Dark Energy

[sigurdV]

Reading a thread on Dark Matter, Dark Energy was mentioned and it struck me that I remember no

attempt to explain it! Theres many suggestions on what dark matter might be made of,

but conjectures on Dark Energy is to my knowledge nowhere to be found.

 

Reckless fool that I am (and provoked by JMJones0424) I dont hesitate to tread into new territory,

so here is an explanation of where the Mysterious Dark Energy comes from:

 

Our universe rotates and is producing a centrifugal force known as the Dark Energy!

Now a conjecture exists and your job is to refute and replace it :rant:

[coldcreation]

[snip]

Our universe rotates and is producing a centrifugal force known as the Dark Energy!

Now a conjecture exists and your job is to refute and replace it

 

Actually you have it backwards. It is your job to refute the mainstream view of dark energy, namely, that a negative pressure, cosmological constant or quintessence is causing the universe to expand at an accelerated rate (good luck with that), and replace it it with the conjecture that the universe rotates and is producing a centrifugal force.

 

The current view of dark energy is based on observational evidence that suggests accelerated expansion.

 

What observational evidence suggests the universe is rotating (good luck with this one too)?

 

 

 

CC

[sigurdV]

Good! So to three already existing conjectures I added a fourth. Not so bad huh?

 

But, no , its not my job to refute the other conjectures , I just wanted to focus some light on the question of what the dark energy really is and now we have four conjectures to consider:

 

1 Negative pressure

2 Cosmological constant

3 Quintessence

4 Centrifugal effect of universal rotation

 

Should I be content with the thought that Dark Energy "obviously" cannot be an effect of Rotation since instead it surely is either an effect of Negative pressure , effect of the cosmological constant or an effect of Quintessence?

 

I am waiting for a refutation like: Whatever is causing our universe to expand at an accelerated rate cannot be an effect of our universe rotating so and so because of this and that.

 

Meanwhile it would be nice to know more on why we cant decide between the tree mainstream alternatives referred to above...

[JMJones0424]

I am waiting for an answer like: What is causing our universe to expand at an accelerated rate cannot be an effect of our universe rotating so and so because of this and that.

 

I'll take an uneducated stab. If the observed accelerated expansion were due to a centrifugal force caused by the rotation of the universe, we should expect to see things that we don't observe. There is no plane of expansion perpendicular to an axis of rotation, instead, we observe accelerated expansion in all directions. Likewise, since centrifugal force is inversely proportional to the distance from the axis of rotation, we should expect to see anisotropy in the rate of expansion which we do not observe. Finally, since centrifugal force is directly proportional to mass, we should expect to see a correlation between not only redshift and distance, but also redshift and mass, which we do not.

 

I referenced the GSU HyperPhysics entry on centrifugal force in the dark matter thread which spawned this conversation, but because I value that site so much as a reference and because it explains centripetal acceleration and centrifugal force so plainly, I'll link to it here again.

[sigurdV]

And ill try a last defence

 

The universe might rotate in every point and in all its space dimensions, and (hopefully) this takes care of your first objections

 

But the point on mass and redshift worries me...

 

Id better restate my conjecture as a question:

Is there a way for the universe to rotate so as to get dark energy as a consequence?

 

And You make me think the answer is: No!

 

Good work there warrior :)

[JMJones0424]

I think Id better restate my conjecture as a question: Is there a way for the universe to rotate so as to get dark energy as a consequence?

 

No, even if you devise a way to rotate in every direction, centrifugal force is F=mv²/r

 

We do not observe a correlation between mass and redshift.

We do not observe a redshift anisotropy away from the origin of rotation.

 

Therefore, rotation cannot be the cause of accelerated expansion.

 

This of course does not rule out that the universe rotates, only that the effect that we observe (from which we infer dark energy) can not be caused by rotation.

[sigurdV]

This was fun :)

Thanks for taking my question seriously.

[JMJones0424]

Don't be too quick to thank me :)

 

I wonder if I haven't made a critical error in my argument.

