Lambda-CDM theory - Woo or not?

[Michael Mozina]

How about all the light/radiation that reaches earth from space, proving that inflation exists?

How does light reaching earth demonstrate that inflation isn't a figment of Guth's imagination? I've never seen any empirical connection between inflation and light.

What do you want? A mini-universe in a lab on earth that you can poke and prod?

No, I'd like to see you demonstrate the Guth didn't just "make up" inflation. I'd like to see a test of concept please.

It seems like your qualifications for "proving" these matters, would cause an environment where the pursuit of any cosmological knowledge is pointless. Is that what you want?

Certainly not. All I want is what everyone wants in every field of science. I want to see some *empirical support* that inflation actually exists in nature and isn't just a figment of Guth's imagination. Is that really too much to ask for?

 

[Ziggurat]

No, it's not. There is a *physically demonstratable* aspect you keep ignoring.

Which had nothing to do with what Newton contributed.

He could do this by "testing" his theory and by varying the conditions. He could select different objects to drop. He could vary the height of the drop. He could drop things simultaneously and watch what happened and compare his results to his mathematical model. At no time was his idea "unverifiable."

It absolutely was. None of what you mention would have revealed anything about the 1/r² form. And THAT was his idea, not that things fall. As I already said (and what you seem determined to ignore), the idea that things fall preceded Newton.

Show me one empirical demonstration of inflation here on Earth.

Show me one empirical demonstration of the 1/r² form of gravity here on earth. Every demonstration we have of that requires a sensitivity that Newton was not able to achieve.

False. The objects were *always* affected by gravity

We only know that now. How could Newton know that? Nobody before him knew that the moon was held in orbit by the same force that makes apples fall. Nobody knew what would happen with gravity if you got very far away.

and math formulas could be compared to the physical drops he performed.

Nope. Any drop tests would have only confirmed Galileo's ideas. None of them would have revealed Newton's ideas.

But it was a math formula that could be "tested" here on Earth.

At the time it could not be. Sensitivity was not nearly good enough: within experimental error, gravity would have looked constant. Even now, drop tests can't give you the 1/r² form, because the earth is inhomogenous. You need other sorts of measurements.

No, they believed him because he could show that gravity affected objects on Earth.

Galileo already did that. And every test on earth suggested gravity was constant, not that it had a 1/r² form. Furthermore, there was no available evidence on earth that it was a force acting between all masses, as Newton proposed. Yes, it's easy to show that an apple is attracted to the earth, but how do you show that an apple is attracted towards you?

 

[Michael Mozina]

You missed the point entirely. By your logic, if you cannot make it on Earth it is just maths. Since you can't make a complete star on Earth, stars don't exist. This is your ridiculous logic thats digging a hole for you.

It's you that keep missing the point IMO. I'm not asking you to create a "complete" anything. I'm simply asking for physical evidence that you aren't just making up the whole idea. Fusion is something I can "test" here on Earth. I therefore don't have a problem with you trying to use it as an energy source of a star. Inflation however doesn't do anything here on Earth, so pointing to objects in the sky and claiming "inflation did it" isn't particularly useful, meaningful or verifiable in any physical way.

If you could demonstrate that inflation can move atoms here on Earth, I wouldn't have any doubt that it might cause a universe to "inflate". Since you can't do that, I can't tell your idea from "magic". I have to accept the concept of "faith" because you cannot demonstrate that inflation has any affect on any material objects.

 

[drkitten]

All I want is what everyone wants in every field of science. I want to see some *empirical support* that inflation actually exists in nature?

You haven't been able to offer empirical support that gravity as a force exists in nature.

I suggest that your evidentiary standards are unreasonable.

But I'll be far more magnanimous than you. I'll give you, for the sake of argument, the idea that there exists a universal force of gravity.

Give me *empirical support* for the idea that this force drops off at a rate proportional to the square of the distance, and not at the cube of the distance.

(Using 17th century technology, please.)

 

[Michael Mozina]

But they all fall with the same acceleration.

Which is one of the reasons why he came up with the formula he came up with.

You think he had equipment sensitive enough to measure the variation of g on Earth with height?

No, but I think he could physically demonstrate that gravity wasn't a figment of his imagination and he could physically demonstrate that it had an affect on objects here on Earth. That is light years ahead of what Guth can do with inflation.

