Dark Matter?

GA redfred. I am curious to know the relation between "dark matter" and "anti matter". Can "dark matter" and "anti matter" stay together or can never stay together?

Well that's hard to tell because as I mentioned, nobody is really sure (and have proven their certainty to peers ) what constitutes dark matter if dark matter answers the question about galaxies not dispersing. Now the stable dark matter that makes up you and me does react with the anti-matter that we know of. I seem to remember though that one proposed explanation was that inter-galactic space might have larger amounts of neutrally charged anti-matter that generated the anti-gravity to matter that I mentioned. I think this proposal has been dismissed because of other unseen events one should expect if this were true.

The difficulty of solving this and other cosmology puzzles is that we can only obtain information indirectly, we cannot go to these locations and take a sample to a lab. The James Webb telescope will likely add very relevant new data to this puzzle if it does get deployed.

There is another answer to the dark matter problem, and that is that photons and neutrinos have mass. To accomplish this feat, it is necessary to have another theory of matter that allows this inherent mass containment to exist within all types of energy carrying particles. It is called Ultrawave Theory, and it provides an answer as to how gravity interacts with matter on the subatomic scale. And because it predicts that gravity is not an infinitely reaching force, it can account for the apparent dark energy that seems to be pushing large scale structures apart in the Universe.

Hi Redfred. I don't think that there is something outside our solar system (and not inside) which produces this additional gravitational field (needed to form our galaxy and all other galaxies). Why it should be so? The simpler hypothesis should be the right one: whatever is 'outside' our solar system must, also, be 'inside'. You are right by saying that (probably) most of the matter of our solar system is luminus. However this issue doesn't consist a "paradox". It is so, because it is supposed that the dark matter fills a very large area around a galaxy (much, much larger than the galaxy itself). So, although its density is significant smaller than that of the ordinary (luminus or baryonic) matter, its overall quantity is, actually, much larger.

Also, it seems that the 'black holes' issue doesn't solve the problem. First of all, the multitude of black holes are rather small (their existence is observable due to their bright, accumulation discs and X-rays emissions). Also, black holes consists of baryonic matter... and, as you know, it is supposed that dark matter consists of 'non-baryonic matter'...

Dark matter was postulated by Fritz Zwicky back in 1934 to account for exactly the "missing mass" required to keep galaxies intact with their measured rotational velocities. Big bang mass production calculations now predict that considerably more non-luminous mass should have been produced. This agrees with Zwicky's proposal but disagrees with what is easily observed in our solar system. This secondary paradox has generated two camps of ideas to sole this additional paradox. The concept that our solar system's luminous to dark matter ratio maybe typical around other stars but that it is not typical elsewhere in the galaxy is the Massive Compact Halo Object (MACHO) concept. Black holes and brown dwarf stars are the two dominant massive candidates in this camp. Then there is the Weakly Interacting Massive Particle (WIMP) camp that believes that a very large number of barely massive particles are dispersed around the galaxy. Inside a star system their effect is so minor that it is difficult if not impossible to detect. However, once you consider the volume of the enormous interstellar space this amount of mass becomes huge in total. One of the leading candidates for a WIMP is the tiny mass that appears to exist in a neutrino.

As I mentioned earlier, this is an on going debate in the Physics community. Nobody has yet to come up with the correct data and analysis to say which perspective, an alternative perspective or a combination of all appears to be true.

I know all this stuff. Actually, what I mentioned in my previous post was the WIMP approach of the issue. It is supposed that there is an "halo" around each galaxy consisting of dark matter. This "halo" is much, much larger than the galaxy itself and that's why the quantity of the dark matter is much larger than that of the ordinary, baryonic matter (although the density of the dark matter is much smaller than that of the ordinary matter). I think that this scenario is more likely to be true.

However, we haven't the slightest idea what exactly the dark matter is. It could consist of neutrinos (as it seems that they have a tiny -but not zero- mass), or magnetic monopoles (very massive particles emerging by some theories but not observable yet) or exotic, WIMP particles.

