Split Thread Michael Mozina's thread on Dark Matter, Inflation and Cosmology

[ben m]

The fact that the geometry of space-time and other factors were relevant to speculations about the future of the universe, does not negate the fact that the CC had been abandoned and was only discussed in that context.

So you're saying that the CC was abandoned except when it wasn't?

I was only agreeing with MM that using a positive CC to explain the acceleration of the expansion of the universe is a new application of the CC. That was not Einstein's original purpose and it was no longer part of cosmology until the discovery of cosmic acceleration.

This is flatly incorrect. Before Hubble's data came in, de Sitter and Lemaitre and Friedmann were using the CC in models of expanding, accelerating Universes. Einstein himself was using CC acceleration to counteract mass deceleration, and the "instability" that he (almost immediately) knew about was towards either acceleration or collapse. There are literally hundreds of cosmology papers from the 40s through the 80s---before precision CMB data---talking about the constant and the possibility that a small acceleration might be present. After COBE the number of such papers exploded, and after the supernova data it exploded further.

"No longer part of cosmology" my foot.

 

[Chucky]

It has nothing to do with *MATH*. I don't mind MHD theory. I might argue about how which is more relevant, the E or B perspective, but we can clearly test our theories in a standard scientific manner. When they start attaching math to invisible, make believe entities, that came straight from a single human being "imagination", then I balk. I'm not balking at the math however, just the lack of empirical physical support, just like any ordinary 'religion'. My invisible friend did this! My invisible friend did that! See, here's the math! Physical support? Oh, my invisible friend is shy around other people. He doesn't show up in empirical experiments.

Ya, but you can apply these maths to real objects and real things like photons and physical objects. We can "test" our equations in the standard empirical manner and measure their effect on real things.

I simply had a series of epiphanies over the years related to solar satellite images. That process led me to study EU theory from the likes of Birkeland and Bruce (whom these folks avoid like the plague by the way) and Alfven (you know that guy with the Nobel Prize for MHD theory that applied it to space). I don't find events in space to be "counter-intuitive" anymore. I find them to be quite logical, quite 'normal', and actually quite "predictable" as Birkeland demonstrated over 100 years ago.

Ah, so you do have a way of predicting an event for us.

Perhaps someone think of measurable, re-occurring events that happen on a time scale reasonable enough to log a few events using what you cited. Particularly Michael, if they are in your comfort zone? Where enough results could be gathered into a common data base on how the prediction fares as empirical experimentation.

If your understanding is correct you can settle this once and for all Michael. Sooner or later you know that you must, because without providing a working model that holds up to replicated results, a theory ain't a theory.

I would have absolutely no trouble at all with sticking anything 'real/empirical' into that constant/function related to GR. In other words, I'd have no trouble at all allowing someone to put MHD equations into that constant. Anything that is actually "real" and "exists" is a reasonable way to attempt to explain the expansion. Simply stuffing our ignorance with magic energies isn't an "empirical solution", it's a "make believe" solution that evidently defies empirical testing in a lab on Earth or anywhere humans can travel.

I am asking you to run the experiment yourself. Can you set it up for us and perform it? You have to be able to do that to demonstrate that your theory is right.

I am still waiting for your answer to this Michael. I think this is critical. Even if you are right, if you cannot set up the experiment, how would you ever convince someone? Obviously, a war of words is not a winning approach. Why should they believe you? But more importantly, if you have not yet done the science and gotten results, how do you have a leg to stand on in your own mind without it? Again, it isn’t science without replicable results by you and others that prove you can make accurate predictions in the first place. No predictions, no science.

I'm also interested in hearing how Michael will apply his theory to an expanding universe. I don't yet understand how he would provide his empiricism to astronomical scenarios. I didn't feel that he explained that earlier in a way I can understand. Why aren't all observations that take place off the planet unusable as they are not replicable in a laboratory?

You also never responded to this question either. As others have pointed out, simple observation of phenomena in nature is the best result whereas controls require human interaction which can overlook or interfere with other natural processes. As opposed to when things occur on their own untouched by human hands. All of which has me greatly confused about your point of view and leads me to suspect that you cherry pick.

 

[ben m]

Was not the following:

[latex] R_\mu_\nu - \dfrac{1}{2}g_\mu_\nu R = \dfrac{8\pi G}{c^4}T_\mu_\nu [/latex]

the equation Einstein settled on after Hubble's discovery?

