The Cosmos

11
Apr

Who’s Afraid of the Dark? Alternatives to Dark Matter

What is dark matter?

An invisible substance thought to make up a quarter of all the “stuff” in the universe, dark matter leaves its gravitational fingerprints all over the cosmos. But despite decades of trying, scientists have failed to capture a single speck of dark matter, in part because they don’t have a clear idea of what it actually is.

But what if the solution to the mystery of dark matter is that dark matter doesn’t actually exist? What if this ghostly stuff is just a phantom of astronomers’ imaginations? Could there be another answer to the puzzles dark matter was invoked to solve?

Since the 1930s, astronomers have suspected that galaxies contain more mass that we can account for. That’s because, when astronomers clock the speed of stars circling around the center of the Milky Way and of galaxies moving in distant clusters, they all seem to be going too fast. They are going so fast that they should overtake the force of gravity tugging them inward and fly out into the void beyond. Yet something holds them back.

That “something,” most astronomers believe, is dark matter: matter we can’t see yet which has enough mass to keep those speeding stars in stable galactic orbits. But what is dark matter? Scientists have largely ruled out all known materials. The consensus is that dark matter must be a new species of particle, one that interacts only very weakly with all the known forces of the universe except gravity, with which it interacts as strongly as ordinary matter does. Dark matter is invisible and intangible, its presence detectable only via the gravitational pull it exerts.

But not every astronomer is satisfied with this interpretation. Some, like Stacy McGaugh at the University of Maryland, College Park, believe that the definition of dark matter is so slippery that it is impossible to prove or disprove. Researchers might be able rule out the existence of any specific conjectured form of dark matter particles, but “we cannot falsify the concept, so if one fails, we are free to make up another,” says McGaugh. “This cycle can be endless — as long as we’re convinced as a community that it has to be dark matter, we won’t take alternatives seriously, but we can never be disabused of the concept of dark matter.”

Instead of relying on mystery particles, a small community of researchers suggests an intriguing alternative: What if the answer lies in changing what we know about the laws of gravity? The leading alternative to dark matter is known as Modified Newtonian Dynamics (MOND). The assumption is that at large scales, the laws of gravity are different from Einstein’s theory of general relativity. “MOND merely tweaks the way a known force, gravity, works—we don’t have to accept that the universe is filled with invisible mass,” McGaugh said.

In general, by tweaking Newton’s laws of gravity when it comes to orbits at large scales, MOND predicts the velocities of stars within galaxies even better than dark matter does. “It works so well it seems there must be something to it,” McGaugh said. MOND works especially well on a class of galaxies known as low surface brightness galaxies, very faint galaxies without bright centers, explains theoretical cosmologist Priyamvada Natarajan at Yale University. “It’s better than dark matter at explaining the rotation curves of these galaxies, the speeds at which stars in a galaxy orbit the center.”

However, critics point out that dark matter beats out MOND on other astronomical puzzles. “The biggest problem is perhaps clusters of galaxies—though MOND works well in individual galaxies, it doesn’t fit clusters terribly well,” McGaugh said.

In fact, even with MOND, there is still a need for dark matter. “The need for dark matter in such a theory is horrible,” McGaugh said. “On the other hand, it is a fairly limited problem in scope—we believe there is more than enough ordinary matter in the universe that is yet undetected that would easily suffice to make up the difference.”

Skeptics of MOND, however, point at the Bullet Cluster, two colliding clusters of galaxies. There is a clear separation of luminous and unseen matter seen there exactly matches what one would expect with the dark matter model—dark matter, being largely intangible even to itself, would “feel” the forces of the collision very differently than ordinary matter. MOND advocates say that although unseen matter could be involved, it might again be unseen forms of ordinary matter.

Maps of the cosmic microwave background—radiation left over from the Big Bang—also provide strong support for dark matter. Temperature aberrations seen in the cosmic microwave background seem to reflect the presence of both ordinary matter, which interacts with both matter and radiation, and dark matter, which influences matter but is essentially invisible to radiation.

