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Fraser
2003-Jul-25, 09:55 PM
Apparently, there are some people who don't seem to believe that dark energy/dark matter actually exist. I've created this discussion thread to contain the conversaton. Talk about it here all you like; however, keep the conversation to this thread. I'll be actively moderating other discussions and pushing any arguments about dark matter/energy into this thread.

Thanks!

So... do you have a problem with the concept of dark energy or dark matter?

duffer
2003-Jul-26, 12:47 AM
So... do you have a problem with the concept of dark energy or dark matter?

In a word, yes, because most of what I've read is extremely vague on what it actually is. My dumb questions on the subject are: could you describe it using the periodic table? i.e. is it normal matter that simply happens not to have collapsed into light-emitting stellar systems? If not, could it ever be synthesised in lab/particle accelerator etc?

N3373H
2003-Jul-26, 01:19 AM
I agree, it sounds dubious. If it does exist, it must be invisible or we wouldn't be able to see billions of light years away. Also, if it has enough repulsive mass (sic) to accelerate the universe apart, wouldn't it have the reverse effect of gravitational lensing and distort our views of distant galaxies? I'm still not sure I understand the nature of dark matter/energy (where it is or where it emanates from). If it's between galaxies, then why isn't it also closer to home where we can detect it? Perhaps the calculations that predict it are in error. ? :wacko:

Tinaa
2003-Jul-26, 02:16 PM
From what I learned in Intro to Astronomy, we may being sitting on dark matter and it could be streaming through our bodies. Planets, brown dwarfs, neutrinos, WIMPS, MACHOS, and exotic matter (stuff not made of protons, neutrons and electrons), and who knows what else are candidates for dark matter.
The more I learned, the more questions I had! I don't know who said this, but it fits, "Not only is the universe stranger than we imagine, it's stranger than we can imagine."

Decimal
2003-Jul-26, 03:53 PM
I personally Believe Gravity, Light and Dark Matter are Similar and Have resembling Characteristic Properties

I also believe that in time we will be able to distort warp or even alter these to fold space (kinda like stargate..but not as perfect :unsure: ) it wont be such like creating a worm hole through space from one location to another, but like cutting two circles out of a peice of paper and making them meet...

I understand me..

N3373H
2003-Jul-26, 06:40 PM
I'm still confused. If dark matter is made up of massless or almost massless particles, then how can it be repulsive? I understood that in Einstein's terms, gravity wasn't so much a force as a result of mass warping time/space, and objects moving past the mass were drawn to it by the curvature of space. In this view then wouldn't dark matter be the opposite of mass and warp time/space in such a way as to cause the object to follow the curvature of space away from it? If so, then with so much predicted dark matter, the universe's appearance would be so warped it would look as if we were in a giant funhouse. I'm starting to get too deep for my own understanding. :blink:

Fraser
2003-Jul-26, 09:07 PM
Dark energy and dark matter are two different things.

Dark matter has mass. If you look at a distant galaxy and consider it as a single object, in terms of how it attracts other galaxies, bends light, and even stays together as it rotates instead of flying apart, you would calculate its mass as being X. If you actually added up all the stars, planets, dust, etc in the galaxy, you would end up with a visible mass of Y. It turns out that X is several times Y. In other words, it has more mass than you can see, and astronomers don't know what that extra mass is. They know it's there by how it interacts with objects, etc.

Dark energy is completely different, and has absolutely nothing to do with dark matter. Sadly, they have similar names. Dark energy was only discovered about 5 years ago by astronomers who wanted to know how expansion of the Universe was slowing down. They did this by measuring the distance to various supernovae in the Universe. They found that the supernovae were more distant than they were supposed to be. The only way they could be as far away as they are is if the Universe isn't slowing down, but actually speeding up. In other words, some repulsive force is being generated in the vacuum of space between objects. The further apart they are, the force is being generated. What this force could be is a complete mystery.

So there you go. Dark matter is just like regular matter, we just can't see it. Dark energy is a strange repulsive force that is created in vacuum.

Evil Steve
2003-Jul-26, 10:22 PM
you would calculate its mass as being X. If you actually added up all the stars, planets, dust, etc in the galaxy, you would end up with a visible mass of Y. It turns out that X is several times Y.

Wouldn't Y be several times X ( :rolleyes: sorry pedantic)


some repulsive force is being generated in the vacuum of space between objects.... What this force could be is a complete mystery.

It may seem stupid but someone has to say it.
They have taken into account the lessening effect of gravity as objects get further away from each other, haven't they?

Evil (not answering just asking)

Fraser
2003-Jul-26, 10:51 PM
No, X is the total mass of the galaxy, and it seems to be several times the visible mass.

Visible Mass + Dark Matter = Total Matter

Regarding the dark energy, the distance is too far for it just to be coasting. Gravity should be slowing everything down, but the opposite is happening. One theory I've heard is that at great distances, gravity actually flips around and starts repelling.

Cambo
2003-Jul-27, 12:21 AM
Have I got this straight?

Dark matter is non light emitting matter?

If not what is dark matter made of?

Dark energy is something that is out there but we don't know what it is made from or how it is made?

I am wondering is this my first post with nothing but questions?


:blink:

cswift1
2003-Jul-27, 04:01 AM
This topic is insanely confusing, I think, for one reason - the logic of it is running backwards. Having made observations of the rate of expansion of the universe, something is simply not adding up. And that something is the mass of the universe. It seems that we need more, alot more, for the observations to start making sense. It's the same with dark energy. It appears that the outer reaches of the observable universe are expanding faster than they "should" be. Again, only by hypothesizing some form of energy can observations start coming into line. It's working it backwards the same way that Mendeleev did in putting together the Periodic Table of the Elements. He had to leave "holes" in the table where certain elements "should" be but had yet to be discovered. He could not tell you what these elements looked like or even what they were, but he was able to say something about what they did. Only later was he proved to be correct in predicting a) their existence and b) their chemical behavior. In the same sense as Mendeleevv, there is (for now) no way to get anything other than vague explanations about what they "are" or what they "look like". All we do know is that IF dark matter/energy existed, our observations would make more sense. Again, it's kind of working backwards but it's a technique that has produced a great amount of fruit in past scientific discoveries.

Fraser
2003-Jul-27, 04:45 AM
Welcome to the Universe Today forums cswift1.

Great explaination. We haven't seen dark matter directly, but we can measure its effect on objects in space. Dark matter could very well be normal stuff, like brown dwarfs or clouds of dust which aren't emitting enough heat or light for us to see them. Of course, it would mean that there are hundreds of brown dwarfs for every regular star. But it's still a possibility.

Once again, the only way we know dark energy is out there is because of the effect it's having on objects in space. Imagine you're throwing a ball up into the air. The ball leaves your hand, slows down from gravity and then falls back. That's the way the Universe was supposed to work. But instead, imagine you throw the ball and instead of slowing down, it just keeps accelerating into the sky. The discovery was completely unexpected. After the initial momentum from the Big Bang, the Universe is accelerating apart.

scott712
2003-Jul-27, 05:01 AM
The requirement for more matter than we can see or "Dark Matter" arises from the observation that galaxies seem to spin far too fast to not spin apart unless there was more mass than is apparent from the dust, interstellar gases, stars, black holes etc.

I see a possible flaw in this assessment. Gravity might be a great deal more powerful over long distances than we have been able to verify. Was it the Pioneer Space Probe that left our Solar System? Anyway, there were reports that this probe's trajectory was signifigantly different from expected.

Some have postulated that there is a relatively strong repulsive force between any two given pieces of matter that partially overcomes the gravitational attraction that we might measure between them in a laboratory. This strong repulsive force would fall off more rapidly with distance than gravity. Thus in a laboratory we might be left with the impression that gravity is a lot weaker than it really is.

This close range repulsive force is probably not the "Dark Energy" everybody is talking about that causes the Universal Accelerating Expansion.

Wm. Scott Smith

kashi
2003-Jul-27, 09:48 AM
:unsure: I like the idea that our universe is a "brane" (a 4 dimensional sheet) which is next to a whole lot of other universes of a simular formation. When objects have a very large mass (eg. black holes at the centre of galaxies), the sheet bulges and can actually affect other sheets (universes). Think of layers of paper, one of which has a marble shaped bulge in it. The gravitational effects from one universe could therefore affect another. Perhaps there is a universe close to ours wondering where all of the gravitational effects of their matter has gone!

