what is dark matter ?

[AtomSplitter]

we have found dark matter, we can even map out its distribution. QUOTE]

 

if we know where it is why cannot we test it for anything?

[Klaynos]

we have found dark matter' date=' we can even map out its distribution. QUOTE']

 

if we know where it is why cannot we test it for anything?

 

It's a long long way away...

 

And doesn't interact very strongly at all...

[AtomSplitter]

 

It's a long long way away...

 

And doesn't interact very strongly at all...

 

 

 

so you are saying that it DOES interact??

[Klaynos]

 

so you are saying that it DOES interact??

 

Well yes, it's massive, it interacts with gravity, we know this.

Edited October 20, 2008 by Klaynos

[AtomSplitter]

I know it interacts with gravity, insane alien already said this in a previous post

[Klaynos]

I know it interacts with gravity, insane alien already said this in a previous post

 

Well, so then yes it interacts.

[JohnB]

The way our galaxies move in the universe implies that there should be more mass than we can see. We do calculations based on all of the mass we expect (based on what we can see), and it doesn't account for the way things move and interact.

 

So, the idea is that there must be some kind of mass out there which we just cannot see. We're still looking for it.

Just thinking, and pure speculation on my part. Why do we assume dark matter has mass?

 

What we see is a gravitational effect. We attribute this to mass we cannot see. We assume that dark mass has the same relationship to gravity as normal mass. Can we really justify this assumption?

 

We know that X amount of "normal" mass generates Y amount of gravity, we are then assuming that Y amount of gravity is generated by X amount of "dark" matter.

 

Why should the effect be symmetrical? I'm not saying it isn't, but the only reason I can think of as to why it should be symmetrical is "That's how normal matter works." But DM is not normal.

 

I should add that I think dark matter and dark energy are spread throughout the Universe. They're not just 4.3 billion LY away, but are also travelling between your eyes and this post right now. (Probably in very small amounts, granted, but if the gravitational relationship is not symmetrical, possibly in large amounts.)

 

This BTW is why I don't instantly dismiss so called "Free energy" devices as against the laws of physics. I kind of hope that someone with maybe his device of "27 specially arranged magnets" or whatever has accidentally built a dark energy to electricity converter.

[iNow]

Just thinking, and pure speculation on my part. Why do we assume dark matter has mass?

 

What we see is a gravitational effect. We attribute this to mass we cannot see. We assume that dark mass has the same relationship to gravity as normal mass. Can we really justify this assumption?

There is an effect, it seems like gravity, gravity is a result of spacetime curvature from massive objects (objects with mass). We don't see nor detect any objects, but we do detect the force of gravity, and we're not sure why. Hence, dark matter...

 

Would you be more comfortable if we called it "that thing we cannot see or detect which is causing that effect that looks a lot like gravity everywhere else" instead of "dark matter?" I mean, it's just semantics really. We're talking about the same thing, but one description causes the keyboard to break more quickly on the laptops of those who study and report on this.

[JohnB]

Sorry mate, I wasn't clear.

 

Normal mass produces gravity at the standard M1M2/DD. I'm wondering if this is true for dark mass.

 

Think of it this way.

 

Let's assume that there are gravitons and normal mass emits them at a rate one/second/gram. So 1 kilogram of mass emits 1,000 gravitons per second. We are assuming that DM follows the same pattern. Can we justify this assumption? If DM emits gravitons at 1/2 the rate of normal matter, then there would be twice as much of the stuff as we think there is.

 

Of course the converse could be true and it emits at a much higher rate, and therefore less mass is needed to give the observed gravitational effect.

 

Here's another speculation. Is it all the same stuff? Is there more than one type of non baryonic matter?

 

Our normal matter is associated with the electro-magnetic spectrum, would dark matter be associated with a totally different spectrum? If so, what are the Laws?

 

DM only appears to interact with normal matter gravitationally. If there was a block of it sitting on the desk in front of you, could you see it? Could you touch and feel it? Or would your hand just pass through it?

