Lambda-CDM theory - Woo or not?

[Reality Check]

Pffft: "Electrical discharges in plasma? What discharges?" Please!

You are really determined to permanently record your inability to learn any physics.

An electrical discharge is a suddent electric current (and its accompaning release of mnagnetic and electric energy) caused by the breakdown of a dielectric medium.
For example, see Peratt
N.B. his examples are capacitors, lightning and the aurora. He does not give any examples of electrical dicharges in plasma:

1 .5 Electrίcal Discharges in Cosmic Plasma

An electrical discharge is a sudden release of electric or magnetic stored energy. This generally occurs when the electromagnetic stress exceeds some threshold for breakdown that is usually determined by small scale properties of the energy transmission medium. As such, discharges are local phenomena and are usually accompanied by violent processes such as rapid heating, ionization, the creation of pinched and filamentary conduction channels, particle acceleration, and the generation of prodigious amounts of electromagnetic radiation. As an example, multi-terawatt pulsed-power generators on earth rely on strong electrical discharges to produce intense particle beams, Χrays, and microwανes . Megajoules of energy are electrically stored in capacitor banks, whose volume may encompass 250 m^3 . This energy is then transferred to a discharge regίοn, located many meters from the source, viα a transmission line.

The discharge region, or load, encompasses at most a few cubic centimeters of space, and is the site of high-variability, intense, electromagnetic radiation (Figure 1 .2). On earth, lightning is another example of the discharge mechanism at work where electrostatic energy is stored in clouds whose volume may be of the order of 3,000 km3. This energy is released in a few cubic meters of the discharge channel.

 

[Reality Check]

problem from my perspective is that you folks aren't actually deriving that number from direct observation, rather that number comes from a subjective "interpretation" of data, typically of redshift data.

http://arxiv.org/PS_cache/arxiv/pdf/1109/1109.6571v1.pdf

An almost relevant citation (for once) to Gravitational redshift of galaxies in clusters as predicted by general relativity

The theoretical framework of cosmology is mainly defined by gravity, of which general relativity is the current model. Recent tests of general relativity within the \Lambda Cold Dark Matter (CDM) model have found a concordance between predictions and the observations of the growth rate and clustering of the cosmic web. General relativity has not hitherto been tested on cosmological scales independent of the assumptions of the \Lambda CDM model. Here we report observation of the gravitational redshift of light coming from galaxies in clusters at the 99 per cent confidence level, based upon archival data. The measurement agrees with the predictions of general relativity and its modification created to explain cosmic acceleration without the need for dark energy (f(R) theory), but is inconsistent with alternative models designed to avoid the presence of dark matter.

However you have not understood the abstract or the paper. The paper's conclusions are that

• direct observations producing objective data agrees with GR.
• direct observations producing objective data agrees with the f(R) theory.

The important thing to note is that these direct observations producing objective data do not invalidate GR (or f(R)!). That means that other observations are needed to distinguish between the two theories.

 

[ben m]

Well, yes and no. Do you believe it's 'ok' to put "God" into some constant in a GR formula?

Well, for starters I can question the empirical legitimacy of stuffing "magic" into one of those constants, right?

Sol covers this, but I'll pile on. The cosmological constant is not magic, omnipotent, all-powerful, or mysterious. The only thing it does is add a constant (in a certain, mathematically specific way) to the curvature of spacetime. It does that, exactly that in every detail; it does not not do anything else, now or anywhere or ever. We're not using it at some times and not others; we're not using it inconsistently; we're not using bits of it sometimes to do one thing and other bits to do other things. It's one of the fundamental constants of GR, just like g, and we learned what it is from observations.

 

[sol invictus]

That all sounds quite logical. The problem from my perspective is that you folks aren't actually deriving that number from direct observation, rather that number comes from a subjective "interpretation" of data, typically of redshift data.

