual book "Relativity Gravitation and World Structure" are not permitted on Wikipedia, because it is a Primary Source. Furthermore, direct quotes from Relativity, Gravitation, and World Structure are considered "original research" and are not permitted on Wikipedia. 

You can see plainly in the text here, "The particles near the boundary tend towards invisibility as seen by the cntral observer, and fade into a continuous background of finite intensity."

He is talking about what is now known as the Cosmic Microwave Background radiation.

But yes, if you look at the diagram in the picture, you can see a center-point in that sphere; an (x=0,y=0,z=0) and if you back up in time to the event where all of this expansion started, it is (x=0,y=0,z=0,t=0).  That is, a single event in four-dimensional space.

Written Dec 3 • Asked to answer by Kia Karbasi

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Erik Anson

>> He is talking about what is now known as the Cosmic Microwave Background radiation.

Except that no, he's not. It may well have been a perfectly lovely theory at the time it was published, but there's a reason why it isn't taught today, namely that we actually have data now, and that theory doesn't match it.

1. There's a difference between cosmological redshift and Doppler redshift (see: Page on cwru.edu).
2. The CMB has features that are inconsistent with being distant nebulae / galaxies, e.g.,Baryon acoustic oscillations. Many of the same observations and arguments that falsified Hoyle falsified this as well.




I'll never understand why people insist on looking up old theories of cosmology and adopting them without checking whether they even match modern observations. Trying to research cosmology in 1930 was like trying to research medicine in 1300. You have some information, so you might get some things right, but you're missing so much that it would be insane for someone to pick up that research and uncritically accept it because it sounds reasonable.

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Jonathan Doolin

There's something called a "surface of last scattering" where protons and electrons formed the first permanent hydrogen atoms, and were essentially a plasma.

In Milne's model, this observed surface is simply moving away at nearly the speed of light, and thus red-shifted by the relativistic Doppler effect.

In the standard model, this observed surface is ... whatever the standard model proponents are saying it is doing, but it is redshifted by cosmological redshift.

There are some major features of the apparent universe that do differ significantly from Milne's model.  For one, the observed universe appears to be at least 40 billion light years in radius, while the apparent age, according to Hubble's Law puts it around 13.7 billion years.

Both models can explain this by inflation.  However, Milne's model actually has a strong explanation for inflation in the already well-known "twin paradox".

I've never got access to the data but here are some features that I would be looking for (as evidence for Milne's model) if I had the opportunity.

(1) at about 6-7 billion light years away from here, there shoud be a statistically significant peak in type I supernovae... Because this would represent a secondary explosion within an older and larger existing universe.
(2) beyond 7 billion light years away, Measurement of Hubble's constant would go down by a factor of 13.7/40 or so, if my figures above are correct.  Also, there should be an asymmetry in these values along the same axis as the CMBR dipole anisotropy.
(3) beyond 7 billion light years away, there would be greater deviation in the Hubble's constant.


>>I'll never understand why people insist on looking up old theories of cosmology and adopting them without checking whether they even match modern observations.

What I can never understand is how someone who clearly doesn't understand a theory, can claim to have found the data that disproves it.

What I would need to see, before I stopped insisting on bringing up this theory is for someone to demonstrate an understanding of the idea, with sufficient clarity that they convinced me that they understood the idea.  Then, they could point to the data which disproved the idea...

And then, what would I do?  I might not give up just yet.  Because I might have another idea. 

Why shouldn't an idea from the 1930's evolve?  This is the way the standard model has been evolving for many decades.  They will make a prediction, then it doesn't fit with their expectations, and they will introduce another idea... Dark matter... Dark energy... cosmological constants... scale factor... cosmological redshift.... whatever they need to get the idea to work.  They have had the ability to see the data, and adapt their theory to that data.

The only additional adaptations that I want to have allowed for Milne's model, that Milne didn't originally appear to think of is Brownian motion in the early universe, and a few rather mysteriously massive hypernova explosions, later on.

If the standard cosmological model is correct, additional data and analysis is going to tell you precisely the number for the cosmological constant--exactly how much dark energy, and dark matter, precisely how the scale-factor of the universe is changing.

If Milne's model is correct, then an analysis of the data should show you the locations where huge cosmological events happened in the distant past.

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Erik Anson

>> There's something called a "surface of last scattering" where protons  and electrons formed the first permanent hydrogen atoms, and were  essentially a plasma.

I'm a PhD student in cosmology, so you don't have to tell me what the surface of last scattering is.



>> In Milne's model, this observed surface is simply moving away at nearly  the speed of light, and thus red-shifted by the relativistic Doppler  effect.
In the standard model, this observed surface is ...  whatever the standard model proponents are saying it is doing, but it is  redshifted by cosmological redshift.

