Galaxies and Dark Energy

[Karlos]

The universe is expanding, that we do know.

Galaxies are moving futher apart when they should be staying together (Or close).

We use the term Dark Energy for the force acting on the galaxies moving them apart eventually pushing them into isolation. But what if the expansion of the universe is not happening from the perimeter as we might assume but rather throughout the universe space is expanding? This might explain why the galaxies are moving apart from this seemingly dark force, when actually the space inbetween them is expanding and placing more distance between them.

Any thoughts or any corrections are welcome

Karl Wilkins

[meteoriot]

The Space between IS expanding. Stretching like an inflated balloon. The galaxies are not traveling 'through' space but are along for the ride as space itself expands. Like if you drew dots on the balloon.

I've heard the dark energy idea too however I don't know how it effects the expansion. Maybe it is the force behind it, as the expansion of 'space' is getting faster. The more distant galaxies are travelling faster than nearer ones.

[Earl]

The Space between IS expanding. Stretching like an inflated balloon. The galaxies are not traveling 'through' space but are along for the ride as space itself expands. Like if you drew dots on the balloon.

I've heard the dark energy idea too however I don't know how it effects the expansion. Maybe it is the force behind it, as the expansion of 'space' is getting faster. The more distant galaxies are travelling faster than nearer ones.

Objects are also moving in space, for example M31 is getting closer to us even though the space is expanding between us

[Stephen]

Objects are also moving in space, for example M31 is getting closer to us even though the space is expanding between us

It's coming straight for us!!!

Reason being is it's just close enough for gravity to be able to do that quicker than the expansion of the space time between the two galaxies.

AFAIK dark energy is the evil so and so that's thought to be causing the expansion / acceleration.

[Karlos]

The Space between IS expanding. Stretching like an inflated balloon. The galaxies are not traveling 'through' space but are along for the ride as space itself expands. Like if you drew dots on the balloon.

I've heard the dark energy idea too however I don't know how it effects the expansion. Maybe it is the force behind it, as the expansion of 'space' is getting faster. The more distant galaxies are travelling faster than nearer ones.

I guess Dark energy at the moment is just the name for the unknown variable that controls the expansion, but what really intrigues me, is the pictures of the universe showing it to be full of dark voids and almost veins of galaxies where they seem to exist together along these lines. The expansion certainly doesn't look regular by any means! I mean in the sense that unlike a balloon as it is inflated, expanding evenly and retaining original shape, surely this isn't the case in the universe as the bigger pictures seem to show "deposits", almost orderly lines of universes.

[meteoriot]

I guess Dark energy at the moment is just the name for the unknown variable that controls the expansion, but what really intrigues me, is the pictures of the universe showing it to be full of dark voids and almost veins of galaxies where they seem to exist together along these lines. The expansion certainly doesn't look regular by any means! I mean in the sense that unlike a balloon as it is inflated, expanding evenly and retaining original shape, surely this isn't the case in the universe as the bigger pictures seem to show "deposits", almost orderly lines of universes.

I love the picture I believe you are referring too. 'the cosmic web'

I know what your saying, some people believe that the 'filaments' and condensed areas of galaxies are held together by 'dark matter' which is yet another mystery. The universe was apparently 'uneven' from the beginning some areas denser than others, wether this is the reason for the cosmic web or if it formed that way due to gravity I do not know but if you look at good detailed pics of the 'crab nebula' you can see similar structure just on a smaller scale. I hope to learn more, keep me posted

[Karlos]

I love the picture I believe you are referring too. 'the cosmic web'

I know what your saying, some people believe that the 'filaments' and condensed areas of galaxies are held together by 'dark matter' which is yet another mystery. The universe was apparently 'uneven' from the beginning some areas denser than others, wether this is the reason for the cosmic web or if it formed that way due to gravity I do not know but if you look at good detailed pics of the 'crab nebula' you can see similar structure just on a smaller scale. I hope to learn more, keep me posted

Yes, absolutely, everytime I see it I get shivers up my spine, just puts everything into perspective, what a weird place we exist in!