Kashi

N3373H
2003-Jul-27, 11:29 PM
If the universe is truly infinite then perhaps big bangs are a common thing. As the matter from one big bang heads towards the matter of another big bang, the matter would pull itself together to eventually form a super super massive black hole that would explode under it's own weight and cause another big bang. If these big bangs were, say, 28 billion light years away, we'd never be able to detect them but we would be able to observe an acceleration in our own visible part of the universe when there should be a deceleration. Then we wouldn't need any dark matter or dark energy. Am I making sense here, or have we already proven this not to be the case?

Just curious, do we know where the center of our known universe is? Where the big bang happened?

Arramon
2003-Jul-28, 06:35 PM
sorry... i wrote this under another topic... so i'll just cut & paste...
----------------------

Dark Matter seems to be concentrated around the outer edges of our galaxy, more clustered as it recedes, and less the closer in it gets..... sort of like an outer layer to our galaxy, keepng things in.... Dark Energy seems to be keeping that Dark Matter in one globule, which constitutes our galaxy... if the ISM is comprised of mostly Dark Energy, which seems to repulse the matter around it, making the ISM expand, the globule of our galaxy will continue to expand along as well... but, seems to remain intact due to the gravity of our galactic bulge, and the pressures from the outer layer (dark matter) versus the repulsion of the Dark Energy (keeping that Dark matter within a 'cell' form)...

we are voids in space, connected by thins wisps of hot gas...
our galaxy is just a big pocket of hot gasses... filled with whatever else we now know... with small shafts of hot gas streaming from it... some connecting with other galaxies or globules of pocketed gas, and some with ends to nothing...

If Dark Matter can be analyzed to show its 'true' properties, then maybe we can start to theorize what the functionality of Dark matter might be... it seems to be helping stablilize the structure of our galaxy, so one function can be that it is, is some way, a protective shell around us, keeping the coldness of the ISM seperate from the temperatures within, and the Dark Energy from ripping our galaxy into many small individual elements that would be scattered if the Dark Matter were not present... that is to say if the galactic core couldn't hold the outer layers within its pull.

All speculation, of course... but, hope it helps some =)


. ..-={A}=-.. .

Bill AH
2003-Jul-29, 01:08 AM
Is it possible that dark matter (or energy depending on the line of reasoning) is only part of the problem and the other problem is with the theories themselves (heaven forbid we as humans could be wrong :P ). Perhaps there is a large amount of dark matter out there but not the several times factor of X to Y. A better understanding of the theories that are predicting this dark matter may reveal that there is another part of the equation that hasn't come to light in the scientists minds yet. Therefore, it may be a combination of the two where dark matter can be a smaller, more believable amount.

curry
2003-Jul-29, 06:09 PM
Dark matter does not have to be very complicated. We know that there is a lot of extra mass in the galaxies, we just don't know what it is yet. We can't see it, so we call it dark. It is similar to when we detect a wobble in another star. We know that some other mass is nearby, even if we cannot see it. This is one of the ways that we are detecting planets at other stars. The motion of galaxies clearly show that there is a lot more mass than what we can see. For now we call it dark matter. Some people want to think that this dark matter is something strange, could be, but most likely it will turn out to be just extra matter that we don't see yet.
Dark energy, unfortunately, has the same dark word in its name. This has led a lot of people to think that it has something to do with dark matter. It does not. They are completely different things. Dark energy comes about because it seems like the expansion of the universe is speeding up and It would seem like some form of energy would be needed to make this happen. We don't know what this energy is so we call it dark. The answer to this one is more likely to be something strange.
Curry

Fraser
2003-Jul-30, 07:24 PM
Welcome to the Universe Today forums Curry.

Thanks for bringing it down to Earth. I really think that the term "dark matter" was a poor choice. It sounds cool, but it seems to rub people the wrong way.

imported_Tintin
2003-Jul-30, 07:36 PM
The good thing about a pseudonym is that you can ask nonsensical questions without feeling ashamed :)

Does anyone know who it was who coined the terms dark energy and dark matter ?

Tinnin'

Faulkner
2003-Jul-30, 11:57 PM
We are told that the universe is structured like the surface of the earth, but in 4(?) dimensions instead of 2! So in effect there is no "centre" or "boundary", but a seamless, endless "finite infinity". So I imagine if one travels in a "straight line" (if this is possible?) one would arrive back at the starting point! SO...relating this back to dark energy & the repulsive force of gravity...COULD IT BE that gravity is not in fact "repelling", but what we are observing is gravity "attracting" at long distances, matter looping back on itself, kinda thing. Hmm, hard to explain properly...does this make sense? In other words, we are seeing distant galaxies NOT accelerating AWAY, but accelerating TOWARDS us (but from another direction)!... well, I know I sound crazy, but believe me, it's just my inability to put this properly into words! Ha! I still find it IMPOSSIBLE to visualize such a universe. My commonsense tells me the universe MUST have boundaries, the "edges of the Big Bang", so to speak. Also, doesn't Hubble's latest findings of a "flat" universe (rather than a "curved" one) rule out this whole notion of a "finite universe" with "no boundaries"??

I guess, in a nutshell: I'M MINDBLOWN AND CONFUSED!!!!! :blink:

Fraser
2003-Jul-31, 03:39 AM
The Universe isn't curved the same way the Earth is. If you head off in a straight line, you will never return to your original position.

kashi
2003-Jul-31, 05:14 AM
Because space and time are both curved, maybe time curves around on itself. It's weird and counterintuitive. I think I'll stop thinking about it.

Kashi

Faulkner
2003-Jul-31, 09:40 AM
Hmmm...well OK...but why do cosmologists describe the expanding universe in terms of an inflating balloon with black dots on it representing the galaxies? Is there a better way to describe the universe's geometry?? Are we talking a 3D universe, or multi-dimensional? I'm flabbergasted. How can there be no "edge" to this universe?? If the universe has no "edge", then it is either infinite (which goes against the Big Bang theory) or it warps back upon itself in some geometrical trickery!!?!... In which case, yes, you WOULD arrive back at your starting point, wouldn't you?? Cosmologists seem full of convoluted ideas that simply cannot be translated into layman's terms. :wacko:

NeoDinian
2003-Aug-01, 12:28 AM
Dark matter was first used by Carl Sagan. I belive dark energy (as well as dark matter) was Steven Hawking.

polymath
2003-Aug-03, 10:08 AM
This is the most fascinating discussion I have seen on the Net for a long time. I am in the same position as many contributors in that I am confused about the relationship between dark matter and dark energy. Before dark energy was discovered, dark matter was said to make up more than 95% of the Universe. Now that we have dark energy, the percentages seem to be 73% dark energy and 23% cold (what's that?) dark matter. I am taking these figures from a Sky and Telascope report on the findings of the WMAP satellite of earlier this year. So there must be some connection between dak matter and dark energy if they are both thought to be constituents of the Universe. Or have I completely misunderstood!

Arramon
2003-Aug-04, 02:56 PM
I would say that we may need about another 5 years max to truelly chart and dimensionalize the degrees at which 'matter' and 'energy' flood our regions of galaxies and galaxy clusters...
I was just reading from a ESA website that they now believe that dark matter may be used as some sort of 'smeared paste' that helps 'draw & stick' galaxies together... it was from a team that was given like 100 hours of hubble time to examine a cluster of galaxies, or a certain range of sky...
it was previously thought (and said by me in here =P ) that dark matter may be more condensed towards the outer regions of a galaxy or cluster, but with these new findings, its being said that the dark matter may be less condensed towards the outer regions and more the closer in to the center of the cluster or galaxy you go... and that dark matter also clumps together in places, which could then attract galaxies together that may be close enough to eachother...
...and that the expansion of the universe may have been slower at first, because of high gravity, but then accellerated the farther the expansion due to the effects of dark energy...
i believe the team plans to release a mapping of this cluster that they were studying, a detailed chart of where dark matter & other compounds lay, the relations to each, pulling/tugging, the temperatures and the speeds that the particles may be repulsing at from the surrounding dark energy...

all very interesting... but this may change in a heart beat from someone else's studies... or alot of heart beats... whenever...

i give them 5 more years to be able to speak with any form of certainty...

. ..-={A}=-.. .

Arramon
2003-Aug-05, 11:45 PM
Bling bling, said the scientist... =P

Check this article out about Dark Energy just released... (http://www.space.com/scienceastronomy/dark_energy_030805.html)

hmm...

. ..-={A}=-.. .

budcamp
2003-Aug-22, 03:17 AM
We have no idea if either dark energy or dark matter exist. They are theories, which were created to solve a particular problem. They are not even really to the theory point. They are more like theory wannabe's.

