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What’s the (dark) matter? Physicist Peter Fisher says we may not know for 10 years

The views expressed are those of the author and are not necessarily those of Scientific American.


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Dark matterMaybe science really is back in vogue. Or maybe "dark matter" is a case of remarkably successful scientific branding—who wouldn’t be drawn in by a name like that? Then again, maybe people just want to know what the heck makes up the vast majority of the universe, a question to which science has provided only sketchy answers.

Whatever the reason, a dark matter lecture by physicist Peter Fisher at the American Museum of Natural History in New York drew a sellout crowd April 12 in a theater that seats more than 400, with museum staff turning away disappointed comers and at least one gentleman trying to talk his way in as if he were working to get past the velvet rope at a nightclub.

Fisher, of the Massachusetts Institute of Technology, gave his sizable audience a tidy roundup of what we know about dark matter and what we hope to find out in the coming years. He began by explaining a well-known but nonetheless perpetually jaw-dropping consequence of modern cosmological theory: The matter we can see and touch, all the atoms and molecules in existence, accounts for only about 4 percent of the universe. The rest is dark matter, an invisible substance discernable only by its gravitational effects on large-scale structures such as galaxy clusters, and dark energy, under whose influence the expansion of the universe appears to be accelerating.

Fisher chose to focus on the former issue. "I’m not going to talk too much about dark energy, because no one has the first clue of what dark energy is," Fisher said. That’s not all that surprising given that the case for dark energy was not made until the late 1990s. Dark matter, on the other hand, is on firmer footing, thanks to a long scientific history stretching back to the 1930s, when California Institute of Technology astronomer Fritz Zwicky noticed that the galaxies of the Coma cluster moved as if they had far more mass than was observable.

Physicists might even identify a particle culprit for dark matter in the near future. "We could get at it in a number of different ways," Fisher said, adding that "the person who finds it is going to get a quick trip to Stockholm," where the Nobel Prizes are awarded.

For starters, the Large Hadron Collider (LHC) in Europe could actually produce dark matter in its record-breakingly powerful particle collisions. The problem, Fisher said, is that LHC physicists might not be able to recognize the signature of dark matter if they created it. In more targeted experiments, physicists are on the trail of ambient dark matter—Fisher noted that, according to prevailing theories, the theater in which he spoke held about three dark matter particles per liter of air. That may seem like a lot, but among the roughly 1020 other particles in each liter, dark matter remains elusive.

In experiments such as XENON100 and CDMS, physicists have placed cryogenic sensors in underground laboratories, shielded by rock from cosmic rays, in the hopes that passing dark matter particles will induce subtle but telltale recoil or ionization effects when they bump into atoms in the detectors. Those experiments have set some limits on the strength of dark matter’s interactions with normal matter, but Fisher thinks the detectors will have to grow 100 times more sensitive before a conclusive dark matter signal is found. Given that their sensitivity has increased by a factor of 10 every six or seven years, in part by increasing the mass of the detector, "I think we’ll be at it another decade," Fisher said.

One problem with those searches is that particles known as neutrinos can mimic the kind of weakly interacting massive particle, or WIMP, that is the most likely candidate for dark matter. If the underground detectors grow to a certain size—about 10 times as large as the current generation—without spotting the effects of dark matter, Fisher said, neutrino interactions will generate an irreducible level of background noise in which any putative dark matter signal would be lost. He is part of a group seeking to circumvent that issue by building a detector that can discriminate the direction of an incoming particle, whether neutrino, dark matter or something else entirely. The DMTPC experiment, which will be installed underground in New Mexico, should therefore be able to better discern neutrinos, which stream at us from the sun, from dark matter, which models suggest should pass through Earth in a predictable direction as the planet rotates and the solar system moves through the galaxy.

A composite image of the Bullet Cluster reveals the presence of dark matter through the misalignment of normal matter (pink) and inferred mass (blue). Image credit: X-ray: NASA/CXC/CfA/M.Markevitch et al.; Optical: NASA/STScI; Magellan/U.Arizona/D.Clowe et al.; Lensing Map: NASA/STScI; ESO WFI; Magellan/U.Arizona/D.Clowe et al.





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  1. 1. candide 9:45 am 04/17/2010

    While the effects of "dark matter" are interesting the name itself leaves a bit to be desired.

    Let’s hope the LHC gets up to full energy, produces lots of bosons.