I completely agree with the way you compare it to the crab nebula, it literally is a mini version of the aftermath of the creation with its veins and voids. Maybe we should be paying extra attention to physics happening in the universe on smaller more manageable scales where we can make easier observations that could give us clues to the processes working on a bigger scale, ultimately if we can describe smaller systems we can eventually understand the bigger systems they exist within, and ultimately understand the whole picture.

I will keep looking out for stuff on this as I find it most interesting, I think we're in for a shock story as more unfolds

[Tsaprazi Eleni]

According to a scientifical approach, dark energy does not exist, as long as the dark matter concept is enough to explain our universe.

The dark energy is considered to be an ideal gravitational fluid of negative pressure, which accelerates the expansion of the universe. Dark matter is a kind of matter, which is observed through its gravitational effects on the surrounding visible celestial bodies. Our universe is a fluid without pressure. As a result, the motion of particles is explained by a geodesic frame.

Argument 1:The acceleration of gravity shall be reduced as we are moving away from the source of the tractive force. Based on experimental observation, the scientists have observed that, as the distance from the center of the Galaxy is increased, the acceleration of gravity is augmented.

Argument 2: The Pioneer space probe, when escaped the heliopause limit, was supposed to travel bigger distance than it actually did. This is to say that, a force was pulling it back.

Argument 3: This kind of cosmic energy which was explained by the dark energy, can be replaced by the internal energy of the universe.

Argument 4: The luminance of standard candles is being reduced, which means that the expansion of the universe is accelerated.

Argument 5: According to Zwicky, the cosmological structures at big scales, should have been demolished by their own gravity. However, something invisible seems to keep them together.

[Shibby]

I think the Pioneer effect is now generally believed to be due to more mundane reasons, such as something leaking from the probe.

Dark energy, as I understand it, is just a term used to describe the unknown cause of the acceleration. By some theories, this change in rate of expansion is more complex and not universal. Check out Inflation Theory.

[George Jones]

According to a scientifical approach, dark energy does not exist, as long as the dark matter concept is enough to explain our universe.

I am not sure what you mean.

The dark energy is considered to be an ideal gravitational fluid of negative pressure, which accelerates the expansion of the universe. Dark matter is a kind of matter, which is observed through its gravitational effects on the surrounding visible celestial bodies. Our universe is a fluid without pressure.

The matter component of our universe is modeled by a perfect fluid that has zero pressure (dust), but the radiation and vacuum components of our universe are modeled as perfect fluids that have pressure. The early universe was radiation-dominated, and it is important to take its positive pressure into account. According to Einstein's theory of gravity, positive pressure is a source of attractive gravity. The universe has now moved into a vacuum-dominated phase. According to Einstein's theory of gravity, negative pressure is a source of repulsive "gravity".

Argument 2: The Pioneer space probe, when escaped the heliopause limit, was supposed to travel bigger distance than it actually did. This is to say that, a force was pulling it back.

The Pioneer anomaly has been resolved,

[1103.5222] Modelling the reflective thermal contribution to the acceleration of the Pioneer spacecraft

[0912.2947] Does the Neptunian system of satellites challenge a gravitational origin for the Pioneer anomaly?.

Argument 3: This kind of cosmic energy which was explained by the dark energy, can be replaced by the internal energy of the universe.

Do you mean vacuum energy? Or something else?

Argument 4: The luminance of standard candles is being reduced, which means that the expansion of the universe is accelerated.

Yes.

Argument 5: According to Zwicky, the cosmological structures at big scales, should have been demolished by their own gravity. However, something invisible seems to keep them together.

Dark matter.

[meteoriot]

According to a scientifical approach, dark energy does not exist, as long as the dark matter concept is enough to explain our universe.

The dark energy is considered to be an ideal gravitational fluid of negative pressure, which accelerates the expansion of the universe. Dark matter is a kind of matter, which is observed through its gravitational effects on the surrounding visible celestial bodies. Our universe is a fluid without pressure. As a result, the motion of particles is explained by a geodesic frame.

Argument 1:The acceleration of gravity shall be reduced as we are moving away from the source of the tractive force. Based on experimental observation, the scientists have observed that, as the distance from the center of the Galaxy is increased, the acceleration of gravity is augmented.