Dark matter was created to solve the problem of what holds galaxies together. We watch them spin and compute that they should be spinning apart, but they are not. When all of the mater we can see in them is calculated, there is not nearly enough to hold them together. So what is it that holds them in place.

If it is mater, it does not reflect or emit light: x-rays, infrared, or radio waves. Is there a possibility that it is not there? There certainly is! It is possible we do not understand gravity as well as we think we do.

Dark energy is not nearly as likely to exist as is dark matter. Dark energy was invented when two research teams studied (I believe nine), super novae. They concluded that these nine objects were farther away than they should have been. They transposed that conclusion into the fact that the entire universe is accelerating. I know everybody needs their fifteen minutes of fame, but it is quite a stretch to accelerate billions and billions of galaxies based on the observations of nine stars. Even if they are correct and the universe they observed was accelerating, it was doing so eight billion years ago, which is the look back in time to where the observations were made. We have no idea of what those stars are doing today.

This is not much of an answer, but then there are no really good answers on this subject. We call them "DARK" because we know nothing about them.

Bud

Arramon
2003-Aug-22, 04:11 PM
...thats a point that people seem to keep wanting to say...

i think i've read about 10 post like that....

It doesn't hurt to try to organize the chaotic into thinkable structures...
....and if the structures are proven to be otherwise later on, then the organizing can be altered to fit the newer findings....

its the process of where we are at now... we can't see into the future to know what others may find.. we can just try to organize our work now, so that others down the way can use this data to try and evaluate their own findings...

...and to call something by a particular name doesn;t put a branding upon that name that will stand beyond the test of time... names can change...
and maybe Dark matter, or Dark Energy, may be realized to be another form of Light Matter and Energy.... electromagnetic sources that produce their own currents and tows and forces....

In order to realize the extent of the universe, we must have knowledge banished from the forefront of our current minds, our current time, our current thoughts and processes of learning.... leave an open mind to allow all forms of information to enter for analyses... acquiring all data before computing a possible fact that should or shouldn't be..... theories don't claim to be facts.... its the ones who cliam that these theories don't exist or CAN'T exist that are claiming these theories to NOT be facts....

I, for one, will allow the theorists to strive as hard as they may.. for they are the ones who are conquering the unknown.... and are allowing us to learn more and more each day, each year, each decade, each moment....

Hail to these leaders who are unknown to most, but will forever be known to the likes of us who believe in the ways of discovery...

. ..-={A}=-.. .

budcamp
2003-Aug-24, 03:55 PM
I love reading science fiction. It is a great place for suppositions. The problem with some science today is that suppositions are taken to be fact. In science, for something to be accepted as "provisionally true", it needs to be established by experimantation, not by theory. "I can dream it up", is not a guarentee of the dreams reality!

Bud

Fraser
2003-Aug-24, 04:22 PM
I really liked your explaination Bud, I think that's what I was fumbling to explain as well. :-)

VanderL
2003-Sep-08, 07:36 PM
Gee,

I missed this thread completely, I've been discussing in another thread on dark energy. Is it still active?

If so, let me say something on dark matter; actually "missing" matter was the term first used by Jan Oort when he calculated the velocities in spiral galaxies and found that gravity could only hold these galaxies together when extra mass is postulated. Nothing wrong there, just one basic assumption, gravity is the only force keeping the galaxy together, leading to the problem of the missing matter. After more than 50 years of speculation it is embarrassing that science hasn't come up with an answer yet.
There is another force in the universe that can do the job of accelerating/moving matter around. Electrical fields and magnetic fields can move matter (charged as well as neutral matter) much better than gravity. The gravitational field of the entire earth can't keep a spoon down when a magnet picks it up! If it is recognized that space is filled with electric fields and currents we don't need "invisible" matter to explain what we see happening in galaxies.

President_Nemerov
2003-Sep-10, 04:53 AM
This Dark Matter business is really tricky.... Nobody knows for sure what it is anyway. that's y scientists r also describing it very vaguely. i guess at the present moment only mathematics in their computers imply the existence of Dark energy/matter. no HARD evidence as yet, eventhough there is vague observational evidence...
I guess this has got something to do with zero point energy...

VanderL
2003-Sep-11, 07:51 PM
Dark matter is indeed something that's only implied because the universe is not acting the way it theoretically should.
Dark energey on the other hand is the endpoint of a long series of assumptions and interpretations ( normally known as Big Bang theory) that can all be proven to be false. One way or another I think the truth will eventually be found, although realistically this will take a few decades because people who have strong feelings for a certain model won't simply convert to another, better model; it will have to slowly die out. Hopefully I will live to see the day that Big Bang theory is remembered as one of those silly ideas that had its charm for a while.

budcamp
2003-Sep-24, 02:29 AM
My grandfather used to describe theories without demonstrated proofs as "farting words". Let me try to come up with a different theory for the multi-dimensional world of String Theory, Dark Matter, and Dark Energy.

I propose that ghosts did it. I say the reason that planets orbit the sun is that ghosts push them around. They also make galaxies spin and hold them together at the same time (some people call them Dark Matter because we can not see them and they appear to supply mass: while in reality the ghosts just push the galaxy the way they wish it to go [Very Low-Tech] ). Inflation of the early universe was caused when a bunch of ghosts went back in time and sped up expansion as a joke on those of us who try to understand such things. Ghosts did not cause dark energy, because dark energy does not exist. We now think the acceleration of the universe is the results of “Dark Energy”, because we can’t figure out what could be causing the acceleration. The truth is that we have almost no data establishing this acceleration. The entire conception of the accelerating universe came from two small studies. You don't accept radical theories without more than they have provided in the way of data. These two studies were of interest, but not very difinitive.

By the way, the reason some galaxies are not spirals is because we still do not have enough ghosts to spin all of them.

Now the way science operates today, I don’t have to prove ghosts did it (since reality is variable), others have to prove ghosts did not do it. String theory has done nothing to prove there are 11 or 26 dimensions; all it has done is to say that if these dimensions exist, their theory might work ! “Big Deal”!

That the ghosts did it, makes just as much sense as many modern theories and is no more difficult to prove.

Bud

eggplant
2003-Sep-24, 05:24 AM
So I'll see if I got this straight...
Dark Matter is an adjusted variable of gravity to compensate for the observations that didn't add up without adjusting that specific variable... (but it may be caused by some other undesignated force that fits the gravity equation.)
Dark Energy is an under replicated observation of galaxies moving faster than they should, and a new force variable introduced to explain the observation.
(I'm wondering if they're just riding the waves of space that could have been created not, by the big bang per se, but a really very large bang perhaps. As space warping occurs... ) a few more observations or any investigation into those studies will debunk my rant... they may not be far enough away or old enough th ride those theoretical waves... Just makin it up as I go...
Gohsts? I was thinkin' "blue meanies"...

Josh
2003-Sep-24, 05:28 AM
Throughout history humans have been adding fudge factors into things in order to make the original hypothesis work.Why?? The discovery of planets in some cases was as i direct result of people not agreeing with the fudge factors. For eg, one planet's orbit was highly erratic and so fudge factors were continually being added into the equations to account for this. Someone not agreeing with the fudge factors set about trying to find another explaination and ended up finding another planet.

Instead of insisting on trying to make theories work which continually need updating and fudging to hold, why not look for another theory that doesn't require dark matter or energy? these seem to taste a lot like fudge to me. a number of people have put forward ideas in here that go against the grain of current scientific "beliefs" and while being very difficult to fathom, seem to make a lot of sense.

I don't know if dark matter or energy are there or not. But i wonder why we insist on holding back other ideas and continue to propound the ideas that don't work. Instead of trying to find an answer that works we insist on trying say there is a thing that we can't see or feel or detect ... but we'll blame that and consider it as real .. well .. that sounds very much like something else we don't want to talk about in these forums.

Fraser
2003-Sep-24, 06:54 AM
Who's the "we" that's holding back alternative new theories? All a new theory has to do to gain general acceptance is explain current phenomena and predict new observable data. Simple.

There isn't some kind of conspiracy to hold the alternative theories down. There are, however, skeptical peers ready to poke holes in your theory wherever they can; which is exactly what they do to each other.

If you have an alternative theory about the Universe, start with reviewing the current astrophysical/cosmological literature. Check out the NASA Astrophysics Data System, which is a repository of published papers - http://adswww.harvard.edu/. Astronomy is one area where amateurs regularly contribute their time and energy to help advance scientific knowledge.

But if you think you've got an idea that will completely explain the Universe, you've got your work cut out for you to find people to take you seriously.

Josh
2003-Sep-24, 09:35 AM
The collective "we" are the same people as the "they".