    Link to this
  2. 2. BodhiRobin 10:13 am 04/17/2010

    Dark Matter is the manifestation within our consciousness of the darkness within our hearts. – BodhiRobin

    Link to this
  3. 3. RHill 1:13 pm 04/17/2010

    I think the gravitational effects of "dark matter" are the physical signatures of parallel universe’s or extra-dimensions which we are otherwise unable to detect. Similarly, "dark energy" and the seeming acceleration of cosmic expansion is simply the matter in our universe being gravatationally drawn towards a much larger multiverse, far too distant for it’s light to have arrived after a mere 14-15 billion years. I presume, of course, that the effect of matter on space/time is instantaneous and not limited by relativistic speed-of-light barriers or propagation delays.

    Link to this
  4. 4. MCMalkemus 1:29 pm 04/17/2010

    What I’d like to see stated, is that in ten years: "We will know what dark matter is, or understand that we were barking up the wrong tree all long".

    It took a hundred years to give up the idea of phlogiston.

    Link to this
  5. 5. jtdwyer 4:55 pm 04/17/2010

    Also, the author stated:

    Physicists might even identify a particle culprit for dark matter in the near future. "We could get at it in a number of different ways," Fisher said, adding that "the person who finds it is going to get a quick trip to Stockholm," where the Nobel Prizes are awarded.

    Note that the Nobel prize is only mention for a physicist who identifies a particle confirming the entire Dark Matter cosmythology.

    In that I am only some guy explaining how dark matter never existed, I expect to be heavily penalized if I’m successful…

    Link to this
  6. 6. Radonballoon 5:00 pm 04/17/2010

    Jtdwyer- If dark matter doesn’t exist, and it’s all due to some flaw in calculation then we’ll know soon enough. If nothing in the LHC is found, if nothing is found with high precision detection then new theories will start to develop. If you believe your theory is correct then present it somewhere other than the comment section of a scientific american article-it doesn’t lend much credibility. As for what I think of your theory: pseudo-scientific trash. You just want your time in the spotlight, well do it right. Newton’s gravitation law is slightly incorrect, this has been proven, and has been replaced by Einstein’s relativity. Learn physics before you try to destroy it

    Link to this
  7. 7. DonsWrld 5:17 pm 04/17/2010

    Did you forget to take your meds today Bodhi?

    Link to this
  8. 8. jtdwyer 6:09 pm 04/17/2010

    Radonballoon – That’s fine: it’s really not important to me that you learn anything, or what you think of my analysis. I’m only responsible for making the information available. Do you really believe that exposing the Dark Matter myth would destroy physics? Do you think it soon enough to discover this, after 40 years?

    One of the problems is that all of astronomers continue to rely on Newton’s equations in identifying observations that seem to indicate to presence of dark matter. It has not been replaced in practice.

    In an unpublished 2005 paper,"General Relativity Resolves Galactic Rotation Without Exotic Dark Matter", F.I. Cooperstock and S.Tieu identified the source of dark matter error: gravitational binding among galactic stars.

    http://arxiv.org/abs/astro-ph/0507619v1

    That paper preceded my discovery in 2009 by four years. My completely independent arrival at the exact same conclusion certainly corroborates its correct identification of the error that produced the original requirement for dark matter to resolve the erroneous Galaxy Rotation Problem.

    I have submitted admittedly inadequate papers to the Astrophysics Journal, Physical Review D and others, but I’m not quitting.

    Link to this
  9. 9. jdbapat 7:12 pm 04/17/2010

    Dark Matter: three molecules per liter of air and undetectable. It is omnipresent and accounts for 96% mass of the universe. Everything sounds mysterious. http://jdbapat.blogspot.com

    Link to this
  10. 10. Radonballoon 7:13 pm 04/17/2010

    Again, do some research man! Or even some work! I read your theory you linked to, and it lacks something: equations! Physics is hard, and it takes a very long time and a lot of practice to learn it. General relativity is even harder. Rigorous proofs are needed for something as grand as you propose, and you give none. The paper you just linked me to was dis-proven rigorously:
    http://www.physics.drexel.edu/~dcross/academics/papers/cooperstock_review.pdf

    If dark matter proves to not exist, then it won’t destroy physics, no, it will be even more exciting, for we have a greater mystery on our hands! Even using general relativity is not enough to explain the rotation problem, as you will read from the linked paper.

    Again, please try and learn physics before trying to disprove some of its theories.

    Link to this
  11. 11. Radonballoon 7:23 pm 04/17/2010

    And if that isn’t enough evidence for you:
    http://arxiv.org/abs/astro-ph/0508377
    http://arstechnica.com/science/news/2005/10/1497.ars
    http://scienceandreason.blogspot.com/2005/10/revisiting-evidence-for-dark-matter.html

    Link to this
  12. 12. PotatoChip 8:40 pm 04/17/2010

    jdbapat, I believe that dark matter (as proposed) accounts for about 23% of the mass-energy density of the universe, while dark energy (as proposed) accounts for about 72%.