So MOND advocates have a difficult task: Their theory must explain all the puzzles that dark matter has already solved, and it must present a new way of accounting for everything Einstein’s theory of general relativity currently explains. For instance, general relativity proposes that matter and energy curve spacetime, creating the effect we know of as gravity. Massive bodies curve spacetime enough to visibly bend light, an effect known as gravitational lensing that astronomers have witnessed for decades. “We cannot explain the phenomenon of gravitational lensing without general relativity, and this is where MOND spectacularly fails,” Natarajan said.

“It has proven hard to construct a relativistic version of MOND,” acknowledges McGaugh. “If one is going to introduce a new theory, it has to encompass existing, successful theories.”

Meanwhile, physicists continue the quest to directly detect dark matter particles. “There are no significant results yet, but I am optimistic,” says Natarajan. “In any case, I’m quite comfortable as it is with the evidence for the existence of dark matter.”

But until physicists actually “see” a dark matter particle, researchers will continue to investigate alternatives to the dark matter model. “It could be wrong,” McGaugh says. “We do not understand all there is to understand yet—there do remain fundamental mysteries to explore.”

This is the first part of a two-part series on critics of dark matter and dark energy. Return next week for a look at alternatives to dark energy.

Go Deeper
Editor’s picks for further reading

FQXi: Out of the Darkness
Physicist Glenn Starkman is evaluating alternatives to general relativity.

NOVA scienceNOW: The Dark Matter Mystery
In this video, explore the evidence for dark matter.

Scientific American: What if There is no Dark Matter?
Could modifications to the theory of gravity eliminate the need for dark matter?

  • sean s.

    I’m sticking with my theory: that dark matterexists in other dimensions, of which there may be 9 or more (not counting time). If string theory is correct, the forces and matter in our universe are confined to our three dimensions except for gravity which reaches into all dimensions. If there were other dimensions with similar matter, their matter would exert and respond to gravity just as ours does, and this would account for the gravitational effect we call “dark matter”. Gravitational force reaches across all dimensions and connects them gravitationally to each other. But since only the gravitational influence of this dark matter reaches into our dimensions, we cannot detect the constituents of dark matter, we can only infer it’s attributes.
    Any region in one of these other dimensions filled with dark matter would manifest itself in our dimensions as a gravitational field with no detectable matter, which is precisely how dark matter appears to us.

    • stelex

      Of course that rules out the possibility of ever detecting dark matter in our space-time dimensions, which makes all the research on detecting particles of dark matter futile – which I’m not entirely willing to accept yet. It may be that we just can’t probe at the correct energies yet to detect dark matter, or a combination of both (it exerts it’s influence but can’t be detected due to its existence only in other dimensions as sean s. points out) or neither. Who knows. Hopefully we will have an answer to this in the next decade, or in our lifetime.

      • sean s.

        Stelex, if my guess is correct, yes we can never actually detect it directly. But as we’ve already seen, we can detect it indirectly already, which ability may increase over time.

      • http://www.facebook.com/profile.php?id=526516626 Aneesh Lohani

        If gravity is leaking into other dimensions, LHC’s may, hopefully, be able to detect missing mass in particle collisions. While this would not be a litmus test for the existence of gravitons to explain what dark matter could be, it would surely point out that somethings can seep into the unknown. The unknown could be extra dimensions.

        We don’t have a great deal to go by! The ideas of string theory are as bizarre as the very simple, yet bizarre, idea that certain kinds of matter do exist, but you simply can’t detect it.

    • Hentroisry

      More hooey.

    • http://www.facebook.com/profile.php?id=526516626 Aneesh Lohani

      This is exactly what I think also. It’s got to be gravity leaking into these extra dimensions that’s causing the unaccounted additional gravitational effect seen in galaxies. I also think extra dimensions have something to do with dark energy, as well.

      • coolduderino

        In M-theory braneworlds there’s an idea that gravitons are string loops which can transcend the brane while other types of particle are composed of non-loops, the ends of which are bound to the brane so they all sort of crawl around on the brane “surface” like worms but can’t ever detach their end points from it, while the gravitons disperse evenly into the rest of the multiverse, seeping out of our 3-brane and causing us to measure a much weaker force, which could also be a reason why we don’t detect the gravitons? I also wonder if dark matter will disperse the way regular matter does in such a way that in trillions of years the entire universe has faded away except for the dark matter blobs? I suppose it’s still a particle so it must decay, but do particles in other dimensions even decay, could they decay if there wasn’t time flowing in that dimension? Is that even a proper way to think about it?