There's nothing subjective about that part of it. You have a theory that makes predictions. You take observations and compare them to the predictions, and see if they match. Either they do or they don't (to some confidence level, since data is always uncertain at some level).

The subjective part is what you do if they don't match, or what you do if there are multiple theories that match.

http://arxiv.org/PS_cache/arxiv/pdf/1109/1109.6571v1.pdf

There are typically multiple ways to interpret that very same data.

True. In my language, there are typically (pretty much always, actually) multiple theories that match the data.

What makes a "dark energy" interpretation preferable in your mind, particularly since you can't even tell me where it comes from?

The paper you linked to mentions f(R) gravity. Actually that's ruled out by other (precision solar system) data - or at least the versions of it that I'm familiar with are (it's an infinite class of theories, so maybe there are some in there that survive, but if so I don't know of them).

 

[Vorpal]

From Einstein's own words, we can infer that identifying gravity with the coordinate-dependent connection is less than ideal. It seems to me that Einstein probably would have preferred to use the more modern, coordinate-independent tensorial notion had the modern tensor notation been available at the time. Einstein used explicit connections because that was the notation of his time. This may be a case of notion following notation.

I don't think he would. Though the concept of connection itself was not explicated until a few years after GTR (Levi-Civita, et. al.), its identification with the gravitational field not only jives with his early publications on GTR, but later throughout, e.g., in "The Meaning of Relativity". He definitely saw the gravitational field as explicitly coordinate-dependent, that even for a rotating frame in Minwkoski spacetime, the proper interpretation of the "inertial forces" (aka "fictitious forces") like the centrifugal or Coriolis is that they represent a genuine gravitational field. For example, he's a excerpt of a letter copied from "Einstein from 'B' to 'Z'", in which he objects to von Laue's identification of gravity with curvature:

It is true that case the R_iklm vanishes, so that one might say: "There is no gravitational field present." However, what characterizes the existence of a gravitational field from the empirical standpoint is the non-vanishing of the Γⁱ_ik, not the nonvanishing of the R_iklm. If one does not think in such intuitive ways, one cannot comprehend why something like curvature should have anything to do with gravitational in the first place. In any case no reasonable man would have hit upon something in that way. The key to understanding of the equality of inertial and gravitational mass would have been missing.

It's true that many authors on books on relativity didn't like Einstein's view because the connection coefficients do not form a tensorial, but he was definitely aware of such criticisms (some of which came before even 1920s), and still maintained that it is only necessary for (dx^α + Γ^α_μνdx^μdx^ν)/dλ² to transform covariantly.

Now, I'm certainly not an expert of relativity (probably Sol is the only in this thread who is, unless I'm forgetting someone), but to me Einstein's view makes the a lot of sense. The gravitational field is "fictitious" in the same sense as centrifugal and Coriolis forces are; GTR says it's not really a force. Freefalling frames are inertial, and 'inertial' means constant velocity. In GTR generalized as an affine geodesic: a curve such that parallel-transporting the four-velocity along itself does not change it. So a choice of connection coefficients seems the most natural. Sure, they don't form a single tensor, but that's also why they can be locally transformed away, which is an important property for the equivalence principle.

However, if there's a modern view, it's probably best expressed by MTW:

"I know how to measure the electromagnetic field using test charges; what is the analogous procedure for measuring the gravitational field?" This question has, at the same time, many answers and none.
It has no answers because nowhere has a precise definition of the term "gravitational field" been given--nor will one be given. Many different mathematical entities are associated with gravitation: the metric, the Riemann curvature tensor, the Ricci curvature tensor, the curvature scalar, the covariant derivative, the connection coefficients, etc. Each of these plays an important role in gravitational theory, and non is so much more central than the others that it deserves the name "gravitational field." Thus it is that throughout this book the terms "gravitational field" and "gravity" refer in a vague, collective sort of way to all of these entities. Another, equivalent term used for them is the "geometry of spacetime."

And perhaps reducing the expression to essentially "whichever one makes the most sense in context" might be better. But beyond with the historical issues and interpretational nitpicks, I agree with you.

