Dark matter dark energy conundrum

[wallflash]

I have a question on these issues I have never seen addressed as a whole .

 

We believe in the probability of dark matter because the universe hasnt flown apart, but there isnt enough visible mass to account for the necessary gravity to prevent this. We believe in the probability of dark energy because something is driving the universe apart at an increasing rate, yet we cannot see this energy.

 

These seem almost like contradictory statements. We believe in DM because the universe HASNT flown apart, yet we believe in DE because the universe IS flying apart and eventually every galaxy will be too remote to see any other galaxy in the universe.

 

What is the solution to this? I suspect maybe that it has something to do with the universe should have already flown apart by now if this dark matter doesnt exist, so its a time frame issue, but I have never seen in anything I have read where the concepts of needing dark matter for sufficient gravity to prevent the universe flying apart and dark energy to explain the increasing expansion dealt with simultaneously as a whole.

 

An explanation for the scientifically interested but mathematically challenged laymen to understand would be appreciated.

[Airbrush]

wf: "We believe in DM because the universe HASNT flown apart, yet we believe in DE because the universe IS flying apart"

 

Not exactly. We believe in dark matter because the outer regions of galaxies rotate at nearly the same speed as the inner regions, and galaxy SUPERCLUSTERS do not fly apart, and gravitational lensing.

 

"Although dark matter has not been directly observed, its existence and properties are inferred from its gravitational effects such as the motions of visible matter, gravitational lensing, its influence on the universe's large-scale structure, on galaxies, and its effects in the cosmic microwave background​."

 

https://en.wikipedia.org/wiki/Dark_matter

 

We believe in dark energy because the expansion of the universe appears to be accelerating. Those are not contradictory.

Edited April 10, 2017 by Airbrush

[EdEarl]

An explanation for the scientifically interested but mathematically challenged laymen to understand would be appreciated.

There are hypothesis about the nature of dark matter and dark energy, but no one knows much about either. Thus, your question may not be answerable.

[imatfaal]

!

Moderator Note

 

Numerology Hijack hidden .

 

LaurieAG never introduce crap like that into a mainstream forum when a member has asked a straightforward question.

 

You have been warned. Do not respond to this moderation within the thread

 

[Strange]

There are hypothesis about the nature of dark matter and dark energy, but no one knows much about either. Thus, your question may not be answerable.

 

 

I think we know enough about the relevant effects to answer the question (I don't think I have anything to add to Airbrush's answer).

[goldglow]

 

 

We believe in dark matter because the outer regions of galaxies rotate at nearly the same speed as the inner regions, and galaxy SUPERCLUSTERS do not fly apart, and gravitational lensing

 

"Although dark matter has not been directly observed, its existence and properties are inferred from its gravitational effects such as the motions of visible matter, gravitational lensing, its influence on the universe's large-scale structure, on galaxies, and its effects in the cosmic microwave background​."

 

https://en.wikipedia.org/wiki/Dark_matter

 

We believe in dark energy because the expansion of the universe appears to be accelerating. Those are not contradictory.

In the case of dark matter, does it have a direct effect on centrifugal force, which otherwise would not be strong enough to sustain galactic integrity? In the case of dark energy, is it identical to observable energy and just more of the same,but unobservable apart from it's effects; or is it possibly a different type of (kinetic) energy - if these are not silly questions?

[Mordred]

In the case of dark matter, does it have a direct effect on centrifugal force, which otherwise would not be strong enough to sustain galactic integrity?

To answer this accurately first we must understand an essential detail on galaxy rotation curves in terms of the distribution of the mass.

 

First we will cover the Keplarian curve prior to explaining the mass distribution of due to dark matter.

Now take a mass distribution with a center of mass as our focal point. Ie center of our galaxy. With baryonic matter only the mass distribution is greatest towards the center. This distribution of mass will end up with a Keplar rotation curve. (Keplar decline).

 

Dark matter however envelopes and surrounds our galaxies with sufficient mass that it is evenly distributed throughout our galaxy. You no longer have a Keplar decline as your mass is evenly distributed.

So yes dark matter influenced rotation curves via their mass/gravity influence but not any other known interaction.