  • Hentroisry

    “MOND” is far more far-fetched than “dark matter”. It is almost certainly hooey.

  • Ianfirestone

    The recent speculation about “renegade planets” (planets ejected from their stars and novae) in galaxies, possibly outnumbering suns up to 50,000 to 1, might well account for a significant amount of “unseen” matter, especially as they are traveling at greater velocities than most orbiting planets. I am surprised there is not more scholarly dialogue connecting the two phenomena.

  • http://pulse.yahoo.com/_V2OMT4S4EBFMCSCYWHEGHUXJRI Jay

    To me, its all science fiction until they sort it out, although, sure, I’ll still give my weak support for dark matter (or even MOND) in the meantime. Since I’m not an astronomer, I’m not sure it matters that much. As long as the general public understands the issues of dark matter and dark energy, I’m fine. The issue, of course, is that we have no freaking clue what they are, or if they really exist, but we do see interactions that prove something isn’t behaving as it ought to per our understanding of gravity, requiring either modification of the law of gravity or the existence of something yet *unseen* (where “seeing” encompasses a spectrum a far greater than just the visible spectrum). There is certainly mystery involved, but this isn’t sorcery or paganism. I don’t know how well that message has been relayed, in general, but it’s good to see stories like this to relay it!

    • Pantheory Org

      As to dark matter and the luminiferous Aether (LA):

      My own cosmological model proposes a MOND-like formulation of gravity that “comically” explains what they perceiving to be the additional bendings of light now attributed to dark matter as gravitational lensing, as being caused by vortex currents of aether surrounding galaxies. The same orbital mechanics of spiral galaxies in the same way would be greatly influenced by the spiraling inward currents of aether which would be the cause of both gravity and the carrier of EM radiation, having different gravitational equations and mechanics.

      Why did we not find this aether in the last century? The number one reason would accordingly be that aether flows into the Earth and all matter rather than having a perpendicular speed relative to the Earth. The Michelson & Morley-like interferometers were looking for a change in the speed of light which would not exist if the aether were the cause of gravity and therefore gravity centered. Secondly their equipment was not sensitive enough to detect the actual aether speed even if its design enabled the equipment to be able to look up vs. down concerning the speed of light.

      So my belief is that the LA will finally be discovered as evidenced by what was considered to be dark matter observations such as gravitational lensing,. while dark matter and dark energy will eventually be unneeded for any explanation, gradually being replaced in text books by far simpler explanations not requiring unseen particles or forces.

      • Dan

        Newtonian mechanics doesn’t even work well on a three body problem, much less 1 billion+ stars in an elliptical galaxy (or 2 or 3+ billions in a galactic collision! So, I’m not a fan of MOND as an explanation. Doesn’t a rigid disk (even a very, very thin one) spin with v = omega * r (flat v vs r curve)? What if mutual gravitational attraction between billions of gravitating bodies is all that is keeping the rotation curve flat? That isn’t Newton or Einstein, just common sense. Or perhaps, the (interstellar gas + dust + planets + planetoids + wandering black holes + a few thousand neutron stars) actually make up more than 0.9 of the total mass of a galaxy. Is that really such a stretch that we need something like dark matter to explain it? Go show me a chunk of DM you found in the Earth’s crust, and I’ll believe it.

        If you were looking at our own solar system in the Milky Way from directly above the Sun’s North magnetic pole, and the light coming from Jupiter happened to be traveling in a direction opposite that of our solar system orbiting the galactic center, that refelected light would totally mess up any Doppler Red shift measurements of the direction the whole system. Binary stars likewise would muck up any Doppler shift measurements, big time.

        Unless you are Edwin Hubble, any Doppler Shift you measure is only an inertial (acceleration) measurement, which gives no clue about the actual velocities involved unless you have complete odometry of the object you are observing since the beginning of time. Don’t Astrophysicists need to study basic calculus any more?