    Link to this
  13. 13. jtdwyer 8:54 pm 04/17/2010

    Radonballoon – Thanks very much! I do not pretend to be a physicist, I’m a retired information systems analyst with highly successful experience solving very difficult problems in the world’s largest computer systems. I’m no longer capable of working.

    I’m not capable of assessing the model Cooperstock constructed: his discovery that is critical to my argument is simply stated in this extract from his paper:

    "…insufficient attention has been paid to the fact that the stars that compose the galaxies are essentially in motion under gravity alone (‘gravitationally bound’)."

    While the physicists debate the validity of Cooperstock’s mathematical representation of the galactic disc, no one considers the methods used by Vera Rubin, which presumed that galactic stars would behave like planets. The principal error is that astronomers solve galactic gravitational effects as a remote two body problem, completely ignoring the gravitational effects imposed by innumerable nearer objects!

    I’m guilty of not being an accredited physicist, but I stand by my comprehension of the problem. I can’t produce a mathematical solution, but the current analyses presume an invalid model of galactic mass distributions and resulting gravitational effects. They are not those of our Solar system.

    You have pointed me to more current information – thanks very much. I will be posting a more complete essay (a format that does not require mathematical proofs).

    Link to this
  14. 14. UFO 9:16 pm 04/17/2010

    DM does not exist:
    Why we accept a ‘space’ evolution and do not discuss instead ‘matter’ evolution?
    The ever spreading fields (gravitoelectric) must fed on something, matter for sure.
    Consider atoms larger in the past as compared to the ones we observe locally. Atoms are the physical reference standards. They seem invariant, but they are not.
    In the present we have: less mass, greater distances and shorter time units as compared to past ones.
    Physical Laws keep as usual, with no extra parameters.
    Redshift can be linked to actual age of matter instead of distance.
    The physcal model was presented (and not discussed elsewere) here:

    http://arxiv.org/abs/astro-ph/0208365v1
    A relativistic time variation of matter/space fits both local and cosmic data

    With a simple shift of viewpoint the need of dark matter, goes away. And a lot more…like space expansion, BB, DM, DE,
    check the paper !

    Link to this
  15. 15. jtdwyer 10:14 pm 04/17/2010

    Radonballoon – Please check the logical correctness of your statement:

    "Even using general relativity is not enough to explain the rotation problem, as you will read from the linked paper."

    Unless I misunderstood, the linked paper criticized and presumedly disproved Cooperstock’s mathematical representation of spiral galaxy discs, which was based on the equations of general relativity. I don’t think it was proven that the equations of general relativity cannot correctly represent the discs of spiral galaxies.

    The last time I checked, no mathematical methodology had been developed that could verify the logical correctness of computer programs.

    Link to this
  16. 16. TonyK 11:18 pm 04/17/2010

    Maybe there’s no "dark" matter. The apparent extra mass in the universe comes from our faulty understanding of gravity. With gravity, maybe (1+1) >2.

    Link to this
  17. 17. jtdwyer 5:32 am 04/18/2010

    Radonballoon –
    In "Singular disk of matter in the Cooperstock-Tieu galaxy model", the most rigorous critique of the Cooperstock-Tieu galaxy model, Mikolaj Korzynski argues that an additional solid disc is implicit in the model description; that since no such thin disc has been observed, the model is dismissed as ‘unphysical’.

    A simple physical model of galactic mass can be represented by a Frisbee spinning on a rotating ice pick. The rotational velocity of the ice pick is applied to the Frisbee by a frictional coupling. Its velocity is imparted equally to the entire structure, producing a flat rotational curve. Despite this high peripheral velocity, the Frisbee does not fly apart because it is structurally composed of a bound, cohesive material.

    Alternatively, in the established galactic model the vast majority of galactic mass is undetected, located in an enormous halo surrounding the observed galactic matter. This model has not received critical review since the early 1970s. It is based on Newtonian gravitational equations.

    Link to this
  18. 18. RHill 9:41 am 04/18/2010

    It’s no doubt clear that I’m no scientist … here it comes … BUT, your essays make a lot of sense and pass the "Occam"s Razor" test with flying colors!! Your solution to the Galactic Rotational yada yada Problem implies that members of the "Dark Matter" community would do just as well by sharpening their pencils rather than building exotic detectors – not very good for business. You are lucky they stopped burning heretics!