Again, I have to mention that the black holes, neutron stars or brown dwarfs don't seem to be a solution. I repeat: it is supposed that the 'dark matter' is not baryonic matter. And all the above objects consist of baryonic matter (even the black holes).

My apologies, I misread your earlier post and was just trying to keep things to what is clearly known to answer the original question by HiTekRedNek. I was also trying to introduce the presently plausible ideas that try to answer this paradox without interjecting my own bias on which ideas I prefer. What I personally like is a combination of MACHO and MOND but that's just me. We all should remember though that while many proposed ideas to solve this mystery have been found to be untrue, we still have not solved this paradox.

One thing that has always bothered me about the "halo" explanation for the matter outside of the galaxy to solve the dark matter paradox is that this is not what the shell theorem predicts for the net force inside the shell. The mass outside of the galaxy will either make it more likely to destabilize the star trajectories (when the mass outside is not uniform) or will have no effect on the matter inside the galaxy (when the the mass outside is uniform). A uniform WIMP ether will similarly have little to no effect. A concentration of matter at the galactic center is required for gravity to be the sole binding force. This is why I like a combination of MACHO and MOND. The concept I like in MOND is what if gravity does not asymptotically decrease to zero as we go out to infinity, but instead decreased to some small non-zero number.

The best reference I've heard to dark matter and dark energy is that they are "placeholders"; we don't have any real answers, so we extrapolate from our existing understanding of matter and energy, and make up these spooky theories to get us by until we know more.

One possibility for the "dark matter" effects we think we see is that Newton's law of gravity is not complete. We know it doesn't work at the quantum level, maybe it also diverges somehow at the very big (light-year) level.

Yep, that's another one of the theories. It also has an acronym for MOdified Newtonian Dynamics, MOND.

This is a very interesting subject to me (a layperson who likes to read posts like this one). There has always been something about the Dark Matter theory that just gets under my skin. There seems to be many different answers to the puzzle regarding the luminous matter and why there is not enough of it to satisfy our observations. The galexies should "fly apart" if not for "Dark Matter".

Why is it never discussed that there could simply be a whole lot of dead solar systems within the galexy and these "dead stars" have simply burnt out, never to be observed again by earthly telescopes? There could be limitless numbers of these dead solar systems and we would never see them. We would only infer their existence based on their gravitational effect on the galexy.

I just don't understand why Dark Matter has taken the physics world by storm when it could be normal matter that we just cannot see.

Well you do bring up one of the ideas that has been debated as a possibility. The fundamental problem with this being a galaxy aging problem is that this problem exists for even the youngest galaxies that we can resolve. Also if you take a reverse analysis of galaxy formations that do show an increase in luminous matter at younger ages, then these galaxies will have to be formed before the Big Bang happened for there to be enough luminous matter ever to hold a galaxy together.

The trouble with any real physical paradox, nobody knows what is really happening.

GA for outofBox thinking, not steriotype. In fact Big Bang theory itself for evolution of universe can not be believed, and so the dark matter and anti matter. Can we think without taking shelter of these theories?

Hi Pritam. Could you explain in a bit more detail why you are sure that the 'Big Bang theory...for evolution of universe can not be believed'? I'm also interested to hear why you question dark matter and anti matter? You seem to be making some pretty strong assertions, which is fine but I'm just curious to learn your reasoning.

Hi johnfoti. I didn' say I'm sure. I'm not an expert in this field, only I have interest to know which can be believed. Big Bang and anti matter theory suggests that this universe came out of nothing, which appears to me as unbelievable. Most of the people in this field believe on Big Bang theory but many still not. May be some more clinching evidance needed for it which scientific community may provide in future. It will be worth to quote redfred at#11.

"this is an on going debate in the Physics community. Nobody has yet to come up with the correct data and analysis to say which perspective, an alternative perspective or a combination of all appears to be true."

You have stated two common misconceptions about the Big Bang Theory that I wish to correct.