  • Kalderete1

    The problem with this is that it assumes that every theory that is now currently accepted is correct. We have seen time and time again that universally accepted theories can be disproved. Perhaps it would make more sense to throw out all known and accepted theories and start from scratch utilizing the knowledge and technology of recent times instead of relying on theories created before much of what we do know had been proved. Then again, such uncertainty would leave us hurtling through space without a tether and no one wants to do that!

    • Rankinbeard

      The problem here is that the currently accepted theories do work. They explain everything BUT dark matter.

  • Jason B

    both theories sound like mathematical gymnastics.. if the equation fits, it must be legit!? there has to be a more simple and elegant answer

  • JustTryinToHelp

    One grammatical error in a scholarly paper published at this level is ok, but Two?… Not to detract from the subject matter or the scientific minds responsible, but I suggest checking it twice next time.

  • Vvaivo

    The scientiffic community rushed into the “Dark Matter” explanation unadvisedly and put the cart in front of the horse. Let us instead follow logically what we know, instead of making assumptions.
    1) To call space curved is a misnomer. Space is a scalar field, with no direction, how can it curve? Space has only one property, and that is spaciousness, or strength of field at any given point. It is the only thing that there is that can change. Gravitational fields are regions of variation in this strength of field, forming field gradients, and it is this gradient that we see as exerting a force on matter and light.
    2) It is by no means known or proven that a variation in spce field strength is caused by matter only. To the contrary, vast regons of space have been mapped that produce optical distortion without any presence of mass. Why make an unnecessary assumption of the prsence of a “Dark Matter”, when the actual observation indicates a zone of variation in the strength of space field energy? Space is a manifestation of energy in its own right and does not need matter to justify it.

  • http://www.facebook.com/cjbrens Carlos Brens

    So, if Dark Matter (and energy) is going away in the same manner the Luminiferous Aether ceased to be in vogue, it just means we were guessing (albeit educatedly) in order to make up for some incorrect calculations and theories about how matter and space really behave. We can guess some more about “extra dimensions” and infer that energy and matter pass between the ones we know and the ones we will most probably always fail to verify or experiment upon. That won’t get us any closer. That answer will be a theory that is both sound and testable. That is, until we find that it too has some subtle problems, as Relativity turned out to have. MOND seems to be anything that seeks an alternative or perhaps an adjustment of not just the Newtonian model but of the Einsteinian model as well. I had hoped that Julian Barbour’s work would convince more people by now that eliminating Time in both the Newtonian and Einsteinian sense would solve the problem of having to come up with the Dark Matter/Energy chimera.

    • sean s.

      As of now, there’s no sign Dark Matter is going the way of the LA. There are doubters, there are ALWAYS doubters.

  • Vvaivo

    Mr Carlos,
    right on. I think the mainstream is barking up the wrong tree because we started off with misconceptions about space(and time). Isn’t it obvious that everything in the universe we know came from the burst of energy called Big Bang, That goes for space too. As for time, the more one looks for it, the more elusive it becomes. It has no energy, it exerts no force. It is a human observation of the rate something occurs in comparison to another series of events, for instance of our clock ticking. This observation is a strictly local correlation, this rate being dependent on the strength of the space field strength of locality.

    • http://www.facebook.com/cjbrens Carlos Brens

      The most interesting thing I find about the elimination of time is that it can correct for the observations of the trajectory of light (not a fully relativistic speed nor a universal clock-work scheme like Newton’s), which seem to indicate the universe is expanding more rapidly than we can account for. If I got it right, it preserves the gravitational “lensing”, but adjusts and accounts for all the “bending” light makes, which influences our measurements of distance and speed of galaxy recessions.