    Link to this
  19. 19. icarus2 5:02 pm 04/18/2010

    Dark matter is negative mass(energy). So it has a antigravity.
    http://vixra.org/abs/0907.0015

    Link to this
  20. 20. jtdwyer 6:05 pm 04/18/2010

    RHill – Thanks. I’ll quit when I’m wrong, but I haven’t been dissuaded yet. I’ll post a clearer, enhanced essay soon.

    Link to this
  21. 21. chrisg307 8:26 pm 04/18/2010

    I read recently that those who have walked in space said that it smells like metal. They carry the scent back inside on their suits. They said the smell was unforgettable and distinct. I don’t know what that means, but find it of interest. Heavy metal rules?

    Link to this
  22. 22. jtdwyer 9:44 am 04/19/2010

    Dark Matter has been a cancer growing in the body of astrophysics. It was almost unnoticed when it first appeared in the study of galactic clusters. It reappeared in models of galaxy formation, then metastasized in the observation of spiral galaxies and galactic lensing, quickly spreading throughout cosmology. Today, with astrophysics in full denial, excision without damage to healthy science will be impossible, but deferring any longer only jeopardizes the survival of physics.

    Link to this
  23. 23. JackSarfatti 3:57 pm 04/19/2010

    In http://arxiv.org/abs/0902.0032 Creon Levit of NASA AMES and I propose a very simple mainstream physics unified explanation for both dark energy and dark matter, both are exotic phases of the quantum vacuum’s virtual processes.

    This model predicts that deep mine detectors, the LHC et-al will never find real on-mass-shell exotic particles whizzing through space that can explain Omega(dark matter) ~ 0.23. Looking for such WIMPS, MACHOs etc as the explanation for dark matter is like looking for the motion of Earth through the aether in the Michelson-Morley inteferometer experiment. Therefore, our model is Popper falsifiable.

    Dark energy corresponds to a preponderance of virtual bosons over virtual femion-antifermion pairs. Dark matter is the opposite. The Einstein equivalence principle then gives the correct (anti) gravity properties for each phase.

    Of course there is also some new physics needed for the detailed internal structure of the vacuum, which appears to need the hologram approach of ‘t Hooft and Susskind.

    Link to this
  24. 24. JackSarfatti 4:32 pm 04/19/2010

    http://arxiv.org/abs/0902.0032
    Has a simple unified mainstream physics explanation of both dark matter and dark energy as virtual processes inside the quantum vacuum that has distinct phases. The model is testable and predicts that no WIMPS, no MACHOs etc will be found as a matter of principle.

    Link to this
  25. 25. Bill Crofut 10:38 am 04/20/2010

    “Dark energy,” “dark matter” and “dark force” seem to me to be terms made up by cosmologists attempting to explain away the anomalies of the alleged “big-bang.”

    Link to this
  26. 26. IceComm 12:41 pm 04/20/2010

    Astroparticle physics can be fun. And dark matter (even if it doesn’t exist) is interesting enough to possibly engage the public. Reading this article after a slew of others about the LHC being so close to creating dark matter makes me wonder-Dark matter: Coming soon to a scientist near you?
    https://blog.icecube.wisc.edu/wp-admin/post.php?action=edit&post=837

    Link to this
  27. 27. jimhenson 7:47 pm 04/20/2010

    Many are calling dark matter mini or millimeter sized black holes, but einstein field equations and relativity applies for calling them tiny time reverse quantum white holes. Peter Engels has produced stable vortex / antivortex dipoles from Bose-Einstein condensate, and states this works for neutron stars. Considering Blackholes as vortices, and using Engels’s new experimental diagrams, and placing alongside photos from David Law’s dark matter 3 axial direction halos around the milky way, we put up a page on what dark matter is and why it forms around the galaxy. please check it out :
    http://quantauniverse.com

    Link to this
  28. 28. elderlybloke 6:52 pm 04/23/2010

    BodhiRobin ,

    The same goes for Gravity

    Link to this
  29. 29. GregMN 12:35 pm 04/26/2010

    No Higgs-Boson (God Particle) at the LHC

    The key elemental particle physicists claim to exist, but which has not yet been found — God in a Mirror? — (Max Hadron)
    ==========================

    No Higgs-Boson particle today.
    That Large Hadron Collider
    has not been my confider.

    The LHC has not yet seen the ray,
    – a glimpse of God’s existence.
    at 7-volt-tera’lectro-resistance.

    What’s found, at any rate
    Some say is just a boson’s mate,
    Through the Atlas chambered meters

    Some old neutrinos crept on…
    With a leap of faith they lept-on
    Like some Immaculate Concept-ion

    They say the "missing energy" — has glue on
    Like when a cow jumps over the muon
    Leaves a trace, an image in the mirror,
    So maybe God was here.

