Lambda-CDM theory - Woo or not?

[Michael Mozina]

Really?

Does anyone have any logical reason to doubt the existence of gravity in nature? Really?

The fact you're still trying to compare GR theory to inflation theory shows how little you folks have actually evolved here in your thinking. Gravity exists in nature and has a tangible effect on things in nature. The math related to GR may be replaced one day by a QM explanation of gravity, but gravity will be here for the duration. It is a physical process of nature that may defy *all* our current mathematical models for all I know. What I do know however is that gravity exists in nature and has an effect on objects in nature. EM fields also exist in nature and show up in real experiments. Comparing inflation to either of these other known processes is just silly. Inflation does not exist nor does it have any influence on my daily life. I'd be in a hurting place without gravity and electricity, but my life is not dependent upon, nor influenced by inflation.

 

[Reality Check]

Of course you do! I don't believe it's going to reach infinity in the *real world* with *real things*.

Hi temporalillusion: You should please MM and replace infinity with 10¹⁰¹⁰⁰ KPa !

 

[Michael Mozina]

That's a rather... unscientific criteria for evaluating what counts as science.

How so? I can personally experience the effect of gravity on my body. How is that "unscientific"?

No, it is not: either space is physically curved, or it is not. The distinction is NOT simply math.

Conceptually speaking I hear you, there is a conceptual difference in these two approaches to explaining gravity. From a "qualification" perspective however it doesn't matter if either mathematical model is the "ultimate truth" or the last word on gravity. What matters is that gravity isn't shy around a lab, so we can in theory create real empirical tests to verify aspects of GR that remain unverified. Gravity wave experiments come to mind.

He wasn't able to test any points of his theory in a controlled experiment.

Would an apple fall to Earth in curved space according to Einstein's theory?

 

[Reality Check]

MM: You have been ignoring this question since the 13th of March 2009 so here it is for the fourth time.

So is this what you are saying:

• If the plates are such that the net force is replusive then the net pressure (force divided by area) is positive.
• If the plates are such that the net force is attractive then the net pressure is still positive despite the fact that the net force has changed sign.

If so your conclusion must be that the area of the plates must have also changed sign to keep the pressure positive. Can you tell us how to measure a negative area? Do we construct square plates with imaginary sides and square their imaginary lengths?

Note this is not sarcasm - it is a serious question about whether you really believe in imaginary length or negative areas.

If this is too complex for you then here is a simpler situation (no Casimir stuff involved!):

Consider these 2 scenarios

1. A force F pushes on a surface that has an area of A.
2. A force F pulls on a surface that has an area of A.

What is the pressure in these 2 scenarios?
​

If you cannot answer that then:

Is the pressure positive or negative in each of the 2 scenerios?
​

 

[Tubbythin]

Does anyone have any logical reason to doubt the existence of gravity in nature? Really?

I was merely querying in what sense gravity kept Einstein in his chair.

The fact you're still trying to compare GR theory to inflation theory shows how little you folks have actually evolved here in your thinking. Gravity exists in nature and has a tangible effect on things in nature. The math related to GR may be replaced one day by a QM explanation of gravity, but gravity will be here for the duration. It is a physical process of nature that may defy *all* our current mathematical models for all I know. What I do know however is that gravity exists in nature and has an effect on objects in nature. EM fields also exist in nature and show up in real experiments. Comparing inflation to either of these other known processes is just silly. Inflation does not exist

We have empirical evidence that suggests it happened at early times after the Big Bang.

nor does it have any influence on my daily life. I'd be in a hurting place without gravity and electricity, but my life is not dependent upon, nor influenced by inflation.

Actually, it could have every influence on your daily life. Without it we have no reason to think the Universe should be close to flat. And without a close to flat Universe you wouldn't be here.

 

[GeeMack]

What I do know however is that gravity exists in nature and has an effect on objects in nature. EM fields also exist in nature and show up in real experiments. Comparing inflation to either of these other known processes is just silly. Inflation does not exist nor does it have any influence on my daily life. I'd be in a hurting place without gravity and electricity, but my life is not dependent upon, nor influenced by inflation.

