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Dark Matter Could Become a Hypochondriac’s New Nightmare

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

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A map of possible dark matter distribution in a cluster of galaxies

If you still worry about the millirems of radiation you get at the dentist’s office, you might soon have yet another reason to gobble down an Ambien at bedtime. A paper just posted to the arXiv physics preprint server outlines the amount of dark matter that all of us are exposed to on a regular basis.

Dark matter—the missing mass in the universe, estimated to make up 80 percent of the known there there—may collide with a “70 kg lump of meat made largely of oxygen, hydrogen, carbon and nitrogen,” as a post at Technology Review’s Physics arXiv blog put it—30 times a year for one plausible candidate for a dark matter particle and nearly once a minute for a more lightweight version.

The researchers don’t make any estimate of the health impact, which is contingent on the energy and motion of an oxygen or hydrogen nucleus—the most likely targets—after being broadsided by a shot of the dark.  “It must surely represent a tiny risk per human but what are the implications for the population as a whole? That would be an interesting next step for a biological physicist with a little spare calculating time,” the blog post notes wryly.

It’s a little early to reach for the pill bottle, actually, as the measurements of the spooky stuff are still a bit on the shaky side, to say the least. The estimates made in the paper by two physicists—Katherine Freese of the University of Michigan and Christopher Savage of Stockholm University—are based on a few experiments that have furnished suggestions of the prevalence of what are endearingly called WIMPs, Weakly Interacting Massive Particles.

But don’t sweat it, more research is needed. These experiments have not even actually found the dark substance, only “intriguing hints” of it. As the researchers themselves acknowledge, WIMPs could be supersymmetric particles, or Kaluza-Klein particles “motivated by theories with extra dimensions.” Not enough for the insurance actuaries to fire up the spreadsheets just yet.

Stay tuned to this channel for periodic health advisories.







Gary Stix About the Author: Gary Stix, a senior editor, commissions, writes, and edits features, news articles and Web blogs for SCIENTIFIC AMERICAN. His area of coverage is neuroscience. He also has frequently been the issue or section editor for special issues or reports on topics ranging from nanotechnology to obesity. He has worked for more than 20 years at SCIENTIFIC AMERICAN, following three years as a science journalist at IEEE Spectrum, the flagship publication for the Institute of Electrical and Electronics Engineers. He has an undergraduate degree in journalism from New York University. With his wife, Miriam Lacob, he wrote a general primer on technology called Who Gives a Gigabyte? Follow on Twitter @@gstix1.

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

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  1. 1. gwhiteiii 5:06 pm 04/12/2012

    Dark matter will someday be understood to be source of gravity. Gravity doesn’t exist because there is an attraction between two masses like the sun and the moon; rather gravity exists because any body with mass creates a shadow in dark matter; dark matter then pushes in the direction of the shadow. It makes a lot more sense to assume that dark matter is constantly passing through our bodies in all directions but with a slight drag. In other words, dark matter is creating pressure that is more or less counterbalanced. However, dark matter only travels in a straight line at the speed of light, so two bodies can sense each other by creating shadows. The perception of gravity is simply the push from the dark matter as it is partially interacts with mass as it travels through it…in the direction of other bodies that also partially absorbed it.

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  2. 2. MarkB4 7:52 pm 04/12/2012

    And,based on the above what would it be like if I have a dark matter shield, like a space suit? Would I be gravitationally neutral? And what could I do with that? Just a thought or two.

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  3. 3. David Illig 1:17 pm 04/13/2012

    Mark84: As in related cases, a tinfoil hat will work as well as anything.

    “Not enough for the insurance actuaries to fire up the spreadsheets just yet.” Hah! The insurance industry is way ahead on the dark-matter threat and they have already developed an air-tight case for not paying off, should the stuff prove harmful. By the same token, the 1% already have a plan to get exclusive rights from the gov’t if D.M. turns out to be useful.

