Bjarne on: Dark Energy, only an illusion.

[dafydd]

Ehr, yes we can. If Earth expands, either it gets heavier, or it gets less dense. Even if our meter also expanded, we could still observe this.

Also, you are claiming that space expands at different rates in different places. Such a phenomenon would be extremely easy to observe.



Perhaps. Then why exactly do you feel it is relevant what YOU believe or don't believe? After all, ALL your arguments so far has been merely beliefs and disbeliefs. So, by your own standard everything you have written up to now is irrelevant.

Hans

And wrong.

 

[Bjarne]

Bjarne
No
We would not be able to measure this when the yardstick expands too.
Hans
Ehr, yes we can. If Earth expands, either it gets heavier, or it gets less dense. Even if our meter also expanded, we could still observe this.

No everything would look the same.
Acceleration due to gravity would also be the same; a meter would just be relative “longer” than now but still a meter. A kilo weight would just be the double the size but still one kilo. The distance to the centre of the Earth would still be 6354 km. Nothing would seem to have “change” also not weight since weight depend on distance, and distance are still the same, just "blown up a bit"

Perhaps. Then why exactly do you feel it is relevant what YOU believe or don't believe? After all, ALL your arguments so far has been merely beliefs and disbeliefs. So, by your own standard everything you have written up to now is irrelevant

You could say the same about the must of that what you call science and what in the end of the day only are believes. .
I am not satisfied only to believe, what I am saying is possible to prove.
Shortly it is possible to prove whether the curvature of space is the exact same property than expanding spaced.

If so this will change a lot;

• The perspective from where we try to understand the relation between gravity and dark energy.
• What dark matter really is.
• What causes gravity,
• and a lot more.

I can't comment on those parts of the discussion to do with cosmology, but I can say quite definitively that the idea of subduction is not speculation

Where is the evidence?

Also remember that, while these lines of evidence support the mechanism of accommodation of plate convergence by subduction, tectonic uplift due to convergence is evidenced by the folded and faulted crust that constitutes the Earth's great mountain chains. Such structures simply could not form on a planet whose crust experiences only tension on a large scale.

In or near Denmark there are no subduction zones, but we have earthquakes too.
Why do you think ?
I believe this is why the crust is all the time re-curving, - simply because this makes sense.

Here is how you get mountains (and earthquakes)
http://www.youtube.com/watch?v=qe-Rsbl_NIA&feature=related

http://www.youtube.com/watch?v=J8tsuZde7rU&feature=related

Subduction is superstition, this is a desperate invention, only reflecting that we MUST (pretend that we) understand what happens we can not accept the simply and painful truth - that we don't know....
Gravity prove B “should” have proven it, still there is no news, - no proves.
Is that not bad news do you think?
I think it is good news, we do not need more science fiction, but just really to understand we live in a expanding universe, that off course not accepts any limits, - because there are no limits, except in our fantasy, - that the Earth is unique, - and a exception...

 

[dafydd]

I think it is good news, we do not need more science fiction, but just really to understand we live in a expanding universe, that off course not accepts any limits, - because there are no limits, except in our my fantasy, - that the Earth is unique, - and a exception...

Fixed that for you.

 

[Cosmic Roy]

Where is the evidence?

Bjarne, that sentence of mine that you quoted so selectively came immediately before a short description of the evidence. I will say it again here: not only can tectonic motion itself be observed directly, but subducting slabs can be imaged within the mantle by seismic tomography and earthquake focal mechanism studies.

Allow me to expand on that. Seismic tomography allows one to image the deep Earth by analysis of seismic wave speeds. Slabs of lithosphere which have been subducted into the mantle are revealed by this method, since they have different seismic properties to their surroundings. A quick search on Google Scholar will be a good place to start if you're interested.