Show me an empirical demonstration of a galaxy here on Earth. No? Then Galaxies can't exist by your logic either.

As long as you aren't trying to claim they are made of something you can't demonstrate to exist in nature, I don't really have a problem. If you claim that galaxies are made of "ofuoiu", I will expect you to demonstrate that this exists in nature too before you point at a galaxy and claim "ofuoiu did it".

So how did he measure 1/r² nature on Earth?

You are overly fixated on a mathematical model, and you keep ignoring the part about being able to physically demonstrate the the force of nature your applying the math formula to actually exists in nature. It's not the mathematical model of inflation I have a problem with, it's the fact you can't demonstrate that inflation exists in nature that is a problem.

 

[Gate2501]

How does light reaching earth demonstrate that inflation isn't a figment of Guth's imagination? I've never seen any empirical connection between inflation and light.



No, I'd like to see you demonstrate the Guth didn't just "make up" inflation. I'd like to see a test of concept please.



Certainly not. All I want is what everyone wants in every field of science. I want to see some *empirical support* that inflation actually exists in nature and isn't just a figment of Guth's imagination. Is that really too much to ask for?

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

Read the "observational status" area. CMB among other things.

If the only proof that you will accept, is making 2 tennis balls move away from each other in a lab due to cosmic inflation, then you are going to be impossible to argue with.

As was also pointed out however, we cannot create a star here on earth either. So everything that we know about them must be made up?

 

[Michael Mozina]

You haven't been able to offer empirical support that gravity as a force exists in nature.

That is absolutely not true. I can pick up objects, let them go, and demonstrate that something (now called gravity) causes them to accelerate right here on Earth.

I suggest that your evidentiary standards are unreasonable.

I suggest your lack of evidence to support the notion that inflation exists in nature is unreasonable. I have to accept on "Faith" that inflation even exists!

But I'll be far more magnanimous than you. I'll give you, for the sake of argument, the idea that there exists a universal force of gravity.

I'll be reasonable too. All I want is some evidence that inflation exists in nature. If you can do that, I'll be happy to let you apply it universally.

Give me *empirical support* for the idea that this force drops off at a rate proportional to the square of the distance, and not at the cube of the distance.

(Using 17th century technology, please.)

Again, it's not the math that is the problem or that is in question, it's the lack of empirical support for Guth's inflation theory that is the problem and the part that I question. That math isn't the issue. The empirical support, or lack thereof that is the issue and the part that is in doubt and dispute.

 

[Michael Mozina]

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

Read the "observational status" area. CMB among other things.

But how about those "holes" and "dark flows"? Shall we simply ignore them altogether because they don't "fit" with your preconceived ideas?

If the only proof that you will accept, is making 2 tennis balls move away from each other in a lab due to cosmic inflation, then you are going to be impossible to argue with.

If you could demonstrate this, we wouldn't be arguing at all. It's the fact that you *can't* do this that creates "doubt' and that makes me a "skeptic" of the idea. It's also because those unexpected hole and dark flows keep being "discovered' that makes me doubt in inflation. All I know is that you *can't* do this, and yet I'm supposed to believe you anyway.

As was also pointed out however, we cannot create a star here on earth either. So everything that we know about them must be made up?

No. You can demonstrate that fusion releases energy. You can demonstrate that sun contains hydrogen and helium. I therefore have no problem with you theorizing that fusion is the power source of stars. Right or wrong, your core idea can be demonstrated in a lab. I'm not asking you to created objects on Earth, I'm simply asking you to demonstrate that a presumed force of nature isn't a figment of your imagination. Is that really too much to ask?

 

[drkitten]

That is absolutely not true. I can pick up objects, let them go, and demonstrate that something (now called gravity) causes them to accelerate right here on Earth.

That proves that things fall. It doesn't prove that gravity exists.

Again, it's not the math that is the problem or that is in question, it's the lack of empirical support for Guth's inflation theory that is the problem and the part that I question.

But the agreement between reality and the math is the empirical support.

The equations describe what we expect to see. That's the theory.

We see what the equations predict. That's the empirical support.

 

[Ziggurat]

Which is one of the reasons why he came up with the formula he came up with.

Wrong, wrong, wrong. His formula predicts different accelerations. But such different accelerations were not observable on earth.