----

There’s a distinction to make. If you fall into a supermassive black hole, the tidal forces are weak so you don’t get spaghettified. The gravitational field is so nearly uniform that locally it looks uniform. Think of the bowling ball analogy. The gradient at your feet is so similar to the gradient at your head, that there’s no curvature between the two gradients. Just like a man falling off a ladder, you don’t feel a tug at your feet, but you still fall in, and passing light still bends. In extremis you’ve still got curved spacetime even without Reimann curvature.

Making a black hole supermassive is completely equivalent to making yourself smaller. Of course you experience less spaghettification if you're small compared to the black hole. It's just another instance of "if you look close enough, it looks more and more flat."

I think I read somewhere that the gedanken situation for this is falling towards a massive plane.

Makes sense. Constant acceleration should be what's expected based on Newtonian gravity, and in GTR, you can make a patch near the horizon of a Schwarzschild black hole that's closely approximated by the Rindler chart of Minwkoski spacetime, i.e., constant acceleration. On smaller and smaller scale (or black hole larger compared to you), that approximation would become better and better.

I don't understand why you think this is any sort of problem that's being overlooked, or how you resolve it in light of:

There is no such thing as a uniform gravitational field.

...

I don’t follow that.

It's very simple: if you're adopting Einstein's own interpretation, as you've implicitly claimed to have, then the components of the gravitational field are the connection coefficients. He says so explicitly in his paper on GTR (referenced and translated above) and affirms it several times. The connection coefficients determine inertial motion. So it follows that gravity is (physically) inertia and (mathematically) the connection. Do particles in flat spacetime have inertia? Yes. Does flat spacetime have a connection? Yes.

If you are surrounded by homogeneous space you don't fall down. If the space remains homogeneous but is expanding you can say that spacetime is curved, but there's no actual gravity in the space. The gravitational potential is the same everywhere. It varies over time, but it's always the same above you and below you. You don’t fall toward the centre of the universe.

At this point I think W.D.Clinger's criticisms are relevant. For one, you're apparently confusing spatial curvature with spacetime curvature.

If space is expanding you can say it's inhomogeneous over time, and that the spacetime is curved. But it's like the whole of space is like the space you go through when you zoom through the gap between two stars. There's gravitational potential in spades. But you don't fall down. Your path is straight.

You're just restating the fact that one can always find a locally inertial frame. That's true. And if you're far from gravitating bodies, it becomes better and better. So what?
It's not just compatible with GTR, it's downright required by it. (And actually, something essentially the same was proven by Newton himself.)

Divide up the energy of those two stars and smear it evenly thoughout a smaller universe. There's gravitational potential in spades. But you don't fall down, and nor do galaxies.

Even in a Newtonian universe, a uniform fluid of stars would gravitate. That's obvious from Newton's shell theorem: for any given (arbitrary!) center, a bit of matter at a distance r would feel a gravitational force determined by the mass enclosed by a sphere of that radius. So an initially static configuration would collapse, and since the center is arbitrary, completely uniformly throughout space: every point sees everything else collapsing towards it. Time-reverse it or give it an outward initial velocity, and you get uniform, homogeneous expansion governed by gravity instead.

This very closely mimics how it happens in some FLRW cosmologies in GTR.

 

[W.D.Clinger]

I don't think he would. Though the concept of connection itself was not explicated until a few years after GTR (Levi-Civita, et. al.), its identification with the gravitational field not only jives with his early publications on GTR, but later throughout, e.g., in "The Meaning of Relativity". He definitely saw the gravitational field as explicitly coordinate-dependent, that even for a rotating frame in Minwkoski spacetime, the proper interpretation of the "inertial forces" (aka "fictitious forces") like the centrifugal or Coriolis is that they represent a genuine gravitational field.

Interesting, thanks.