  • Vvaivo

    Come come, all you fine gentlemen! You have already distinguished yourselves by reading and commenting on a subject that is a total blank for 95% of the populace. For those who take this opportunity to knit pick on spelling and grammer, I say, not all thinking is done by english speakers and in english; could we focus on the ideas? For many others I say, using other dimensions or parallel universes to explain what otherwise they can not, is a cheap way out. It is like the proverbial magicians stone, makes all possible. There is just one thing wrong with it – no one has ever seen one. The scientific enterprise is an act of inquiry, not a voting event, as some of you have chosen. The subject of gravity, space, time, and energy is a fascinating field for thought and it is within reach of all of you, no expensive machinery needed. It is said that Einstein had two pieces of equipment to accomplish his monumental work, a blackboard and his pipe. The most complicated, sophisticated device we know of is the human brain, and each of you has one, Use it! In an earlier letter I made clear statements offering an alternate explanation to the question of Dark Matter. If despite my intent, it is not comprehensble, I will be glad to elaborate. If left unchallenged and left as true, it makes other speculations mute. If you think it is not true, please tell me where my error(s) are. Many years ago, I came across this saying, and have cherished it since: “Debate is the fire in which we temper the steel of our truths.” So, hammer away.

  • Vvaivo

    To Jay I say,
    you seem to have both feet firmly on solid ground; much that is being offered is wild speculation, or as you put it, SF. You got it right, there is not a shred of real evidence for the existance of Dark Matter, most likely because we made it up from a misleading label used for an unknown cause. That being the case, why not look for alternatives that might advance our understanding of reality? What the general public knows or believes does matter in that eventually money for reachearch comes from them, and keeping them informed and involved is necessary on that ground. As to what difference new insights in fundamental nature of reality may make, we wan’t know until we get there. Atomic energy, lasers, MRI technique are a sampling of previous results. But, we have to work on t, Answers will not fall into our lap unless we ask the questions and then search. And, we have to ask the right questions.

  • Neil1236

    I think the astronomers are misapplying Newton’s Gravitational Formula when estimating the mass of a galaxy from the “rotation curves” which show that the speed of rotation is often nearly constant at various distances from the center of a galaxy, like 250 kilometers per second.

    A sphere of mass M can be shown (via advanced calculus) to have gravity that is exactly equivalent to the gravity of a point-mass M (excluding all points inside the sphere). But galaxies have many shapes, few of which are spheres. I think astonomers are misapplying the “sphere gravity” formula, thus overstating the mass of a tyical galaxy, which overestates the amount of dark matter.

    Dark matter may still be “required”, but less is required than they think.

  • Keith

    I definitely agree that it could be wrong. I think “dark matter is the 21st century equivalent of the “luminiferous aether” of the previous century. Nobody has ever found any of this substance. We have a pet theory that we want to work and we will invent any substance that is necessary for that to happen. Bottom line: if you can’t find it, it probably does not exist. A theorist should be required to demonstrate proof and not the other way around. I think we need to examine the evidence more closely using alternative (known to exist) possibilities before we invent fictional ones to make all our numbers add up the way like.

    • Vvaivo

      I concur, the assumption of dark matter, and the long fruitless search for it must be a wrong trail. My suggestion is to change our view of space from the passive one manipulated by matter, to one that accepts space as a form of energy with properties of it’s own and acting independently from matter, although reacting to it.

    • The Watcher

      Agreed. Although I think this sort of thinking has run riot through out cosmology.

  • http://www.facebook.com/profile.php?id=1004345945 Anonymous

    The answer lies probably somewhere in the middle.

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  • Anonymous

    I am privileged to be able to sense dark matter in two ways.
    First I can see the gravitational lensing effects and star rotational effects in and around galaxies.
    Second I feel it physically in my body. I sense it as something like a continuous orgasm.

    • The Watcher

      O.o Surely you jest…

  • Morbas

    And what of a basic physical Bremsstrahlung property that prefectly accounts for the Hubble Red Shift as non-doppler, ehh? This also solves the dissagreement between geoligic hot-cold cycles at 134M-year intervals, unifying the Geologic strong 417M-year signal, into a beautiful expression of the MW Galaxy. I have yet to see a Bremsstrahlung critique, is this a paridigm issue. BB may be invalid.

