Dark Energy and Gravity are one, and neither are actual forces.

a reply to: JohanikaDeVries

the way i see it, you suggest that dark energy is negative gravity, being a counter-force to it - or rather, the same thing but on the opposite side of the spectrum. lack of movement cancels dark energy, movement cancels gravity, hence the universe exists in a state of perpetual balance between both.

Dark darker darkest....


In physical cosmology and astronomy, dark energy is an unknown form of energy which is hypothesized to permeate all of space,

And what if redshift != distance hypothesized again.

Mathematical models generating mathematical models....

Now deduce the workings for the GTA 6 render engine from a mathematical model... Would be easy , the physical universe is far more complex.

So it is theorized that there is a tyre pushing things around and keeping the outer edges of galaxies there.

I fixed it for you with the underlined word, you can thank me later.

In a manner of speaking, OP you are describing an analogy of what the current state of play is, but without actually understanding what is happening on 'small scale', and getting your pull directions sort of wrong. The other thing is that, Dark energy is not a force, and dark matter is not a force... So yes a little confused.

Firstly, Dark is a catch all word used in particle physics and cosmology to mean unknown/unobserved. There are lots of misconceptions about it and what is thought to be 'expected'. Me saying they are not forces is because, even in the current state of play, Dark matter is considered matter... that such follows regular physics laws and causes a gravitational attractive force. Dark energy is exactly that, it is thought to be a vacuum energy related to the fabric of spacetime. It appears as though it is a force, but fundamentally it isn't a force.

The comment earlier

originally posted by: Willtell
Great topic.

The crux of the matter is them finding out the universe has been speeding up rather than, as they supposed, slowing down.
Only some kind of DARK undetected ENERGY can be responsible for this.

Is a vast misquoting of what the article says, or maybe the content is wrong. Scientists have never expected to know what the universe is doing... the cosmological models always gave 3 options, open, flat, closed. They were always the options and expectation would be, if all is going to play nice and not cause any issues would be flat or closed.

Open is where the universe expands and continues to expand and begin accelerating
Flat is where the universe expands and eventually stops in a stable configuration
Closed is where the universe expands and eventually stops and contracts.

There was no preference, though most people would say, as i said above, that flat or closed appear more 'natural' but, the universe doesn't care what we think to be normal or not.


So lets briefly look at the evidence and the kinds of things that a model MUST be able to reproduce.

Dark Matter - from small to large scales
1) Spiral galaxies exhibit rapid rotation in their disks.
- Standard gravitational models and observed light curves suggest that the rotation of stars and gas around a galactic core should fall off the further you go out. What is instead observed is a flattening of the rotation speed, meaning that the gas and stars on the outer edge of a galaxy, cannot be bound without there being more mass present. Not only this but the mass present also cannot be confined just to the disk, such as unobserved mass from red dwarfs, brown dwarfs etc. The models that fit, show the most likely distribution of mass is in a sphere or halo in which the galaxy rotates.

This behaviour is almost universal

2) Dark Galaxies. There are clusters of stars in diffuse systems rotating in what looks like galaxies although don't have nearly the regular amount of stars you might expect, but still have rapid rotation.

3) Gravitational lensing of galaxy clusters produces matter distributions that show galaxies have large matter fall off that far extends outside of the optical counter part, seeming to back up 1. Clusters also typically show that galaxies move around each other in a manner that would mean that clusters should not form and all galaxies should be basically freely moving.

4) Optical mass vs velocity mass show a huge difference in clusters, some of it can be the measurement itself undercounting mass (Definitely true in the case of optical) but the velocity mass doesn't really lie all that much. Basically if you 'weigh' a galaxy from how bright it is and how distant it is, and then look at how it is bulk moving within the host cluster and environment... they move too fast.


So for Dark matter, thats roughly what you are dealing with.

For dark energy it is mostly the observation of non linear (flat), non decelerating (closed) redshift with increasing distance as stated in the previous article. That is literally it there are little to no more observables, hence it being somewhat of an enigma.

Any model saying it to be manifestation of the same thing... force or not, has to have a model that produces all of the above. OP... id on't believe yours does at all. Yes it paints a pretty picture in the mind, but its not fully even correct.

a reply to: JohanikaDeVries

The pebbles which are relatively close will draw toward each other trying to escape the center point due to Centrafugal effect. This is gravity.

Gravity and Centrifugal forces are not the same thing.
Centrifugal force is inertia, the resistance to acceleration, and this makes it a “fictitious force”. The real force is centripetal, or ‘center seeking’, and the resistance to this acceleration is what we call centrifugal force.
Gravity is related to mass, not rotation. It is not changed by acceleration or direction until we get near light speed which is another topic.

Centrifugal effect is caused by inertia: An object in motion keeps moving at the same speed in the same direction unless a force acts on it. Everything on the rotating Earth tries to keep moving in a straight line and fly off into Space. The force of gravity continuously changes this direction of motion, making objects move in circles around Earth's rotation axis.