Yes, that is the equation which Einstein said described the effect on the geometry of the universe of the energies he thought were there. This is not a "generic" GR equation; it is not the equation for (e.g.) spacetime in a galaxy, or near a star, or in the throat of a wormhole, or in a gravitational wave. This is the particular equation for a perfectly smooth, isotropic Universe with a mass-energy density (T_mu_nu) and zero vacuum-energy density. That's what Einstein thought the energy budget of the Universe was, so that's what he wrote down.

 

[Perpetual Student]

So you're saying that the CC was abandoned except when it wasn't?



This is flatly incorrect. Before Hubble's data came in, de Sitter and Lemaitre and Friedmann were using the CC in models of expanding, accelerating Universes. Einstein himself was using CC acceleration to counteract mass deceleration, and the "instability" that he (almost immediately) knew about was towards either acceleration or collapse. There are literally hundreds of cosmology papers from the 40s through the 80s---before precision CMB data---talking about the constant and the possibility that a small acceleration might be present. After COBE the number of such papers exploded, and after the supernova data it exploded further.

"No longer part of cosmology" my foot.

I will readily admit that I do not know for certain that the CC was abandoned and I have not been aware of the work of de Sitter, Lemaitre and Friedmann in this regard.
Look, I have been an avid reader, as a layman, about cosmology for some 50 years now. As stated in an earlier post, in the many books and articles I read by physicists and cosmologists, discussing GR and cosmology, Einstein's rejection of the CC after Hubble's discoveries has been consistently described as well as the abandonment of the CC in mainstream models.
It certainly appears to have been reintroduced in the context of the acceleration of cosmic expansion to this layman. If it was always part of GR within the inner circles of physics, but not communicated to us non-physicists, I have no way of knowing that but I do find it quite strange.

 

[Perpetual Student]

Yes, that is the equation which Einstein said described the effect on the geometry of the universe of the energies he thought were there. This is not a "generic" GR equation; it is not the equation for (e.g.) spacetime in a galaxy, or near a star, or in the throat of a wormhole, or in a gravitational wave. This is the particular equation for a perfectly smooth, isotropic Universe with a mass-energy density (T_mu_nu) and zero vacuum-energy density. That's what Einstein thought the energy budget of the Universe was, so that's what he wrote down.

Well, does that not imply that he abandoned the CC?

 

[ben m]

Well, does that not imply that he abandoned the CC?

Yes, he thought it was zero.

Listen, there's one and only one thing that I want to combat here. MM kept suggesting that Einstein abandoned the CC because it was impossible, or because it violated GR, or because it could only possibly be zero, or for some other my-god-how-could-we-have-been-such-fools sort of reason. I simply want to emphasize that this is not, was not, and never has been the case.

The most scientific thing would have been for Einstein to write down the equation with the CC term still there, but then to quote both T and lambda as experimental values (T large, lambda apparently small) with error bars. (That sounds obvious today, but this is a surprisingly modern way of thinking---even particle experimentalists weren't using error bars properly (in what I've read) until the 1940s or so. )

 

[Perpetual Student]

Yes, he thought it was zero.

Listen, there's one and only one thing that I want to combat here. MM kept suggesting that Einstein abandoned the CC because it was impossible, or because it violated GR, or because it could only possibly be zero, or for some other my-god-how-could-we-have-been-such-fools sort of reason. I simply want to emphasize that this is not, was not, and never has been the case.

The most scientific thing would have been for Einstein to write down the equation with the CC term still there, but then to quote both T and lambda as experimental values (T large, lambda apparently small) with error bars. (That sounds obvious today, but this is a surprisingly modern way of thinking---even particle experimentalists weren't using error bars properly (in what I've read) until the 1940s or so. )

I understand that and do not disagree. I have never thought the CC violates GR. In fact, I find also find MM's views on this subject bizarre. My comments were only intended to discuss the history behind the CC.

 

[Michael Mozina]

Yes, he thought it was zero.

Listen, there's one and only one thing that I want to combat here. MM kept suggesting that Einstein abandoned the CC because it was impossible, or because it violated GR, or because it could only possibly be zero, or for some other my-god-how-could-we-have-been-such-fools sort of reason.

It wasn't a foolish reason. It was simply unnecessary. Gravity (not necessarily cosmology) is explained properly without it. "Nothing" else was required to correctly describe the effects of gravity.

Einstein set it back to zero, because with "nothing" else than the rest of the formula he could accurately describe and predict all the fundamental properties of "gravity". In an expanding or contracting universe, nothing else was required to explain "gravity".

By inserting "something" back in there where "nothing" (actually a zero constant) once existed in Einstein's GR theory, you should at least differentiate your theory from "General Relativity" proper. If I added MHD formulas in there, it would be "General Relativity and/with/effected by/plus MHD theory". If I add magic in there, it's "General relativity with magic".