This excerpt from Hermann Weyl's preface to the third edition of Raum, Zeit, Materie, written in August 1919, documents Levi-Civita's influence:

Whereas the second edition was a reprint of the first, I have now undertaken a thorough revision which affects Chapters II and IV above all. The discovery by Levi-Civita, in 1917, of the concept of infinitesimal parallel displacements suggested a renewed examination of the mathematical foundation of Riemann's geometry.

Weyl seems to have been an early adopter of that new math.

It's true that many authors on books on relativity didn't like Einstein's view because the connection coefficients do not form a tensorial, but he was definitely aware of such criticisms (some of which came before even 1920s), and still maintained that it is only necessary for (dx^α + Γ^α_μνdx^μdx^ν)/dλ² to transform covariantly.

Weyl introduces connection coefficients in his §14, calling them "components of the affine relationship". He warns that they "are certainly not components of a tensor" (complete with that bold-faced "not"), uses them to define "a straight or geodetic line", and goes on to discuss parallel transport and curvature in §15. It then takes him another two sections to motivate and to develop the Riemann tensor. Near the end of §16, he writes this:

....Now, we shall find at the close of our investigations that this distinction between physics and geometry is false, and that physics does not extend beyond geometry. The world is a (3+1)-dimensional metrical manifold, and all physical phenomena that occur in it are only modes of expression of the metrical field. In particular, the affine relationship of the world is nothing more than the gravitational field, but its metrical character is an expression of the state of the "aether" that fills the word; even matter itself is reduced to this kind of geometry and loses its character as a permanent substance. Clifford's prediction, in an article of the Fortnightly Review of 1875, becomes confirmed here with remarkable accuracy; in this he says that "the theory of space curvature hints at a possibility of describing matter and motion in terms of extension only".

These are, however, as yet dreams of the future....

If I read that correctly, Weyl was speculating about how future generations would think about geometry, gravitation, and physics generally. He seems to be looking beyond Einstein's concept of gravitation, even as he still identifies the gravitational field with "the affine relationship of the world".

That's an interestingly ambiguous phrase. It could refer to coefficients of the affine connection, or it could refer to purely geometric aspects such as curvature.

You'll appreciate this, from near the end of §17:

Although the author has aimed at lucidity of expression many a reader will have viewed with abhorrence the flood of formulae and indices that encumber the fundamental ideas of infinitesimal geometry. It is certainly regrettable that we have to enter into the purely formal aspect in such detail and to give it so much space but, nevertheless, it cannot be avoided....

Those notations have been improved during the subsequent 90 years, but they're still a chore.

 

[sol invictus]

Regarding this issue of what the gravitational field is in GR, I agree that the connection is the most natural object to identify with it. I've always had an aversion (explained perfectly here) to the notion of "fictitious forces", and the equivalence principle makes it clear that you must either regard gravity as fictitious, or regard fictitious forces as real.

The situation is exacerbated in universes (such as our own) that are full of complicated distributions of energy. There is no such thing as a global inertial frame, nor is there a global preferred frame in which the metric etc. is simplest (there's the FRW slicing, but it's not unique because of inhomogeneities). Given that, it's completely impossible to distinguish between "real" gravity and "fictitious forces".

Accepting fictitious forces as real doesn't lead to any catastrophe. One simply needs to formulate the fundamental laws of physics in terms of truly coordinate invariant quantities (like an action principle) rather than, as before, in terms of equations of motion in intertial coordinate systems.

I think this does go a little against the grain of the main-stream "modern" view, but only a little. Certainly I think many people would say that if the metric is fixed (no metric fluctuations, G=0) Minkowski space, there's no gravity. On the other hand they would also say that if the metric is fixed (no metric fluctuations, G=0) de Sitter space, there is gravity. I regard those two points of view as mutually inconsistent. It's fine to say that G=0 means no gravity. But if you're going to do that, you have to allow for the possibility of curved spacetimes (G=0 doesn't imply zero curvature), and regard all the gravitational effects one observes in them as fictitious. Instead, I think it's better to instead regard all fictitious forces as gravity.