Source

Your title got my attention. “Dark Energy and Gravity are one, and neither are actual forces.”
Gravity, like centrifugal force, is considered a fictitious force so it is not a real force. However, define “dark energy”. Is it gravitational in nature and therefore considered a fictitious force also or is it electromagnetic and a real force or perhaps something different altogether. Or perhaps it doesn’t exist at all and it is a product, ad hoc, of our misunderstanding of the nature of the Universe.

I think people are misunderstanding. This is not Einstein theory, this is different. And no, gravity is not itself a force either.

a reply to: JohanikaDeVries
Me being a simple soul, a very simple soul ,explain this. The Earth, which is the tyre, is rotating and humans are the stones. How come we are not flying off away from the centre of force?

a reply to: chr0naut

The issue that caused science to consider dark matter and dark energy is that galaxies are rotating but they should be flinging out stars from the outer arms. Instead, the outer arms are chugging around at great velocity with nothing to hold them in place.

The theories behind dark matter and dark energy were ad hoc to discrepancies observed that contradicted what we know about astrophysics.
Dark matter was used to explain the problem with an observed lack of galactic rotational curve.
Wiki
The farther a star is form the center of a galaxy the slower it should be rotating which is represented in the dashed line on that image. Yet what is observed is everything rotating at the same rate, the upper line denoting observations, which implies an unknown force.

In my opinion the theory of dark matter does not satisfy the violation of the inverse square law nor how the amount of dark matter increases as it gets farther from the galactic center in such a way as to balance the rotation curve, keep it flat. There is an unknown force here at work and I don't think it's dark matter.

Dark energy was used to help explain the increase in the expansion of space against gravity as observed in the Hubble redshift of light of distant galaxies. There is some controversial evidence that the Hubble is not a constant and there may be some intrinsic value that is unknown. Or 'H' is constant and the Universe is expanding faster than the speed of light which somehow is not a violation of relativity.

a reply to: crayzeed

No, the tyre is the fabric of the universe. Earth is one pebble, the moon is another pebble. Both pebbles are inside the tyre, but on the inner surface. The tyre rotates rapido, and the pebbles are phlushed into the rubber deforming the tyre surface. The conical shape causes the pebbles to push together, but one moves past for a reason, trapped in the deformed pocket it go around in circles. Looks like the generic ball on rubber sheet (bad) analogy for Relativity, but works differently.

originally posted by: JohanikaDeVries
And no, gravity is not itself a force either.

Gravity is considered a fictitious force but that does not mean all fictitious forces, like centrifugal force, are the same.

originally posted by: Devino
In my opinion the theory of dark matter does not satisfy the violation of the inverse square law nor how the amount of dark matter increases as it gets farther from the galactic center in such a way as to balance the rotation curve, keep it flat. There is an unknown force here at work and I don't think it's dark matter.

Then your opinion is without looking at the model or understanding what is going on. On the dark matter model, you might actually want to read about what it actually is and the structure it takes in relation to a galaxy before you write it off as you do. It is pretty easy to imagine a very very simple geometrical structure filled with a almost flat density of 'unknown matter' which will completely flattern and give you what is observed.

Its a matter of considering a 3D volume of a 'halo' vs a 2D disk in terms of a matter distribution. There is simply no evidence of an unknown force except an unknown presence of non luminous non interacting matter when you look at the actual evidence.

a reply to: Devino

I am stating that Centrafugal effect in extradimensional (outside the three you can understand) pressing three dimensional matter into a four dimensional membrain due to a characteristict like inertia warps thay four dimensional membrain causing matter to interact with other groups of matter on the curved surface. Einstein was not totally wrong, just ran out of time working on it. Then scientists locked the theories down as if it was the Torah, not letting it have anything added to it.

Added, Dark Matter exists, but is jot related to dark energy, which I what I was talking about and irrelevant to this. It operates within spacetime similar to matter, just not reacting with much else.

I would like your opinion on my idea; I posted it on reddit back in march:

I propose that gravity reverses and becomes repulsive at approximately 1.5 million light years. It becomes more and more strongly repulsive, reaches a peak, and then decreases trailing off to zero.

This does away both with dark matter and also dark energy. It would explain why most galaxies are accelerating away from each other – leaving no need for cosmological expansion or dark energy.

It also explains gravitational rotational rates without the need of dark matter. Galaxies are pushing dust and gas into the interstitial space between galaxies. This dust and gas means that each galaxy or small galaxy cluster is surrounded by a womb of material at a distance that repulsive gravity operates. This repulsive womb, along with the pressure from other galaxies, holds outer stars in place, explaining higher than expected rotation.
You may read the justification for this theory here, along with responses to objections at the bottom:
www.reddit.com...
I think that General Relativity can be adjusted such that we keep time dilation, BUT ditch curved or dilated space. I.e. we should work with flat, 3D , Euclidean space + time dilation. I explain about this in the notes at the bottom of the article.

i am going to be needing new tires soon, thanks for reminding me.... gonna cost me the universe !

a reply to: ErosA433

When you say it isn’t a force can you extrapolate on that

a reply to: ErosA433

Then your opinion is without looking at the model or understanding what is going on.

