Jump to content

Talk:Dark energy/Archive 1

Page contents not supported in other languages.
From Wikipedia, the free encyclopedia
Archive 1Archive 2Archive 3→Archive 5

Article content duplicated from press release

Much of this article has been adapted from a press release at http://hubblesite.org/newscenter/newsdesk/archive/releases/2004/12/text/

This appears to be OK from a copyright point of view, as the press release appears to be in the public domain, but we should a) give credit to the source, b) rewrite in a style suited to an encyclopedia article. -- The Anome 18:27, 22 Feb 2004 (UTC)

Yes. I agree. Perl 18:30, 22 Feb 2004 (UTC)

new content

Someone added the following content which reads very poorly, and seems POV, but may be possible to work in more coherently. --zandperl 01:41, 18 Mar 2004 (UTC)

In cosmology, dark energy The concept of dark energy is more-so concerning quantum physics than astronomy. However, it is part of the study of the nature of the universe and thus does form a branch of astronomy. Dark energy is even more of a mysterious subject than dark matter. Dark energy was first proposed by Albert Einstein to explain the phenomenon of galactic acceleration. He claimed that the force behind the unexplained acceleration was dark energy. Dark energy is termed to be thee force directly opposite gravity. For in reality thee galactic expansion should be slowed by gravity rather than sped up. The form of dark energy is disputed. Einstein called the form he theorized the “cosmological constant”. The cosmological constant is represented by the Greek letter lambda (Λ). Its formula is , where G=gravity, c=the speed of light, π=3.14…, and ρ=the energy density of the vacuum of space. Others who believe it has another function than what Einstein thought call the energy “quintessence” (Literally Meaning the “Fifth Element”).

Einstein’s version of the cosmological constant (which I will refer to as Λ) is extremely flawed, however. The Λ dark energy is said by him to form a balance with gravity creating a static or flat universe (model of the universe where there is a set limit to the size of the universe). However, if the universe even slightly expanded somehow, energy is released causing more expansion throwing off the balance. The same is true for contraction. Because of these circumstances Einstein said that his formulation of the Λ was “the biggest blunder” of his life. However, many physicists say it could be the greatest legacy of his life despite these problems. Quintessence is simply another theory on the mechanics of dark matter. There is much less information about this simply because it is a variable to the Λ where the dark energy will push the universe further and further out into the void for infinity. Thus, there may never be a new universe caused by a Big Crunch and then Big Bang in succession. is a hypothetical form of energy which permeates all of space and has negative pressure resulting in an effective "repulsive gravitational force". Dark energy may account for the accelerating universe as well as a significant portion of the mass in the universe. Two proposed forms of dark energy are the cosmological constant and quintessence, where the former is static and the latter is dynamic. Distinguishing between the two requires high precision measurements of the expansion of the universe to see how the speed of the expansion changes over time. Making such measurements is a topic of current research.

Why is it "energy"?

Dark energy and Dr Baez's article

[some older stuff and some retorical questions are sent to history pages; questions that might be real are responded to below]

What on earth do you mean with "real" energy? How is the energy contained in the zero-point fluctuations of quantum fields different from "real" energy, in your opinion? Bjoern 15:49, 3 Dec 2004 (UTC)

By "real" energy I meant energy that could be utilized in some practical way to do some "work". E.g. the heat energy contained in the air around us isn't "real" in this sense. So for us it is as good as non existent since it can't make the universe expanding (unless by some non physical mechanism like e.g. imagination). I'd rather discuss physics here so if you can describe a 'physical mechanism how this energy causes expansion we have something concrete to discuss (if you really want to discuss physics). Jim 18:14, 1 Jan 2005 (UTC)

Besides, you only allowed creation of energy from nothing in gravitation, not in particle physics.

If you did not notice: a quantum theory of gravity would unify the two.Bjoern 15:49, 3 Dec 2004 (UTC)
How? So far a quantum theory of gravity is only a job security program for those physicists who are too dumb to notice that "gravitational attractive force" is gone from physics since 1916, and so it can't be carried by "gravitons". And that GR is already a quantum theory because it deals only in wave functions (geometry) and not "gravitational attractive forces". It is rather a sad story (for those physicists) so it is the best not to mention it unless you want them to lose their jobs Jim

Explaining every unexplained phenomenon (like e.g. dark energy) with another unexplained phenomenon (like e.g. creation of energy from nothing) won't explain much, will it?

What, exactly, do you think is unexplained here? Bjoern 15:49, 3 Dec 2004 (UTC)
The accelerating expansion of the universe if treated as a real phenomenon. IMO it can be explained only as an apparent phenomenon (the way I described it for you already). Jim

Why couldn't the density of matter be smaller than the density of the vacuum energy???Bjoern 15:49, 3 Dec 2004 (UTC)

Because the sum of sets (density of matter) couldn't be smaller than any of them (density of the vacuum energy). Why isn't it obvious to you? Jim

Those measurment are not direct measurements of dark energy but (correct me if I'm wrong) only conclusions drawn from an assumption that dark energy causes accelerating expansion, by some so far unknown mechanism.