In the sense that Einstein himself opened up pandora's box for all the metaphysical baggage you're now stuffing into "General Relativity Theory", you might "sort of" justify adding things in there, but you still have to explain what you're physically adding, and demonstrate it has all the physical properties you claim.

"General Relativity' and "gravity'' can be explain with nothing else but a zero in that term. If you want to explain "cosmology' rather than "gravity", you still have to justify what you're stuffing in there, and you should post a "buyer beware" sign about calling it "general relativity". If my added formulas involve magic energy, it's hardly "General relativity" anymore, nor does it necessarily accurately describe "gravity" anymore.

 

[ben m]

I understand that and do not disagree. I have never thought the CC violates GR. In fact, I find also find MM's views on this subject bizarre. My comments were only intended to discuss the history behind the CC.

Fair enough. I'd be curious to dig through the history and find the first author who puts an error bar on the value of lambda. (A quick look: Hubble had error bars on his distance-velocity curve in 1929. Well done sir! But it certainly wasn't standard at the time.)

 

[ben m]

It wasn't a foolish reason. It was simply unnecessary. Gravity (not necessarily cosmology) is explained properly without it. "Nothing" else was required to correctly describe the effects of gravity.

was, past tense. The CC term is required to explain the effects of gravity seen in today's precise measurement.

In an expanding or contracting universe, nothing else was required to explain "gravity".

You're still wrong about this. The 1917 EFE equation, with lambda in it, is using the 1915 gravity equations to describe a set of sources. The 1929 EFE equation with lambda=zero, is also using the 1915 gravity equations to describe a different set of sources. The 2010 EFE equation with lambda=0.75 is using the 1915 gravity equations to describe a different set of sources. The Kerr equation for motion near a rotating black hole is also using the 1915 gravity equations to describe yet another source.

At no time has anyone ever changed anything in the 1915 gravity equations.

We've been through this how many times? What of the above do you not get? What part of the 1915 gravity equations is changed between its use in the 1917 paper, in the 1929 Hubble emendation, and in modern lambda-CDM cosmology?

(ETA: you don't know, of course, because you haven't read any of these papers, nor any relevant textbooks. The answer is that 1915GR does not change and is used and reused to describe each of the different sources that people thought were out there at different times. I think you're confabulating the existence of "good" and "bad" versions of GR, apparently, for the sake of being able to say "Lambda is impossible in GR" and "I don't dispute GR" in the same thread.)

 

[Perpetual Student]

It wasn't a foolish reason. It was simply unnecessary. Gravity (not necessarily cosmology) is explained properly without it. "Nothing" else was required to correctly describe the effects of gravity.

Einstein set it back to zero, because with "nothing" else than the rest of the formula he could accurately describe and predict all the fundamental properties of "gravity". In an expanding or contracting universe, nothing else was required to explain "gravity".

By inserting "something" back in there where "nothing" (actually a zero constant) once existed in Einstein's GR theory, you should at least differentiate your theory from "General Relativity" proper. If I added MHD formulas in there, it would be "General Relativity and/with/effected by/plus MHD theory". If I add magic in there, it's "General relativity with magic".

In the sense that Einstein himself opened up pandora's box for all the metaphysical baggage you're now stuffing into "General Relativity Theory", you might "sort of" justify adding things in there, but you still have to explain what you're physically adding, and demonstrate it has all the physical properties you claim.

"General Relativity' and "gravity'' can be explain with nothing else but a zero in that term. If you want to explain "cosmology' rather than "gravity", you still have to justify what you're stuffing in there, and you should post a "buyer beware" sign about calling it "general relativity". If my added formulas involve magic energy, it's hardly "General relativity" anymore, nor does it necessarily accurately describe "gravity" anymore.

However, there is the instability of a static universe that sol so well described. If I understand this, a zero CC is much more difficult to deal with than some positive of negative value associated with an expanding or contracting universe, so that physicists never quite eliminated the CC from their speculations.

 

[ben m]

However, there is the instability of a static universe that sol so well described. If I understand this, a zero CC is much more difficult to deal with than some positive of negative value associated with an expanding or contracting universe, so that physicists never quite eliminated the CC from their speculations.

That's not right, PS. The unstable, static Universe is one with a (positive) CC with an energy density equal to the matter energy density. A zero-CC Universe is very "easy to deal with"---it either expands forever or it expands-and-recollapses, depending on the initial conditions.

 

[Perpetual Student]

That's not right, PS. The unstable, static Universe is one with a (positive) CC with an energy density equal to the matter energy density. A zero-CC Universe is very "easy to deal with"---it either expands forever or it expands-and-recollapses, depending on the initial conditions.