Argument 2: The Pioneer space probe, when escaped the heliopause limit, was supposed to travel bigger distance than it actually did. This is to say that, a force was pulling it back.

Argument 3: This kind of cosmic energy which was explained by the dark energy, can be replaced by the internal energy of the universe.

Argument 4: The luminance of standard candles is being reduced, which means that the expansion of the universe is accelerated.

Argument 5: According to Zwicky, the cosmological structures at big scales, should have been demolished by their own gravity. However, something invisible seems to keep them together.

Argument for what exactly?

[Tsaprazi Eleni]

Replying to all the posts:

Arguments about the existance of dark matter, which indicate the lack of utility of the dark energy concept.

Everything I wrote above, comes from notes by an academic's lecture on conformal dynamical equivalence.

[meteoriot]

So are you suggesting dark matter exists but dark energy does not? I was and am still a little confused as to what the above is suggesting?

As far as I'm aware dark matter has gravity so like normal matter this would pull objects together and provides the additional mass required to hold galaxies together but like normal matter it should have it's counterpart... energy.

With normal matter and energy they are both the same thing in different forms. (e=mc2) so why if dark matter exists shouldn't it have an energy equivalent too?

There is an invisible outward force expanding the universe. This would require energy and as we can't observe it I thought thats why we named it dark energy?

[Tsaprazi Eleni]

So are you suggesting dark matter exists but dark energy does not? I was and am still a little confused as to what the above is suggesting?

I just quoted the arguments I heard in a lecture about the existence of dark matter and the non existence of dark energy.

As far as I'm aware dark matter has gravity so like normal matter this would pull objects together and provides the additional mass required to hold galaxies together but like normal matter it should have it's counterpart... energy. With normal matter and energy they are both the same thing in different forms. (e=mc2) so why if dark matter exists shouldn't it have an energy equivalent too?

Dark matter is inferred to exist from gravitational effects on visible matter. So, I suppose that this is the only kind of observed force between DM and normal matter, except the one which influences the experimental results on CMB intensity values. However, this is a good question, whose answer I'm looking forward to find.

There is an invisible outward force expanding the universe. This would require energy and as we can't observe it I thought thats why we named it dark energy?

By googling a term like: "Dark matter does not exist", I found some interesting views on new cosmological models, not requiring any kind of exotic energy.

Inspite of what I have mentioned above, this is just a new point of view. No one can have a reliable opinion, just by reffering to it. We can speak by facts, without being extremely open minded simultaneously. Let's say that we should check our sources. But I still think we can conversate on these arguments and combine the knowledge, so that we reach acommon conclusion.

[JulianO]

I think there are pretty good reasons to think dark matter exists. If I recall there are 4 separate lines of evidence showing its presence. Things like MOND can explain some of the observed DM observations, but not all.

Dark energy is the reason the galaxies in general are flying further apart faster. It is accelerating the expansion.

[meteoriot]

New method confirms dark energy...

http://www.bbc.co.uk/news/science-environment-13462926

[Adamski]

I watched a "The Universe" program last night all about what the biggest structure was in the universe, galaxies, galaxy clusters, super clusters, cosmic web and even the biggest void in the cosmic web. Unfortunately I fell asleep half way through so i missed the prognosis. will get back with that one.

[Tsaprazi Eleni]

Here is exactly what I was talking about. I am looking forward to hear your opinions and conversate on this topic.

A conventional approach to the dark-energy concept.pdf

[GazA]

im no physicist but is this dark energy just not weaking gravity? dont wish to sound ignorant but in laymens terms this is what it sounds like?

[Karlos]

Gaza, Its the force believed to be accelerating the expansion of the universe. (The link above posted by Meteoriot has information of it being confirmed)

As for dark matter, I believe this is what they hope to compensate for galaxies staying together despite speeds of objects within are moving faster than what the escape velocity should allow, in other words the known matter should not have enough gravity to hold the extremely fast moving objects in its gravitional "grasp". This dark matter would add upto to the right amount of total matter holding them together as we do see.