 

[Vorpal]

Thanks for your input, sol invictus. And the quotes, W.D.Clinger. I'll have to check out Weyl's book; it'd be interesting perspective.

(P.S. I see my English was broken more than usual in my previous post. English is not my first language, sorry.)

 

[Michael Mozina]

Sol covers this, but I'll pile on. The cosmological constant is not magic, omnipotent, all-powerful, or mysterious.

Sure it is. Unless you can tell us the CAUSE, it's CAUSE is still a mystery. Not a single member of your "faith based organization" can even tell me where "dark energy" comes from, so clearly it's a mystery to you. In terms of is "properties" it's about as "magical" as it gets. When have you ever seen "space" do any expanding in the lab? That nifty trick sounds pretty darn magical to me. Objects in motion stay in motion and objects can expand, but only in magical stories and cosmological lore does "space" do any expanding.

The only thing it does is add a constant (in a certain, mathematically specific way) to the curvature of spacetime. It does that, exactly that in every detail; it does not not do anything else, now or anywhere or ever. We're not using it at some times and not others; we're not using it inconsistently;

That part is the part I debate. Yes, you are using it inconsistently and yes, you are using it in a way that "tickles your fancy", not based on anything you learned in the lab.

we're not using bits of it sometimes to do one thing and other bits to do other things.

Oh boloney. You have "space" doing expanding tricks "somewhere out there" where humans can never reach, but magically here on Earth, it's a total no show! You've gone out of your way to get this thing to work in "mysterious ways".

It's one of the fundamental constants of GR, just like g, and we learned what it is from observations.

The way Einstein himself used it? Sure. He never tried to violate and other speed limits of matter with it. He never tried to claim it didn't have an "ordinary" cause. He didn't try to make magical things happen "somewhere out there" where humans could never reach. He just tried to explain a STATIC universe with that constant. Such a 'cause' could in fact be quite mundane. Nothing "exotic" would necessarily be required, nor would "space" itself have to do any expanding since Einstein's constant COULD have been anything. Your constant however is MYTHICAL, MAGICAL and MYSTERIOUS in nature, and unlike anything else in nature. Nothing else in nature causes "space" to do any "expanding".

 

[Michael Mozina]

There's nothing subjective about that part of it.

Sure it is. Tired light theories have been kicked around for as long as expansion theories. (No, Ari hasn't written me back yet, nor it is relevant). There are other 'approaches'.

You have a theory that makes predictions.

Not exactly. It makes "postdictions" that happen to fit with your expansion oriented philosophy. By virtue of adding enough of the new stuff to reach a postdicted fit, you may inadvertently add other real 'predictions' mind you, but typically the primary "property" that is added is meant to fill in the gaps of your otherwise falsified expansion theory. Dark energy is just the most recent of these ad hoc additions. Inflation was added before that.

You take observations and compare them to the predictions, and see if they match.

Well, of course the PRIMARY postdiction/prediction matches. Some of the secondary or tertiary properties might fail, but come on! The primary "prediction" is a given.

Either they do or they don't (to some confidence level, since data is always uncertain at some level).

Well, that fine and all, but from my perspective you just stuffed magic gap filler into your expansion oriented theory.

The subjective part is what you do if they don't match, or what you do if there are multiple theories that match.

It's actually more fundamental than that IMO. It's more of a question of whether your "method' to make things match was valid in the first place! I don't believe that you even have the empirical right to claim that you made it "match" without cheating in the first place.

The paper you linked to mentions f(R) gravity. Actually that's ruled out by other (precision solar system) data - or at least the versions of it that I'm familiar with are (it's an infinite class of theories, so maybe there are some in there that survive, but if so I don't know of them).

Hmm. I'll have to do some additional research I suppose. My point is that there will always be multiple subjective ways to interpret the same data. IMO you aren't simply 'observing', there's a subjective interpretation component in there as well.

