Lambda-CDM theory - Woo or not?

[Reality Check]

As long as you continue to insist that some a constant in a math formula is a physical "cause", I don't think we'll ever see eye to eye.

What about the math formula: F=ma
For a given constant value of F, you get a specific value of a.
So a constant F is the physical cause of a specific acceleration.

In science, a non-zero cosmological constant is an probable (and 'physical') cause of dark energy.

 

[sol invictus]

When you can accept that this statement of yours is a "statement of faith" on your part, and it's one that I don't share with you, then it's probably worth trying to continue.

It's a definition, Michael. It's what those terms mean. How in the world can that be a "'statement of faith'"?

 

[Tubbythin]

When you can accept that this statement of yours is a "statement of faith" on your part, and it's one that I don't share with you, then it's probably worth trying to continue.

Wuh. He's saying that if we have a cosmological constant that fits the data then that would be an explanation of dark energy and the acceleration of the Universe. That isn't a statement of faith. That's true pretty much by definition of "dark energy"

As long as you continue to insist that some a constant in a math formula is a physical "cause", I don't think we'll ever see eye to eye. Thanks for trying, but I just do not agree with you. It is just a constant in a math formula.

What is the cause of G or e or hbar Michael?

The "cause" of any sort of acceleration is something completely different from that constant in terms of physics. We both agree that there is a physical cause and a physical reason for acceleration. I just think that the statement "dark energy did it" is a combo of logical fallacies, specifically a non-sequitur and an affirming the consequent fallacy.

It isn't either of those things. It is the most parsimonious (at least in the form of a CC) solution to the supernova observations.

There's no empirical link between acceleration of matter and magic energy or dark energy.

Of course there is (ignoring your BS about magic energy). A cosmological constant is part of Einstein's equations that describe gravity. These equations have been tested to very high precision empirically. If you set a non-zero CC in these equations then you get an accelerating universe.

 

[Reality Check]

Sean Carroll likes the term "smooth tension" rather than dark energy.

He posted a Q and A today that is relevant I think:

http://blogs.discovermagazine.com/cosmicvariance/2011/10/04/dark-energy-faq/

That is very relevant, especially the section on the properties of dark energy:

Okay, so: what is dark energy?
Glad you asked! Dark energy has three crucial properties. First, it’s dark: we don’t see it, and as far as we can observe it doesn’t interact with matter at all. (Maybe it does, but beneath our ability to currently detect.) Second, it’s smoothly distributed: it doesn’t fall into galaxies and clusters, or we would have found it by studying the dynamics of those objects. Third, it’s persistent: the density of dark energy (amount of energy per cubic light-year) remains approximately constant as the universe expands. It doesn’t dilute away like matter does.

These last two properties (smooth and persistent) are why we call it “energy” rather than “matter.” Dark energy doesn’t seem to act like particles, which have local dynamics and dilute away as the universe expands. Dark energy is something else.

 

[Tubbythin]

I've never had a problem with that concept, just the concept "God/dark energy did it".

Nobody is claiming God did it. How about Einstein's general relativity with a non-zero cosmological constant did it?

I'm not even convinced that dark energy is even warranted after discovering that galaxies are twice as bright as first predicted. It seems to me that the whole technique is predicted on outdated data!

What the hell are you talking about? The acceleration of the Universe comes from supernova typeI a data.

Which only demonstrates that anyone can create a religion that fits your criteria. It's much harder to do it with actual empirical physics.

Yeah. general relativity really is a religion. I know loads of people that go to the church of relativity every Sunday. Some go twice! If only there were empirical texts of GR eh? Maybe then we could all take it a bit more seriously.

 

[Michael Mozina]

It's a definition, Michael. It's what those terms mean. How in the world can that be a "'statement of faith'"?

Since you cannot even tell me where dark energy comes from, let alone EMPIRICALLY demonstrate that it can accelerate even a single atom in a controlled experiment, what else CAN it be other than a "statement of faith in the unseen (in the lab)"?

 

[Michael Mozina]

What the hell are you talking about? The acceleration of the Universe comes from supernova typeI a data.

From the interview:

How do we know the supernovae not dimmer because something is obscuring them, or just because things were different in the far past?