Another method by which subducting lithospheric slabs can be imaged is in analysis of the earthquakes which occur within them. The depth of subduction-related earthquakes, and their distance from the surface trace of the subduction zone, plot the course of the sinking slab. Furthermore, the variation of earthquake focal mechanisms throughout the slab is just as one would expect in such a situation.

In or near Denmark there are no subduction zones, but we have earthquakes too.
Why do you think ?

You seem to have misunderstood me. I did not claim that subduction zones are the only source of seismicity. I do not know much about the tectonics of Denmark, but I would guess that earthquakes there might be caused by isostatic readjustment of the crust since the removal of the ice sheets.

Here is how you get mountains (and earthquakes)
http://www.youtube.com/watch?v=qe-Rsbl_NIA&feature=related

http://www.youtube.com/watch?v=J8tsuZde7rU&feature=related

Bjarne, these are incredibly unscholarly references to cite in support of your argument. In the video that focuses on India and the Himalayas, for example, the narrator asks "how can an island uproot itself from the ocean floor [and] seemingly float across the ocean?" This is such an elementary misunderstanding that I can scarcely believe it's not a deliberate misrepresentation; I don't know which paints the maker of the video in a worse light. Is this the quality of evidence that you really intended to bring to this discussion?

In the same video it is claimed that the plain of India to the south of the Himalayas was stretched. This is a claim that is falsified by the reverse faulting which characterises the southern edge of the Himalayan arc. If mountain ranges were built by the adjustment of continental plates to a greater radius of curvature, then compressional structures at the surface would be mirrored by extensional structures at the base of the lithosphere, and the thickness across the plates would be conserved. This is the opposite of what is revealed to us by seismic and gravimetric studies. Furthermore, if the expansion of the Earth is accommodated at the surface by creation of new oceanic crust around relatively undeformed continents, reverse faulting in the flexing continents would be expected to occur at their centres and not their margins. Can the theory you support explain crustal shortening in the Andes?

One of the videos shows the deformation of North America, with Hudson Bay appearing to grow like a rifting ocean basin. This situation, if it were reality, would be easily provable by the detection of extensional faults and active rifting perpendicular to the axis of extension (appearing to be east-west in the video). Do I need to tell you that this idea conflicts with reality?

Subduction is superstition, this is a desperate invention, only reflecting that we MUST (pretend that we) understand what happens we can not accept the simply and painful truth - that we don't know....
Gravity prove B “should” have proven it, still there is no news, - no proves.
Is that not bad news do you think?

What relationship do you think Gravity Probe B has to plate tectonics? I was not aware of a link.

 

[Bjarne]

Slabs of lithosphere which have been subducted into the mantle are revealed by this method

Re-curving of the crust would do the same.

 

[Cosmic Roy]

Re-curving of the crust would do the same.

I would be very pleased to know how.

 

[Reality Check]

Re-curving of the crust would do the same.

What is "re-curving" of the crust?
This sounds like you are now changing your idea regurgitated from the cartoonist Neal Adams and others to an new one of your own involving an expanding and contractng Earth.

However I suggest that you do not derail your own thread which is about your ideas about dark energy. Why not start yet another thread in which you can display your extensive knowledge of science and mathematics?

 

[RussDill]

It isn't true Russ. The real cranks are the people who dismiss Einstein along with the obvious evidence and the crushingly simple logic, because they believe that they know better. They don't. Take a look at http://en.wikipedia.org/wiki/Crank_(person) and pay careful attention to this bit:

No argument or evidence can ever be sufficient to make a crank abandon his belief.

Scary, isn't it?

OK, then try this, stop mentioning scientists by name and stop quoting them. Instead, refer only to relevant theories and experiments that support or negate them.

 

[Brian-M]

Take a look at http://en.wikipedia.org/wiki/Crank_(person) and pay careful attention to this bit:

No argument or evidence can ever be sufficient to make a crank abandon his belief.

Scary, isn't it?

Actually, it sounds exactly like religion to me.