I know of one particular instance of a guy (i know him personally) shunned by the scientific community. his papers generally won't be published and he's considered a "crackpot". Now ... saying that you're probably saying, "well then he probably is". This guy is a mathmatician and cosmologist. Many of his theories now ten/fifteen years on are being accepted as true. He tried to come out with things saying preeminent scientists were plain wrong and was outcast because of it.

Scientists are just as susceptible to getting stuck in old theories as religions (sorry to bring up the taboo topic) are.

I personally have no new theory that explains the universe. What I'm saying is that more often than not the fudge factors are exactly that and eventually it's the premises that are found to be wrong.

VanderL
2003-Sep-24, 09:19 PM
This is a very interesting discussion, I think. We can clearly see that science at this moment is falling short of explaining a lot of the new data. Whenever unverifiable concepts like dark matter are invoked to save a theory you can be sure it is in deep trouble.
The problem with something like dark matter (actually it is better to call it missing matter) is that in 70 years of trying, science hasn't given us a clue. There are plenty of ideas but no proof. So, isn't it time to look at the assumptions that underly the problem of the missing matter? I say it is, and the first thing that I found was that there are many people unhappy with the "dark matter" concept, I think many mainstream scientists as well.

Now is there anyone who is telling us that the matter isn't missing? Yes, and what I have found in the last couple of years is that the ideas found in the Plasma (or Electric) Universe (see below) are telling us exactly why we are stuck with this problem.

For almost a century space is considered to be electrically dead. In space there are no currents, no electricity. All the bodies in space are neutral and spin around in a neutral environment. But we do see a lot of magnetism, we can see the solar flares, we know about the solar wind, we have neutron stars (another unproven concept) with strong magnetic fields, we see polarised radiation (proof of magnetic fields) and Jupiter, like earth has aurora's only many times stronger. What is missing in this picture is the cause of the magnetic fields, ELECTRIC CURRENTS!
We can show in a laboratory setting what a plasma (electrified/ionized gas) behaves like, Anthony Peratt has done many experiments and has shown that plasma's behave very strange and more importantly, they can explain why gravity isn't enough to keep the Universe going.
I know that this model has been around for many years and it is only really appreciated by people like Peratt and Thornhill who are plasma physicists.
The real problem is that in textbooks space is electrically neutral, so most scientists are not aware that this concept is wrong. 99.99% of all matter in the Universe is plasma, so why don't we consider its properties and then reconsider what powers the Sun and what drives "black holes" and what forces shape galaxies.

Fraser, you are right that there is no conspiracy trying to keep competing models from recognition, that's what we do ourselves when we don't ask the right questions about the "standard" models. We have to ask what the assumptions are that underly the models. Is gravity the only force shaping the Universe? I think not. And I haven't seen anyone trying to falsify the Electric Model
When you are interested to learn more try www.electric-cosmos.org or www.holoscience.org, the book The Big Bang Never Happened by Eric Lerner contains the outlines of the Plasma Model (as well as some stuff about the state of the world I don't really care about). Happy reading!

Dave Mitsky
2003-Sep-25, 02:24 PM
Originally posted by VanderL@Sep 24 2003, 09:19 PM
Is gravity the only force shaping the Universe? I think not. And I haven't seen anyone trying to falsify the Electric Model
When you are interested to learn more try www.electric-cosmos.org or www.holoscience.org, the book The Big Bang Never Happened by Eric Lerner contains the outlines of the Plasma Model (as well as some stuff about the state of the world I don't really care about). Happy reading!


Perhaps folks should have a look at this first - http://www.astro.ucla.edu/~wright/lerner_errors.html

Dave Mitsky

Arramon
2003-Sep-25, 02:56 PM
it seems that all educated minds or even quick learning novices seem to have their own theory about what is and what isn't..... when things can't be proved or disproven, its only logical to assume all possibilities...

it will take first hand experience with these objects and materials that seem so mysterious before any of us could possibly understand what is going on.... because all in all, no one can say one way is more true than the other..... its just waiting... watching.... exploring.... developing.... testing.... acquiring..... implementing that will do the most towards understanding...

. ..-={A}=-.. .

VanderL
2003-Sep-25, 06:06 PM
Arramon,

All you say is true, but also very much like saying that discussing things doesn't matter; it does, while people talk and argue about models, we will eventually find truth. Models are always incomplete because we don't know everything, in spite of some people claiming differently.
And Dave, in the link you posted, errors in Lerner's book are discussed. What I understand from the criticism is that he over-interpreted some points, but basically he was stating that there is an alternative to Big Bang cosmology, the Plasma cosmology. Since the appearance of the book (around 1992) a lot has changed. Big Bang cosmology has changed, but also the view on how a Plasma Universe works. He (Lerner) never mentioned that our Sun is powered by electrical fields and not by fusion energy. The links I posted are more up-to-date.
The criticism on the large-scale structures of the Universe are more tricky, because both Lerner and Big Bang cosmology use redshift data to show the structures, but since in my opinion Halton Arp has clearly shown that there is an intrinsic redshift especially for high-redshift objects, (indicating their youth) the large scale structures will look very different.
There are more points of criticism, that I don't understand (yes, I'm not an expert on astronomy) but I would like to the experts respond to Don Scott's "Electric Star" version of the Hertzsprung-Russell diagram. I think it is the best point to start when looking at this model.
Thanks.

Faulkner
2003-Sep-26, 01:33 PM
Look at a distant quasar. It is 12 billion light years away from you. Look at your hands. They are a trillionth of a light-second away from you. YOU are the edge of the Big Bang explosion!

In other words, we are all isolated in our individual futures...."Every man(sic) is an island"...

(Or something like that!)

:(

imported_ROB
2003-Oct-02, 11:37 AM
I have just come accross the artical below



The outstanding mystery of modern astronomy may finally have been solved. Researchers believe they may have discovered the identity of the Universe's mysterious dark matter - the matter which cannot be seen as it emits no electromagnetic radiation but must outweigh visible matter by at least a factor of seven. The researchers believe that gamma rays coming from the centre of our galaxy carry the hall marks of these ghostly particles

Astronomers claim dark matter breakthrough (http://www.newscientist.com/news/news.jsp?id=ns99994214)


any thoughts?

Arramon
2003-Oct-02, 02:45 PM
That is VERY interesting...

So they think that Dark Matter was so small that they couldn't detect it...
and it seems to fit in ther formula for the missing component when tested, but wouldn't it fit in that formula if they created one to account for the missing data? There may be other figures that aren't 'dark matter' that they aren't detecting just yet... so this could just be a handful of elements they're finally beginning to view.
What if there are elements hundreds of times smaller than these dark matter ones? is that super dark matter? =P
all very interesting...

and the thread goes on =)

. ..-={A}=-.. .

Matthew
2003-Oct-06, 10:02 AM
How about neutrinos? The Sun alone produces 4 × 10^38 neutrinos every second. If neutrinos did have mass they would account for at least some of the Dark Matter. A new experiment suggests that neutrinos may have a mass 1/100000 of an electron. Which is enough for neutrinos to account for a large proportion of dark matter.

VanderL
2003-Oct-07, 07:35 PM
Sure Matthew,
Neutrinos will account for some of the "missing" matter, only problem is that the missing matter has to be in certain places and stay there. And there's the problem, neutrinos will be more plentiful in an area that is already full of normal matter (although neutrinos are quite normal matter as well). To make up the parts that keep rotating galaxies from flying apart (because that's what's missing), they need to be either in a halo around the galaxies, or in the "empty" space between the galaxy's "arms".
Neutrino's won't do that for you, so we must consider either some new form of matter, or our assumption that gravity is enough to explain everything in the universe is wrong.

Arramon
2003-Oct-07, 09:54 PM
What keeps our atmosphere from dissipating?
What are the forces that are involved?
The rotation of earth? The gravitational pull? Magnetics?
Chemical reactions? Elemental properties working against one another and everything in between?

Dave Mitsky
2003-Oct-09, 09:20 AM
Originally posted by matthew@Oct 6 2003, 10:02 AM
How about neutrinos? The Sun alone produces 4 × 10^38 neutrinos every second. If neutrinos did have mass they would account for at least some of the Dark Matter. A new experiment suggests that neutrinos may have a mass 1/100000 of an electron. Which is enough for neutrinos to account for a large proportion of dark matter.
Certainly a part of the total to be sure but not a large part, 20% according to this article - http://unisci.com/stories/20022/0410026.htm

Dave Mitsky

Matthew
2003-Oct-09, 10:39 AM
I've heard WIMPs (Weakly interacting Massive Particles) could be another part of dark matter. What a WIMP is I do not know.