You are partly right, partly wrong. They are not direct measurements, agreed - but they do not all use the assumption that dark energy causes accelerating expansion. They simply consider models with different amount of matter and (dark) energy, and conclude that a model with a certain amount of dark energy (about 70% of the total energy density) fits the data best. Do you have a problem with such indirect determinations of parameters? If yes, hint: this is done in all of science, all the time.Bjoern 15:49, 3 Dec 2004 (UTC)
I don't have problem with the method. I dont' believe the result. Jim

If you happen to know a physical mechanism of this effect please provide.

Use the equations of General Relativity for the case of a homogeneous, isotropic universe (i.e. the Friedmann-Lemaitre equations) and insert for the equation of state that the energy density is minus the pressure. Look at the result which you obtain. Hint: acceleration. If you quibble that this is not a "physical mechanism", then you say essentially that you deny the ability of General Relativity to describe gravity.Bjoern 15:49, 3 Dec 2004 (UTC)
Yes. This is because GR (as you define it) is based on Riemannian geometry, and our physical spacetime can be described by this geometry only approximately (with accuracy to the Hubble redshift) because:
(conservation of energy) => (degenerate metric tensor) <=> (non Riemannian geometry).
Do you see any error in the above scheme? Jim

So far you proposed cosmological constant which is only a mathematical term

Err, I also pointed out the probable physical origin of the dark energy (which is described and quantified by that constant). Already forgotten?Bjoern 15:49, 3 Dec 2004 (UTC)

which purpose has been originally to prevent Einstein equation from predicting expansion of the universe.

Yes. So what?Bjoern 15:49, 3 Dec 2004 (UTC)
So if we assume that the value that Einstein predicted then is the real value of this constantthen we already have a stationary universe, and a lot of other stuff for astrophysicists to explain but not "dark energy" between them. Jim

There is also possible another assumption, namely that expansion (accelerating or otherwise) is an illusion and so what would be the dark energy according to this other assumption if it were true? Jim

Yes, this is obviously a possibility. But why should we consider this possibility as long as there is no evidence to back it up, as long as you are not even able to explain the actually observed redshift data?Bjoern 15:49, 3 Dec 2004 (UTC)
Leave it to astrophysicists and wait a little while. Jim 18:14, 1 Jan 2005 (UTC)

Problem of metaphysics in gravitation

Don't you remember that Einstein was wrong the first time about the deflection of light by half and had to correct his ideas after Edington's expedition proved him wrong (or I was mislead by some historian of science)? And that this was when he discoverd the curvature of space after he proposed gravitational time dilation, by which he explained all the Newtonian gravitation?

That would be indeed news to me. That makes no sense at all, since Eddington's expedition was 1919, whereas Einstein proposed GR in 1916, and IIRC in the same year Schwarzschild published the solution for a spherically symmetric system. So it would be very strange if Einstein did not include space curvature until after 1919!129.206.21.125 17:01, 3 Dec 2004 (UTC)
This time you are right and I'm wrong (it turns out that I was mislead by some historian of science:). I've just learned the supposedly true version from a radio talk show about Einstein: Einstein made an error by factor of 2 in his calculations. When the results came twice as big as his prediction he looked into his calculations, found his error, corrected it, and submitted a corrected version. So it was not an error of not predicting the curvature of space the first time but only an error in calculations, corrected immediately after the data came.
He explains in one of his popular texts why the angle has to be twice as big as Newtonian prediction. If you look hard you are bound to find it. I might have time earliest in July 2005 to look for it for you. Jim 19:40, 1 Jan 2005 (UTC)

Back to conservation of energy

There are several errors in your derivation. For starters, you might consider that it would apply to *any* acceleration, not just acceleration by gravity. Hence your calculation would show that a body does not gain energy when it is accelerated. Don't you think that that is a somehow weird result?

No.
Consider this: suddenly you start running along a street. All the houses around you accelerate with acceleration equal to yours with opposite sign. But there is nothing that forces you to assume that they gain energy. It may be simpler if you assume that it is you who gain the energy. So the result is that you see a lot of big accelerating houses that don't gain any energy. Weired? I don't think so. You just learned that all the movement is relative and you have a freedom of selecting your frame for defining kinetic energies.Jim

For a more direct error, you assert that half of the bending of the light comes from time dilation and the other half from the curvature of space. Where on earth did you get that strange idea from? You also mentioned that in some other places, and attributed this to Einstein himself. I would like you to give a reference where he says that (please not a popular science quote, but an actual calculation!)

They are in most (all?) textbooks on (relativistic) gravitation. Jim

And even more important is the error which I have explained several times now, but which you still fail to understand: The change in the mass is measured in the system of the *non-accelerated* observer. The change in the speed of light is measured in the system of the *accelerated* object. It simply makes no sense to use the changes of m and c in two different systems of reference in order to calculate the change in the energy of the object!!!

