Do we know what Dark Matter/Energy is?

[harry]

G'day Chris

I think you may need to do a bit of research as to dark matter/energy.

Phase transitions give us the various phases of Nuclear matter that can explain the missing mass and most imposrtant the intrinsic properties of supernova and the so called black holes.

[Chris Peterson]

Phase transitions give us the various phases of Nuclear matter that can explain the missing mass and most imposrtant the intrinsic properties of supernova and the so called black holes.

There is no missing mass. And phase transitions, "nuclear matter", supernovas, and black holes have nothing at all to do with either dark matter or dark energy, which are the subject of this discussion. You are completely non-topical here.

[harry]

G'day Chris

The topic is:

Do we know what Dark matter/enery is?

So please do not talk about topics.

[harry]

G'day from the land of ozzzzz

With little understanding of dark/energy matter people will have a close mind of other research and explanations.
Bystander rightfully or wrongly deleted a post on Phase transitions Astrophysics 2009 search in arXiv.
These phase transitions are a key into understanding one form if not most of the dark/energy matter within the universe.
I just hope he does not delete this one. By doing so he will be directing scientific information along the lines of what he knows, which could be correct.

http://arxiv.org/abs/0908.4082
Gamma rays from ultracompact primordial dark matter minihalos

Authors: Pat Scott (OKC/Stockholm U), Sofia Sivertsson (OKC/KTH)
(Submitted on 27 Aug 2009 (v1), last revised 23 Oct 2009 (this version, v2))

Abstract: Ultracompact minihalos have recently been proposed as a new class of dark matter structure. These minihalos would be produced by phase transitions in the early Universe or features in the inflaton potential, and constitute non-baryonic massive compact halo objects (MACHOs) today. We examine the prospects of detecting ultracompact minihalos in gamma-rays if dark matter consists of self-annihilating particles. We compute present-day fluxes from minihalos produced in the e+ e- annihilation epoch, and the QCD and electroweak phase transitions in the early Universe. Even at a distance of 4 kpc, minihalos produced during the e+ e- epoch should be eminently detectable today, either by the Fermi satellite, current Air Cherenkov telescopes, or even in archival EGRET data. Within 2 kpc, they will appear as extended sources to Fermi. At 4 kpc, minihalos formed in the QCD phase transition have similar predicted fluxes to the dwarf spheroidal galaxies targeted by current indirect dark matter searches, so might also be detectable by present or upcoming experiments.

The identity of dark matter remains one of the key outstanding
problems in physics. Weakly-interacting massive
particles (WIMPs) provide a compelling solution [1]
because their weak-scale masses and cross-sections make
for a natural explanation of the observed abundance of
dark matter. As most proposed WIMPs are their own antiparticles,
high WIMP densities would also lead to high
rates of self-annihilation. Annihilation products might
then provide indirect evidence of the nature of dark matter.
Gamma-rays are particularly attractive in this respect,
as they do not suer the same problems of defection
and attenuation as massive, charged species.

But! on the same token, Chris maybe right in his definition of Dark/Energy matter as per what ever model he uses.

[The Code]

G day harry

Some indication of an even bigger more complex universe?



http://en.wikipedia.org/wiki/Weakly_int ... _particles

[harry]

G'day Mark Swain

Yes I agree.

As time goes on we get to know and understand the working parts.

At this moment we are just learning.

To say we know is a trap in learning.

[bystander]

With little understanding of dark/energy matter people will have a close mind of other research and explanations.
Bystander rightfully or wrongly deleted a post on Phase transitions Astrophysics 2009 search in arXiv.
These phase transitions are a key into understanding one form if not most of the dark/energy matter within the universe.
I just hope he does not delete this one. By doing so he will be directing scientific information along the lines of what he knows, which could be correct.

Harry

Since you decided to make this public, I just did what I told you I would do. If you do not explain what the article is about and how it applies to the topic at hand, I can only assume:

• 1. You did not read the article,
  2. You do not understand the article, or
  3. The article does not apply.

And since you insist the first two are not true, I can only assume the third, and I will remove the article. So, in the future, if you wish me to not remove your articles, explain what they are about and how they apply to the topic at hand before you post them. I will not take the time to determine if the article is applicable or not, it's up to you to do that.

Most people on this forum know how to put key words into search engines, and come up with large number of articles that may or may not apply. But if they can't take the time to read said articles and explain how they might be applicable, then why should anybody else take the time to read those articles for for them.

Posting the abstract is not sufficient, nor is just throwing a few key words about. You need to explain how the article is applicable to the current topic. Otherwise I will do as I said I would.

Many people have complained about your plethora of articles and their lack of applicability. So, either stop posting the articles, or explain why I should care.