VanderL
2003-Oct-09, 02:36 PM
No one knows what WIMP's are because they have not been measured, only theorised, just like a number of other particles that are automatically promoted as the answer to the "missing mass" problem.

Arramon
2003-Oct-09, 02:41 PM
Its getting our scopes down to the smallest particle sizes ever conceived.. and then even smaller. Like our microscopes we use to examine the body and other tissues, we've got to have lenses that can penetrate the smallest areas in space, possibly revealing thin layers of elements that are keeping the Mediums in their current forms out in space. If we could up the resolution of our cameras and scopes... =)

. ..-={A}=-.. .

Matthew
2003-Oct-10, 06:52 AM
Its getting our scopes down to the smallest particle sizes ever conceived.. and then even smaller. Like our microscopes we use to examine the body and other tissues, we've got to have lenses that can penetrate the smallest areas in space, possibly revealing thin layers of elements that are keeping the Mediums in their current forms out in space. If we could up the resolution of our cameras and scopes... =)

We cannot obseve everything perfectly, if we up the resolution of cameras to observe particles smaller than an atom noting would happen. We would not be able to accuratly enough observe anything accuratly enough. Heisenberg’s uncertainty principle states that by trying to observe something more and more accuratly you actually have the reverse effect.

To observe something we bounce light off what we want to observe, which on a large scale is fine, but on a small scale (an atom and smaller) by bouncing light off a tiny particle you affect it. If the beam of light has a wavelength shorter than the particle you can observe it easily but you affect it (light as a particle has energy and momentum so will affect the readings of the observations). To decrease the light as a particle affect physisists can increase the wavelength (decreasing the energy of a photon), but by decreasing the wavelength you increase diffraction (where light bends around a particle, making it look fuzzy).

Too cancel out diffraction you decrease the wavelength (increasing the energy of the photon) but then you affect it with momentum. So in conclusion we cannot accuratly measure tiny particles under a microscope. :(

Arramon
2003-Oct-10, 03:21 PM
I say.... let them show what they can view within the next... 10 years, and then we'll see of they have been able to manuever around the affects of reflection and light. If we could examine something without affecting it, then we could examine as close as we needed to.
Maybe magnifying and using enhanced digital optics to resolve fine detail could help.
We just need to concentrate on whats around us first. Learn all we can from our own neighbor hood before we search another. Don't stop checking out the other galaxies and locations, but don't spend an immense amount time which could better be used here.

=)

. .-={A}=-.. .

VanderL
2003-Oct-12, 12:44 PM
Anyone ever hear of the "ether drift" experiments by Dayton Miller? In the late twenties, early thirties, he measured a positive value for light speed in different directions, meaning that there is something like an "aether". He basically repeated the famous Michelson-Morley experiment with a more sensitive apparatus, for longer periods and also on high altitude, coming up with positive results. He had Einstein worried, because the existence of an ether would invalidate General Relativity. I have never heard of others trying to repeat these experiments, although they seem to be very important. It could basically mean that cosmology has to start again (and we might need a new thread).

Dennis Archambault
2003-Nov-17, 09:11 PM
I don't have a problem with the concept of Dark Matter/Dark Energy. What I most want to know is "Has it been mapped throughout all the Constellations?"

As a new owner of a telescope, since I am looking at the Constellations - and trying to understand the 'symbolic pictures' (ie, LEO, etc.) with their positioning of key stars, I would also like to 'imagine' the existence, within each Constellation, of where a known Dark Matter concentration is calculated to be.

VanderL
2003-Nov-18, 08:28 PM
Hi Dennis,

Sorry, but I don't think it is posible. You'll have a problem imagining dark matter concentrations in constellations, because constellations are made up of a variety of objects. For instance close stars and distant galaxies that have little connection in real space can make up a constellation because our view from earth make them seem related. Of course there are some objects that are related, like the Pleiades, but generally constellations won't give you an indication where the dark matter is.
Then again, since dark matter is totally imaginary already (my guess is that we have to revise our understanding of the importance of gravity) why don't you picture it where you think it should be and show us the results?

hmmmmmmm
2004-Feb-25, 05:18 PM
I had an interedting theory while sitting in class couple days back. After hearing the news of the possible discovery of dark matter. Here it is: (well, broken down)

Empty space in the universe; not so. A good analogy of it would be that looking into the universe is like looking into a glass of water. Appears clear and that nothings there, but it is indeed full. If we were inside it it would appear this way, but from the outside we would see its limitations. Then we would know that it is not empty space. The forces, or "waves", of the glass are like gravity waves in space. In conclusion, i believe that if we could use a 4th spatial dimension, we could get a total understanding of dark matter.

This is just a thought. Let me know what you think.

Thanks,

Ryan

ebbixx
2004-Feb-25, 06:43 PM
First let me point out that my formal physics education ended in high school (though I did have a college level Intro Astronomy course that included some astrophysics). I've tried to follow the dark matter/dark energy debate, within physics circles, as well as a layperson can, and I do keep a current subscription to Nature, which is probably one of the few subscriptions I actually read with any regularity. Still, I am well aware of my likely ignorance in the subtleties, particularly when it comes to defining what would qualify as either dark matter or dark energy.

A few things have come to my attention recently, though, and I wonder to what degree these have been integrated into the physics mainstream? One, I read recently (and I wish I could recall exactly where) of an astronomer in (Georgia?) whose main project has been to complete a detailed census of objects within 10 parsecs of our solar system.

Among the survey's more interesting findings have been a much higher than anticipated concentration of "relatively" dark bodies, including brown and red dwarfs. I've long wondered just how much of "dark matter" is simply ordinary matter that is not particularly luminous -- interstellar dust clouds that we do not pick up because there is no nearby star (or no star poised between us and the cloud) to reveal the existence of the matter in question. I'm sure this still leaves room for all sorts of other exotic particles, energies and whatnot, but if our assumptions about the composition of local space are significantly "off" it only stands to reason that some of this reassessment may be useful in recalculating our estimates of existing matter in the universe as a whole, and in particular sections of it.

I also seem to recall reading recently that some investigators have questioned the calculations that led to the fairly recent assumption that there was a need for "dark energy" above and beyond the fairly accepted premise of needing dark matter to explain accelerating universal inflation.

I've always tended to assume that "dark matter" etc. was a sort of "placeholder" value that astrophysicists used to account for effects and motion that would otherwise not be consistent with current theories of physics. It is always good to remember that multiple possibilities are open -- yes, the theories might be wrong (though it seems unlikely they can be entirely wrong -- Newtonian mechanics continues to be a perfectly valid way of predicting outcomes under most conditions, relativistic mechanics only have a noticeable impact at the extremes. Any future revisions are far more likely to apply to the extremes of the extremes than they are to entirely replace both Newton's and Einstein's theories.

But, because nothing is ever entirely certain, it remains both wise and accurate to regard both Newton's and Einstein's laws in some regards as "theoretical." Observation so far continues to bear them out.

I suppose I regard "dark matter" etc. as hypothesis rather than theory, and unless I'm mistaken, so does the rest of the physics "establishment." It is unfortunate that human frailty enters the picture and often prevents a revolutionary thinker and his theories from gaining general acceptance, but it is also understandable. I'm in no position to judge the merits of this "Electric Universe" concept (though it seems to me to be taking many self-evident aspects of physical reality and if I understand it correctly quite probably overextending them). For instance, I wouldn't deny that some weak electromagnetic forces apply across great distances, but the greater the distances, the more the inverse squares "law" tends to apply, I would think, implying that there impact would most likely be marginal at best. As for electrical current, wouldn't that be generated (and dispersed) locally, around those objects most likely to generate electrical fields, namely spinning objects with large iron cores, such as the Earth and some other planets, and most stars (and especially dim and basically dead ones . . . brown dwarfs or even deader stars that have converted all their fusionable matter to iron?)

Perhaps I just can't follow the argument being made, and, to be honest, I don't feel equipped to make such evaluations given my current degree of (or lack of) expert knowledge in these areas. The best I can do is to read the abstracts of relevant research as it comes out and try to remain somewhat aware of where the generally accepted "gray areas" happen to be.