    – Greg Molenaar, New London, Minnesota
    19 April 2010
    ===

    Link to this
  30. 30. GregMN 12:36 pm 04/26/2010

    No Higgs-Boson (God Particle) at the LHC

    The key elemental particle physicists claim to exist, but which has not yet been found — God in a Mirror? — (Max Hadron)
    ==========================

    No Higgs-Boson particle today.
    That Large Hadron Collider
    has not been my confider.

    The LHC has not yet seen the ray,
    – a glimpse of God’s existence.
    at 7-volt-tera’lectro-resistance.

    What’s found, at any rate
    Some say is just a boson’s mate,
    Through the Atlas chambered meters

    Some old neutrinos crept on…
    With a leap of faith they lept-on
    Like some Immaculate Concept-ion

    They say the "missing energy" — has glue on
    Like when a cow jumps over the muon
    Leaves a trace, an image in the mirror,
    So maybe God was here.

    – Greg Molenaar, New London, Minnesota
    19 April 2010
    ===

    Link to this
  31. 31. gelunelu 8:38 pm 04/26/2010

    Obviously there is something about us humans, (especially when we step on someone’s foot, (or better said we same to counter attack ones idea))
    We should never forget, that we do, and explained to others, (always) from our imagination, observations, or intuitions.
    Newton did it, and so did Einstein, yes everyone of you could be a great Scientist, the fact that you are here debating this, shows your scientific interest.
    A wise Scientist, respects everyone’s opinion, and encourages everyone else’s.

    Link to this
  32. 32. jtdwyer 4:07 pm 05/2/2010

    Please review the more complete essay/article,

    "Mass Distribution Characteristics Invalidate the Galaxy Rotation Problem"

    posted at:

    http://www.sciencewithoutfiction.com/uploads/Mass_Distribution-_Galaxy_Rotation_Problem.pdf

    Link to this
  33. 33. scotthenderson37 2:53 pm 05/6/2010

    Einstiens reletivity was also flawed because a photon is a partical and particals have mass. according to einstiens relitivity theory light would never reach us because it would never achieve its own speed.

    Link to this
  34. 34. jtdwyer 5:40 pm 05/6/2010

    scotthenderson37 – Actually, as I understand, photons are considered to have zero rest mass, which allows light to achieve the speed of light while acquiring effective mass, which prevents it from exceeding that velocity.

    Not to say that relativity isn’t flawed… Einstein revised gravitation because he couldn’t justifiably accept Newton’s imaginary attractive force. Einstein described only the effects of gravitation on the abstract dimensional coordinates of space and time.

    Apparently Einstein could not identify the actual causal force producing the effects of gravitation, either. I think it is directly related to the velocity of not only objects in motion but the potential velocity of mass – that produces and affects space and time, but I’m just guessing…

    Link to this
  35. 35. Neptunerover 3:20 am 05/8/2010

    Gravity is the same as a constant acceleration, but just which participant is accelerating cannot be determined, meaning it is equally valid to say that the surface of the Earth is accelerating upward toward a falling weight.
    Conceptually, the idea of an upward accelerating Earth runs into problems when the planet’s three dimensional characteristics are considered, but this is only due to a misunderstanding of the nature the earth’s acceleration. The Earth is accelerating outward in all directions, just like everything in the universe is expanding. But it’s all expanding relative to nothing, which doesn’t take us back to a big bang because expansion in relation to nothing will not give you any actual size increase (!). It will give you gravity however as smaller things become trapped on the surface of much larger things while everything is expanding.

    Link to this
  36. 36. jtdwyer 3:09 pm 05/23/2010

    Neptunerover – I find it much simpler to consider that small bodies are accelerated by an external gravitational field of massive objects rather than the spatial expansion of all objects proportional to their mass. If all masses were simply expanding, it seems that they would all soon merge.

    Large masses in fact do not collide, since they each produce a localized field of kinetic velocity proportionate to the potential velocity of their collective mass, directed to the collective center of localized mass in addition to their independent relative linear velocities. They orbit the remote point rather than collide.

    Only when small bodies are directed to the collective center of localized mass which happens to reside within a larger object of mass to collisions occur. If only I could do the math…

    Link to this
  37. 37. voxoceanus 6:35 pm 06/17/2010

    Dark matter – funny name but yet inexplicable! I think the day physicists would be able to resolve the ‘interaction’ of quantum mechanics and gravity, the dark matter issue would be more like a ‘piece of cake’!

    Link to this
  38. 38. Andromeda 1:06 pm 07/17/2010

    There is no such thing as Dark Matter, it’s an ad hoc explanation designed to plug in gaps in an already failing theory!

    Link to this

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