What Is Dark Matter Made Of?

[cozzmikjoker]

then what is dark matter made of?
Is it made of energy, also (in line with the theory that dark matter is what's causing expansion)

 

[selfAdjoint]

then what is dark matter made of?
Is it made of energy, also (in line with the theory that dark matter is what's causing expansion)

Dark matter is not causing the expansion, that's dark energy which is something else. Dark matter was theorized to explain the rotation profiles of the galaxies. It is supposed to be ordinary matter (well, maybe some special particles), that doesn't shine or interact with light, but which has gravity.

 

[cozzmikjoker]

Isn't there only a small amount of dark energy everywhere (compared to the prevalence of dark matter)?

And if so, then how does is such a small amount of energy capable of pushing things outward?
Kaku says that the nuclear force (the outward explosion) of the sun is what keeps it from collapsing into itself, so it would seem there is sort of a balance between inward pull and outward expansion in a way.

So if there's some kind of huge black hole at the center of our universe which we're all rotating around, pulling everything inward (just as our planets are kept in rotation around our sun), what's the force that's pushing outward, keeping us from all getting pulled in? Is it theorized to be this dark energy?

 

[selfAdjoint]

Isn't there only a small amount of dark energy everywhere (compared to the prevalence of dark matter)?

And if so, then how does is such a small amount of energy capable of pushing things outward?
Kaku says that the nuclear force (the outward explosion) of the sun is what keeps it from collapsing into itself, so it would seem there is sort of a balance between inward pull and outward expansion in a way.

So if there's some kind of huge black hole at the center of our universe which we're all rotating around, pulling everything inward (just as our planets are kept in rotation around our sun), what's the force that's pushing outward, keeping us from all getting pulled in? Is it theorized to be this dark energy?

Right, the outward push from the dark energy is tiny, but like gravity it is additive, and since there is a little bit in every cubic inch, over the cubic light years it builds up.

There isn't (as far as we know!) a black hole "at the center of the universe". That phrase has no meaning anyway, as there is no reason to call one point rather than another the center of our universe.

There are strong concentrated gravity sources at the center of our milky way galaxy and of othe galaxies that we can see. These are conjectured to be black holes, but we can't observe them in enough detail to absolutely confirm this.

 

[Sempiternity]

Isn't there only a small amount of dark energy everywhere (compared to the prevalence of dark matter)?

From observations, the constituents of the universe are:
Matter: 5%
Dark Matter: 25%
Dark Energy: 70%

The dark energy may be due to a cosmological constant that's gained enough of a reign in the vast reaches of outer space 7 billion years after the big bang in such that it could reverse any sort of gravitational contraction and set the universe into a global expansion.

If that's true, then dark energy is "made out of" negative preassure, which creates repulsive gravity.

 

[cozzmikjoker]

There isn't (as far as we know!) a black hole "at the center of the universe". That phrase has no meaning anyway, as there is no reason to call one point rather than another the center of our universe.

There are strong concentrated gravity sources at the center of our milky way galaxy and of othe galaxies that we can see. These are conjectured to be black holes, but we can't observe them in enough detail to absolutely confirm this.

Okay, center of our galaxy then. Suns are rotating around something so there's a centralized pull. There seems to be an outward push/inward pull to everything (a balance) is what I was asking.

 

[cozzmikjoker]

From observations, the constituents of the universe are:
Matter: 5%
Dark Matter: 25%
Dark Energy: 70%

The dark energy may be due to a cosmological constant that's gained enough of a reign in the vast reaches of outer space 7 billion years after the big bang in such that it could reverse any sort of gravitational contraction and set the universe into a global expansion.

If that's true, then dark energy is "made out of" negative preassure, which creates repulsive gravity.

So we're being balanced by the after effects of the big bang (dark energy) and by some source of inward pull of gravity?

 

[selfAdjoint]

So we're being balanced by the after effects of the big bang (dark energy) and by some source of inward pull of gravity?

Yes, that's about it. From the observed motions of the galaxies, from observations of ancient supernovas, and from careful anaysis of the Cosmological Microwave Background (CMB), we conclude that the kind of matter we know - baryonic matter made of neutrons and protons - is only one part in twenty of the energy, one part in four is a gravitating matter we don't understand, and the rest is the zero energy level of the big bang, which is positive, and causing an accelerated expansion of the universe.

 

[cozzmikjoker]

An axis? http://www.npr.org/templates/story/story.php?storyId=1040015

Up and down have no meaning in space because everything is "out". I can't make heads or tails of this article about there being an axis in space. Anyone care to enlighten?