[Chris Peterson]

These phase transitions are a key into understanding one form if not most of the dark/energy matter within the universe.
http://arxiv.org/abs/0908.4082
Gamma rays from ultracompact primordial dark matter minihalos

What I don't think you grasp is that "phase transition" by itself doesn't mean anything without context. The first paper you posted (the one that got deleted for non-topicality) was about phase transitions of hadronic particles in neutron stars. This paper is about dark matter structures (not dark matter properties) in the early Universe caused by a phase transition in the Universe itself, affecting one of the fundamental forces of nature. There is no connection between these two ideas, and the "phase transitions" they discuss have no more in common than either does with the "phase transition" of water to ice.

But! on the same token, Chris maybe right in his definition of Dark/Energy matter as per what ever model he uses.

Quit lumping dark energy and dark matter together like they are the same thing! It just demonstrates your ignorance. Nothing in the papers you have posted discusses dark energy. The latter paper is about dark matter, and the model it is using is the same as the one I use, which is that dark matter is made up of non-baryonic particles. That is the model that most physicists consider closest to the truth.

[canuck100]

http://arxiv.org/abs/0908.4082
Gamma rays from ultracompact primordial dark matter minihalos

Authors: Pat Scott (OKC/Stockholm U), Sofia Sivertsson (OKC/KTH)
(Submitted on 27 Aug 2009 (v1), last revised 23 Oct 2009 (this version, v2))

Abstract: Ultracompact minihalos have recently been proposed as a new class of dark matter structure. These minihalos would be produced by phase transitions in the early Universe or features in the inflaton potential, and constitute non-baryonic massive compact halo objects (MACHOs) today. We examine the prospects of detecting ultracompact minihalos in gamma-rays if dark matter consists of self-annihilating particles. We compute present-day fluxes from minihalos produced in the e+ e- annihilation epoch, and the QCD and electroweak phase transitions in the early Universe. Even at a distance of 4 kpc, minihalos produced during the e+ e- epoch should be eminently detectable today, either by the Fermi satellite, current Air Cherenkov telescopes, or even in archival EGRET data. Within 2 kpc, they will appear as extended sources to Fermi. At 4 kpc, minihalos formed in the QCD phase transition have similar predicted fluxes to the dwarf spheroidal galaxies targeted by current indirect dark matter searches, so might also be detectable by present or upcoming experiments.

The identity of dark matter remains one of the key outstanding problems in physics. Weakly-interacting massive particles (WIMPs) provide a compelling solution [1] because their weak-scale masses and cross-sections make for a natural explanation of the observed abundance of dark matter. As most proposed WIMPs are their own antiparticles, high WIMP densities would also lead to high rates of self-annihilation. Annihilation products might then provide indirect evidence of the nature of dark matter. Gamma-rays are particularly attractive in this respect, as they do not suer the same problems of defection and attenuation as massive, charged species.

This article is about dark matter and it supports WIMPs as the candidate particle to explain its existence. It argues against MACHOs (large objects) as they should be observable.

The electroweak phase transition refers, I believe, to the separation of the electroweak force at BB + 10^^–36 s to 10^^–12 s which triggers inflation.
The QCD (quantum chromodynamics) phase transition appears to refer to the transition from quarks to hadrons at approx BB + 10^^–6 seconds to 1 s.

As I said earlier, presently all BBT/LambdaCDM says is that dark matter dominates by the time we get to matter domination at BB + 70,000 years. So this paper is an attempt to place the creation of dark matter as WIMPs back as early as either the electroweak epoch or the quark to hadron epoch in a manner consistent with BBT/LambdaCDM. The paper argues against MACHOs as candidates for dark matter.

This type of theoretical justification or one along these very general lines plus some corroborating observations is what is required to properly explain dark matter in the context of existing theory and it is working towards that goal.

At http://www.lbl.gov/abc/wallchart/chapters/09/0.html there is an extremely understandable discussion of Phases of Nuclear Matter that explains the analogy between the phases of water and the phases of nuclear matter and the relevance to BBT:

Phases of Nuclear Matter
As we know, water (H2O) can exist as ice, liquid, or steam. . . . We can make a diagram, which shows the states of H2O depending on pressure and temperature. . . . We call the mathematical relations inferred by the chart the "equation of state" of water.
. . .
Just as the state of a collection of atoms or molecules depends on temperature and pressure, we find that the state of a nucleus depends on temperature and on the density of the nucleons. Thus we may ask what is the equation of state for nuclear matter?
. . .
In a laboratory, the only possible way to heat nuclei to significant temperatures is by colliding them with other nuclei. The temperatures reached during these collisions are astounding. . . . The temperatures we can reach in nuclear collisions range up to 100 MeV and above–more than 200 million times the temperature at the surface of the Sun (~5,500 K)!
. . .
As we heat nuclei to a temperature of a few MeV, some of the nuclear "liquid" evaporates. From knowing the general form of the interactions between nucleons, we know that, just like water, the nuclear liquid also has a latent heat of vaporization, and nuclei should undergo a first-order phase transition. This liquid-gas coexistence is also expected to terminate at a critical point, the critical point of nuclear matter. One of the major thrusts of heavy ion research at laboratories such as Michigan State University’s National Superconducting Cyclotron Laboratory is to find out if these theoretical expectations are correct. Experiments try to determine at what temperature and density the critical point of nuclear matter is located.