Imagine how intellectually deficient a person would have to be to declare that dinosaurs never existed because...

What I do know however is that cows exist in nature and have an effect on objects in nature. Soy beans also exist in nature and show up in real experiments. Comparing dinosaurs to either of these other known things is just silly. Dinosaurs do not exist nor do they have any influence on my daily life. I'd be in a hurting place without cows and soy beans, but my life is not dependent upon, nor influenced by dinosaurs.​

I'm sure we'd all agree, even Michael, that pursuing that line of logic to suggest that dinosaurs never existed would be totally inane, the epitome of stupid. Yet some (one, anyway) would make such a statement to support the claim that inflation never occurred. Massively flawed logic? Indeed. Epitome of stupid? Sure seems so.

 

[Michael Mozina]

So is this what you are saying:

* If the plates are such that the net force is replusive then the net pressure (force divided by area) is positive.

If the plates are moving away from one another then there is more "force" pushing on the inside of the plates than there is force pushing on the outside of the plates. If the reverse it true, then there is more force applied on the outside of the plates than inside the plates. Those blue arrows in the Casimir image are accurate. There is more force being applied to the outside surface of the plates than inside of the plates and therefore the plates are pushed together (from the outside).

 

[Michael Mozina]

Imagine how intellectually deficient a person would have to be to declare that dinosaurs never existed because...

What I do know however is that cows exist in nature and have an effect on objects in nature. Soy beans also exist in nature and show up in real experiments. Comparing dinosaurs to either of these other known things is just silly. Dinosaurs do not exist nor do they have any influence on my daily life. I'd be in a hurting place without cows and soy beans, but my life is not dependent upon, nor influenced by dinosaurs.​

You guys are really terrible at creating useful analogies. I can and have seen dinosaur fossils up close and personal. In fact I've dug up a few ancient fossils myself. I've never dug up any inflation monsters or dark energy gnomes.

 

[GeeMack]

You guys are really terrible at creating useful analogies. I can and have seen dinosaur fossils up close and personal. In fact I've dug up a few ancient fossils myself. I've never dug up any inflation monsters or dark energy gnomes.

Good. Then you agree that line of logic stinks, that only an idiot would use it, and you'll stop using it to support your claim that inflation never existed.

 

[Michael Mozina]

I was merely querying in what sense gravity kept Einstein in his chair.

I imagine he got up from his chair to eat and sleep once in awhile. I doubt he ever floated up and away from his chair on accident.

We have empirical evidence that suggests it happened at early times after the Big Bang.

You do not. You have "subjective personal faith" in the notion based on a little redshift.

Actually, it could have every influence on your daily life.

Only if we *assume* inflation has some effect on nature.

Without it we have no reason to think the Universe should be close to flat. And without a close to flat Universe you wouldn't be here.

All we know is that we are here and the universe is as we observe it to be. Even on a gamma ray spectrum the universe can be observed to be relatively uniformly distributed. That's all we really "know".

 

[Michael Mozina]

Good. Then you agree that line of logic stinks, that only an idiot would use it, and you'll stop using it to support your claim that inflation never existed.

No, I'm saying your analogy failed.

 

[Michael Mozina]

So......

Who among you still supports the ideas of:

A) Negative pressure in a vacuum?
B) A net zero energy state of the universe?

 

[GeeMack]

No, I'm saying your analogy failed.

Oh, well then you didn't get out of my comment what you should have gotten. And you saying an analogy failed only serves to prove, as usual, that you don't understand it. But here, I'll make it simple. Your line of logic stinks, only an idiot would use it, and you should stop using it to support your claim that inflation never existed.

 

[temporalillusion]

Oh for crying out loud. You are the single most unethical personal I've ever met in debate. My incredulous response was at the idea of sol trying to take their side in this debate rather than just staying out of it. It has nothing to do with his actual comments. I was surprise sol was attempting to suggest we live in a 'net zero' energy state, not at his comments, hence my question related to 'net zero energy'. Leave it to you however to "spin' it into something it was not.

It's unethical to read something someone wrote literally? It is a forum you know, sometimes sarcasm can be hard to detect.

Of course you do! I don't believe it's going to reach infinity in the *real world* with *real things*.