As I have already said (and posted a reference for), there are differences in how cosmological redshift and Doppler redshift depend on distance in an expanding Universe. We observe the former.



>> beyond 7 billion light years away, Measurement of Hubble's constant  would go down by a factor of 13.7/40 or so, if my figures above are  correct.

Hubble's constant goes up as you go back in time (and, thus, far away in distance).



>> What I can never understand is how someone who clearly doesn't  understand a theory, can claim to have found the data that disproves it.

I can also tell you that a flat-Earth theory is wrong without needing to understand its nuances. The model of an actual explosion of stuff into empty space doesn't work. I would be happy to go into more detail if you gave me Milne's theory in more detail.



>> Why shouldn't an idea from the 1930's evolve?  This is the way the  standard model has been evolving for many decades. 

Sometimes things are minorly wrong, and need tweaking. Sometimes things arefundamentally wrong, and trying to tweak it just gets embarrassing (see: Fred Hoyle).



>> They will make a  prediction, then it doesn't fit with their expectations, and they will  introduce another idea... Dark matter... Dark energy... cosmological  constants... scale factor... cosmological redshift.... whatever they  need to get the idea to work.

The possibility of a cosmological constant has been around since the beginning (almost a century now). As has the idea of a scale factor, which was a fundamental part of even early versions of Big Bang Theory. Cosmological redshift is a straight-forward result that falls out of General Relativity, and was not "added in". Dark matter was first postulated for astrophysical reasons, not cosmological ones, although we now have cosmological evidence of dark matter as well (and there's nothing at all in the original theory that would be in tension with the existence of dark matter; it's just an extra thing to plug in). Dark energy is (in our current models) the same thing as the cosmological constant, so you can't really count it twice.

Looking at that list of stuff you just mentioned, and the way you described it, it's clear you don't particularly know what you're talking about in this area. The irony of writing a list like that after railing against criticising things you don't understand is astounding.

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Jonathan Doolin

>>the idea of a scale factor, which was a fundamental part of even early versions of Big Bang Theory

Do you think the scale factor was a fundamental part of Milne's model?

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Erik Anson

My guess would be "no", from your description, but your description was so incomplete that I couldn't say with certainty. I'm talking about what happens when you apply General Relativity to a Universe that is homogeneous and isotropic on large scales (which, to the limits of our ability to measure, ours is): the Friedmann–Lemaître–Robertson–Walker metric.

By the way, a quick look on Wikipedia explains the contradictions between Milne's model and observations: Milne model.

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Jonathan Doolin

Yeah... I think I mentioned Wikipedia's policies in my original answer... Take a quick look at the talk page and the archived history of the Milne model.

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Erik Anson

I looked at the Talk page. There are many things showing the holes in your background knowledge, such as this exchange:

"Because GR is Minkowski space when there is no curvature."

"Perhaps you mean SR (not GR) is Minkowski space when there is no curvature."

(No, they were right the first time... GR without curvature is SR.)

The fact that Milne may not contradict the things that you personally know about cosmology does not mean that the two are consistent. Making claims that contradict the scientific consensus, without actually studying the field in detail, is rather silly.

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Jonathan Doolin

Oh wow, you just totally nailed 2006 me.  You're right, I probably wouldn't have made that argument today.  But I have also not seen any real evidence that Milne was wrong.  You're quite correct sir.  Notihng that I PERSONALLY knew about cosmology conflicts with Milne's model.  Nothing that I have learned in the 9 years since conflicts with Milne's model.  
You might think it is silly to go by what I personally know.  But I think it is rather sillier to go by what you don't personally know.

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Erik Anson

>> Oh wow, you just totally nailed 2006 me. 

That was one particular example out of many (both in that Talk page and in our exchanges), and you directed me to the Talk page as counter-evidence to the page itself, which describes contradiction with observation.



>> You might think it is silly to go by what I personally know.  But I  think it is rather sillier to go by what you don't personally know.

Holding off on making claims about things you don't know is reasonable. That's not what you're doing, though... you're making negative claims. That's not supportable. When people who have studied the field in more detail try to tell you that something doesn't work, you should consider listening to them, instead of standing by a long-falsified theory that the world of science moved on from ages ago.

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Jonathan Doolin

I'm making a positive claim... in support of Milne's model.

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Erik Anson

Without the relevant knowledge. In disagreement with the people who do have the relevant knowledge.

This is exactly the problem.

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Jonathan Doolin

>>My guess would be "no", from your description, but your description was so incomplete that I couldn't say with certainty.

I think this is interesting that you getting near having a PhD in cosmology and you don't know whether Milne's model has a cosmological scale factor or not. 


>>(No, they were right the first time... GR without curvature isSR.)