 

[hhh79bigo]

If you look at the universe as being finite, then there must be an axis, if the universe is infinite then up=down, left=right etc.

If the universe is finite consider it as a gigantic sphere with a radius there are 3 planes in the COM frame.

I could be wrong by saying this, its based on my limited knowledge in this field.

 

[Yaaks]

From observations, the constituents of the universe are:
Matter: 5%
Dark Matter: 25%
Dark Energy: 70%

im not sure whether these facts have been Observed, if so the inflation theory would be given a big boost..
If they have been observed, Plz link me..

 

[selfAdjoint]

im not sure whether these facts have been Observed, if so the inflation theory would be given a big boost..
If they have been observed, Plz link me..

They have been inferred from observation plus theory. The galactic rotation curves (observed) plus the theory that they are caused by gravitating non baryonic matter ("Dark Matter") gives the amount of dark matter per galaxy and since the baryonic matter (our ordinary matter) is mostly in galaxies that gives us the ratio of those two.

The expansion energy of spacetime ("Dark Energy") is inferred from the statistics on very old supernova remains, plus the details of the cosmic background radiation; these are the observations and the theory is that these observations are caused by the accelerated expansion of the universe, which is attributed to an expansionist energy of spacetime. Given this explanation, the ratio of the expansionist energy to all forms of gravitating energy can be estimated which completes the ratios.

I want to emphasize that these theories are CONSISTENT with the observation, but they are possibly not the only explanations of them, and that exploring alternative explanations is a respected part of theoretical physics.

 

[sfraise]

But what if gravity isn't really a force, rather is simply a result of the force of space pushing?

 

[Mk]

Silly "push" meanings post

Ok space, let's play blackjack, I'll be the dealer. wtf! Twenty and twenty!

When space and time have a baby...

 

[cozzmikjoker]

But what if gravity isn't really a force, rather is simply a result of the force of space pushing?

Care to elaborate? (i.e. why would space push two objects together; I'm assuming you mean the space between matter is what is pushing).

 

[Agnostic]

Instead of saying matter is made of energy, would it not be better to day that matter is a manifestation of energy?

 

[Mk]

Instead of saying matter is made of energy, would it not be better to day that matter is a manifestation of energy?
Yes.

 

[Deckers]

Instead of saying matter is made of energy, would it not be better to day that matter is a manifestation of energy?
Yes.

I feel okay with that too.

 

[cozzmikjoker]

Well if it's a manifestation, we have to ask the trite question "why the difference between solid matter and energy"? I understand differences between things can be based upon different combinations of molecules, atoms, subatomic particles and so on but there's got to be a more intuitive explanation to describe such a glaring difference between matter and energy.
Maybe a bad example but let's start with "Why does a table seem more substantial than empty space?"...Is there more dark matter in space than there is in the "condensed energy" that makes up the table?
Are these differences only the product of our perception? Perhaps a conscious quark sees itself as very solid and everything else as "airy"?

 

[Mk]

Well if it's a manifestation, we have to ask the trite question "why the difference between solid matter and energy"? I understand differences between things can be based upon different combinations of molecules, atoms, subatomic particles and so on but there's got to be a more intuitive explanation to describe such a glaring difference between matter and energy.

That is one of the great unsolved problems of physics. The current main theoretical explanation is the Higgs boson, a particle hypothosized to give mass to matter. Here's some links:

Wikipedia: http://en.wikipedia.org/wiki/Higgs_boson
CERN: http://www.exploratorium.edu/origins/cern/ideas/higgs.html
Wired: http://www.wired.com/wired/archive/12.04/grid_pr.html
http://www.hep.lu.se/atlas//thesis/egede/thesis-node6.html
http://www.zen45800.zen.co.uk/projex5/page3.htm
Spacedaily news: http://www.spacedaily.com/news/physics-04s.html
PhysicsWeb news: http://physicsweb.org/articles/news/4/9/2/1
BBC news: http://news.bbc.co.uk/1/hi/sci/tech/3546973.stm

 

[cozzmikjoker]

whoa, that's a ton of information for someone looking at this in layman's terms.
I'll get back with ya.

 

[Mk]

Here's also a Scientific American feature, from the July 2005 issue.

http://www.sciam.com/article.cfm?articleID=000005FC-2927-12B3-A92783414B7F0000&pageNumber=1&catID=2
Maybe something you should read first?