No, but I think he could physically demonstrate that gravity wasn't a figment of his imagination and he could physically demonstrate that it had an affect on objects here on Earth.

In other words, he could demonstrate what Galileo did before he was born. He could not physically demonstrate on earth that his own ideas about gravity were right.

You are overly fixated on a mathematical model,

A mathematical model you haven't shown you understand anything about. Do you even know what it means when I say that gravity is a 1/r² force?

 

[Tubbythin]

Which is one of the reasons why he came up with the formula he came up with.

His formula is
F=-GM₁M₂/r².

But on Earth in Newton's time it was impossible to compare this with, say,
F=-GM₁M₂/r
or

F=-GM₁M₂/r³.

Are you getting this yet?

No, but I think he could physically demonstrate that gravity wasn't a figment of his imagination and he could physically demonstrate that it had an affect on objects here on Earth. That is light years ahead of what Guth can do with inflation.

So could other people.

As long as you aren't trying to claim they are made of something you can't demonstrate to exist in nature, I don't really have a problem. If you claim that galaxies are made of "ofuoiu", I will expect you to demonstrate that this exists in nature too before you point at a galaxy and claim "ofuoiu did it".

What are your standards of proof for "demonstrate to exist"?

You are overly fixated on a mathematical model, and you keep ignoring the part about being able to physically demonstrate the the force of nature your applying the math formula to actually exists in nature. It's not the mathematical model of inflation I have a problem with, it's the fact you can't demonstrate that inflation exists in nature that is a problem.

But when you reject any evidence that comes from outside Earth ts hardly surprising you have a problem. Why should cosmological phenomena be demonstratable (is that a word?) on Earth?

 

[Michael Mozina]

That proves that things fall. It doesn't prove that gravity exists.

It proves that something (now called gravity) causes objects to accelerate.

But the agreement between reality and the math is the empirical support.

No. I can't tell from his math formula whether or not inflation is a figment of Guth's imagination. The only way I can know if inflation actually exists in nature is to somehow show it has an effect on nature and somehow "measure" that effect. A *claim* that inflation causes objects to "inflate" is not demonstrated and has never been demonstrated. All I have is a magic math formula and no way to "test" it in any controlled experiment. If I doubt Newton's math, I can at least "Test" it here on Earth and see how well it works on Earth. I may not be able to test every aspect of that math, but I can show that it works here on Earth.

The equations describe what we expect to see. That's the theory.

The equations don't relate to anything known to actually exist in nature. They are simply "made up" and they don't actually "predict" what we observe or we would not observe those "holes" and those "dark flows".

We see what the equations predict. That's the empirical support.

A math formula is not a controlled test. A controlled test is a *physical* test and has a "physical control mechanism" that allows me to be sure that it is in fact "inflation" that is causing this to occur as opposed to some other cause. The "empirical" support of concept comes "empirical testing", not from the math formula. One might falsify or verify a mathematical model based on controlled testing, but one cannot verify or falsify the existence of something based on a math formula and an uncontrolled observation.

 

[Michael Mozina]

His formula is
F=-GM₁M₂/r².

But on Earth in Newton's time it was impossible to compare this with, say,
F=-GM₁M₂/r
or

F=-GM₁M₂/r³.

Are you getting this yet?

I think we you aren't "getting" here is the fact that I don't have to know that the math is correct to know that gravity is a *real* force of nature that has a *real* affect on *real* objects. The only way I can actually "test" the math is to perform experiments. I can't even experiment with inflation to make sure that the mathematical expression is correct *anywhere*.

So could other people.

Sure. That's why I know for a fact that gravity exists in nature, even if I don't buy into Newtons mathematical model for some reason. The only thing I can tell about Guth's inflation here on Earth is that it has no affect whatsoever. I therefore have no evidence it exists *anywhere* and I have no way to physically *test* the mathematical properties being assigned to it.

What are your standards of proof for "demonstrate to exist"?

Any standard empirical, complete with "control mechanism" will do. The control mechanism can be extremely simple. In the case of neutrinos, they were able to turn on and off the "source" of neutrinos and make sure it had some affect on their experiments. I'm not particularly picky, as long as there is in fact a "control mechanism" involved in the "test".