 

[Brian-M]

Space is more as math. For exsample: does space have 2 properties:

• Curvature
• Expansive

or are these properties two the same ?.
This is a BIG and important question.

In that case the "BIG and important" answer is NO, the curvature of space is not the same thing as the expansion of space.

For example:

1. We know that the sizes of galaxies are proportional to the size of black holes, but not why.
2. We know almost nothing why galaxies have black holes.
3. We know nothing about why galaxies form.
4. Our model of how solar system form is cracking (more and more).
5. Nobody has ever seen dark matter nobody knows what it is. (PLEASE don’t try to convince me that it exists).

1. Could it be because larger galaxies have more matter with which to form larger black holes?
2. I thought it had something to do with vast amounts of matter coalescing into a relatively small space.
3. Gravity. It tends to hold draw together, but angular momentum tends to prevent everything from collapsing into the center. Where's the problem?
4. Alternatively, it would be equally true to say that our understanding of how the solar system formed is improving, more and more.
5. Personally, I'm not entirely convinced that dark matter/energy is anything more than an artifact of our standard models. So I have no problem with the purpose of this thread in claiming that Dark Matter is "only an illusion" (I did mention MOND earlier). But I do have a problem with all the nonsense you're spouting to support this claim.

I don’t agree.
Lets say that curvature of space = stretching space, then you would be forces to change that opinion right ?

While we're at it, we may as well say that PI = 3 and that light is made up of electrons. Then you'd be forced to change your opinion on other matters of physics, right?

Let me ask you the question, why do you think times somewhere runs slower ?
I believe this is only possible because distances are different from place to place.

Because if you count the rate at which certain subatomic atoms emit photons, or measure the life-span of short-lived subatomic particles, time demonstrably runs slower. It's also demonstrable that this is directly related to acceleration.

(I simply don’t believe there is force enough in inner convection to rise mountains.)

Argument from incredulity?

Think about that everything around you also you own body could tomorrow be the double so “big” – BUT you would not be able to measure it. – It could be 100 or 1000 times so big and still you would not discover anything.

You may not be able to measure it with your hypothetical yardstick because that too would have grown. But if distances are greater, then you would be able to measure it by observing the apparent diminishing of gravity and electromagnetic forces due to the inverse square law. Also, light & radio waves would be red-shifted proportional to distance from the source, so you could measure the rate of expansion of the earth with carefully calibrated radio transmitters and receivers placed in different locations.

Nothing would seem to have “change” also not weight since weight depend on distance, and distance are still the same, just "blown up a bit"

Wait... if distance is the same, then in what sense has anything expanded or grown? You're babbling nonsense.

Subduction is superstition, this is a desperate invention, only reflecting that we MUST (pretend that we) understand what happens we can not accept the simply and painful truth - that we don't know....

Funny... for a superstition it has an awful lot of empirical evidence to support it. (See here.)

 

[PixyMisa]

No everything would look the same.
Acceleration due to gravity would also be the same; a meter would just be relative “longer” than now but still a meter. A kilo weight would just be the double the size but still one kilo. The distance to the centre of the Earth would still be 6354 km. Nothing would seem to have “change” also not weight since weight depend on distance, and distance are still the same, just "blown up a bit"

WRONG.

You didn't read the article. Read the article.

 

[Vorpal]

Think it through Tubby, step by step. Start with a large region of "empty" space. This space has its vacuum energy, and whilst there are random fluctuations, it's fairly evenly distributed. Now mentally divide the space into cubes, and fill the central cube with matter. Since E=mc² your energy distribution is no longer uniform.

Outside the cube, it is uniform in the sense that the stress-energy tensor is the same everywhere.

This results in a gravitational field in the surrounding cubes. So what then is the energy density of these surrounding cubes? See The Foundation of the General Theory of Relativity and look at page 185 where Einstein says "the energy of the gravitational field shall act gravitatively in the same way as any other kind of energy". What that means is that there's a higher energy density in those surrounding cubes than in the original empty space.