OK, thanks for that correction. It's kind of obvious; I should have seen that.

 

[Michael Mozina]

However, there is the instability of a static universe that sol so well described. If I understand this, a zero CC is much more difficult to deal with than some positive of negative value associated with an expanding or contracting universe, so that physicists never quite eliminated the CC from their speculations.

Just keep in mind that "gravity", at least by itself if perfectly explained without anything in that constant. Even an expanding and contracting universe is explained without it. The only thing that isn't "explained" is cosmology, but we have no certainly that gravity alone is the only relevant force of nature.

I don't really mind someone adding MHD theories in there, because they apply to real physical things with established physical properties. If however we start putting stuff in there that has nothing to do with any other relevant branch of empirical physics, can this even be called an empirical theory anymore? It's just a basic philosophical question that can never really be answered in their favor *without* a real empirical demonstration of concept.

Putting in "constant" other than zero, with no "physical explanation' isn't really an "explanation", it's more of an enigmatic observation.

I guess I simply think there should be some sort of "buyer beware" clause that we have deviated from simply "gravity" theories, into "cosmology theories" that may or may not relate back to empirical physical processes, and may have very little to do with "gravity" rather than another force of nature acting upon gravity. Calling everything we might put into that constant a "form of GR" seems "confusing" to the say the least. If I choose to put magic into that constant, can I honestly look you in the eye and call it "General relativity theory"?

 

[Tim Thompson]

Cosmological Constant

My comments were only intended to discuss the history behind the CC.

I suggest you seek out The Expanding Universe by Sir Arthur Eddington (Cambridge University Press, 1933; still in print). He has quite a bit to say about the cosmological constant (which he calls the cosmical constant). He considered it an absolute requirement for general relativity to be a complete theory and thought Einstein was wrong to abandon it; just look up cosmical constant in the index. The book is readable by a general audience. There is also a fair amount of discussion of the cosmological constant in Gravitation by Misner, Thorne & Wheeler (W.H. Freeman & Co., 1970; also still in print). Builds strong muscles just lifting its 1279 pages off the shelf and definitely not for a general audience. However, bits & pieces of the discussion might be accessible. Although Einstein never liked the cosmological or cosmical constant, it never went away.

 

[Michael Mozina]

was, past tense. The CC term is required to explain the effects of gravity seen in today's precise measurement.

You're *assuming* that whatever is causing acceleration is related to "gravity", when in fact "gravity" seems to be a "bit player" in the process, or we wouldn't see "acceleration".

You're still wrong about this.

No I'm not. "Gravity" is not "cosmology"! Cosmology need not necessarily only be effected by gravity.

The 1917 EFE equation, with lambda in it, is using the 1915 gravity equations to describe a set of sources. The 1929 EFE equation with lambda=zero, is also using the 1915 gravity equations to describe a different set of sources. The 2010 EFE equation with lambda=0.75 is using the 1915 gravity equations to describe a different set of sources. The Kerr equation for motion near a rotating black hole is also using the 1915 gravity equations to describe yet another source.

At no time has anyone ever changed anything in the 1915 gravity equations.

We've been through this how many times? What of the above do you not get?

What part of "Gravity and cosmology are not interchangeable terms" don't you understand"?

I said quite some time ago that I had some sympathy for sol's position because it was Einstein himself that put that constant in there in the first place. He did not however ever try to personally use it to explain anything other than a static universe and he ultimately set it to zero and left it there till he died. I don't know why you have a problem with my position because you'd feel exactly the same way if I were stuffing Michael's magic energy into that term and trying to pass it off as "general relativity theory". Sure, the constant was always there, but how does that empirically justify my use of "Michael's magic energy" to turn gravity and matter into a bit player and then calling it "general relativity theory"?

 

[sol invictus]

A couple of comments on this CC business.

1. as far as I know the only source for Einstein having said that the CC was his biggest blunder is Gamow 40 years or so after the fact. So one might take that with a grain of salt.
   
   
2. GR does not belong to Einstein. GR is a theory that exists independently of Einstein, Einstein's beliefs at various times, and Einstein's motivations at various times. In fact Einstein's beliefs and motivations are totally irrelevant to any discussion of the value of the CC.
   
   
3. the CC is in fact unique in several ways:
   
   
   • Thought of as a geometrical term, it is the only modification of the Einstein-Hilbert action that is consistent with general covariance, effective at "long" (i.e. longer than the Planck length) distances, and that doesn't involve inverse powers of curvature and derivatives. In other words, by the standard logic of effective field theory, it must be included as a parameter and cannot simply be set to zero by fiat. Put another way, even if one sets it to zero in the classical action, it will re-appear at 1-loop due to quantum corrections. And if one sets it to zero in the 1-loop effective action, it re-appears at 2-loops. It's very hard to squash, and it's very hard to get it to be small enough, let alone zero (which is known as the "cosmological constant problem").
     