    • Vvaivo

      I have heard of many things, but not of how Bremsstrahlung explains the reddening of remote galaxies, my shortcoming of course. Would yow be kind enough to post a brief explanation please? Ditto for the long term cycles you mention. Perhaps there are others as well who would benefit from this information. Thanking you in advance, VV

  • Anonymous

    I thought that the Higgs Boson was being considered as a candidate for the Dark Matter – or perhaps even aether particle? I am not a scientist but have a keen interest in theoretical physics and find myself always wanting to ask whether the anthropic principle or language itself creates conceptual barriers to new directions. They may not, but I think it is useful to ask this question when we are stuck just to eliminate the possibility. I would really enjoy thoughts from the scientist posters here regarding this idea as it relates to the concept of dark matter.

    With regard to aether. I have always been comfortable with the concept of curved space-time until I learned that movement, rotational movement in particular, can affect it. I can’t remember the name of the experiment but a satellite was sent into orbit around the earth to detect if there was a measurable drag on “space” created by the rotation of the earth. And indeed there was. The southern axis of this satellite – closest to the earth – tilted toward the direction of the earth’s spin. This experiment made me think of space much more as a physical object than I had before and I think this experiment lends some credence to the notion of space itself being more of a ‘substrate substance’ for the regular matter we perceive in the universe. I always thought space-time curvature was related only to the accretion of matter at a certain point. I didn’t know that space could be ‘pulled or dragged’ by the motion of matter.

    So if space behaves in some ways like a tangible substance, is it possible that space itself contributes a measurable amount of gravity to any given system? Is it possible that it is not Newtonian Dynamics of the very large whixh needs modification but general relativity of the very large? I wonder if gravitational effects increase beyond the degree expected by the normal matter we can detect when there are such high densities of this matter in a certain space. And, necessarily, that the loci of of this additional gravity manifest not as fixed points but in the space between points – a substrate or glue. In light of the experiment I mentioned above, in rotating galaxies at least, is it not possible that surrounding space is being pulled inward along with regular matter? And if so, does this not strongly suggest that space itself has a specific gravity associated with it – albeit one that may be too weak to detect at smaller masses such as that of our solar system but which is quite appreciable when viewing galaxies as a whole?

    Another related idea that I think would be interesing to explore is the thought experiment of suddenly removing all regular matter from a given large system and measuring the amount of additional “space” that is gained when it is no longer curved in on itself by that matter. Take our solar system for example. We know the diameter of our solar system – the ‘space’ which it occupies. What if we suddenly remove all the normal matter from this ‘space.” The space would no longer be curved in on itself due to gravitational effects but would be larger. By a measurable amount? Let’s say yes. Another great question is whether our measurement of the size increase is relativistically bound – meaning does it change if we are inside the space versus observing from outside?

    • Vvaivo

      Since space is variable, what measure of length do you use? Such is the dilemma with relativistic viewpoints – there is no standard. I deal with it thus: divide space into imaginary light year cubes; a cube that contains a large mass has a volume that differs from that of a cube that has no mass in it. Is it more or less voluminous? My hypothesis that matter repels space would indicate a smaller volume, but I am open to contrary arguments. What we do know is that light takes a longer time crossing such space, one explanation for gravitational lensing.
      Just as speed of light is the same for all who measure, the only way to tell is to compare oneself to remote object, does it seem to get smaller or larger.

  • Vvaivo

    In reply to Anonymous:
    !) Language has been developed to describe our experiences. Current discussions of space and gravity are outside any previous concepts of said phenomenon, any attempt to describe them in the old terms is inaccurate; we attempt to form new views of gravity, we may need to evolve language to mach.
    2) Space is not a form of matter, just as light is not a form of matter. Each is a fundamentally unique form of energy, and has to be accepted on it’s own terms. It is up to us to learn what the properties of each of them are and how they interact with each other.
    3) Over any distance greater than micrometers, matter does not attract matter. Matter interacts with space so as to distort space in way called curvature. This is a misnomer, space has no direction, so does not curve. What happens is that a field gradient of the space field is produced, usually called a gravitational field.
    4) space and matter interact, as with all energy reactions, by producing a force between the interacting components. Matter and space appear to repel each other; the gravitational field is a partial repulsion of the space field in the vicinity of matter. Another material body in such a region experiences unbalanced push from space, propelling it towards the other mass, the one causing the gravitational field. In practice, both bodies have their own gravitational fields, combining the effects of the repulsive forces with space.
    5) No “Dark matter” is needed to explain gravitational anomalies in space, it is space that causes the observed phenomenon by an uneven energy content over astronomical distances. In simple terms, space is lumpy.