 

[W.D.Clinger]

Sol covers this, but I'll pile on. The cosmological constant is not magic, omnipotent, all-powerful, or mysterious.

Sure it is. Unless you can tell us the CAUSE, it's CAUSE is still a mystery. Not a single member of your "faith based organization" can even tell me where "dark energy" comes from, so clearly it's a mystery to you. In terms of is "properties" it's about as "magical" as it gets. When have you ever seen "space" do any expanding in the lab? That nifty trick sounds pretty darn magical to me. Objects in motion stay in motion and objects can expand, but only in magical stories and cosmological lore does "space" do any expanding.

Michael Mozina's argument is actually quite general, so let's apply it to a more important subject:

Until you can tell us the CAUSE of the universe, its CAUSE remains a mystery. Not a single member of your "faith based organization" can even tell me where "universes" come from, so clearly it's a mystery to you. In terms of its "properties" it's about as "magical" as it gets. When have you ever seen "a universe" created in the lab? That nifty trick sounds pretty darn magical to me. Michael Mozina says the same thing over and over and nothing changes, but only in magical stories and cosmological lore do "universes" actually exist.
​

By applying Michael Mozina's extraordinarily versatile technique for proving that things don't exist, I conclude that Michael Mozina doesn't exist and can safely be ignored.

 

[edd]

Sure it is. Tired light theories have been kicked around for as long as expansion theories.

Think 'kicked around' is definitely it - they're not standing up to attack at all. How do you deal with geometric measures like BAOs without having the universe expand?

 

[ben m]

Sure it is. Unless you can tell us the CAUSE, it's CAUSE is still a mystery. Not a single member of your "faith based organization" can even tell me where "dark energy" comes from, so clearly it's a mystery to you.

Yep. Some sort of negative pressure term was discovered observationally in 1999-ish, and we're trying to figure out exactly what the source is. Is it a "pure-GR" term, just a fact about the shape of space? Is it a familiar particle-physics-accessible energy density vacuum, that belongs on the source side? Is it a new field, like quintessence, on the source side? We don't know.

We could have an intelligent discussion of this if you'd get past the first sentence.

In terms of is "properties" it's about as "magical" as it gets.

If you think GR is magical to begin with, then cosmology is not an appropriate field for you.

 

[Michael Mozina]

Michael Mozina's argument is actually quite general, so let's apply it to a more important subject:

Until you can tell us the CAUSE of the universe, its CAUSE remains a mystery. Not a single member of your "faith based organization" can even tell me where "universes" come from, so clearly it's a mystery to you. In terms of its "properties" it's about as "magical" as it gets. When have you ever seen "a universe" created in the lab? That nifty trick sounds pretty darn magical to me. Michael Mozina says the same thing over and over and nothing changes, but only in magical stories and cosmological lore do "universes" actually exist.
​

By applying Michael Mozina's extraordinarily versatile technique for proving that things don't exist, I conclude that Michael Mozina doesn't exist and can safely be ignored.

The problem in your logic is obvious. If I simply say "I don't know the cause of the universe", I have no burden of proof. If I say the (now dead) inflation genie did it, I have an additional burden of proof. In your "religion" there is no "empirical proof", just mathematical mythos and dead an/or impotent on Earth sky entities.

 

[Michael Mozina]

Yep. Some sort of negative pressure term was discovered observationally in 1999-ish, and we're trying to figure out exactly what the source is.

No. Some sort of acceleration pattern is ONE POSSIBLE INTERPRETATION of the data. That negative pressure in a vacuum claim is ANOTHER example of the fact that you folks REALLY do not understand subatomic physics and kinetic energy specifically. When you say 'negative pressure' what you mean is you have an outside force PULLING on the mass of this universe. It CANNOT be a "vacuum" because a VACUUM is incapable of holding "negative pressure". That NEGATIVE PRESSURE could be something like a charge or gravitational attraction to an *EXTERNAL* object, but it has nothing to do with a "vacuum".