Thinking a little more about what 2006 me said, I think I was right the first time.  (You did not nail 2006 me... 2006 me was actually correct, though now I can express my point with greater clarity.) 

GR without curvature still has this scale factor a(t)=1/t.  That is NOT the same as SR.

===========
Edit:  This really was in error.

GR without curvature would have a=x⃗ 0,dadt=dx⃗ 0dt,H(t)=da/dta=1/t

My point was that the FLRW metric, even if mathematically identical to dx⃗ dtt=x still presumes that objects are moving away from each other according to an expanding scale factor, rather than ordinary motion through space. 

That generalization should really not be extended to all of General Relativity, but it does apply to the Friedmann-Lemaitre-Robertson-Walker metric.
===========

In SR motion of objects; even the most distant objects, would be modeled by distance=initialposition+velocity∗time

There is no need for a cosmological scale factor.

While a(t)=1/t would be observationally identical to a universe modeled by distance=velocity∗time, it is NOT THE SAME.

When Galileo set Ptolemy's model and Copernicus' model side-by-side to prove that Copernicus was more correct, he did not do so by failing to acknowledge that Ptolemy's model existed.  Rather, he accepted Ptolemy's model for what it was, and then used evidence to show that one model fit the data better than the other.

What cosmologists are doing with Milne's model is failing to acknowledge that it ever existed.

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Erik Anson

>> I think this is interesting that you getting near having a PhD in  cosmology and you don't know whether Milne's model has a cosmological  scale factor or not. 

Why is it essential for me to know the details of a theory that was falsified and abandoned decades before I was born?



>> Thinking a little more about what 2006 me said, I think I was right the  first time.  (You did not nail 2006 me... 2006 me was actually correct,  though now I can express my point with greater clarity.) 

No, 2006 you was wrong. If you no longer agree with that statement, then congratulations, you just removed your "that was 9 years ago" defense; 2015 you is also wrong.



>> GR without curvature still has this scale factor a(t)=1/t.  That is NOT the same as SR.

This is entirely false, in many, many ways. What made you think this?



>> In SR motion of objects; even the most distant objects, would be modeled by distance=initialposition+velocity∗time
There is no need for a cosmological scale factor.

Indeed, there is no scale factor.



>> While a(t)=1/t would be observationally identical to a universe modeled by distance=velocity∗time, it is NOT THE SAME.

I have no idea what you're talking about, and I don't think you do, either. You seem to be confused about what a scale factor is, but I can't tell from what you're saying quite what you do think it is.



>> What cosmologists are doing with Milne's model is failing to acknowledge that it ever existed.

We tend to stop talking about things once they've been falsified, except in a context where they are of historical interest. Every time there's a new epidemic, do you see people considering the Miasma Theory of disease again? No. We already know it doesn't work. We've moved on.

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Jonathan Doolin

>>I have no idea what you're talking about, and I don't think you do, either. You seem to be confused about what a scale factor is, but I can't tell from what you're saying quite what you do think it is.

I erred.  (Correction added above)

I should have said H(t)=da/dta=1/t

I was referring to the Robertson Walker Scale factor (cosmology)

Have they got rid of that with the Lambda-CDM model?

No, it's still there.

Lambda-CDM model

But they've nailed it down, at least...

a(temitted)=11+z(temitted)

>>We tend to stop talking about things once they've been falsified, except in a context where they are of historical interest.

Precisely... But I would think that the falsification of a claim would also be of historical interest, if such a falsification existed.

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Erik Anson

>> I was referring to the Robertson Walker Scale factor (cosmology)

Apparently not, actually... apparently, you were talking about the Hubble parameter, which is very different. Are they related? Of course. But if the Hubble parameter is constant, then the scale factor grows exponentially, so you can't really interchange them.



>> Have they got rid of that with the Lambda-CDM model?
No, it's still there.

You initially wrote something nonsensical. You have since corrected it to something completely different, which is less nonsensical, although it still assumes a power law for the scale factor (which is only a good approximation during some time periods). You do not get to make snarky comments implying that I was somehow ignoring the presence of the scale factor in ΛCDM, when I was the one who explained its history in the first place.



>> But they've nailed it down, at least...
a(temitted)=11+z(temitted)

This comes directly from the definition of redshift and the fact that wavelength is proportional to scale factor. It's a trivial corollary of cosmological redshift, and has been "nailed down" for almost a century.

Why do you insist on trying to explain things to me that you clearly don't understand?



>> Precisely... But I would think that the falsification of a claim would  also be of historical interest, if such a falsification existed.

Sometimes yes, sometimes no. There are far too many false hypotheses to teach all of them, and it's often irrelevant to current science. If you want to study history of science, great, study history of science. If you want to study science, you mostly study the stuff that actually works, with however much historical context is necessary to explain each particular concept. We don't have time to spend weeks on all the incorrect models of electromagnetism, we jump straight to Maxwell.