     
   • Thought of as an energy density, the CC fits perfectly into Einstein's equations. Contrary to what ben said, the equation in PS's post above is completely general (those are Einstein's equations, with no special assumptions). That equation doesn't just apply to homogeneous and isotropic universes, it applies all the time. And T_\mu \nu includes the cosmological constant. The CC is a form of energy and pressure, and therefore it's an additive term that changes the diagonal elements of T. It can arise in many ways: from quantum vacuum energy as above, from a scalar field potential that's non-zero in a minimum, from a 4-form "electric" flux (don't go bananas MM, that's not a standard electromagnetic field energy, it's something much weirder involving significant new physics), or simply from a shift in the zero-point of potential energy.
   
   
4. as ben has been emphasizing, GR is a theory of gravity, not a theory of energy and mass. GR tells us what the gravitational field is given the stress-energy that sources it, just as Maxwell's equations tell us the electromagnetic field given the charges and currents that source it. Maxwell's equations cannot tell us what the charges and currents are at some instant; they can only tell us what the fields will be if the charges and currents are something at that instant (and, coupled with some more equations, what everything will look like later or earlier).
   
   By exactly the same token, GR cannot tell us what the value of the CC is. All it can tell us is what the universe will do given its value. The CC is an input, a source; at least as far as physicists understand now it must be fixed by observation and experiment, and cannot be fixed by theory or set to zero.

 

[Michael Mozina]

I suggest you seek out The Expanding Universe by Sir Arthur Eddington (Cambridge University Press, 1933; still in print). He has quite a bit to say about the cosmological constant (which he calls the cosmical constant). He considered it an absolute requirement for general relativity to be a complete theory and thought Einstein was wrong to abandon it; just look up cosmical constant in the index. The book is readable by a general audience. There is also a fair amount of discussion of the cosmological constant in Gravitation by Misner, Thorne & Wheeler (W.H. Freeman & Co., 1970; also still in print). Builds strong muscles just lifting its 1279 pages off the shelf and definitely not for a general audience. However, bits & pieces of the discussion might be accessible. Although Einstein never liked the cosmological or cosmical constant, it never went away.

For the record, I personally believe that the constant/term is a necessary requirement for GR to be "complete", particularly in a "bang" oriented universe. We could for instance live in a non flat universe and such a term would become necessary. (Yes, I know there is evidence to the contrary). Many things might necessitate the use of such a term, particularly as it relates to cosmology. It's only your insertion of a metaphysical entity into that term that I ultimately object to, not the presence of the term itself. I wouldn't object to using MHD formulas related to real physical processes in that term for instance. It's not that the term itself is the problem, it's the way the term is being abused that's the problem IMO. I also happen to believe that GR theory (with a zero constant) is a pure form of empirical physics. As long as whatever you stuff in there is also a form of pure empirical physics, I won't complain. If however you stuff it full of magic thingamobobs with ad hoc properties galore, I'm going to scream bloody murder when you call it "general relativity theory".

 

[DazzaD]

For the record, I personally believe that the constant/term is a necessary requirement for GR to be "complete", particularly in a "bang" oriented universe. We could for instance live in a non flat universe and such a term would become necessary. (Yes, I know there is evidence to the contrary). Many things might necessitate the use of such a term, particularly as it relates to cosmology. It's only your insertion of a metaphysical entity into that term that I ultimately object to, not the presence of the term itself. I wouldn't object to using MHD formulas related to real physical processes in that term for instance. It's not that the term itself is the problem, it's the way the term is being abused that's the problem IMO. I also happen to believe that GR theory (with a zero constant) is a pure form of empirical physics. As long as whatever you stuff in there is also a form of pure empirical physics, I won't complain. If however you stuff it full of magic thingamobobs with ad hoc properties galore, I'm going to scream bloody murder when you call it "general relativity theory".

Going round in circles here methinks.

Define, clearly, unambiguously, please, define for what you mean by "empirical physics".

I think this is the root of much of the problems we have understanding your point of view Michael.

 

[Michael Mozina]

Going round in circles here methinks.

Define, clearly, unambiguously, please, define for what you mean by "empirical physics".

I think this is the root of much of the problems we have understanding your point of view Michael.

Is "God did it" (with blatantly pilfered math) a form of "empirical science"? if not, why not?