They are both made in frame of an earthbound observer, i.e. an accelerating observer. The free falling body is of course not accelerating but it surely looks like accelerating to the earthbound observerear, which might have confused you. So think about it again. Maybe if you refresh your classical mechanics it saves us a lot of unnecessary questions and answers. Jim

Also I notice that you keep ignoring my actual arguments, namely (1) the geodesic equation implies that something can be accelerated without a force acting on it,

True. See above. Jim

i.e. its kinetic energy can increases without a force acting on it,

True. See above. Jim

i.e. energy is not conserved,

False. The energy AND momentum is conserved in any frame. There is even something called "conservation of 4-momentum". Maybe we stop discussing this subject until you recall your mechanics course and I don't need to remind you about something you should master in your first semester. Jim

... and (2) the energy of a falling body can actually be measured (i.e. by letting it fall on a spring), and the actual measurement shows that its energy indeed *does* increase.Bjoern 15:12, 6 Dec 2004 (UTC)

True. But let to discuss it further after you learn some classical mechanics. Jim

What on earth has a change in the speed of light to do with light deflection at the sun?Bjoern 15:12, 6 Dec 2004 (UTC)

Elementary optics (did you ignore your optics course too?).
To bent a ray of light the speed of light has to be different on one side of the ray than on the other. The phenomenon is called refraction. Jim

The modern view in General Relativity is that light speed indeed does not change in gravitational fields - as measured by free-falling observers. It *does* change for observers who are *not* free-falling -

Yes. Jim

but we were discussing an object which *is* free-falling, if you did not notice.Bjoern 15:12, 6 Dec 2004 (UTC)

Yes but we are considering it in a frame of an earthbound observer and therefore one accelerating together with the earth surface. The one who is seeing the increase of kinetic energy of the free faling body. There is no increase of kinetic energy in a free falling frame so in this frame the conservation of energy is trivial. Jim

(2) People who are far more knowledgeable in GR than both you and I also disagree with you.Bjoern 15:12, 6 Dec 2004 (UTC)

Those people are mathematicians and so they aren't too fluent in mochanics, optics, etc. which they don't have any training in but instead they have a lot of prejudice absorbed from popular science and SF books. We should discuss physics rather than prejudices. Jim

[Einstein] would tell you that you have some strong misunderstandings about his theory. Have you ever read his paper on the application of Hamilton's principle in GR?

I didn't read this paper. And of course Einstein might not know all the consequences of his theory.
So you claim now that you understand GR better than Einstein himself? Man, you are really full of yourself.Bjoern 15:12, 6 Dec 2004 (UTC)
We should discuss physics rather than prejudises. Jim

If [Einstein] had nothing better to do he could predict Hubble redshift and explain it before it was discovered. Even Newton could predict it and explain it if he knew as much as any high school student in 20th century (as truly yours) knew. So if Einstein imagined gravitational energy it means only that he didn't have enough interest in gravitation to spend enough time on it to fix his ideas.

Einstein did not have enough interest in gravitation????? Say, do you ever realize how silly you make yourself look by continuing to write such stupid statements?Bjoern 15:12, 6 Dec 2004 (UTC)
Yes, especially to those who don't understand physics. Do you think I should care? Jim

But we have our own brains to think and don't need to stick to wrong ideas when we see that they are wrong. BTW, did Einstein explain conservation of energy in GR or he supported your idea that it is not conserved? Could you produce any quotes from Einstein's texts to demonstrate that he thought that energy is not conserved in GR? Jim 09:58, 1 Nov 2004 (UTC)

He said that energy is conserved - but only by using the concept of energy contained in the gravitational field, i.e. he said that any change in the energy of matter is accompanied with an opposite change in the energy of the field, so that the total energy change is zero. Since, according to you, the gravitational field does not exist, this leaves us obviously with non-conservation of energy.
The modern view agrees with you on the non-existence of a gravitational field. But in contrast to you, physicists have the intelligence to notice that this non-existence automatically implies the non-conservation of energy.Bjoern 15:12, 6 Dec 2004 (UTC)
Usually when the result of reasoning (non conservation of energy) conradicts a principle based on millions of facts (conservation of energy) one doesn't reject the principle but checks the reasoning first. This is what one should do first and only when one is absolutely sure of one's reasoning one designs an experiment that demonstrates the invalidity of the principle. You nor those physicists didn't seem to follow that road yet and so neither you nor those highly intelligent physicists don't have the reasonable basis for rejecting the principle (of conservation of energy). BTW I didn't meet in my school a single physicist who would believe that energy can be created from nothing. So apparently there is more then one school of thought in physics and we just represent different schools.Jim

... apparently you forgot that Newtonian gravitation was only replaced when (1) evidence accumulated that it could not explain and (2) a new theory was proposed which could not only explain this new evidence, but also all the old stuff which Newtonian gravitation already was able to explain. So far, you have neither of those two points.Bjoern 15:12, 6 Dec 2004 (UTC)

(1) enough evidence accumulated against Big Bang (if it has to introduce creation of energy from nothing to save itself and (2) there is Einsteinian gravitation which could not only explain this new evidence, but also all the old stuff which BB already was able to explain. So it looks that I passed your test. Jim

You have a rather convoluted view of science, I see. Obviously you would *like* science to be that way (because then you would have a better point for your apparent argument that scientists are simply to close-minded and senile to accept your ideas) - but this simply is not true in general. One central point you are missing is e.g. that usually when a new theory comes along, it *incorporates* the old one - the old one is still right as a limiting case of the new one. So your claim that the new people do not even know "the old crap" is simply nonsense. Best counterexample: Newtonian gravitation was replaced by GR, but nevertheless Newtonian gravitation is still taught and used in most applications - simply because it is a useful approximation to GR. I have pointed out this several times now - you keep ignoring this point.Bjoern 15:12, 6 Dec 2004 (UTC)