First, the BBT does not state that the universe came out of nothing. The BBT states that the Bang occurred. It implies that we may never be able to know what existed prior to the Bang. It also implies that the physical laws of our universe are likely not valid prior to the Bang. Despite this limitation there are theoretical physicists that are trying to plumb the depths prior to the Bang, at the moment of the Bang and briefly after the Bang. But it is a misconception that the BBT states that everything came out of nothing. One group of theoretical physicists is exploring the idea that instant in time of the Bang itself never actually happened, that this is just a theoretical point located by regression theory. They postulate that the previous universe's laws changed and made our universe at a point after the extrapolated point but before our present experiments can simulate initial conditions. But this is only an avenue of exploration.

Second, the scientific community is not unanimous on anything. However, there are very, very few astro-physicists, physicists and cosmologists (the scientists where BBT resides in their domain of expertise) that don't believe that the BBT or something close to the BBT is true. This is because the BBT has repeatedly predicted several phenomena to exist before they were observed. The most famous of these observations was the cosmic microwave back ground radiation. Now as plausible alternatives to BBT get proposed, experiments are designed to test the proposal. Most of these experiments are low cost extrapolation experiments to see if the proposed new cosmology agrees with today's universe. If the proposal passes this test, an experiment is conceived that discerns if the BBT or the new proposal is true. Many times the BBT has been found to still be the correct approach or that only a slight adjustment of the BBT needs to be done. Certainly if the new proposal accurately predicts an observed phenomena that the BBT predict shouldn't happen, then a better model has been found.

"the BBT does not state that the universe came out of nothing"

Actually the present BBT does. I doubt that the majority of scientists believes it to that point. (pun intended) The BBT of 50 years ago started with a basketball size "mass". The inflationary versions changed all that.

Excellent link - thanks. There is one paragraph that I think stands out:

'What produced the energy before inflation? This is perhaps the ultimate question. As crazy as it might seem, the energy may have come out of nothing! The meaning of "nothing" is somewhat ambiguous here. It might be the vacuum in some pre-existing space and time, or it could be nothing at all - that is, all concepts of space and time were created with the universe itself.'

What would happen if a big bang occurred in a pre-existing universe? My simple minded guess is that any nearby inhabitants of that universe and their galaxies would be blasted to quark/photon soup by the shock wave. Those lucky enough to live a billion light years or so would in due time be vaporized. Further out they would be killed by radiation, but their galaxy would survive more or less intact.

If I understand it correctly our universe is characterised on the largest scale by huge filaments of matter. Galaxies and galaxy clusters seem to appear at nodes where these filaments intersect. I also believe that most astrophysicists think that most of the 'dark matter' is concentrated along these filaments. Presumably it is concentrated further at these nodes. If you view our big bang, not as a moment of creation, but simply as a ballistic explosion (like a super super nova) within an existing universe that already contains matter, you would expect that rather than being perfectly spherical, it would over time pick up imprints from the existing massive objects. As the expansion continues it would acquire significant variations in density and these irregularities would would tend to become linear as they were 'extruded' through gaps in the pre-existing matter. This is of course pure speculation

Yeah that's one of the ideas consistent with Big Bang Theory but then there's the University of Michigan that recognizes that we don't know from what or where the singularity came from and NASA that also agrees that nobody knows the origin. Maybe you'd prefer the Big Bounce variation. You could always just go with the over referenced Wikipedia site on the Big Bang that includes many different versions including the chaotic inflation model where we are just one of many universes. Each in their own universe bubble bang creation like bubbles in a glass of beer that form on an unseen imperfection on the glass.

All of these are variations of the Big Bang Theory. Some variations do say that a quantum anomaly out of nothing started everything. Some say that this is a Phoenix like rebirth cycle. Some claim that we are but one of many universes that may not have been started at the same time, if that has any meaning in this realm. As I said earlier, which variation is most correct is presently being debated and refined. All of these variations have advocates with theoretical calculations and some corroborating data to support their views.