That’s the right question to ask, and one reason the two supernova teams worked so hard on their analysis. You can never be 100% sure, but you can gain more and more confidence. For example, astronomers have long known that obscuring material tends to scatter blue light more easily than red, leading to “reddening” of stars that sit behind clouds of gas and dust. You can look for reddening, and in the case of these supernovae it doesn’t appear to be important. More crucially, by now we have a lot of independent lines of evidence that reach the same conclusion, so it looks like the original supernova results were solid.

Those assumptions sound pretty suspect actually:

http://www.nytimes.com/2008/05/17/science/space/17univ.html

Yeah. general relativity really is a religion.

Only if you stuff it full of magic. If I don't bow to your religion you'll continue to chastise me personally, just like ordinary religious "believers", just watch and see.

 

[ben m]

I've never had a problem with that concept, just the concept "God/dark energy did it".

Sure you do. Remember that CREIL theory that you linked to, twice, as your best example of a non-dark-energy theory? That was a "redshift isn't even happening" theory, not a "motion (which we observe through redshifts) is explained by THIS acceleration" theory. You've been groping around for reasons to reject the whole cosmology---motions and all---since day one. You have NOT been groping around for non-"energy" ways of explaining an accelerating expansion.

I'm not even convinced that dark energy is even warranted after discovering that galaxies are twice as bright as first predicted. It seems to me that the whole technique is predicted on outdated data!

See?

Secondly, the only force of nature I know of that MIGHT cause plasma to accelerate is a rather "ordinary" field.

Gravity is an ordinary field that acts over long distances.

Wait, are you thinking of E&M forces? Why? They've been tried, they do not explain this aspect of the data. Remember? Try to remember next time.

Ya, but then all I did is throw up my hands and claim "God did it".

Neither do we. We look at the equations known to govern spacetime, and we hypothesize that that spacetime did it. We then compare that hypothesis to the data.

(Just reread your statement. Um. You're going to apply a silly name to an ordinary physics hypothesis, then reject the hypothesis because it sounds silly when referred to by the silly name. Are you having fun?)

 

[W.D.Clinger]

Sorry, but I just went through the lab and you weren't there.

Seriously: When did you ever show up in a lab? Can you give us a citation or other evidence?

Pretty unlikely. I mean, have you ever met an ethics committee?

No illusions were harmed during replication of subject's dance.

Nobody doubts that the constant exists in the math formula. Nobody doubts we can set it to a variety of values.

I'm glad you agree that the constant does appear within the math formula. It's been there for almost a century.

Because it's a free parameter of Einstein's theory, we have to estimate its value. Because this is a matter of science, not religion, everyone (except you) agrees that its value should be estimated from the best available empirical observations. Three guys just won a Nobel Prize in physics for making those observations.

Since you are objecting to the idea that estimates of that constant should be derived from empirical observations, how do you think that constant's value should be estimated?

 

[Wangler]

Since you cannot even tell me where dark energy comes from, let alone EMPIRICALLY demonstrate that it can accelerate even a single atom in a controlled experiment, what else CAN it be other than a "statement of faith in the unseen (in the lab)"?

Michael, I like to look for holes in LCDM theory like a lot of layfolks, but this is getting ridiculous.

To me, your statement is the equivalent of:

"Since you cannot even tell me where sustained nuclear fusion comes from, let along EMPIRICALLY demonstrate that fusion can be sustained over years in a controlled experiment, what else CAN it be other than a "statement of faith in the unseen (in the lab)".

 

[Tubbythin]

From the interview:



Those assumptions sound pretty suspect actually:

Huh? What assumptions? There are no assumptions in the bit of text you quoted.

http://www.nytimes.com/2008/05/17/science/space/17univ.html

It's impossible to comment unless you tell me what assumptions you are talking about.

Only if you stuff it full of magic.

Nonbody has stuffed it full of magic. That was your made-up claim you used when you couldn't make a scientific argument. You seem to think if you make up some nonsense and repeat it enough times then it suddenly becomes true. It doesn't Michael.

If I don't bow to your religion you'll continue to chastise me personally, just like ordinary religious "believers", just watch and see.

Clearly I won't since I don't have a religion. So there is absolutely no point whatsoever me watching and seeing.

 

[Michael Mozina]

Michael, I like to look for holes in LCDM theory like a lot of layfolks, but this is getting ridiculous.

To me, your statement is the equivalent of:

"Since you cannot even tell me where sustained nuclear fusion comes from, let along EMPIRICALLY demonstrate that fusion can be sustained over years in a controlled experiment, what else CAN it be other than a "statement of faith in the unseen (in the lab)".