This is an interesting point and I'm not ignoring it. I already tried (unsuccessfully so far) to convince my physics professor to start his lectures with explanation where the gravitational force comes from and only then to start his lectures on classical mechanics so the future astrophysicists won't be conditioned into believing in reality of gravitational attraction. He promissed to consider the proposition but later decided against it. Being a particle physicist he may not know how to explain the reason for gravitational force in a way that first year physics students would understand it. I doubt whether particle physicists have enough training in Einsteinian gravitation to teach it. That's probably the reason why Newtonian gravitation stays around for such long time while it could be easily replaces by Einstienian one. With advantage of not needing to be replaced later by more exact version of gravitation. Not to mention advantage of teaching real physics instead of Newtonian magic. Jim

The big bang theory didn't manage yet to produce a single prediction that agreed with observations (source: Hawking, 2000, calling for turning BBT into science from pseudoscience, by measuring e.g. deceleration of expansion). Jim

Nice. How many scientists agree with Hawking on this strange statement? Bjoern 15:12, 6 Dec 2004 (UTC)
Probably none, especially now when it turned out that the expansion looks accelerating,
And how is Hawking, someone working in theoretical physics, qualified to judge if the *observational evidence* is sufficient or not?Bjoern 15:12, 6 Dec 2004 (UTC)
Not at all IMO. But for a different reason than his theoretical work. Jim

Reasons why we should think the universe is expanding

Bjoern: Reasons why we should think the universe is expanding (or, more precisely, why the current cosmological model is correct):

1) Nicely explains the observed redshift relation (as long as your model does not explain it, please don't answer this with "but a static universe could also explain this!")

If you insist ... Jim
Well, it is simply a fact that so far, you have not presented a metric which would explain the observed red shift data (remember the paper by Riess I mentioned?).Bjoern 15:04, 3 Dec 2004 (UTC)
BTW I just learned from my math professor that our spacetime isn't a metric space. Also that physicists assume much more then they understand. And they surely don't understand math. So now I have mixed feelings about the necessity of presenting metric. Results confirmed by observations seem to me sufficient. Jim

2) Nicely explains the observed Cosmic Microwave Background Radiation. Not only its existence, but also its homogenity, the scale and gaussianity of the fluctuations observed in it (ever heard the terms "power spectrum" and "acoustic peak"?), and that it changes its temperature with time.

Apparently you choose to ignore this.Bjoern 15:04, 3 Dec 2004 (UTC)

3) Nicely explains the observed abundance of light elements, and that there are less of them if we look at distant galaxies.

Apparently you choose to ignore this.Bjoern 15:04, 3 Dec 2004 (UTC)

4) Nicely explains where the large-scale structure we observe in the universe comes from. (quantitively)

I heard that this "large-scale structure" already turned out to be a myth. Astronomers stopped seeing it when observations improved. Similar to canals on Mars. Jim
You either misremember or misunderstood something. This is simply not true. If you think it is, please provide a reference.Bjoern 15:04, 3 Dec 2004 (UTC)
A ref is usually needed to show that something exists not that something doesn't exist (please provide a ref that Jabberwocky isn't an African animal).
What I said I heard last year (2004) at a seminar on cosmology, from a lecturer, an astronomer who were actively involved in such research. He apparently proved with a statistical analysis that there is no statistical evidence that there is any organized structure greater than a single galaxy and so even the expression "galaxy cluster" is just a reflexion of a subjective judgement. I might add from me that it is just like canals on Mars that all astronomers saw and even made maps of them. Now people have trouble to explain why it happened while there is nothing on Mars that even remotly resembles those structures. As I learned in my astronmy course psychologists explain this by a phenomenon of human brain creating structures wherever there is a slightest reason, real or imaginary. E.g. see abundance of religions and tell me which is them are true ones and which are like canals on Mars. Jim

5) Nicely explains why there seems to be an upper limit on the age of stars.

Apparently you choose to ignore this.Bjoern 15:04, 3 Dec 2004 (UTC)
I just don't have strenght to react to every silly statement. If you think for a while you guess why there has to be such a limit even in an eternal universe. It shouldn't take you more than 5 minutes so it is more effective if you solve such "problems" yourself.

6) Nicely explains why galaxies far away are in general much smaller and less "developed" than the ones we see in our neighbourhood.

Apparently you choose to ignore this.Bjoern 15:04, 3 Dec 2004 (UTC)

More?Bjoern 13:36, 8 Oct 2004 (UTC)

BTW, don't you think that *before* trying to construct an alternative cosmological model, one should first try to find out *why* the *current* cosmological model is accepted by most cosmologists?

No, because if the model uses magic (in form of creation of matter from nothing)
Just because something contradicts your everyday experience, it is not automatically "magic"!Bjoern 15:04, 3 Dec 2004 (UTC)
Of course not automatically. But if it is magic, and there is a simple, tested criterion that it is, and the test tells: "magic", it doesn't matter how this magic was created. Jim
to explain the real world then finding out why it is accepted by most cosmologists, or even the Pope, is a waste of time for someone who is looking for real explanations. Might be interesting for historians though. Jim 20:02, 26 Oct 2004 (UTC)
So you simply choose to ignore that essentially all people who have actually studied the theory and the evidence for it disagree with you?Bjoern 15:04, 3 Dec 2004 (UTC)
Yes, because it is not really "all people" (just "essentially" all peple). There is about 5% who don't belong to the crowd and can tell magic from science. And they happen to be on my side and I don't have time to argue with all the rest that use supernatural to "explain" the nature.
E.g. most of those bright people firmly believe in reality of "gravitational attraction" (in which AFAIK even you don't believe any more). Just read Weinberg's "Dreams of Final Theory" or Michio Kaku's "Beyond Einstein" or "Hyperspace" and explain whow they expect to "unify" gravitation with QM while they don't understand neither? Actually I can tell how because I read their books: they count on luck because despite their creativity they are already out of ideas. So supposedly gravity is going to be explained by either 10 or 26 dimensional hyperspace (details are not worked out yet but it can be only either 10 or 26). IMHO no amount of mathematical sophistication and creativity helps one in explaining the nature if one doesn't understand the real world. If one does, even partly, then one doesn't need to be bright or creative. One may just notice that e.g. gravitation has been already explained and apply the knowledge where others are still looking for solutions to non existent problems. Jim 18:06, 2 Jan 2005 (UTC)