Gravitational energy density has no consistent local meaning in GTR, and in any case, the Einstein field equation makes no reference to it (or if you interpret Einstein's statement above as saying that gravitation is nonlinear, automatically incorporates it).

If you could plot energy density from one side to the other, it rises as you approach the centre, then peaks very high where the matter is, then diminishes as you move away.

In your setup, it's plotting the energy density component of the stress-energy tensor along an axis through the center of the filled cube gives a sharp square wave.

Look at one of those surrounding cubes, consider it to be a "system", and remember that mass is a measure of a system's energy content. It has a mass-equivalence, and "the energy of the gravitational field shall act gravitatively in the same way as any other kind of energy". That's your dark matter.

No--that gravitational energy itself gravitates just forces gravity to be nonlinear. That's already true without this pseudo-DM step.

 

[Tubbythin]

Look at one of those surrounding cubes, consider it to be a "system", and remember that mass is a measure of a system's energy content. It has a mass-equivalence, and "the energy of the gravitational field shall act gravitatively in the same way as any other kind of energy". That's your dark matter. It's down to inhomogeneous space, caused by the expanding universe as per the raisins-in-the-cake analogy - a galaxy is surrounded by a halo of inhomogeneous space. That's why CDMS can't find those WIMPs.

Err.... what?

 

[Brian-M]

WRONG.

You didn't read the article. Read the article.

Actually, the article is not relevant to what he's saying. Re-read the section of his post you quoted very carefully. He's actually saying that even though everything is bigger, everything is still the same size...

I don't think he's taken the time to examine the logic of what he's saying.

 

[Rainer]

Bjarne-

This might help.

http://www.astro.ucla.edu/~wright/cosmology_faq.html#SS

http://arxiv.org/abs/astro-ph/0104349

 

[sol invictus]

This results in a gravitational field in the surrounding cubes. So what then is the energy density of these surrounding cubes? See The Foundation of the General Theory of Relativity and look at page 185 where Einstein says "the energy of the gravitational field shall act gravitatively in the same way as any other kind of energy". What that means is that there's a higher energy density in those surrounding cubes than in the original empty space.

Completely wrong. To the extent that gravitational self-energy can be defined at all, it's negative.

Look at one of those surrounding cubes, consider it to be a "system", and remember that mass is a measure of a system's energy content. It has a mass-equivalence, and "the energy of the gravitational field shall act gravitatively in the same way as any other kind of energy". That's your dark matter.

That's all sorts of wrong. First off, that energy is negative, and dark matter has positive energy. Second, it's far, far, far, far too small to be dark matter even if it had the right sign. We know exactly how big the effect you're talking about - it's just the non-linear part of Einstein gravity - and it's just way too small. Third, it redshifts with expansion in completely the wrong way to be dark matter. Fourth, it wouldn't explain galactic rotation curves, because it falls off with distance also in completely the wrong way. Fifth, it's wildly inconsistent with the CMB, BBN, etc.

Shall I go on? There's more.

 

[PixyMisa]

Actually, the article is not relevant to what he's saying. Re-read the section of his post you quoted very carefully. He's actually saying that even though everything is bigger, everything is still the same size...

Yeah, it depends on how meaningless his point is.

If he's saying that everything is exactly as before, but twice as big, then it's just self-contradictory.

If he's saying that by some metric everything is twice as big, then by that same metric the inverse-square and square-cube laws come into play, and the change would be painfully obvious (to the point that we'd all be dead).

I don't think he's taken the time to examine the logic of what he's saying.

Precisely. It's the retreat to unfalsifiability caught in mid-flight where it's entirely nonsensical.

 

[Cosmic Roy]

What is "re-curving" of the crust?
This sounds like you are now changing your idea regurgitated from the cartoonist Neal Adams and others to an new one of your own involving an expanding and contractng Earth.