 

F=ma

F=mv²/r

 

ma=mv²/r

 

mass is irrelevant?

 

So, unless we get input from a more qualified person, let's throw that out. I think we're better off sticking with the fact that 1)there's no observed rotational plane and that 2)the observed acceleration increases with distance, where centrifugal force decreases with distance.

 

For 1) to fit observations, we need a. )the universe to rotate in all three coordinate axes, and we need b. )to be at the center of rotation.

 

b. ) Is problematic on philosophical grounds.

a. ) Not sure that this is possible? EX: Gyroscope. Anyone have better thoughts?

[sigurdV]

Heh! I thank you for seriously thinking on the same problem as I do.

 

Take your time, hunting for truth has first priority.

 

Meanwhile: How real is the danger that the dark energy eventually will rip everything apart, i read somewhere that not even quarks will be safe in the end. If so, maybe i see a way to save the universe :)

 

Hello! did you say that centrifugal force is decreasing with distance? Are you sure? Isnt the force weakest at the center?

And getting stronger the further out you go?

 

Are you saying that my "last defence" actually worked?

I shouldnt worry about mass and redshift?!

 

This discussion is becoming a thriller!

 

About point b : Since there is no single center point to the universe then if it can rotate it must rotate around every point!

 

About point a : After looking at quantum theory i am careful

with claiming impossibilities.

 

Now only point 2 remains, it seems...

[JMJones0424]

Ack.

 

0----------A----------B

 

Assuming rotational speed is constant and to make it easy, let's say 1 revolution per second.

 

a=v²/r

 

v=pi(2r)/s

 

a=4pi²r/s²

 

Doesn't look like I'm doing well today. While centrifugal force is inversely proportional to radius, it is proportional to the square of velocity, which is proportional to radius.

 

 

 

So we're down to one big complaint, that there is no observed rotational plane. I'm not sure that I follow you on the universe rotating around every point. In the example above, A and B rotate around 0. How can the universe rotate around all points?

 

Also, does the observed redshift increase with distance in the same way as centrifugal force does? I am about to head to work and will need to find some actual data to check that, so I'll need to get back to this later.

[sigurdV]

Some things cannot be visualised! (Compare quantum mechanics)

Then we must rely on logic. If the universe CAN rotate then it cant do it around its non existing center point!

What other possibility is then left than rotating around every point?

 

You go to work and I go to sleep :)

As I said :This discussion has been a THRILLER!

Ill be back in some 13 hours , and hopefully theres no new TWIST!

BTW did you think about the Dark force eventually destroying our universe?

I think that can be avoided provided we produce enough gravity to counteract it.

Perhaps we can seed intergalactic space with life multiplying exponentially...

Sapping energy using the casimir effect.And turning energy into matter.So my thinking here seems to end in a good note :) CYA!

[coldcreation]

The idea that the universe may be rotating has been around for a while. Here are some recommended texts on the topic:

 

Gödel metric

The Gödel metric is an exact solution of the Einstein field equations in which the stress-energy tensor contains two terms, the first representing the matter density of a homogeneous distribution of swirling dust particles, and the second associated with a nonzero cosmological constant (see lambdavacuum solution). It is also known as the Gödel solution. [...]

 

Following Gödel, we can interpret the dust particles as galaxies, so that the Gödel solution becomes a cosmological model of a rotating universe. Besides rotating, this model exhibits no Hubble expansion, so it is not a realistic model of the universe in which we live, but can be taken as illustrating an alternative universe which would in principle be allowed by general relativity (if one admits the legitimacy of a nonzero cosmological constant). A less well known solution of Godel's exhibits both rotation and Hubble expansion, and has the other qualities of his first model, so Godel's model is really killed by the inconvenient observations that the universe is not rotating. [...]

 

Many other exact solutions which can be interpreted as cosmological models of rotating universes are known. See the book by Ryan and Shepley for some of these generalizations. (Ryan, M. P.; and Shepley, L. C. (1975). Homogeneous Relativistic Cosmologies. Princeton: Princeton University Press. ISBN 0-691-08153-0.)