Additionally, weren't at least *some* of the things I mentioned here also mentioned in at least some of all the books you've claimed to have read about GR and cosmology? E.g. Peebles (IIRC you said that you have read his book?) mentions several of these arguments, and adds yet another argument about the surface brightness of galaxies.129.206.21.125 11:51, 9 Oct 2004 (UTC)

But there are also many errors.
Example?Bjoern 15:04, 3 Dec 2004 (UTC)
Read the books, they hit you if you understand the gravitation, and if you don't (which might be the case) you won't agree on my examples. So why to waste time? Jim

So what to do about it? Educate Peebles on gravitation? Do you think it would work before I get my PhD in astrophysics? Jim 20:02, 26 Oct 2004 (UTC)

Do you *really* want to say that you understand General Relativity better than Peebles?
Yes, because it is so simple that once you understand it there is no place left for doubts. Do you doubt that the earth isn't flat? Why. Millions of people, some of them extremely bright and creative believed that it was. Why wouldn't you allow such an "alternative"? Jim

How can you be soooo sure that there is indeed such an alternative explanation?

Because Einsteinian gravitation is not an alternative explanation but the only explanation (do you know "alternative explanation" to the earth being roughly round? Is this rough roundness not the only explanation in your opinion?) Jim

Do you *really* think you are brighter, more creative or whatever than several generations of cosmologists, who have not managed to find such an explanation?Bjoern 15:04, 3 Dec 2004 (UTC)

It is interesting that it is just the opposite. One doesn't need to be brighter. One needs to know much less than they know beause only then one doesn't have their prejudicies.
When I showed that Hubble redshift can be explained in stationary space and numerical results are as observed (including accelerating expansion) I didn't know even the difference between special and general relativities. I just managed to understand the physics of gravitation. So what is all their mathematical sophistication good for if they don't see physics behind it? Its only useful purpose is to prevent them and others from seeing the real physics of gravitation that Einstein stated very simply almost 100 years ago and I learned in about a week. And it could be staded simply because physics is usually simple, only math makes it complicated. As a physicist you must know that. So I don't consider myself "brighter, more creative or whatever than several generations of cosmologists" just luckier that I'm not brighter, more creative or whatever than several generations of cosmologists". Jim

Oh, BTW, you can add as a seventh point the dependence of the surface brightness of galaxies on the redshift.Bjoern 12:04, 11 Oct 2004 (UTC)

What's so special about this dependence that it needs BBT? Jim
This is explained in Peebles, in his section on Tired Light models. Try looking it up.Bjoern 15:04, 3 Dec 2004 (UTC)
I'll do when I get my Peebles back (probably next week). Thanks. Jim 18:06, 2 Jan 2005 (UTC)

Reason why we shouldn't think that the universe is expanding

A good reason seems to be a fact that the hypothesis of expansion of space violates the principle of conservation of energy. The assumption of conservation of energy explains (through Einsteinian gravitation) only the illusion of expansion of the universe

No, it doesn't. As you yourself have admitted, you can't reproduce e.g. the actual redshift data from SN light curves (so far).Bjoern 15:08, 3 Dec 2004 (UTC)


and its acceleration and there is still a number of other phenomena waiting to be explained, yet it seems easier to explain all those other phenomena than to explain the required by the Big bang theory the mechanism of creation of energy from nothing every time the light travels through the universe. Creating energy in the light traveling through the universe is needed in Big bang theory at least to compensate for the energy lost to dynamical friction of photons that otherwise would decrease the real value of speed of expansion to about zero. Jim 19:35, 31 Oct 2004 (UTC)

You seem to be very deeply confused about quite a lot of things... But as I've seen in the past, it is simply of no avail to try correcting you.Bjoern 15:08, 3 Dec 2004 (UTC)

Equations

All the equations present on this page must be appropriately wikified.... having them in text is unreadable and not acceptable.17:02, 23 Feb 2005 (UTC)~~

I agree. I have moved the new content here. It is not clearly written, too technical and is more a discussion of the cosmological constant, or vacuum fluctuation problem than of dark energy.

[That shows how much you know. The point is that the dark energy is vacuum fluctuation energy of negative pressure.]

The material at the beginning is basically correct, but the two paragraphs at the end get a bit weird. --Joke137 18:08, 23 Feb 2005 (UTC)

The unwikified text was restored by 68.122.6.198. I have removed it. It may be a copyright violation -- it looks like it was lifted directly from a paper, and it certainly has no place in its current form. --Joke137 20:34, 23 Feb 2005 (UTC)

[NO IT'S NOT A COPYRIGHT VIOLATION AT ALL. IT'S ORIGINAL MATERIAL by a Ph.D. (UC) physicist. However, I now see how to make the equations properly, but that will take a lot of work. Getting the new ideas out there is more important than having equations Wikified, although that will be done in due course.]