 

The Universe is truly an amazing and wonderful place. And there is so much more to find out.

[jerrygg38]

What exactly is dark matter? Is it even real or is it just made up? I read a small paragraph about it and would like to know more, if anyone could help it would be greatly appreciated. Thanks

 

JG: In my Dot-Wave Unified field theory, space is not empty. the same stuff that electrons, and protons are made up of exist throughtout empty space. space is made of dot-waves. The electric field is not an amazing strange thing. It is made up of dot waves. Photons are dot waves. the magnetic flield is moving dot waves.

Pure empty space consists of pure dot waves. They can come together and form stars and galaxies.

The total amount of mass/energy in pure empty space is huge. When the big bangs occurred simultaneously all over our volume of the total universe, a huge space wave flew toward the center of the total universe and outward to the outer sphere. This huge amount of energy acts like an ocean wave. It expands outward and then returns to our sphere.

We live on the surface of a sphere of approximately 16 billion light years. The circumference of the perfect sphere is 100 billion light years. We cannot see the total universe since the light waves from the far galaxies are reduced to zero energy.

The universe does not expand. Space itself expands but the distance between the center of galaxies do not change.

[iNow]

At present, your dot wave field theory is an unsupported speculation, at best, and should not be presented to novice individuals trying to learn about accepted physics concepts here in the fora.

[SamWalker]

It is something someone made up and lots of idiots repeats like mindless parrots. Anyone trying to explain DARK MATTER is an idiot. By the way, there is such a thing as an educated idiot.

[mooeypoo]

It is something someone made up and lots of idiots repeats like mindless parrots. Anyone trying to explain DARK MATTER is an idiot. By the way, there is such a thing as an educated idiot.

 

You know, if you don't know the origin of Dark Matter, or what it represents, you shouldn't post about it... Though there is quite a mystery about Dark Matter, it is far from being made up, its existence is vastly supported by observations and factual data. The only thing we aren't sure of is *WHAT* it is. We know "it" exists, because we see its effects.

[jjuris]

dark matter is just a term for the things that we cant figure out yet. 75% of the universe, let the math work itself out.

[Moontanman]

Well since the pot is being stirred very hard already I will have to add something to the mix, Mirror Matter could be a small part of what we thing of as the missing mass. It would in all probability be about equal to the mass of regular matter in the universe.

 

currently the percentages are around these figures

 

73% Dark Energy

23% Dark Matter

3.6% Intergalactic gas

0.4% Stars, Planets, ect.....

 

Mirror matter could change this to

 

7.2% Intergalactic gas

0.8% Stars, planets, ect....

19% Dark Matter

73% Dark Energy

 

Not much of a change but it would preserve mirror symmetry in matter.

[iNow]

Chad over at Uncertain Principles posted on the subject of dark matter today in the context of a recent statistical analysis which was hyped by calling CDM into question.

 

In his post, he says:

 

http://scienceblogs.com/principles/2008/10/dark_matter_doesnt_exist.php

Claims of the non-existence of dark matter are a staple of astro-kookery, but Physics World today has a news story with the provocative title "Galaxy survey casts doubts on cold dark matter," which makes it sound like people from reputable collaborations are questioning the existence of dark matter.

 

...but then, further down:

 

That sounds a whole lot squishier than the title would make you think. A complicated statistical analysis suggests that there are correlations between a bunch of parameters, which might invalidate a model of galaxy formation that might predict less of a correlation, and because that model involves cold dark matter, it might invalidate the CDM hypothesis. That's a lot of mights.

 

My own take? CDM may have it's issues, but I'll consider it valid until something better comes along. The news story at Physics World isn't exactly robust enough to shake this science to its core.

[Zolar V]

is it possible that darkmatter is simply the projection of matter from a seperate dimension, and gravity projects itself into that other dimension.

if this were true it would help the string theory(s) and it would explain the reactions between only darkmatter and gravity

 

opps didnt see there was more than one page, sadly i did not read them b4 i posted