A formula is an ideal representation in an ideal situation, duh.

So let me ask you this, if I have an electron and a proton (or whatever you want), and the closer I bring them together, the attractive force between them increases right?

Do you agree with Coulomb's law?

[latex]$$ F=k_e\frac{q_1q_2}{r^2} $$[/latex]

As r approaches zero, what's going to happen to the force? What's the upper limit of that attraction? You can't produce one for the Casimir effect, but you should be able to do so for this since this is your home turf so to speak.

Hypothetically it approaches infinity, do you agree?

How is this any different than the formula for pressure?

How will you physically bring them closer together in a real experiment

By moving them?

In the real world however it's never going to get get close to infinity and will always be much close to 1 atmosphere than to infinity.

Of course you won't get close to infinity, you can't get "close to infinity". The math describes an ideal situation with point charges or impossibly flat and parallel surfaces.

Any real number is closer to 1 than it is to infinity, thanks for describing infinity.

You completely ignore the *physics* part of this debate......again! In a real world, there are real limitation, and your mathematical models are only useful approximations with various physical limits imposed by the sizes of atoms, etc. I'm going to skip the redundant stuff.

Yes I agree.

However the math describes the RELATIONSHIP. Just because the size of atoms gets in the way at some level, or you can never actually move things infinitely apart, doesn't mean the relationship is invalid.

So, back to the dodged question. What do you think happens to the pressure as the distance between the plates goes to zero, if the distance is in the denominator? In an ideal situation with impossibly flat and impossibly parallel and impossibly close plates?

You previously said you agreed with the wiki page on the Casimir effect, do you now disagree with the derived formula?

If you disagree with the derived formula, at which point does the derivation go wrong in your opinion? In the initial calculation of the standing waves?

Each of the fragments has (already possess) kinetic energy and even more energy that is stored inside the mass.

Agreed, nothing I said contradicts that.

That internal energy can be released again should it happen to collide with any other particle of it's antimattter/matter counterpart. Matter *is* energy.

Agreed, mass is energy. And both mass and energy bend space creating negative energy.

Any form of remaining matter is still a form of energy and it can be released by further and further matter/antimatter annihilation.

Sure, or the kinetic energy could be transferred, or get turned back into potential energy, or any number of other things.

Do you agree that no matter what form it's taking, matter or energy, it's all going to be bending space? More of it bends it more, less of it bends it less.

 

[Reality Check]

If the plates are moving away from one another then there is more "force" pushing on the inside of the plates than there is force pushing on the outside of the plates. If the reverse it true, then there is more force applied on the outside of the plates than inside the plates. Those blue arrows in the Casimir image are accurate. There is more force being applied to the outside surface of the plates than inside of the plates and therefore the plates are pushed together (from the outside).

The plates need not move at all. The pressure is there whether the plates move or are held in place.

Perhaps you should answer the simpler situation which ignores all of the Casimir stuff.

 

[Reality Check]

So......

Who among you still supports the ideas of:

A) Negative pressure in a vacuum?
B) A net zero energy state of the universe?

Me.
... and AFAIK the majority of scientists in the world.
... and every textbook that that I have read.
... and every popular science article that I have read.
... and Wikipedia (I know this is not a great citation MM)

 

[DeiRenDopa]

So......

Who among you still supports the ideas of:

A) Negative pressure in a vacuum?
B) A net zero energy state of the universe?

If I may, these need some editing, in order for them to be reasonably free of ambiguity and also phased more appropriately for this section of the JREF Forum.

A) Are there experimental results consistent with "negative pressure in a vacuum"?

B) Are there observations and experimental results consistent with "the observable universe has a net energy of zero"?

The answer to both questions would be yes, IMHO.

It is important to note several features of my edited version:

1) the statements are objectively, and independently, verifiable (it matters not one jot what MM, DRD, si, ... believes, supports, thinks, feels, ...)

2) the parts in quotation marks are only unambiguous wrt standard, contemporary, textbook definitions of the key terms "pressure", "vacuum", and "energy" (change the definition of any term and the statements will be different, and - very likely - ambiguous)

3) both statements assume full acceptance of the aspects of theories in modern physics consistent with every facet of every relevant observation and experiment (so, for example, take QED off the table and every modern experiment and astronomical observation needs to be re-analysed).