In the case of dark energy, is it identical to observable energy and just more of the same,but unobservable apart from it's effects; or is it possibly a different type of (kinetic) energy

I would recommend getting into the habit of remembering energy is the ability to perform work. The term observable energy is rather ambiguous. Anyways lets leave that aside. We don't know the mechanism behind dark energy however we know its influence on expansion. I prefer cosmological constant to dark energy in terminology. To understand DE and its dynamics the best path is to understand its equation of state.

 

Cosmology applies GR as well as the thermodynamic laws. The FLRW metric has two essential components. The metric ie geometry and the Fluid equations, part of those fluid equations being the deceleration/acceleration equation.

 

A brief but rundown on Equations of state can be found here. Its broken down into categories. EoS for matter/radiation Lambda and scalar fields.

 

Each particle species will fall under one of the categories just mentioned. The Eos givez us its density to pressure relations.

 

[latex]w=\frac{p}{\rho}[/latex]

 

For dark energy its EoS is w=-1.

 

https://en.m.wikipedia.org/wiki/Equation_of_state_(cosmology)

 

So DE behaves like negative pressure incompressible fluid. (keeping in mind we are treating all cosmological influences under the ideal gas laws.) via the FLRW metric fluid equations.

 

https://www.google.ca/url?sa=t&source=web&rct=j&url=http://www.damtp.cam.ac.uk/user/db275/Cosmology/Lectures.pdf&ved=0ahUKEwj128jpubjTAhVHx2MKHXT6BAgQFggcMAE&usg=AFQjCNGxvGWwx9QmCl2FyZLAUmB7lkZ7xQ&sig2=KnbYQXLvMRQDErkRBBnrYw

 

The last link covers everything I have just stated above.

Another key detail being universe geometry I wrote a breakdown on this here.

 

http://cosmology101.wikidot.com/universe-geometry

 

page 2 *FLRW metric broken down into dimensions ie 2d/3d and 4d*

 

http://cosmology101.wikidot.com/geometry-flrw-metric/

 

It will help you understand several chapters of the second link.

Edited April 22, 2017 by Mordred

[goldglow]

Thanks. The Baumann PDF download was fine, but the wikiped...tate link only leads to a second link suggestion, which does get straight to the article.( I think it's just because of the brackets around " cosmology ", in the first link above, not matching. ).

[Mordred]

Yeah working from phone didn't copy correct.

 

https://en.m.wikipedia.org/wiki/Equation_of_state_(cosmology)

 

All links should be fine now. I should note the last two links explains the metric aspects not so much the fluid portion except via critical density relations.

 

The first two links however provides those details.

Edited April 22, 2017 by Mordred

[goldglow]

Thanks, they do. Much appreciated.

[Mordred]

your welcome

[Zylacone]

The further out there we look the further back in time we see. The further back in time we look the faster the universe WAS expanding then. There are some new theories which say there was no Big Bang, but rather inflation. There was an experiment which took place decades ago with two gigantic metal plates (Niel De`grass Tyson). This experiment gave rise to more than a dozen string theories, and matter and antimatter being created from nothing which violates two laws of physics. I believe there was a plane of Higgs bosons in that infinitesimally small gap. So I believe in the theory of compression.

[Strange]

The further out there we look the further back in time we see. The further back in time we look the faster the universe WAS expanding then.

 

 

My understanding is that the expansion was slowing until about 5 (?) billion years ago when it started accelerating.

 

 

 

here are some new theories which say there was no Big Bang, but rather inflation.

 

Do you have a reference to these new theories? The big bang model describes the universe expanding from an early hot dense state. I am not aware of any theory that contradicts that.

 

 

 

There was an experiment which took place decades ago with two gigantic metal plates (Niel De`grass Tyson). This experiment gave rise to more than a dozen string theories, and matter and antimatter being created from nothing which violates two laws of physics.

 

That is rather vague. I don't really know what it is about.

OK. After a bit of thought, maybe that is the Casimir effect. Searching for that in relation to Neil deGrasse Tyson, I only found an interesting comment relating it to Hawking Radiation. It is nothing to do with the Higgs Boson, though.

[Janus]

The further out there we look the further back in time we see.

Right.

The further back in time we look the faster the universe WAS expanding then.