Your analogy is inapplicable IMO because you (or someone) CAN in fact tell me which particles are involved in the fusion process. You can demonstrate fusion here on Earth, albeit not a "sustained fusion" process. The claim then that "fusion" is a possible energy source is not a "leap of faith". The sustainability factor could in fact be limited by conditions on Earth for all I know too, so even that concept isn't a great leap of faith.

Compared to "dark energy thingies" did it, it's not even an empirical contest. Nobody can tell me where it comes from. Nobody expects it to have an empirical effect on Earth. Nobody seems to know how to "control" it because they don't even know how to find any!

In theory at least, if I doubted your claims about fusion being an energy source, I could recreate your work based on controlled experiments that have demonstrated the process in the past. In terms of "dark energy did it", there no way to EMPIRICALLY demonstrate that dark energy accelerates *ANYTHING* here on Earth, not even in an "unsustainable" fashion.

Effectively you're comparing empirical oranges (fusion) to metaphysical poisonous apples (dark, impotent on Earth, sky stuff).

 

[Tubbythin]

Your analogy is inapplicable IMO because you (or someone) CAN in fact tell me which particles are involved in the fusion process. You can demonstrate fusion here on Earth, albeit not a "sustained fusion" process. The claim then that "fusion" is a possible energy source is not a "leap of faith". The sustainability factor could in fact be limited by conditions on Earth for all I know too, so even that concept isn't a great leap of faith.

I don't see how the idea of a non-zero cosmological constant constitutes a "leap of faith".

Compared to "dark energy thingies" did it, it's not even an empirical contest. Nobody can tell me where it comes from. Nobody expects it to have an empirical effect on Earth. Nobody seems to know how to "control" it because they don't even know how to find any!

Why should anyone expect it to have a measurable effect on Earth?

In theory at least, if I doubted your claims about fusion being an energy source, I could recreate your work based on controlled experiments that have demonstrated the process in the past. In terms of "dark energy did it", there no way to EMPIRICALLY demonstrate that dark energy accelerates *ANYTHING* here on Earth, not even in an "unsustainable" fashion.

Michael, you don't understand what empirical means.

Effectively you're comparing empirical oranges (fusion) to metaphysical poisonous apples (dark, impotent on Earth, sky stuff).

Once again your inability to make a scientific argument and subsequent need to insert nonsense instead is seen.

 

[Michael Mozina]

Sure you do. Remember that CREIL theory that you linked to, twice, as your best example of a non-dark-energy theory? That was a "redshift isn't even happening" theory, not a "motion (which we observe through redshifts) is explained by THIS acceleration" theory. You've been groping around for reasons to reject the whole cosmology---motions and all---since day one. You have NOT been groping around for non-"energy" ways of explaining an accelerating expansion.

Actually that's not true. I've pointed out to you folk in the past that EXTERNAL influences might give you the acceleration process that you're looking for. You've pretty much gone out of your way to shoot that idea down. I've been clear that I don't have any problem with expansion theories or even accelerated expansion theories. I simply lack belief that "dark evil energies did it ". You folks slap on ad hoc properties galore, so don't you dare bitch about "evil". You made it "dark" just so you could stuff the gaps of your own theory, so I can call it evil if I want to. Hell, you just make this up as you go anyway!

See?

See, I don't have a lot of confidence that your original assumptions were correct in the first place? Do you care that galaxies are now thought to be much brighter than when "dark energy' was first discovered, or is that just something you intend to ignore and/or sweep under the carpet?

Gravity is an ordinary field that acts over long distances.

Ya, and external gravity might in fact be what drives that accelerated expansion, particularly if neutrinos really do travel faster than photons. I'm willing to entertain almost ANY idea so long as it's based on actual PHYSICS, not impotent on Earth sky entities.

(Just reread your statement. Um. You're going to apply a silly name to an ordinary physics hypothesis, then reject the hypothesis because it sounds silly when referred to by the silly name. Are you having fun?)

Ben, it's silly to you because you're on the outside looking in at a "silly' idea that you 'lack belief in'. It's exactly the same way for me. When you folks claim "dark energy" did it, but can't even tell me where it comes from, let alone how to control it, I want to hurl. This isn't "physics", this is nothing short of "dark magic".

 

[Michael Mozina]

I don't see how the idea of a non-zero cosmological constant constitutes a "leap of faith".