So I repeat my earlier comment, "the BBT does not state that the universe came out of nothing." As you found, some variations of the BBT do state this but others do not.

My understanding of inflation is that it requires infinite universes to be created. I have never liked that idea.

"we don't know from what or where the singularity came from..."

It came from general relativity (predicted by it).

As was mentioned, one of the newer theories is the collision of branes. An addition of loop gravity can get rid of the singularity.

It's getting late. That's enough for tonight.

One of the things that has always intrigued me about the 'images' of collisions in particle accelerators is the traces that show some particles spinning away from the impact, either in broadening or tightening spirals. String theory seems to require many unseen dimensions, and one of the explanations offered is that some of these (when viewed from our perspective) appear to be coiled up. Whether or not string theory is eventually demonstrated, I think this hypothesis of hidden coiled up dimensions could explain these images of particles. We may be seeing particles emerging from or spiralling into one of them. I recently (within the last year) read a small article suggesting (I have lost the link) that sufficiently energetic particles in such a coiled dimension would emerge into our observable world. Writ large this COULD be a mechanism (not the cause) underlying our BB. Then again my ignorance on this subject is bottomless.

Very interesting material. I hope that I can find some time to study this in further depth soon.

There's a part of me that likes the idea that an alternate explanation for the red shift has been proposed. I was under the impression from my much earlier understanding of the Compton effect in frequency shifting was that photon energy was randomly lost and gained depending on the interacting particle energy. This would then produce the observed smearing or spreading of the light frequencies and not just a red shift.

I'm certain that somewhere, Fred Hoyle is at least smiling.

To be honest, we have wandered a little away from dark matter here in this tangential discussion.

Do not worry about the tangential direction this discussion has taken, it is all very interesting, because dark energy,dark matter, and multi-dimensions are all interrelated at some level.They are all part of the same elephant being explored by a group of blind men, each examining a different part with different explanations as to the type of animal it is:

The one at the trunk end claims it must be a snake, the one at the leg claims it must be a tree, etc.

They are all right, of course, but no one has the big picture.

We are likewise blind to the big picture, and it will take a merging of all ideas to get, at the most, a skeleton outline of reality.

We are a very young species, and we have much to learn, and I do not expect we will have a valid TOE in our lifetime, but we can certainly keep nibbling away at it.

Interesting to see much comprehensive discussion after I expressed my apprehension on BBT.

Thanks for the link.Very interesting! I scanned it briefly, but what i saw made it worth further study at a later time.

GA

Nicely explained

In fact just one of the excellent posts you have written so far on the topic, but I'm stingey.

I also like 23 so have blown the other half of my quota on that.

GA. A nice explanation.

the term "dark matter" refers to the amount of matter in the universe that physcits can't explain away. it's suppose to make up the about 75% of matter in the universe. it's just another way to say" it's got to be there, but i'll be damned if i know what it is"

And don't forget the brane theory, where there are multiple universes (branes, short for membranes) existing in a higher-dimensional arena, and maybe these branes touch occasionally and spawn a new universe that we perceive as the BB. This all makes my brane hurt...I need an Excedrin.

So we live in a 4 DIMENSIONAL P-Brane, but since Branes are so large, we can ignore them?

Will the next theory be HAIR-Braned---where the universe is composed of HAIRS with split ends, like Gecko feet? (Not to be confused with STRING theory).Galaxies would then merely be dandruff,clusters would be eczema,and the Great Attractor would be a flea.?

"Little fleas have littler fleas,

Upon their back that bite 'em,

And littler fleas have littler still,

An so on,and so on,

Ad Infinitum"

Can't remember who said that.....

I am reminded of the æther. Because, in the human experience, something always waved, waves did not exist otherwise. Based on this "knowledge", and the mathematical proofs that light was a wave, they had to invent the luminiferous æther, a substance with remarkable, perhaps unbelievable, properties. I wonder if "Dark matter" is another explanation made because of a reality we are unable to conceive.

wiki on the Luminiferous_aether