VanderL
2004-Feb-27, 07:55 PM
Well, Ebbixx
I can only say that your thoughts and comments ring very true to me. The estimates that led to the "missing matter" theory could be off, but since no major change in the estimates has occurred in 70 years, I guess that the matter will stay missing. Whether the theories are wrong and need to be replaced, or whether some exotic stuff will be responsible for the behaviour of the visible (measurable) matter, ultimately it will lead to a better understanding of how the Universe works. The electric model is just that, a model and it needs to be proven to have merit (and this seems unlikely as the electric topic shows). Keeping an eye on the "grey areas" is exactly what will help us move towards this understanding, so my guess is that you're on the right track. Just keep asking questions, and make sure that we "assume nothing".
Cheers.

antoniseb
2004-Mar-01, 05:53 PM
I'm fairly new to the Universe Today forum, but thought I'd add my thoughts on this popular topic:

Dark Matter - Something has to account for the gravity observed in galaxies. I haven't bought into the MOND theories yet. My understanding is that a major candidate for dark matter is some fairly heavy elementary particles that do not often interact with proton, electrons, etc. These might be the lightest supersymetric particle [if it exists]. These would have to have little enough kinetic energy that they are mostly orbiting around the galactic centers, and not free [neutrinos are not bound, and fly around at near light speed]. I am very willing to believe that supersymetric particles existed and devolved to these things during the first seconds of the univers's existence. Those were hot times that we'll never see again.

Dark Energy - I look forward to knowing what is accelerating the expansion of the universe. Right now, I have trouble picturing anything doing this, but the evidence that it is happening seems pretty clear cut.

ebbixx
2004-Mar-05, 12:45 AM
Has anyone been discussing the (fairly recent) "ghost condensate" hypothesis, that some claim may offer an all-in-one "entity" that would account for both the presumed effects of dark matter and dark energy?

Refs:

Seminar abstract on the ghost condensate - MIT, Nima Arkani-Hamed (a main proponent & Harvard faculty member) (http://www-ctp.mit.edu/cosmo/y0304/arkani_abs.html)

Univ. Illinois at Chicago High Energy Physics lecture series - abstract Hsin-Chia Cheng on ghost condensate (http://www.uic.edu/depts/phys/talks/04/0126.cheng.shtml)

Summary of New Scientist feature article, 7 Feb. 2004 -- scroll down for feature (http://tonydude.net/NaturalScience100/Topics/Universe/5space_time.php)

I'm sure a google (or other) search on "ghost condensate" will uncover further items, more detailed as time passes. I first read of this hypothesis sometime in late Feb. '04, in an issue (7 Feb? 2004) of New Scientist.

Faulkner
2004-Mar-05, 05:49 AM
What a WIMP is I do not know.

Well, I believe it's the opposite of a MACHO! :P (PS: What's a "macho"?)

Ebbix, those links look real swell & I'm gonna take my time with them...

I believe "brane (epkyrotic) theory" has a simple answer for dark matter. Whether it's true or not is another matter. And what it says about dark energy is another matter again. "Dark matter", supposedly, is the "watered-down" gravity from matter in higher (and bigger) dimensions than our 4D Universe.

In other words, there is a whole Universe sitting right over the top of ours, and gravity is the only connecting force.

So say the "experts" (not me!)....

Ah, hell... Too many theories, not enough FACT!!!

GOURDHEAD
2004-Mar-05, 02:00 PM
In other words, there is a whole Universe sitting right over the top of ours, and gravity is the only connecting force.

What, in this context, is the meaning of "top". Such a semantic quagmire!! Why do the mighty thinkers founder in delusion! Why is Occam's razor given over to corruption! Why have the seekers of truth gone awhoring after fantasy and given themselves over to pseudological epicycling!!

:rolleyes: It's OK. I'll survive. Don't worry. I have been influenzed by Isaiah and Elijah. :rolleyes:

Manchurian Taikonaut
2004-Mar-05, 03:23 PM
Not only gravity, but the dark energy anti-gravity

http://www.site.uottawa.ca:4321/astronomy/...nomicalconstant (http://www.site.uottawa.ca:4321/astronomy/index.html#astronomicalconstant)


Newton's gravitational theory was inconsistent with relativity; in order to resolve this problem, Einstein replaced Newtonian gravity with the theory of general relativity (GR). GR predicted that gravity could be generated not only by mass but also by pressure - and that negative pressure could produce repulsive gravity. Unlike negative mass, negative pressure is not forbidden by any theory of modern physics, so repulsive gravity became at least a theoretical possibility.
::

SCIENTISTS BELIEVE ANTI-GRAVITY ACCELERATES UNIVERSE
> FULL STORY:
http://www.astronomynow.com/breaking/9906/...grav/index.html (http://www.astronomynow.com/breaking/9906/01antigrav/index.html)
>
>



::An important adjunct to the debate over the Hubble constant is the notion that the universe cannot be older than its older stars, which appear to be those in globular clusters, spherical clumps of hundreds of thousands or millions of stars found near and around our galaxy

http://www.space.com/scienceastronomy/hubb...ion_030410.html (http://www.space.com/scienceastronomy/hubble_expansion_030410.html)



Ars reader D. Gaede noticed something in this CNN article that slipped my eyes earlier: Boeing is purportedly working on an anti-gravity propulsion engine. The article is actually just a glimpse into the world of so-called black technology -- tech research "secretly" funded by the US government. In it, however, the author considers the tensions between military development and public knowledge, between governmental silence and commercial deployment.

"GRASP," or Gravity Research for Advanced Space Propulsion, was only recently reported in Jane's Defence Weekly, but the U.S. military may have had the technology for years.
::

http://www.princeton.edu/~chirata/mmr/m020701.html

Faulkner
2004-Mar-05, 05:25 PM
Boeing claim that "GRASP" was merely the name of a paper submitted at a conference, not the codename for secret "anti-gravity" research. (See here (http://www.space.com/businesstechnology/technology/gravity_research_020731.html))

Also NASA experiments in this area, despite some promising results at the start, still remain inconclusive...apparently...

So who knows what really is going on? So much secrecy, disinformation, contradictory statements, etc....

antoniseb
2004-Mar-06, 05:24 PM
Originally posted by Faulkner@Mar 5 2004, 05:49 AM
> What a WIMP is I do not know.

Well, I believe it's the opposite of a MACHO! :P (PS: What's a "macho"?)

WIMP is a Weakly Interacting Massive Particle. This would be something that interacts less often than neutrinos, but weighs more than a proton. We have no proof that such particles exist, but proof would be hard to come by. Many proposed particles fit this bill. The current favorite of theorists is the Neutralino which is the lightest decay product with a supersymetry quantum number that is non-zero.


MaCHO is a Massive Compact Halo Object. This is any of a class of object originating from familiar matter that are dark, and drifting around the galaxy. Examples are old-cold neutron stars, free planets, black-holes. Red dwarfs so dim they can't be seen, very old white dwarfs, unpaired socks from my laundry.

Note that the WMAP data implies that only a small fraction of the missing mass can be composed of MaCHOs, the bulk must be WIMPs of some sort or another. Studies of micro-lensing events draw the same conclusion, i.e. there are MaCHOs, but not enough to account for the speed of stellar orbits around the galaxy.

VanderL
2004-Mar-07, 12:03 AM
That's really neat don't you think? On the one hand there is the assumption of a particle that we can't measure with our instruments, on the other is matter that we can measure, but isn't there because we assume that gravity is the only force acting on cosmological scales.
How to proceed?

Cheers.

GOURDHEAD
2004-Mar-07, 08:31 PM
Here's a quote from my input to a thread in: -> Everything Else in the Universe-> Cold or Hot. Is it true that the driving force for estimating the dark matter is to satisfy the condition that omega must equal one ?


Let's examine this problem from the most basic observations we know about.

The emotional factor that makes dark matter appealing is that we would like the universe to neither collapse nor cool (thin out) to an extremely small density (i.e., discover an omega equal to one). Lay this aside; the universe can't care at all.

The observed phenomenon that we are trying to explain with dark matter is that stars in orbit about galaxies and galaxies in orbit about their groups and clusters of groups have a line of sight velocity component as observed on earth as manifested by the blue shift of the atomic spectra that seems too high for the gravitational field associated with the presumed mass of the objects. Also, I assume the tangential velocity of the peripheral stars/galaxies is somehow not commensurate with that of the stars/galaxies orbiting nearer to the respective mass centers; although I have not seen this concluded/stated by an expert in the field.

Where can one find definitive quantitative analyses that present the details of this dilemma such as: galaxy XXXX with mass YYYY megasols has peripheral stars with tangential velocity VVVV where velocity V'V'V'V' should have been observed? Are the observers certain that gravitationally coupled stars in various star cluster sizes in the periphery have not added their cluster orbiting velocities to that of the orbiting star cluster center of mass. In the galactic periphery their mutual gravitational attraction could be more overwhelming than that of stars closer to the mass center (and therefore subject to cluster disruption by the gravitational effects of the galactic mass center) due to their distance from the galactic center of mass thus generating more star clusters in the periphery. A similar argument applies to galaxies with respect to their groups and groups with respect to their clusters etc., Emission spectral line broadening should be an indication of peripheral star clustering since a number of stars in the cluster will have receding velocities within the star cluster while others will be traveling such that their star cluster orbiting velocity will have no line of sight to earth component.