Is it a "pure-GR" term, just a fact about the shape of space? Is it a familiar particle-physics-accessible energy density vacuum, that belongs on the source side? Is it a new field, like quintessence, on the source side? We don't know.

You don't KNOW anything. You don't KNOW what makes up 96% of your OWN THEORY in fact! It's all UNKNOWN. There is however no such thing as a "negative pressure" in a vacuum, so Guth's inflation theory is DOA!

If you think GR is magical to begin with, then cosmology is not an appropriate field for you.

No, I think GR is a BEAUTIFUL and ELEGANT *EMPIRICAL* theory of physics. What you're doing to it is a crime IMO. You've turned what was a pure empirical theory into a metaphysical monstrosity where real physics only counts for 4% of the theory. I'm disgusted at what you did to the formula, not the formula itself.

 

[Michael Mozina]

By applying Michael Mozina's extraordinarily versatile technique for proving that things don't exist, I conclude that Michael Mozina doesn't exist and can safely be ignored.

FYI, the empirical difference is that I actually show up in the lab, whereas your invisible and/or dead sky entities do not.

 

[ben m]

No. Some sort of acceleration pattern is ONE POSSIBLE INTERPRETATION of the data.

Yep. LCDM is my favorite interpretation, and the favorite interpretation of the vast majority of cosmologists.

Many alternative explanations (f(R) gravity, dark flow) require much more, and uglier, new free parameters than LCDM. Many alternative explanations (grey dust, Sne evolution, most prominently) were disproven by observational cross-checks.

Which interpretation of the data (which is, remember: CMB/CMBpol/Sne/LSS/BAO/BBN/LyA/clusters/weak-lensing/etc.) do you think works at least as well? Let's see the paper. Again.

 

[Tubbythin]

The rest of this crew seem pretty oblivious to subatomic physics if you ask me.

And yet I've written a number of posts trying to explain to you (in hopefully fairly basic terms) aspects of, for example, neutrino physics, nuclear physics and basic details of the standard model.

 

[ben m]

Apparently Michael's preferred interpretation of the data is this:

"I know a-priori that there are no stable particles except baryons, and that GR must refers to a flat spacetime plus point sources. I find it unpleasant to imagine otherwise. Therefore, if flat-spacetime-plus-baryons is not able to describe the data, it means that you're doing the baryons wrong. Or the observations are wrong. No, don't tell me you've checked, don't tell me the details ... it must be wrong somehow. You should stick to your guns on the obviously-superior GR/baryons model. Trust me: new baryonic-plasma-properties will be discovered someday, and when we discover them and plug them into the model they will explain the data. The cosmology data should be ignored---you can't learn anything from it, it's unempirical---until a lab experiment has discovered those baryon-plasma-properties."

Science!

 

[sol invictus]

Not exactly. It makes "postdictions" that happen to fit with your expansion oriented philosophy. By virtue of adding enough of the new stuff to reach a postdicted fit, you may inadvertently add other real 'predictions' mind you, but typically the primary "property" that is added is meant to fill in the gaps of your otherwise falsified expansion theory. Dark energy is just the most recent of these ad hoc additions. Inflation was added before that.

Michael, the cosmological constant has been around since the very beginning of GR - 1920 or so (I forget the exact date). For most of the period since then cosmological data was imprecise enough that it was consistent with CC=0. As of about 12 years ago (did you see the Nobel prize in physics announcement today?) the data was no longer consistent with CC=0. Therefore, in the standard cosmological model, the CC is not zero.

Can you please explain to me what it is that bothers you about that? I really cannot understand your viewpoint. The story with the CC is exactly the same as with any other parameter in any model in physics - you fit it to data, and then you have a theory, and then you can make pre- or post-dictions that might or might not be consistent with other pieces of data. And as I've told you many times, this has basically nothing to do with Guth or inflation - that's a whole different story.