The last one (3) is a biggie, and probably has wide ramifications for much of what you have posted in this thread MM.

 

[sol invictus]

If there was no matter in the early universe, how could there be heat?

Energy has mass, so would create gravity no?

I'm not sure anyone answered this, so I'll take a crack at it.

When people say there was no matter in the early universe, what they mean is that the energies were so high that no matter in any ordinary form could exist. There was lots of radiation, and lots of very fast moving elementary particles (which you might want to call "matter" - it's a matter of taste ). If you were to stick a chunk of, say, iron in there, it would vaporize almost instantaneously into a cloud of very energetic photons, quarks, electrons, gluons, etc.

That might make it difficult to measure the temperature with a thermometer, but there's no difficulty in defining it. Recall that temperature in a gas is a measure of the average kinetic energy of the molecules. In a very hot state like the early universe, the same definition applies - high temperature means high average kinetic energy for the particles (and high frequency for massless particles like photons and gluons).

And yes, all that energy couples to gravity (gravity acts on all forms of energy, democratically).

As for this issue of net zero energy: let me emphasize several points. First, "energy" is a term with a specific mathematical definition. Namely, it's the conserved charge ("conserved" means doesn't change with time, "charge" means a quantity associated with a symmetry) for time translation invariance (which is a symmetry of the laws of physics).

In general relativity, one can define total energy is a very specific way, which is roughly analogous to defining total electric charge via the integral form of Gauss' law - with the integral carried out over a sphere at infinity (the charge inside a sphere of finite radius is not conserved, since charge can flow in and out). The GR result is not always zero (for the same reason it isn't in Gauss' law), but can be both non-zero and conserved only if there is a spatial infinity that lets the gravitational flux escape. In other words, there's a negative energy sink at infinity that precisely cancels the total positive energy inside the sphere - think of Gauss' law for charge and you'll see what I mean).

In a closed universe, the energy is strictly zero, because the "sphere at infinity" actually has zero size, and so there's nowhere for the flux to escape. But closed universes can have plenty of matter and energy in them, can be hot, etc. Ergo, the gravitational contribution to the total energy is negative definite - which is no surprise at all, as the same thing is true in Newtonian gravity.

In a flat or open universe I don't know a good way to define a conserved, non-zero energy (because no matter how big the sphere is there is always energy flowing in or out).

 

[Michael Mozina]

Me.

Gah! How can you *still* believe in negative pressure in a vacuum?

... and AFAIK the majority of scientists in the world.

Nah. The folks that wrote the WIKI article and created the images on the Casimir effect got it right. This negative pressure in a vacuum is almost exclusive limited to your group. Most scientists I meet seem to have a better grasp of QM than this crew.

... and every textbook that that I have read.

What textbook *besides on related to Lambda-CDM theory* claims that a vacuum contains "negative pressure".

... and Wikipedia (I know this is not a great citation MM)

Actually, in the case of the Casimir article, the WIKI presentation was correct. Only your crew seems to be incapable of distinguishing between a QM "force" and pressure and not being able to recognize that there is *force* on both sides of the plates.

 

[Ziggurat]

I can personally experience the effect of gravity on my body. How is that "unscientific"?

People "personally experience" alien abduction too. Furthermore, much of science is based on things which can not be "personally experienced".

Conceptually speaking I hear you, there is a conceptual difference in these two approaches to explaining gravity.

No: there is a physical difference between the two.

From a "qualification" perspective however it doesn't matter if either mathematical model is the "ultimate truth" or the last word on gravity.

But it does matter whether or not space is curved, even if GR isn't correct in its description of curvature. Either space is curved or it isn't. This is a physical difference, not simply a conceptual difference.

What matters is that gravity isn't shy around a lab

Curvature sure as hell is.

Would an apple fall to Earth in curved space according to Einstein's theory?

Would a cut heal after rubbing it with a crystal? That the answer is "yes" doesn't indicate that the crystal had anything to do with it. That apples fall doesn't mean curved space has anything to do with it.