Fine, but the wikipedia is no place for original ideas.

Are you connected with the official adminstration of Wikepedia? Or, is that your personal opinion? My foundation can easily cover the $75,000 Wikepedia is asking for, but if you are speaking officially for Wikepedia then we shall have to reconsider for sure. We thought Wikepedia was an open forum for competent publication - certainly in the section on "Speculation"? If you are going to be that reactionary as official policy then that is a failure of vision. :-)
It is the Wikipedia policy, not my policy. See policies and guidelines and especially original research. Wikipedia is not a forum for competent publication, it is an online encyclopedia, which is different from a free-for-all. --Joke137 22:30, 23 Feb 2005 (UTC)

You still did not give me a direct answer to my question. Are you part of the official Wikepedia or are you just an outsider? In the case of "dark energy" everything is speculative at this point. So if one sticks to rigid "no original ideas" not only does that make the Wikepedia boring and irrelevant but there should be no mention of dark energy at all. Clearly not a good position. Now I have already made a preliminary cash contribution to Wikepedia and I could cover the $75,000 but not if the staff of Wikepedia exercises repressive censorship like you have been doing. Capische?

Put them up on arXiv. The article on dark energy is meant to be a reasonably succinct overview of dark energy, not a place to communicate original, technical ideas. I won't rise to the "that shows how much you know" bait, except to say that there is already an article on the cosmological constant which is a more appropriate framework that this for explaining such ideas, rather than the general dark energy overview. By the way, wikipeda allows you to insert equations in TeX format: see the help pages. --Joke137 20:55, 23 Feb 2005 (UTC)

Fully agree with Joke137 and testify that it is Wikipedia policy. --Pjacobi 00:52, 2005 Feb 24 (UTC)

The removed version

"In cosmology, dark energy is a hypothetical form of energy which permeates all of space and has negative pressure. According to general relativity, the effect of such a negative pressure is qualitatively similar to having a force acting a large scales that works in opposition to gravity. Invoking such an effect is currently the most popular method for explaining the apparent observations of an accelerating universe as well as accounting for a significant portion of the missing mass in the universe." Wikepedia

The reason that negative pressure, if strong enough, causes a universal repulsive anti-gravity field is as follows. Einstein's field equation is

Guv = -(8piG/c^4)Tuv

Guv is the Einstein curvature tensor here has dimensions of (Area)^-1

Tuv is the stress-energy density tensor here has dimensions of Energy/Volume

The coupling coefficient (8piG/c^4) of the source Tuv to the 4D warped space-time geometry Guv has dimensions (Length/Energy) = (String Tension)^-1

To show the basic idea we consider the Galilean-Newtonian limit of Einstein's field equation where the curvature is weak and the speeds v of matter particles in Tuv obey v/c << 1. If we, further assume that Tuv is an isotropic fluid as is done in the standard cosmological FLRW model

TraceGuv = (8piG/c^4)TraceTuv = -(8piG/c^4)[T00 + T11 + T22 + T33] = (8piG/c^4)T00(1 + 3w)

T00 = energy density, T11 = T22 = T33 = isotropic pressure of the "fluid" medium warping the space-time geometry.

In Chapter 1 of John Peacock's "Cosmological Physics" one finds, in the Galilean-Newtonian limit

TraceGuv ~ c^-2 Laplacian (Grad^2) of the gravitational potential energy V per unit test particle at event P created by the source density Tuv at the same event P.

This is essentially the same as the Poisson equation of Newton's gravity theory with the additional Einstein correction of (1 + 3w) where w = (Pressure/Energy Density) of the source.

See Michael Turner's Op/Ed in Physics Today April 2003 for more details on this.

Ordinary cold matter (real on-mass-shell particles) has w ~ 0, which is precisely the assumed source in Newton's gravity theory!

Real photons, i.e. transverse polarized radiation has w = + 1/3. Therefore, (1 + 3w) = 2 for light. This is indeed the origin of the famous factor of 2 in the gravitational lens effect first found by Sir Arthur Eddington's expedition in 1919 that made Einstein a Super Star. Eddington's measurements were rough but recent measurements with new technology show that Einstein's theory is really correct, that factor of 2 for radiation is really there.

Now here comes the weird quantum stuff. It can be shown from Lorentz invariance of quantum field theory and Einstein's equivalence principle (EEP) that gravity and inertial forces in local non-inertial frames (LNIF) are indistinguishable, that the Heisenberg uncertainty "zero point energy" vacuum fluctuations for all fields obey w = -1. This is done in Peacock's book p. 26 and in Michael Turner's Op/Ed. Look again now at the "Poisson equation"

Grad^2V ~ -(8piG/c^2)T00(1 + 3w)

When w = 0 and the energy density is positive T00 > 0, we have Newtonian gravity with a universal attractive field.