There are major challenges that nuclear physicists face in their efforts to explore the nuclear equation of state and these nuclear phase transitions. . . .
Despite these challenges, progress in this field has been significant.
. . .
. . .
The figure shows that the phase transition between the nuclear liquid and a gas of nucleons is not the only phase transition that heavy ion scientists are studying. At even higher temperatures and densities, nucleons themselves can undergo a phase transition.
. . .
All of the theoretical and experimental challenges listed above are also present when studying the transition to the quark-gluon plasma. In addition, there is another, possibly even more severe obstacle to overcome: the quark-gluon plasma cannot survive longer than a few times 10^^-22 seconds.
. . .
What is the purpose of studying the nuclear matter phase diagram? The answer is that we need this information to understand the early history of our universe, and to understand high-density objects, called "neutron stars" in our present-day universe. . . . Thus, the study of the nuclear equation of state is connected to the initial phases of the early Universe, to ultra-violent stellar explosions, and to experiments at laboratories around the world.

While it is certain that not all discussions about "phase transitions" will have relevance to BBT and dark matter, there is a connection between "Phases of Nuclear Matter" and BBT.

I think it's fair to request that "dark energy" and "dark matter" be maintained as separate concepts for discussion. They will end up related somehow in the end but I think that it's safe to say that they will not be related in the normal energy to matter relationship. The similarity in name between the two concepts is already potentially confusing enough!!

I also think that it is fair to request that if someone posts a reference to a highly technical journal article, that they should summarize its content in a manner that contributes to the discussion at hand and leave the deciphering of more technical aspects to those who wish to pursue the matter. This forum, after all, is open to the general public and hopefully the majority of the discussion will be intelligible to an "informed amateur."

I hope it's OK that I did not attempt to paraphrase my quote above -- the author said it far more simply, clearly and eloquently than I ever could!

[harry]

G'day

In a way I was sharing the reading that I do.

Bystander has the opinion that I do not read the links that I post.

He is mistaken

Regardless

Since no one reads the links that I post then there will be no more.

As for being public, I do not mind the links that I post been critisied thats part of the game.

I have no time to break down the posts to what is expected. In most cases the point is expalined within the ABS.

[makc]

In most cases the point is expalined within the ABS.

Even you have to see that you are the only one who thinks so (or says that he does).

[harry]

G'day Makc

The point is I was willing to share the reading.

I will not waste my time ever again.

I do more reading and discuss issues by email, than by forums these days.

[mishkin]

G'day

In a way I was sharing the reading that I do.

Bystander has the opinion that I do not read the links that I post.

He is mistaken

Regardless

Since no one reads the links that I post then there will be no more.

As for being public, I do not mind the links that I post been critisied thats part of the game.

I have no time to break down the posts to what is expected. In most cases the point is expalined within the ABS.

Always you did a wonderful job, Haroldskievitch .. I will miss your links. Many times I look into them. I guess you will have to make broad, unsupported statements as is common in many discussion groups.

[harry]

G'day Mishkin

Smile, did you actually read some?

[The Code]

G'day Mishkin

Smile, did you actually read some?

Yes he did harry. And so do I. Always read your posts.

Mark.

[harry]

G'day Mark Swain

Wow!!!!!!!!! that is amazing

Just think I thought I was wasting my time.

Although I post the links. God only knows of the hard work that some of the scientists have put into them, full credit to them.

So how do I post links that I read and want to share?

I did use the private message to mishkin, could this be the way?

[The Code]

Not 4 me to answer, that one m8.

[harry]

G'day Mark Swain


Smile
I was thinking aloud.

[apodman]

Should we (1) invite Mr. Rogers and Barney the purple dinosaur to join the love fest, (2) get back to the topic, or (3) just lock it and forget it? Technically, Fred Rogers is no longer with us, but neither is mishkin/sputnick and that doesn't stop every member from sending him a Valentine on Halloween.

[The Code]

All work and No Play, makes Jack a Dull Boy.

That,s a fact.

[bystander]

So how do I post links that I read and want to share?

Do I really need to repeat it?

I did use the private message to mishkin, could this be the way?

Your PMs are up to you, and who you send them to. Please unsubscribe me.

Otherwise, if you have a problem, take it offline.

[harry]

G'day Bystander

What do you mean unsubscribe you?

I sent a PM to mishkin

[bystander]

What do you mean unsubscribe you?

I mean don't send me your reading list. And you shouldn't send any PMs to sputnick, either. He can't receive them.

[harry]

G'day

I had no intentions.

[harry]

G'day

It looks and sounds like the fine print at the bottom of the page, oops its been deleted..