  • Vvaivo

    Sean S, Aneesh Lohany,
    it is a weird universe we perceive, but multiple parallel universes? Other than convenience for brushing real problems under the rug, so to say, what evidence is there that any such thing exists? Let us first try to solve the puzzles of this universe with what is in this universe!
    I have made statements in this column to the effect that space is a form of energy, that space is an energy field with no direction, but a field that can, and does, vary in intensity or field strength from place to place. This I can demonstrate with longer explanation than needed here. The gradual change with location of this field strength we call a gravitational field. It is this space gradient that causes gravitational acceleration, not some other piece of matter elsewhere. Over large astronomical distances the strength of the space field varies for other reasons than presence of mass, as recent astronomical studies have discovered; Why hunt for dark matter to justify the obvious?

  • Vvaivo

    Neil 1236,
    a valid and interesting idea; gravitational fields inside a galaxy almost certainly are not simple point source three axis symmetrical forms, since distribution of matter within galaxy is not uniform (spiral arms, etc). Also, changes in gravitational fields propagate at speed of light (slow on galactic scale), so that the shape of the gravitational field galaxy wide is not the same as the visible galaxy.

  • The Watcher

    It’s funny in a way… Our models are not working. In otherwords failing to predict what we are observing. What do we do? We invent a substance that is intangible and might as well be right out of the pages of science fiction to make those models work again.

    So I feel it behooves one to ask. How EXACTLY is this science?

    I was under the impression that if a model fails us we should abandon or rework the model. Not invent invisible almost; dare I say it(?), “Magical” particles/forces/whathaveyou to make them work. But then again cosmology has done this any number of times already. Case in point, the big bang theory. IE the expected temperatures of background microwave radiation, red shift inconsistances and etc.

    And before the classic deflective question pops up. No I do not have a better theory. But, one doesn’t need to have a better idea to know when one is busted.

  • Steven Sherry

    Existence itself can have no real ultimate ‘edge’, in any direction at all, in expanse or duration.

    The presence of such an edge is a fundamental impossibility, as beyond it would necessarily exist an unencompassed ‘state’ of ‘Non-Existence’. The very presence of such a state would forever ensure that its own necessary criteria of ‘absolute absence’ could NEVER be met, and so, is a state of absolute incoherence, in infinite violation of its own definition.

    As such, Non-Existence remains eternally ‘self-cancelled’ as the fundamental contradiction that it is. ‘It’ does not exist, anywhere, ever.

    Existence itself, remaining as it does forever unencompassed and devoid of any actual limitation, is not a ‘thing’.

    Therefore, Existence itself equals ‘ZERO’. In truth, there isn’t anything.

    Yet, the very ‘ISness’ of this ‘ZERO’ necessarily equals ‘ONE’.

    Being intrinsically infinite and eternal, ‘ONE’ is forever choicelessly aware of (and is therefore effortlessly perceiving) the absolute causelessness that it is.

    As ‘ONE’ perceives ‘ONE’, ‘ONE’ SEEMS to be ‘TWO’. These illusory ‘TWO’ are ‘the seer’ (infinite, ever-changeless emptiness) and ‘the seen’ (finite, ever-changing form). The ‘movement’ that is ‘the seen’ is fundamentally manifested as the state of ‘absolute chaos’. The ‘stillness’ that is ‘the seer’ is fundamentally manifested as the state of ‘absolute order’.

    ‘From’ the eternal interaction between this apparent ‘pair’, ‘Everything’ happens, in the ONLY way that it possibly can;

    ‘THIS’ way.

    Ultimately, every’thing’ is essentially an ‘apparent part’ of the forever effortless unfolding of this one illusory happening, which is itself comprised ONLY of the one infinite, eternal, self-aware presence that is ‘ZERO’.

    This is what is most fundamentally ‘going on’, without another, forever and ever.