Wrong. Don't confuse the fact that the further away we look the greater the red shift we measure with the measure of the change in expansion rate over time. There are three possible scenarios:

1. The expansion rate is slowing over time.

2. the expansion rate has remained constant over time.

3. The expansion rate is increasing over time.

 

All three of these scenarios will result in the observation that red-shift increases for objects as the distance increases. (One way to think of this is that we, now, are at the "leading edge" of this expansion, and are measuring ourpresent recession from that earlier universe.)

What distinguishes the three scenarios from each other in terms of observation is how the change in distance and the red shift are related to each other. In scenario 2 the constant rate of the expansion, they are directly related; A doubling of distance gives a doubling of red shift.

For the other two,this is not the case for one the red shift increases less slowly than distance and for the other it increases faster than distance. Present observations match those we should get if the universal expansion rate has been increasing with time.

[beecee]

There are some new theories which say there was no Big Bang, but rather inflation.

 

The BB theory does include Inflation. In fact it is now sometimes called the BB/Inflationary model of the evolution of the universe.

There are though a few hypothetical models of the exact nature of Inflation, including "Eternal Inflation"

https://en.wikipedia.org/wiki/Eternal_inflation

[AbnormallyHonest]

I have a question on these issues I have never seen addressed as a whole .

 

We believe in the probability of dark matter because the universe hasnt flown apart, but there isnt enough visible mass to account for the necessary gravity to prevent this. We believe in the probability of dark energy because something is driving the universe apart at an increasing rate, yet we cannot see this energy.

 

These seem almost like contradictory statements. We believe in DM because the universe HASNT flown apart, yet we believe in DE because the universe IS flying apart and eventually every galaxy will be too remote to see any other galaxy in the universe.

 

What is the solution to this? I suspect maybe that it has something to do with the universe should have already flown apart by now if this dark matter doesnt exist, so its a time frame issue, but I have never seen in anything I have read where the concepts of needing dark matter for sufficient gravity to prevent the universe flying apart and dark energy to explain the increasing expansion dealt with simultaneously as a whole.

 

An explanation for the scientifically interested but mathematically challenged laymen to understand would be appreciated.

 

A better question might be if there is this DE that pushes, and DM that pulls, then why aren't they just cumulative and cancel each other out until there is only one left. It would be like saying that 2+2=4 is actually 2+(9x9)-79=4 kind of...

[beecee]

 

A better question might be if there is this DE that pushes, and DM that pulls, then why aren't they just cumulative and cancel each other out until there is only one left. It would be like saying that 2+2=4 is actually 2+(9x9)-79=4 kind of...

No, you have things confused.

DE is our explanation to explain the observed acceleration in the expansion rate of spacetime. which happens over the largest scales.

DM is invoked and evidenced to explain rotational curves of galaxies over obvious galactic scales.

They are not related.

Edited June 28, 2017 by beecee

[nomanoba]

I'm not up on all the stuff you guys know about, but I've put forward my theory in terms that you might understand.  I discovered this theory when trying to build a generator that utilized a gravity cheat. 

 

Dark matter contains information on the past, present and future, though in truth all three time frames are just a state of being. It's my belief that dark matter contains all information needed for the evolution of the universe, yet those that supposedly know (theorists like me) confer that dark matter cannot interact with baryonic matter, but I say different. Gravity is the conduit that passes information from DM to BM, when processed (used) the affected information is returned to DM.  I think there is a misconception that gravity has an up and down flow, but of course nothing is moving as there is no matter present, so from what I know I've deduced that gravity is hoop like.  The reason DM uses gravity as a carrier is to prevent an intelligent life form from connecting directly to DM.  If someone was to find the coding of gravity they would be God and hold ultimate sway on everyone and everything.

I'm here to be challenged, not bullied because I'm not academic.  

[MigL]

Oh, you are definitely challenged.

[Strange]

1 hour ago, nomanoba said:

I'm here to be challenged

Is there any evidence for any of that drivel?

Edited May 1, 2018 by Strange

[beecee]

1 hour ago, nomanoba said:

I'm here to be challenged, not bullied because I'm not academic.  

So you literally crawl out of the woodwork, admit in the first sentence that you are not familiar with "this stuff" , then go on some rant claiming all those that are in the know are wrong, and you do all this while trying to  build a generator, and all without any scientific evidence?

Flabbergasting to say the least.