But when you reject any evidence that comes from outside Earth ts hardly surprising you have a problem. Why should cosmological phenomena be demonstratable (is that a word?) on Earth?

Put on your skeptic cap for a moment in put yourself in my shoes. You expect me to simply have "faith' in Guth's math formula *without* ever demonstrating it even works here on Earth. I'm simply supposed to "accept on faith' that these formulas apply somewhere out in space but not here on Earth, and I'm supposed to accept on faith that inflation isn't a figment of his imagination based strictly on a unverifiable math formula. I'm also supposed to simply "accept on faith" that it has all the properties he assigned to it even though we now find "holes" and "dark flows' that are not predicted by these mathematical models. You don't find that somewhat "hard to swallow"?

 

[ben m]

In what tangible and demonstrateable way is Lambda-CDM theory any "better" than any other cosmology theory?

Lambda-CDM is what we call a *model*. It's a complete hypothesis for how the Universe evolved from t=early (pre-inflation) to the present.

What do I mean by complete? I mean that the model tells you exactly what its guess is for the law of spacetime, and it tells you its guess for the list of gravitational source terms in the equation. THAT'S IT. Anyone can take this model and evolve it forward in time, make predictions. Other than those four components and standard GR, Lambda-CDM invokes no physics that isn't standard E&M/atomic/plasma/nuclear.

But that's all it is. It's a model.

All scientists do is compare models to data. That's our job. Let's go ahead, shall we?

• The Lambda-CDM model exactly matches the following data: the CMB power spectrum; all CMB polarization spectra and bispectra; all known CMB non-Gaussianity tests; the distribution of galaxy cluster sizes (and its time evolution), velocity dispersions, x-ray virial temperatures, weak lensing masses, and strong lensing masses; the rotation-curve evidence for dark matter in galaxies; the Hubble constant and its time evolution; the lyman-Alpha forest angular size spectrum; the ratio of H/D/He/Li in unevolved gas clouds; the Gunn-Peterson trough in quasar spectra. Scientists know how to quantify the phrase "exactly matches"---we can tell the difference between "fine-tuning 10 parameters to fit 10 data points" and "the various data concurs on the model" using a Chi^2 per degree of freedom---and yes, the match is highly significant.
• The Lambda-CDM model fails to match the following data: nothing whatsoever.

So Lambda-CDM is a good model, according to EVERYTHING SCIENTISTS KNOW about how to compare models to data. Do you know something about model-fitting that we don't know? Is Chi^2 a bad statistic for some reason? Do you have a really-weird Bayesian prior up your sleeve?

Your request for "independent" evidence is dumb; what's our independent evidence for the tau lepton, huh? For the Ice Age? For the idea that Greek and Sanskrit had a common linguistic ancestor? They're all model-data comparisons. Get used to it.

It's a fact that an inflation model gives a GOOD description, a very good description, of the ensemble of cosmology data. (Do you disagree? If so, show math, please?) No one has ever come up with a non-inflation model that gives anywhere near as good a description. (Do you disagree? If so, show math, please?) At the same time, we don't have any evidence *against* the inflaton. (Do you disagree? If so, show math, please?) It doesn't conflict with any current understanding of particle physics and the vacuum. (Do you disagree? If so, show math, please?)

If you can come up with *another* model which also explains the data, good for you---that's how hypotheses work. Please write a paper about it and show us the Chi^2/dof for your model/data fit.

Keep in mind that "inventing a model which explains the data well" has historically been a useful thing to do. Weinberg and Salam "invented" the W and Z bosons in the mid-1970s---in a global fit to data which you'd surely criticize---quite a while before anyone built a collider big enough to discover them. Enrico Fermi "invented" the neutrino in the 1930s, but it remained unseen (except in the unacceptable-to-Mozina sense of "including it makes this other data make sense") until the 1950s. I don't know why the fact "The list of particles in the universe includes a very light, very hard-to-detect particle called the neutrino" doesn't bother you, but the hypothesis "the list of particles includes a very heavy, very hard-to-detect particle called dark matter" makes you think we're crazy. If you don't like standard cosmology because you generally don't like theoretical models, then I suggest you either get used to it, or that you abandon your hobbyist's interest in physics and instead consider a career as a tortoise.