Note the critical threshold w = -1/3 where (1 + 3w) = 0. Any source where -1 < w < -1/3 is called exotic matter because when T00 > 0 it causes a repulsive anti-gravity field. Kip Thorne and his students at Cal Tech showed that exotic matter would enable "traversable wormholes" (AKA "Star Gates') and perhaps permit time travel to the past. Kip debates this with Stephen Hawking and that is another story about the "chronology protection conjecture". Alcubierre showed that this same exotic matter permits faster-than-light weightless/geodesic warp drive without time dilation. The warp is globally faster than light, like in the inflation of the universe, although the "flying saucer" :-) is locally slower than light on a free float timelike geodesic inside its local invariant light cone. What is happening is that the space in front of the ship contracts whilst the space behind the ship expands. The Star Ship in Warp is literally surfing on this Vacuum Tsunami!

Now look at the zero point energy where w = -1. Zero point energy qualifies as "exotic matter"! The problem is that there is too much of it. That leads to the cosmological constant problem that naive quantum field theory predicts ~ 122 Powers of Ten (actual observed dark energy density). This is the greatest catastrophe in physics today. Not only that, but it is easily shown (Peter Milonni's "The Quantum Vacuum" that random incoherent virtual photons inside the vacuum have T00 > 0 with negative pressure causing repulsive anti-gravity exactly like "dark energy" (DE). However, random incoherent virtual electron-positron pair neutral ionized plasma inside the vacuum have T00 < 0 with positive pressure causing attractive gravity exactly like "dark matter" (DM). Wait a minute? Dark matter has w = 0, i.e. CDM. Jack Sarfatti has shown that compact sources of exotic vacuum with T00 < 0 and w = -1 look like w = 0 CDM at a distance in terms of the gravity lensing! Sarfatti also predicts that there are no neutralinos nor any other exotic real on-mass-shell particles that will make dark matter detectors "click with the right stuff" to explain Omega(DM) ~ 0.23. Note that Omega(DE) ~ 0.73 and total Omega ~ 1 consistent with the flat 3D space on large-scale of inflation theory. Sarfatti shows that cohering of the virtual electron-positron zero point false vacuum fluctuations causes inflation and creates the universe in the Big Bang along with Einstein's gravity and dark energy coming out of the phase and amplitude of the Higgs field respectively. Sarfatti has published these ideas in "Developments in Quantum Physics" ed. F. Columbus & V. Krasnoholovets (Nova Scientific Publishers, 2004 ISBN 1-5954-003-9) "Wheeler's World: It From Bit". He also discusses it in popular media in the two books "Destiny Matrix" and "Space-Time and Beyond II" both on Amazon, and in Paramount Pictures Star Trek IV DVD Special Collector's Edition Disk 2 "Time Travel: The Art of the Possible."

Subject: Sakharov, Russian Torsion Field Theory, Cartan's Forms & Metric Engineering W^3

Memorandum For The Record

The complete solution to Sakharov's "Metric Elasticity" 1967 problem for the emergence of gravity from zero point energy is given below. The competing program of Haisch, Puthoff and Rueda does not work as advertised by Eric Davis, Nick Cook, STAIF et-al.

"Einstein-Cartan theory extends general relativity to correctly handle spin angular momentum. There is a qualitative theoretical proof showing that general relativity must be extended to Einstein-Cartan theory when matter with spin is present. Experimental effects are too small to be observed at the present time." Wikepedia

That experimental effects of torsion fields are too small to be detected is controversial. Richard Hammond of the Department of Physics at the University in Fargo, North Dakota, US, then working on a US Navy contract, reported torsion radiation that is forbidden in some versions of torsion theory. Torsion radiation has also been reported by Akimov in Moscow based on a very controversial theory by Gennady Shipov. Akimov and Shipov have been harshly attacked by their Russian colleagues. However, it's much too soon to rush to premature judgment on the reality of torsion fields although the extraordinary claims by Akimov are suspect and cannot be taken on face value.

All the dynamical force fields of physics come from the principle of local gauge invariance. Start with a global symmetry group G of the action S of some dynamical system. Let L be a member of the Lie algebra generating G. The local action density is &S/&V^4. The unitary operator for a symmetry transformation is of the form U(L) = e^iL@/h, where @ is a global phase (constant over space-time region V4). Invariance of the dynamical action under the global symmetry is expressed by &S/&V^4 = U(L)^-1&S/&V^4U(L). The principle of local gauge invariance means allowing the phase @ to be an arbitrary function over space-time. The ordinary partial derivatives ,u need to be replaced by a gauge-covariant partial derivative ;u = ,u - Bu where Bu is the compensating gauge potential that is a new independent dynamical "force" field that restores the dynamically broken global symmetry to the extended action S' that now includes Bu. For example, if G = U(1) and the original source field is the Dirac field of the electron, then Bu -> Au the well-known "4-vector potential" of Maxwell's EM field theory. In terms of Cartan forms, the EM Maxwell field equations are simply F = dA, where d = exterior derivative, d^2 = 0, therefore, dF = 0 contains both Faraday's law of induction and no magnetic monopoles. Taking the Hodge-dual *F of F = "curvature", gives d*F = J which contains both Ampere's law and Gauss's law. The first equation dF = 0 is topological independent of arbitrary metrics. The second equation with the * operation is metric-dependent. The metric is a kind of covariant "aether" combining the Lorentz-Fitzgerald substratum dynamical hidden-variable model for the emergence of the Lorentz group O(1,3) with Einstein's phenomenological geometrodynamics. See also G.E. Volovik's book "The Universe in a Helium Drop" for details on the use of the renormalization group flow to a fixed point for the emergence of O(1,3) from a Galilean relativity substratum where Bohm's quantum potential acts instantly. The gauge force picture with Bu is dual to the geometrodynamic "Force-without-force" picture developed by John Archibald Wheeler. You can switch between them like going back and forth between the Schrodinger and Heisenberg pictures in quantum field theory. When G = U(1)xSU(2)xSU(3) on the parity-violating Dirac lepto-quarks we get the standard model of elementary particles in globally flat space-time without gravity prior to the Higgs-Goldstone spontaneous breaking of symmetry (SBS) for the SU(2) weak sector of the physical vacuum that allegedly should generate all the rest masses m of the lepto-quarks and weak bosons. See for example, "In search of symmetry lost" Frank Wilczek (Nobel Physics Prize 2004), NATURE, 433, 20 Jan. 2005. The model for the origin of rest inertia from friction in the sea of virtual transverse photons suggested by Haisch, Puthoff and Rueda has been rejected by experts as too simple and "not-even-wrong" in Wolfgang Pauli's sense (e.g. Space-Time and Beyond II by Jack Sarfatti, Author House (2002))