Well then, perhaps you could to enlighten me on "what is going on".

On the dark matter model, you might actually want to read about what it actually is and the structure it takes in relation to a galaxy before you write it off as you do.

I have read about it. I fail to see how it adequately explains the lack of galactic rotation curve. Perhaps you could help here as well. What evidence has been found that dark matter exists outside of the observed problem I just mentioned? How much money and time has been spent attempting to find dark matter and what have the results been? I need more than an ad hoc theory before I am convinced so until then I remain skeptical.

It is pretty easy to imagine a very very simple geometrical structure filled with a almost flat density of 'unknown matter' which will completely flattern and give you what is observed.

Sure, I have a vivid imagination and can imagine all sorts of things but this is science and I need evidence before I am convinced. Until then I think we should spend time looking for alternatives.

a reply to: JohanikaDeVries

Added, Dark Matter exists, but is jot related to dark energy, which I what I was talking about and irrelevant to this.

Dark matter is a theory that was created to try and explain an observed problem. We do not know if it actually exists or not. If you think gravity is the only force that shapes galaxies then dark matter must be it, right?

a reply to: Devino

Dark Matter is not matter and not dark or light. It's more closely related to the ancient idea of an aether. But Einsteins theory is closer calling it a fabric. We know it as a membrane.

a reply to: Devino

There is a plethora of observational evidence, which you appear to reject or wish to ignore on based upon what you have said here. If you have read about the subject you are making commenting on, you would know it already and not require an extra explanation. So It is not my duty to educate you, though i can try and explain some of the observations and why they are compelling and are accepted as evidence. To reject them, you are in affect flying in the face of nearly a century of research.

1930s Fritz Zwicky made observations of the Coma cluster, a huge cluster of galaxies and applied the Virial Theorem, this is a theorem that the gravitational potential energy equals the kenetic energy of the system if it is gravitationally bound. It is like saying, the average velocity of the objects in a system that is abound is related to the amount of mass... this is pretty simple and is simple gravitation.

So Zwicky observed the velocities of the galaxies of the cluster and such calculated the total mass of the cluster. He then went ahead and observed the luminosity of the cluster, there exists a relationship based upon stellar classes, temperature and luminosity, he counted the clusters and summed the Luminous mass. The ratio of the two numbers came out at a factor of about 500.

There are a few assumptions in place on these measurements, such as when measuring the velocity we only see the radial velocity. However again due to experimentation and simulation the velocities remain too high if the cluster is to be stable and bound by the observed luminous material.
Since the measurement was made, other methods have been used to measure the mass of the cluster, better galactic models, including dim objects such as brown dwarfs, blackholes and degenerate stars, relativistic considerations, observations of hot gas (muti-spectral mapping) brings the ratio down to about 100, but that still says, there is a large amount of mass in which is unobserved. IF the cluster is bound.

this was the first evidence of the issue...

Roll on to the 1970s, new instruments at the time allowed the mapping of velocities in gas within the milky way and nearby galaxies.

Vera Rubin and Ford used such new instruments to look at M21, They looked at gas bound within M21 and measured the velocity. Plotting this they get a flat rotation curve out to great extended distance, even in gas located in the far edge of the galaxy beyond the optical edge (large star concentration)

This is troubling as in a spiral galaxy, the most simple model predicts a linear increase in the velocity as you go from the centre to the edge of the bulge. This is expected from a test mass being gravitationally bound to a sphere on its inside of some density of material x. Once you get to the edge of the bulge, the stars form a thin disk, while not a pure 2D disk, it is a fairly good simplification. The test mass velocity in this case falls as a rate of 1/sqrt r This is from standard gravitational consideration and the model is the same for a 2D disk also.

So it clearly follows that, in order to maintain a stable galaxy rotation with the profile observed, there is a matter distribution that is not observed which provides the gravitation to maintain the orbital velocities.

An elegant solution to this is to have a galaxy sit within a spherical halo of so called dark matter. The density profile of this sphere is similar to that of the bulge, in which it is more dense in the centre, forming a clump and less dense as you move to the outside edge as might be natural for a gravitationally bound system. The mass distribution set up in this manner, does in fallow you to match the rotation curves observed without fine tuning of the density profile to a high degree. It simply works to the zero order. To get it to work better, we can then consider profiles with different densities and drop offs, but typically it is not required.

The link shows such a model example.


If thus follows that, IF we stipulate dark matter exists, we can fix the rotation curves to match expectation in a very simple manner... Occam's razor style