 

[Ziggurat]

I think we you aren't "getting" here is the fact that I don't have to know that the math is correct to know that gravity is a *real* force

And inflation is just gravity in the presence of a vacuum energy. Ever hear of the Casimir effect?

 

[drkitten]

It proves that something (now called gravity) causes objects to accelerate.

It does not.

In particular, it doesn't prove that some (unique) thing causes objects to accelerate, only that individual objects accelerate. It also doesn't prove that the same thing causes all objects to accelerate -- that the acceleration of a falling pen is caused by the same thing that keeps the moon to its course in the heavens.

And most particularly, it doesn't prove that the force experienced by the moon is substantially less than the force that would be experienced by a moon-sized object sitting on the Earth.

Yet that's one of the things that Newton is credited with "discovering."

I can't tell from his math formula whether or not inflation is a figment of Guth's imagination.

That says more about your competence as a mathematician and as an observer than it does about Guth, I'm afraid.

If I doubt Newton's math, I can at least "Test" it here on Earth and see how well it works on Earth.

No, you can't. Newton's math says --- the stuff that makes it Newton's math as opposed to Galileo's -- that if you get far enough away from the Earth, you will experience less gravity. By definition, you cannot get far enough away from Earth to test this here on Earth.

I may not be able to test every aspect of that math, but I can show that it works here on Earth.

But if you don't test that particular aspect, you're not testing Newton's math at all.

You're not even testing Galileo's math. Aristotle knew that objects fall. Homer knew that objects fall. Cavemen knew that objects fall.

 

[sol invictus]

That isn't a "controlled test". That is an uncontrolled observation. I'm beginning to think that nobody in your industry actually understands what a "controlled experiment" actually is.

What's "your industry"?

Really? What is it? Where can I get some? Where does it come from?

It's a cosmological constant. That's what the "lambda" in "lambda-CDM" means. Why are you posting on something when you don't even know the meaning of the terms in its name?

As for where you can get some - got an empty box? Yes? OK, there you go - it's full of vacuum energy.

How do you know how much is there if you can't tell me any of it's actually properties and show me a controlled test where X amount of "dark energy" move Y amount of matter a distance of Z?

I can tell you the answers to all those questions quite easily. That's what theories are good for.

What? It does not! No known vector or scalar field in nature retains a near constant density over multiple exponential increases in volume. You're just making stuff up as you go.

No, you simply have no clue. The Higgs vacuum energy density is absolutely constant no matter what happens to the volume. That's what scalar condensates are.

No he did not. He could empirically demonstrate that gravity was not a figment of his imagination. Compare and contrast that with Guth's inflation. Guth can't even show any example on Earth where inflation did anything to anything.

"Example on earth"? What do you mean? If you include observations, then inflation makes tons of predictions, as we've been discussing. If you mean lab experiments, I ask you again - how do you test for the existence of Andromeda in a lab without a telescope? If you can't does that mean you don't believe in it?

 

[sol invictus]

Gah! It is so aggravating to not be able to post links. Go to Google and type in "dark flows". They have been "observed" and yet inflation still has not been falsified.

Wrong. Something - most likely systematic error - has been observed. If or when the observations are solidly confirmed, vanilla inflation will be falsified (or at least it's very hard to see how to reconcile them).

Those "holes" they found are another example of an observation that "should" falsify the idea, but again, it's just swept under the carpet.

You've heard of it and yet you think it's been swept under the rug? Don't be ridiculous - it was major news across the world. It's not being taken that seriously by the pros, because pros are very, very used to anomalies like that which come... and then go, because they aren't real. Extraordinary claims require extraordinary evidence, and the evidence so far is rather weak.

 

[sol invictus]

Well, I "sort of" see where you're headed here as it relates to the 'math' side, but again, the existence of gravity is verifiable. Even if the math is not obvious, the force of gravity is obvious.

Einstein would be rather surprised to hear that, wouldn't he? Or haven't you heard of the general theory of relativity, in which there is no such thing as the force of gravity?

 

[drkitten]

Einstein would be rather surprised to hear that, wouldn't he? Or haven't you heard of the general theory of relativity, in which there is no such thing as the force of gravity?

Come on, now.

He hasn't managed to demonstrate why Galileo is more correct than Aristotle; he doesn't even know the difference between Galileo and Newton, and you want to drag Einstein into it?