Einstein's 1916 General Relativity (GR) comes from locally gauging T4 the translation subgroup of the Poincare symmetry group of Einstein's 1905 Special Relativity (SR). The early version of this theory is in "Wheeler's World: It From Bit?" pp. 41-84, "Developments in Quantum Physics", F. Columbus, V. Krsnoholovets ed., Nova Science Publishers, 2004 ISBN 1-59454-003-9.

The compensating gauge potential Bu from locally gauging T4 is

Bu = (Goldstone Macro-Quantum World Hologram Coherent Phase of the SBS "multi-layered multi-colored" (Wilczek) Higgs Field),u = bu^aPa/h

{Pa} = mom-energy Lie algebra of T4 in tangent space indices a = 0,1,2,3,4

h = Planck's quantum of action

The local gauge transformations on Bu -> local GCT tensor Diff(4) transformations of Einstein's geometrodynamics.

bu^a is the non-trivial nonholonomic piece of the Einstein-Cartan tetrad eu^a, where u indices are in the warped base space of the tangent bundle of Einstein's GR.

eu^a = &u^a + bu^a

&u^a = trivial Kronecker delta holonomic tetrads of 1905 SR where the tangent space is degenerate with the base space. Local gauging of T4 removes the degenerary replacing global inertial frames (GIF) with local frames, both inertial non-rotating timelike Levi-Civita connection geodesic (LIF) and non-inertial off-geodesic (LNIF). Einstein's curved metric guv is only for the LNIF where the local equivalence principle (EEP) is

guv(LNIF) = eu^anab(LIF)eu^b

Note the linear elastic terms ~ bu^a&v^b and the nonlinear quadratic "plastic" (Hagen Kleinert) terms ~ bu^abv^b in the EEP. The latter are the spontaneous self-organizing couplings allowing the Wheeler geons of "Mass without mass" solutions of the non-exotic vacuum equation for the Ricci tensor

Ruv = 0

The Ricci rotation coefficients Au^b^c needed for the Riemann tidal stretch-squeeze curvature and for the dynamics of Dirac spinors on curved space-time are

Au^b^c = eu^aAa^b^c

Where, in 1916 GR without torsion fields, the Aa^b^c are constant global phases conjugate to Sbc the space-space rotation and space-time rotation (rapidity) boost Lie algebra of O(1,3) the local Lorentz group in the tangent vector fiber space. If we locally gauge O(1,3) as Gennady Shipov does and as Kibble and Utiyama did in the 1960's, then Aa^bc are arbitrary functions, the torsion field is then

Tu = eu^aAa^b^cSbc/h

The extended covariant derivative is then

Du = ;u - Tu = ,u - Bu - Tu

we then expect Einstein-Cartan field equations of the same Cartan form as Maxwell theory, ie.

R = DB

DR = D^2B = 0

Bianchi identities for local conservation of both curvature and torsion current densities (the key to practical metric engineering the fabric of space-time using the generalized Bohm-Aharonov-Josephson-Berry effect from the weak link/\ZPF ~ cosine(phase difference) between a real macro-quantum control system and the virtual physical macro-quantum coherent vacuum.

D*B = J

i.e., generalized Einstein field equations with both translational curvature and rotational torsion sources from exotic vacuum virtual (off-mass-shell) dark energy/matter sources as well as real (on-mass-shell) sources like rotating superconductors (e.g. Podkletnov/Ning Li - both highly controversial like Akimov's claims. See Marc Millis NASA BPP and STAIF Exotic Propulsion Proceedings of AIP).

D^2*B = DJ = 0

mutual transfer of source current densities to curvature and torsion current densities with total local conservation.

D = Dudx^u

B = Budx^u

John Archibald Wheeler calls these kinds of dynamics "The boundary of a boundary is zero."

R = DB is a boundary, but D*B is not a boundary.

Thanks to R. Kiehn for explaining Cartan's forms and to Art Wagner for telling me about an interesting paper from Brazil from Arcos and Pereira (gr-qc0501017).

end of removed stuff --Pjacobi 00:52, 2005 Feb 24 (UTC)

Retrieved from "https://en.wikipedia.org/w/index.php?title=Talk:Dark_energy/Archive_1&oldid=789369782"