 

 

 

Here's another:

 

Is the Universe Rotating?

 

Models of a rotating universe have been studied widely since Gödel, who showed an example that is consistent with General Relativity (GR). By now, the possibility of a rotating universe has been discussed comprehensively in the framework of some types of Bianchi’s models, such as Type V, VII and IX, and different approaches have been proposed to constrain the rotation. Recent discoveries of some non-Gaussian properties of the Cosmic Microwave Background Anisotropies (CMBA), such as the suppression of the quadrupole and the alignment of some multipoles draw attention to some Bianchi models with rotation. However, cosmological data, such as those of the CMBA, strongly prefer a homogeneous and isotropic model. Therefore, it is of interest to discuss the rotation of the universe as a perturbation of the Robertson-Walker metric, to constrain the rotating speed by cosmological data and to discuss whether it could be the origin of the non-Gaussian properties of the CMBA mentioned above.

 

 

CC

[JMJones0424]

While I try to regain some core body heat (repeatedly moving from warm, humid greenhouses to cold, windy walkways is a surefire way to bring on the chills), I am struck by a few realizations.

 

I did some googling about rotation of the universe and axes and hyperspheres. I have reached the point that I cannot distinguish between legitimate sources and woo, which is usually a good sign that I'm in over my head.

 

I gave up trying to determine if the universe could rotate around all points simultaneously. However, after some more time with HyperPhysics, the problems haven't ended yet for me regarding the dark energy = centrifugal force conjecture. The Hubble Parameter is given as a velocity, not acceleration. Redshift implies a velocity of 72 km/s per megaparsec (+/- 10%). Centrifugal force is an acceleration (increases every second, like gravity).

 

In other words, redshift is linear, centrifugal force is curved. Square peg and round hole. I need to know the change of the Hubble Parameter over time, but I really don't know what that'll prove anyway. If I concede rotation without an observable axis due to ignorance, then the rate of rotation hardly matters anymore. I was hoping to be able to determine what the rate of rotation must be and compare that to the limits observed through other means, but I must throw in the towel for now until either something clicks in my head after more reading or someone throws me a lifeline.

 

In short, "I am waiting for a refutation like: Whatever is causing our universe to expand at an accelerated rate cannot be an effect of our universe rotating so and so because of this and that." All I've done so far is remove my objections :)

[sigurdV]

You have done a great job! I have difficulties in assimilating it. The tecnical level is too high for me, but your mental actions are very interesting. Alas, Im more a visionary than a technician :(

 

So far 2 persons have commented my idea and in both cases Ive been asked for reasons to believe

that our universe is rotating... Before I got the idea that dark energy is a consequense of universal rotation I harboured no such suspicion, the only thing pointing towards a rotating universe is if dark energy consistently CAN be explained that way!

 

Still i think that soon my conjecture will be proven wrong, since a rotating universe surely needs an environment to rotate IN !

Hi there Multiverse :)

[Qfwfq]

OK guys, try this: In any flat and euclidean space with an even number of dimensions, [imath]\mathbb{R}^{2n}[/imath], it is indeed possible to have rotations around a point. Also, a rotation around one point can be composed with a translation to form a rotation around another point, so it doesn't really make a difference which point is the centre.

 

It seems though it would be a mighty concidence to have linearity of velocity with distance.

[sigurdV]

Excuse me folks but my head is spinning :wacko:

To my utter astonishment the Dark Energy = Centrifugal Force Conjecture has survived some 15 entries... This is ridiculous! The mainstream conjectures must have been backed up by really heavy thinkers, and how plausible is it they missed such an obvious cause as centrifugal force?

 

The refutation must exist out there somewhwhere!

[Qfwfq]

...they missed such an obvious cause as centrifugal force?

Obvious? How obvious is a way to explain linearity in distance, as well as the lack of an rotation axis when there are three (an odd number of) spatial dimensions?