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Jonathan Doolin

>>Indeed, there is no scale factor.

When you said this, in an earlier, I believed you were saying, "in general" there is no scale factor.  So I responded, pointing to references on the scale factor in lambda CDM, and in the Friedman, Lemaitre, Robertson, Walker metric.

>>apparently, you were talking about the Hubble parameter, which is very different. Are theyrelated? Of course.

>>You have since corrected it to something completely different,

>>it still assumes a power law for the scale factor

>>is only a good approximation during some time periods).

>>wavelength is proportional to scale factor

>>has been "nailed down" for almost a century.

In your last post, you have acknowledged that indeed this scale factor exists within these models.  I've attempted to edit out the parts where you seemed to be trying to denigrate my character.  Certainly, I could be the worst human being in all the world, and I suppose you can impugn my integrity all you like, but it doesn't change the fact that the FLRW metric, and the Lambda-CDM models HAVE a universal scale factor.

The distinction I wanted to make was that Milne's model has no such scale factor.  And that difference alone makes it so significantly different from all the other models in cosmology, that it deserves to be held up (at least *somewhere*) as a completely different hypothesis. 

Now as for snarkiness, the only place in this thread I would confess to being snarky is when I said "You almost have your PhD and you don't know whether Milne's model has a scale factor?"

I think that has been the only place in this thread where I actually made a value criticism towards you or your education.

I am not actually surprised that PhD institutions do not teach Milne's model as part of their coursework.  But I am disappointed, because I think that Milne's model is actually deserving of much more credit as an independent model, than it is given credit for.

>>Why do you insist on trying to explain things to me that you clearly don't understand?

I am hesitant to defend my integrity, or to claim understanding of something which I really believe, at some intrinsic level, doesn't make sense.

But I have tried, as much as I can, in this, and other threads to keep my discussion fact-based.  I have not tried to shame you based on criticism of your behavior, integrity, or intellect.  Rather, I am trying to elevate the conversation to find points of agreement.

So if you find me explaining things that you already understand, then my expectation is that you would say "I agree". 

So it took me a while to get back to you on your last post.  You seem to have objectively agreed with everything I said, adding nothing, as far as I can tell, to contribute objectively to the discussion, and your subjective contribution to the discussion was to make value judgments, about my character, and about the worthiness of studying Milne's model.

You are stating your opinion that Milne's model is not worthy of study. I am stating my opinion that Milne's model is worthy of study.

If you really want to make this personal, and convince me of your subjective moral value judgments against me, I ask you from where do you get your moral authority on these matters?  Are you a religious person?  Are these moral principles you have, welling up from something in your soul, that you were born with?  Do your moral principles come from scripture? 

My usual assumption is that when people make moral criticisms of me or my behavior, they are usually repeating something that others have said to them, and projecting something of their own nature onto me.  Sometimes that projection is deserved, and sometimes, I really should change my ways to become a better person, or to relate better to others. 

My own guiding principle, is described, vaguely in Matthew 13:15b:  "Otherwise they might see with their eyes, hear with their ears, understand with their hearts and turn, and I would heal them."

This is the loophole in the prophecy of Isaiah.  As much as I can, I would like to pursue that loophole.

This is also, I think what is meant in part by "Assume good faith" on Wikipedia.  My assumption would be that you are pursuing the truth.  But when I give you the truth, you cover your acknowledgment of that truth with moral outrage against me. 

Okay.  Guilty, guilty, guilty.  You make up the terms of your moral outrage, and I will confess. 

>>You initially wrote something nonsensical

Guilty, but I already acknowledged that.

>>Why do you insist on trying to explain things to me that you clearly don't understand?

Guilty, but the reason to repeat it is to attempt to represent your reasoning fairly without building strawman arguments.

>>You do not get to make snarky comments implying that I was somehow ignoring the presence of the scale factor in ΛCDM, when I was the one who explained its history in the first place.

I reacted to your statement of "Indeed there is no scale factor" with what might be interpreted as "snarkiness" because I thought you were saying there is no scale factor in the standard model of cosmology.  Now I think you meant to say "Indeed there is no scale factor in SR" or "There is no scale factor in Minkowski space".

There was no snarkiness intended here.  I genuinely believed for the moment that you did not know there was a scale factor in the lambda-CDM model, and FLRW metric.  I thought, in all likelyhood, there was a momentary lapse in your memory, so my information was intended to be a reminder to the facts.  I genuinely did not mean this as an insult. 

However, I am still not quite sure what you actually meant when you said "Indeed, there is no scale factor."  Did you mean "Ah, I understand what you meant now.  I agree with you."? 

Because that is not how I interpreted it... Somehow it gave me the impression that you were still arguing the facts with me.