Is the distribution configuration of the dark matter such that it is additive to that of the center of mass of the visible matter? Does guessing at a larger mass for the galactic central black hole assist in the resolution of this problem? How does assuming that the dark matter hovers just outside the galactic halo in either a toroidal shape or a spherical shape help? Would the axiomatic constancy of the speed of light result in light coming from a star inside the dark matter shell cause it to be blue-shifted as it traveled toward the shell and subsequently red-shifted after it has passed through the shell and is on its way to earthbound observers?
Is the shifting required to be symmetrically distributed?

Do we have substantive evidence for dark matter or do we just hope it may be there to support a favorite "set of epicyclic musings".


Can anyone answer the questions?

antoniseb
2004-Mar-07, 10:05 PM
Originally posted by GOURDHEAD@Mar 7 2004, 08:31 PM
Can anyone answer the questions?
Personally, I'm not offended by cold dark matter. Something happened in the first few seconds of the universe that must have produced a lot of very high energy particle interactions. I can believe that 80% of the matter in the universe is stuff that can't be seen because the universe is now way to cold and empty to light it up.


Where can one find definitive quantitative analyses that present the details of this dilemma such as: galaxy XXXX with mass YYYY megasols has peripheral stars with tangential velocity VVVV where velocity V'V'V'V' should have been observed?

There are frequent articles in arXive concerning this sort of thing. Typically, they look at a nearly edge on spiral galaxy and measure the red-shift on many small zones. Most of these articles recently have focussed on the implied dark mater distribution from the measured velocities. The zones avoid confusion with stars with less line-of-sight motion.


Are the observers certain that gravitationally coupled stars in various star cluster sizes in the periphery have not added their cluster orbiting velocities to that of the orbiting star cluster center of mass.

Most of these studies look at large groups of stars, and so a a few close binaries would not alter the result. Also, for scale, note that the sun goes around the galaxy about 8 times faster than the earth goes around the sun.



Is the distribution configuration of the dark matter such that it is additive to that of the center of mass of the visible matter?

Yes. Cold dark matter is graviationally bound to the galaxy or cluster. Typically, a significant fraction of it is close to the center of the galaxy. There are loads of papers about this. They are a little heavy on the math. I haven't yet bothered plowing through the analysis, just the discussion and conclusions.


Does guessing at a larger mass for the galactic central black hole assist in the resolution of this problem?

No. The central black holes of galaxies are very small in mass compared to the total dark mater of the galaxy. Our galaxy has a central black hole of about 3 or 4 million times the mass of the sun [if you include matter that hasn't quite fallen in yet]. The mass of the galaxy is about 300,000 times that much.


How does assuming that the dark matter hovers just outside the galactic halo in either a toroidal shape or a spherical shape help?

I don't think that would help. The observed velocities are best explained by a smoother distribution, increasing in density toward the center of the galaxy.


Would the axiomatic constancy of the speed of light result in light coming from a star inside the dark matter shell cause it to be blue-shifted as it traveled toward the shell and subsequently red-shifted after it has passed through the shell and is on its way to earthbound observers?

Yes, light is blueshifted as it falls into a gravitational potential well. This is a small but measured affect. I didn't really follow what observation was intended to be explained away with this.


Do we have substantive evidence for dark matter or do we just hope it may be there to support a favorite "set of epicyclic musings".

I'd place it as better than epicycles, but still waiting for some unambiguous physical data. The fact is that the implied density of this matter can be measured in clusters and galaxies through a variety of means such as lensing and velocity studies. These measurements will become increasingly accurate in the years ahead, and if they require some hard to swallow ideas to explain what we see, new ideas will be advanced. So far WIMPs of some sort or another are doing great at supplying a plausible explanation with the fewest rash assumptions. Hopefully some kind of accelerator experiment will start turning up super-symetric particles soon, or some other direct cosmic detection of supersymetric anihilations will be seen. Until then, we are talking about the most plausible model to explain something that the material we see can't explain.

VanderL
2004-Mar-07, 11:42 PM
Suppose dark matter doesn't exist; no exotic particles will be found and all the dead stars are accounted for and still don't add up to explain the orbital behaviour of galaxies. Do we have a plan B, that would have to be evaluated as a next step? And if we have a plan B, maybe we could discuss that one first (MOND comes to mind, but I haven't heard much about it lately).
I'd hate to wait 50-odd years until we exhausted every possible way of proving something that doesn't exist.
Anyone?
Cheers.

antoniseb
2004-Mar-08, 03:28 AM
Originally posted by VanderL@Mar 7 2004, 11:42 PM
Do we have a plan B
The journals are full of ideas being explored, including a few MOND articles every month, plus things that deal with the gravitational influence of nearby parallel universes. There are other ideas that I see expressed to, which to my eye seem like crackpot ideas, but that doesn't rule them out. Some of them are pretty entertaining reads.

People love thinking about this stuff, so there is no shortage of plan B material.

Going back to your original question about flat omega, that's another option.

Currently, however, I'd have to say that for observation matching theory, and theory predicting observation, the LCDM theory is worked out to the greatest level of detail of all options present so far.

ebbixx
2004-Mar-08, 05:56 AM
Originally posted by Faulkner@Mar 5 2004, 05:49 AM
I believe "brane (epkyrotic) theory" has a simple answer for dark matter. Whether it's true or not is another matter. And what it says about dark energy is another matter again. "Dark matter", supposedly, is the "watered-down" gravity from matter in higher (and bigger) dimensions than our 4D Universe.
Those who've forwarded the -- let's call it a ghost condensate hypothesis, in the hope of retaining some clarity -- are not prepared to contend that this is or isn't the explanation for all those observations that have tended to be accounted for by the intentionally vague terms "dark matter" and "dark energy." I think their only claim is that a "ghost condensate" would serve as a sort of unified factor that could account for all of the unanticipated anomalies. While logically attractive, and, if it stands, perhaps a better "answer" at least in terms of applying Occam's razor, until it can be relatively proven by some of the proposed tests that would potentially prove or disprove its existence, it remains at the very most a hypothesis, a classification which I expect it's originators would agree with wholeheartedly.

No scientist I know of likes to wind up with egg on their face because they jumped the gun and declared a problem solved or a question answered, without adequate proof. Despite what by now have been many observations that support the theory of special relativity, physicists and astronomers continue to seek additional confirmation, and also at least try to remain open to the possibility that another theory might one day take the place of the present hybrid we use of Newtonian mechanics and relativity.

I have trouble wrapping my head around the idea of "brane theory" but I'll be certain to look for current studies etc.

Faulkner
2004-Mar-08, 12:34 PM
Do we have a plan B

No, but I've got a "Plan 9 from Outer Space", buddy! :P

The trouble is, how are we to differentiate between crackpot theories & "science"? I think "science" is an ambiguous term. Just look at quantum mechanics, string theories, etc. I won't mention relativity theory because I believe you can follow that through in a logical way (if you're smart & patient enough; I'm not! :P ). But these new "esoteric" scientific theories defy common-sense and don't even TRY to paint a rational picture in our minds.

But we believe in them...because they come from a physics journal, or something...even tho' they are stating outright absurdities...

I've read MANY physicists saying how they know if they're on the right path, because the theory is "aesthetic" and "feels right". String theory is an example. It is mathematically "beautiful" (so they say, I wouldn't know!)...

antoniseb
2004-Mar-08, 03:17 PM
Originally posted by Faulkner@Mar 8 2004, 12:34 PM
But we believe in them...because they come from a physics journal, or something...even tho' they are stating outright absurdities...
:) Yes, a lot of the theories seems pretty wacky. I agree that being elegant doesn't make it real. I prefer reading papers that describe what we are seeing, and provide concrete ways to describe it. I find the popular articles that try to summarize theories and explain String [or M-Brane] thoeries, or describe collapsed coiled dimensions in layman's terms kind of off-putting. These articles hide real science work being done.

Here's a pointer to an article describing Dark-Matter Halo Structure (http://www.arxiv.org/PS_cache/astro-ph/pdf/0403/0403135.pdf). [requires Acrobat reader, and takes part of a minute to download] Don't be thrown off by the term [b]six dimensional phase-space. The six dimensions are simply three normal dimensions for the positions of particles, and the same three dimensions again for their momentum. It has nothing to do with stuff we can't see or measure or imagine easily.