However I suggest that you do not derail your own thread which is about your ideas about dark energy. Why not start yet another thread in which you can display your extensive knowledge of science and mathematics?

I appreciate that you want to keep the discussion on topic, but it seems to me that Bjarne outght to know himself what his own thread is about. If he considers a supposedly expanding Earth to be an important enough line of evidence to reference in his opening post and a couple of times since, then I don't see why it should be excluded. If an expanding Earth would be evidence for Bjarne's ideas about dark energy and gravity, then the fact that the Earth is not expanding has significance to the discussion.

As for the 're-curving' of the crust, I believe Bjarne means that as the continents adjust to a larger radius of curvature (since expansion is supposedly expressed at the surface by creation of oceanic crust), compressional forces act at the continents' centres. Although it is wrong, this idea at least makes more sense than the explanation given in the video that Bjarne linked to, whereby continental mountain ranges apparently form by crustal thinning and subsidence at the centre.

 

[Fredrik]

It makes plenty of sense. The expansion of the universe is so small that it's not measurable over distance the size of a solar system, and is relatively minor over the size of a galaxy. It's only over the truly vast distances of intergalactic distances that the cumulative effect of the expansion adds up to something huge. No problem.

That's actually not the issue here. The expansion of space in the solar system is expected to be many orders of magnitude less than what a naive application of Hubble's law would predict.

Also, if everything had been expanding according to Hubble's law (or more precisely, as described by the solutions of Einstein's equation that describe the large-scale behavior of our universe) then even the redshift from distant galaxies would be unobservable, because our measuring devices would be expanding too.

Here's how I would explain these things:

All the solutions of Einstein's equations that we can write down explicitly describe very idealized situations. For example, the Schwarzschild solution that we use to describe spacetime near a star, actually describes a universe that's completely empty except for a single star with zero rotation, zero electric charge, and perfect spherical symmetry. The FLRW solutions that we use to make predictions about the large-scale behavior of our universe (e.g. the cosmological expansion) actually describe universes in which at any time t, matter is distributed with the same density ρ(t) everywhere.

The universe we actually live in isn't like that at all. Not on small scales anyway. There's a chair under you, but you're not surrounded by an equal amount of chair in all directions. Most of the matter in the solar system is in the sun, and even the space you're occupying has a much higher density than the space between planets. So there is no reason to expect that the FLRW solutions, which are based on the assumption that the universe is homogeneous and isotropic, should describe spacetime accurately in the solar system.

So what is spacetime actually like in the solar system. My best guess is "very much like a Schwarzschild solution and very little like a FLRW solution". I expect that some tiny part of the cosmological expansion will be present even at solar system scales, but it has to be really small.

Note that since Einstein's equation isn't a linear differential equation, we can't just add the Schwarzschild solution to a FLRW solution to get a solution that describes a universe that contains a homogeneous and isotropic distribution of matter and a single star on top of that, but maybe it makes sense to do that as a first order approximation.

 

[Reality Check]

For example think about; where is the “border” in space, - between where space expands and not expands.

Something seems to be totally wrong.

A point about the OP and this statement: There is no “border” in space.
Bjarne,
You seem to have a misconception that may stem from the expanding balloon analogy to expanding space-time. The analogy is a good illustration for students since they can see the expansion. They see the surface of the balloon getting further out from its center. They see objects on the surface getting further apart.

What is often not emphasized and what you have missed is that the proper point to observe the expanding balloon analogy is as an inhabitant of the surface, not as a observer outside of the balloon universe. That inhabitant sees that objects in their entire 2D space (the balloon surface) move apart with time, i.e. in 3D space-time.

We see the same thing happening in our 4D space-time. All of space-time is expanding. There is no "border" between expanding and non-expanding parts. The reason that we do not notice this expansion locally is that gravity from local objects dominates over expansion on scales smaller than galaxies, EM forces dominate on atomic scales and nuclear forces dominate on nuclear scales.