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  4. 4. MarkB4 12:12 pm 04/14/2012

    And what if the tinfoil hat is counterfeit? Just saying, not all attempts to articulate the ‘unfamiliar’ are invalid. Given science, or the scientist, keeps catching up with the fact and morphing, isn’t that the history of it.

    Did you know the theory of relativity begins to break down with the recent discovery the speed of light is getting faster? What then? Will it have any effect on the unhappiness of religionists?

    Not being a scientist I have the advantage of an absence of fixed perspectives. Or even the need to be rational. But logic may not be what you think it is.

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  5. 5. Grumpyoleman 5:37 pm 04/14/2012

    Maybe dark matter is not matter at all, but the measured gravitational effects of alternate universes that exist side by side with our universe.

    I love it when the non-scientists are on a roll.

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  6. 6. MarkB4 2:05 am 04/15/2012

    Hmmm! That could be closer to the truth than an over-educated mind could ever hope to get.

    Perhaps it is even the gravitational effect of death, since we all end up there anyway? And then life can really begin … :)

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  7. 7. jtdwyer 9:00 am 04/17/2012

    The second paragraph describes dark matter: “…the missing mass in the universe, estimated to make up 80 percent of the known there there…”

    Yes there, there, children. Physicists are still stretching their imaginations to identify some hypothetical candidate particle (none of which are predicted by the highly successful standard model of particle physics). The decades long unsuccessful experiments referred to in the referenced uselessly silly ‘research’ report all presume that dark matter must be distributed throughout the galaxy. However, the galactic gravitational effects that seemed to infer the presence of some missing mass require that it effects only the galactic periphery – a homogenous distribution would produce unobserved, accelerated rotational velocities within the inner diameter of the galactic disc!

    What’s so astonishing now is that the 1970s era astronomers expected that spiral galaxy rotational velocities would diminish as a function of radial distance because they’d simply presumed that Kepler’s third ‘law’ of planetary motion should implicitly apply to all orbital systems. However, spiral galaxies are not planetary systems.

    Actually, Newton proved in his ‘Principia’ that Kepler’s equations included an error component for orbitals (planets) that contained non-zero mass. While Kepler’s empirically derived equations provided reasonably useful approximations, they were peculiarly well suited to the Solar system, whose mass is dominated by the Sun (containing 99.86% of total system mass).

    The mass of spiral galaxies is largely distributed throughout their spiral disks. As a result, the motions of individual stars within the disks (especially at the disk periphery) are determined far more by their gravitational interactions with neighboring masses than any masses located within a central galactic bulge. Actually, some large, well formed spiral galaxies do not have a central bulge. The disks of spiral galaxies are self-gravitating: their component masses are primarily bound to each other.

    In more recent years it has been demonstrated that the rotational characteristics of spiral galaxies can be described using Newtonian dynamics and universal law of gravitation, without dark matter or modified gravity. Please see: Feng & Gallo, (2011), “Modeling the Newtonian dynamics for rotation curve analysis of thin-disk galaxies”,

    While the self-gravitating disks of spiral galaxies do not behave as planetary orbital systems, more distant objects at the galactic periphery do independently orbit the Milky Way ‘just like planets in the Solar system’. This observation conflicts with the presence of an enormous dark matter halo containing most of the galaxy’s mass. Please also see: Bratek et al, (2011), “Keplerian Ensemble Approximation. The issue of motions of Galactic halo compact objects”,

    Please see a brief commentary with additional references:

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  8. 8. Quinn the Eskimo 5:02 pm 04/22/2012

    Has anyone proven Dark Matter? Other than mathematics, because our theories aren’t complete we need this new Universal Constant to fudge it out. Dark Matter. Kinda like the Force be With You.

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  9. 9. Dredd 10:23 pm 04/22/2012

    A recent paper published in Nature concluded that, at most, only 10% of expected quantities of hypothesized dark matter could exist in our galaxy.

    The paper also indicated that efforts to find any single quantum of dark matter, in ongoing experiments here on Earth, were doomed to failure.

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