You can see that this article pretty much assumes only that we have gravity much as Newton described it. The article describes the density of dark matter [as observed by gravitational forces] as a function of its distance from the center of the galaxy. It gives a snapshot of where we stand at understanding dark matter today, without claiming to know more than we do. A year from now more refined measurements will have allowed scientists to say a little more. Slowly the constraints on what we are looking for in the laboratory will be narrowed enough to make a successful search possible.

Arramon
2004-Mar-08, 05:00 PM
I don't think that our technology is good enough just yet to see everything thats out there.... we can see far out into the Universe, but can't really ZOOM in on any one spot other than whats in our own solar system.... and thats not even that great... I dont see any pictures of the insides of Jupiter, or topographical terrain maps of Pluto or the orbits of all the objects floating around the Kuipier(sp?) Belt... we can't even track how many comets or Death NEO's are out there, just waiting to find our little habited world.

gonna take Time... and patience... and newer technology more than likely....

Plus the courage to update any outdated theories floating around.... like is the CMB really the edge of our Universe, or just a Wave spreading out, with mores waves infront of it, like ripples in water when a stone drops into it... the waves ripple outwards... and maybe we arent the only 'dropped stone' out there....
we could be within a massive 'lake/ocean' with many 'stones' being dropped in....

=P

. ..-={A}=-.. .

VanderL
2004-Mar-18, 05:23 PM
String theory is not what I see as a "plan B", it is more an effort to explain everything at once. What I would like to know is what would happen if we assume that what we see is what we get. We can measure photons and spectra, some radiation (in 2-D) and everything else depends on assumptions. We assume that stellar movements (and galaxies as well) are only governed by gravity, mostly Newton's description of it.
When we look at how most galaxies rotate, there is something missing from the equations; mass. Either we can't see this mass (hence dark matter) or we need something else that can account for the rotation (or gravity can be fudged, as MOND would have it). There are some galaxies that do not show this missing mass component, this only deepens the mystery. Are there other ways to move matter around that are not incorporated in Newton's equations? That is the line of thought that led me to include the plasma model as a possible way to explain the missing mass. But there must be more options, I guess. I'll do some googling, maybe there is more to find.

Cheers.

Arramon
2004-Mar-18, 05:38 PM
heh... good ol' google....

I wouldn't want to think that Einstein knew it ALL.... but, he did think of equations that have stayed constant to today...
But, I'm sure that there are many things that we don't know about, and that our technology can't pick up everything.... just what our senses can perceive... Wavelengths, Spectras, etc, with the help of instruments. But I think that it may take us to actually be in the IGM to tell what it is truelly made of... maybe our instruments can't detect certain anamolies such as intergalactic gravitational forces other than how they interact with eachother, and not really how a system of galaxies may be interacting within a more vast area of clusters of galaixes, over millions of lightyears wide.... and being within our own galaxy, its kind of hard to look from the outside in, to see whats happening right here, right now, with the surround environment, while our Galactic Center may be putting certain nudges upn our instruments that may be giving us 'warped/blurred/inconsistent' answers, or answers that are not truelly 'Factual', but just hypothetical, because we can't be in the best place to view what is really there....
Astronomers throw these factors in there, to better help their equations make sense, but who's to say one factor is too much or not... or that its being used in the wrong fashion.

We're trudgin along =)

knicholson
2004-Dec-04, 06:27 AM
Dark matter is now carefully defined as matter that can only be detected by gravitational means, and not by its own or reflected radiation. Thus planets, rocks, sand, dust, gas, and other ordinary matter cannot be dark matter. It's origin is not really Fritz Zwicky, since he probably meant that what he needed was ordinary matter that he couldn't detect with the instruments he had. The most referenced paper is by van Albada et al (1985), and they tried to find the mass distribution in NGC 3198, by first assuming an exponential mass distribution for the disk. When that did not produce the rotation speeds to match experiment, they added spherical shells centered on the galaxy and called them dark matter, since no such shells could be detected (then or since). Since they are quite bright, and probably knew they were making a mistake, dark matter may be a hoax.

They probable wanted to add the extra mass needed in the plane of the disk, but didn't know how. Actually gravity would cause such shells to collapse into the disk.
When done right Newton's law works fine and dark matter is not needed to find the mass distribution in the disk that causes the rotation speeds (www.galaxymethods.net).

It is a fair bet that dark energy is also the invention of someone that made a math mistake.

Arramon
2004-Dec-06, 03:37 PM
What if the invisible force keeping a galaxy in it's form is what's coming from the supermassive blackhole at it's center... the pressure in the middle could be sucking at in extreme force, and releasing in extreme force, the IGM keeps the galaxies in their 'bubble' through extreme temperature changes and the blackhole expands the 'bubble' while it feeds on the star masses closest to it, expelling the heated gaseous/plasma that makes our Galaxies so damn hot... kind of like a helium balloon, except its one in an ocean instead of in the sky.. and the helium is ionized hydrogen. =/

Prime
2004-Dec-06, 09:37 PM
That dark energy, etc, is about the color of fudge, in the first place, in analogy.
http://community.webtv.net/hotmail.com/pri...ingsofthePlasma (http://community.webtv.net/hotmail.com/prime137/WorkingsofthePlasma)

Prime

o_r_slave
2004-Dec-07, 12:33 AM
Maybe dark matter is something from another dimention that projects into our universe and we, in our limited 3D perception, just see it as dark matter.

Essel
2004-Dec-07, 07:40 PM
Hi All,

I have some observations and some questions too.

Dark matter:

1. Just consider : a) Our inability to detect even massive planets around nearby stars sometime back, it is only indirect method of detecting the wobbling caused by gravity that is helping us now to detect them B) Sedna and other objects beyond Ku belt are being discovered so late c) many more dwarfs are appearing in the vicinity than earlier expected. So in short we are all learning and finding many more objects in close proximity to our solar system itself. Their mass may not add up much but we could not notice them till recently in such a close proximity!

2. We are located in one arm of the milky way galaxy, far from its center, our understanding of what it is like at the center is limited. What we know is limited to signatures in the electromagnetic spectrum – all about active hot matter – visible or indirectly detected. The occurrence of cold dead and simple matter, as simple as Iron (not exotic elements) may be very high there – at the center of a galaxy. We know the celestial void is just too large between active stars, just imagine how many dim and dead matter like dead stars can fit in between?

3. Has anyone actually counted hairs in the scalp? It is very homogeneous and therefore we can count a Sq cm and extrapolate. What about a balding person like me? I hope the same method is used to calculate the number of stars in a galaxy. The sun is unfortunately near the balding patch. When we look around the sun, which is not at the center of the galaxy, we could always go wrong in our calculation for the mass of milky way by a large factor.

4. Only recently we have figured out that there is something as large as double the size of the moon that would have been visible if we had x-ray eyes.

So we have a milky way that has large number of visible stars, radio telescope visible stars and dead/cold/feeble IR detectable stars. In addition we have lots of ‘dust’ like the Earth and Jupiter, which do not weigh much in our solar system but could be significant elsewhere. If some assumptions of a few decades back are reviewed afresh with new scientific inputs, will it be difficult to explain 80% missing mass of our milky way or we still have to look for exotic matter? I am not sure it may still be there! So we need to look for the exotic thing as well as not so exotic thing and review our every hypothesis on the ‘missing matter’

For my understanding can anyone update me on: If we just consider the milky way galaxy, why is extra mass required to hold it together? If its mass were just 20% of what it is, why will it fall apart? Is it required at the center or almost uniformly? Where is the missing mass more prominent as per calculations?

Dark Energy:

1. Since we have had limited scientific observation, are we so sure that the universe is expanding just by observing nine supernovae?

2. Why is Andromeda going to collide with milky way if we are all going apart? Why is cannibalism amongst galaxies seen nearby if galaxies are spreading out? At what distance this dark energy becomes prominent – beyond the distance of milky way from Andromeda for sure?

3. Why is this dark energy not affecting spreading within a galaxy? Within our solar system?

4. Can there be a form of energy which behaves just the opposite of inverse square of distance? More prominent as you go further?

Maybe we are all being pulled towards what we see as the edge of the universe as we are all part of a ripple in the pool.

I really look for some enlightenment on above.

Cheers

knicholson
2004-Dec-14, 05:04 PM
Again I recommend www.galaxymethods.net for an easy explanation about dark matter and why it probably doesn't exist.