It's not. "Dark energy did it" is a "leap of faith".

Why should anyone expect it to have a measurable effect on Earth?

Suppose I claim "God energy did it" and handed that same statement back to you? Are you instantly a "believer"?

Michael, you don't understand what empirical means.

No, you don't know what it means. Your trio of sky entities are known to be more impotent on Earth than your average religious icon.

Once again your inability to make a scientific argument and subsequent need to insert nonsense instead is seen.

It's only nonsense to you because you don't like the comparison. The comparison is valid however because you can't tell me where dark energy comes from, you just stuff the gaps of your otherwise falsified theory and shrug.

 

[Michael Mozina]

Because it's a free parameter of Einstein's theory, we have to estimate its value. Because this is a matter of science, not religion, everyone (except you) agrees that its value should be estimated from the best available empirical observations. Three guys just won a Nobel Prize in physics for making those observations.

For the record, I didn't bitch about the observations, I bitched about the claim 'dark energy did it'.

 

[ben m]

Your analogy is inapplicable IMO because you (or someone) CAN in fact tell me which particles are involved in the fusion process.

It's funny how you can see your side of this and not the other.

You happily linked to a paper about a plasma-redshift phenomenon that's unobservable in 20th-c Earth labs. You happily linked to a paper about f(R) gravity, a long-range modification of GR with no "cause" and with consequences observable in 20th-c Earth labs. Oh well.

(In other words, you don't actually have an "empirical physics" criterion, you just think it's a handy contrarian cudgel to swing at mainstream theories you dislike.)

At the same time, in this world where 19th-century-classical-physicists like Birkeland discovered the only physics you claim to trust: when it comes time to actually figure out how cosmic baryons and photons behave---are there long range forces between stars? Do stars get caught up in a "plasma flow" in the galaxy? Do photons undergo a non-scattering redshift in diffuse plasmas? Does hot, current-carrying neon plasma get into a weird, cold, transparent state? Well, in those cases suddenly you ignore classical physics, or refuse to calculate it, or refuse to listen to calculations. Oh well.

(In other words, you don't actually have respect for empirical physics. You just have mainstream theories you dislike and will ignore any physics you need to in order to continue disliking them.)

 

[ben m]

"Dark energy did it" is a "leap of faith".

Saying "Dark energy didn't do it" is also a leap of faith.

What we have are observations which say that there's a additive constant in the Einstein field equations. That constant must have one of several sources. Whatever the source is, its inclusion in the EFE is simple enough that you can translate it into energy-density units as though it was a vacuum energy density.

That's what the phrase "dark energy" is. It's a shorthand term for whatever is responsible for the additive constant in the EFE.. We don't know what the underlying physics is, we just know what the contribution to GR is.

This has been explained to you 50 times.

 

[Michael Mozina]

Saying "Dark energy didn't do it" is also a leap of faith.

True, but LACKING BELIEF that dark energy did it is not a leap of faith anymore than lacking belief that God energy did it is a leap of faith.

What we have are observations which say that there's a additive constant in the Einstein field equations.

Ok.

That constant must have one of several sources. Whatever the source is, its inclusion in the EFE is simple enough that you can translate it into energy-density units as though it was a vacuum energy density.

I doubt it. No vacuum contains "negative pressure" or negative kinetic energy.

This has been explained to you 50 times.

Ya, and I've explained to you 50 times that a vacuum cannot and does not contain negative kinetic energy or negative pressure too, but you refuse to deal with that fact.

 

[Tubbythin]

It's not. "Dark energy did it" is a "leap of faith".

But a non-zero cc solution is a "dark energy did it" solution.

Suppose I claim "God energy did it" and handed that same statement back to you? Are you instantly a "believer"?

Not without a formal definition of God energy and evidence for the existence of said God energy.

No, you don't know what it means. Your trio of sky entities are known to be more impotent on Earth than your average religious icon.

There is nothing in the definition of empirical that requires empirical data to come from Earth. Like I said, you don't know what empirical means.

It's only nonsense to you because you don't like the comparison.

Nope. Its nonsense because it gibberish.

The comparison is valid however because you can't tell me where dark energy comes from, you just stuff the gaps of your otherwise falsified theory and shrug.

Well the cosmo constant comes from general relativity. Just as 'normal' gravity does. I don't hear you asking for the origins of Newtonian gravity though. Odd.
What falsified theory? GR is still very much in-tact thank you.