Forgot your password?
typodupeerror
Space Science

Is Earth Weighed Down By Dark Matter? 247

Posted by samzenpus
from the big-boned dept.
Nerval's Lobster writes "There may be a giant ring of dark matter invisibly encircling the Earth, increasing its mass and pulling much harder on orbiting satellites than anything invisible should pull, according to preliminary research from a scientist specializing the physics of GPS signaling and satellite engineering. The dark-matter belt around the Earth could represent the beginning of a radically new understanding of how dark matter works and how it affects the human universe, or it could be something perfectly valid but less exciting despite having been written up by New Scientist and spreading to the rest of the geek universe on the basis of a single oral presentation of preliminary research at a meeting of the American Geophysical Union in December. The presentation came from telecom- and GPS satellite expert Ben Harris, an assistant professor of mechanical and aerospace engineering at the University of Texas- Arlington, who based his conclusion on nine months' worth of data that could indicate Earth's gravity was pulling harder on its ring of geostationary GPS satellites than the accepted mass of the Earth would normally allow. Since planets can't gain weight over the holidays like the rest of us, Harris' conclusion was that something else was adding to the mass and gravitational power of Earth – something that would have to be pretty massive but almost completely undetectable, which would sound crazy if predominant theories about the composition of the universe didn't assume 80 percent of it was made up of invisible dark matter. Harris calculated that the increase in gravity could have come from dark matter, but would have had to be an unexpectedly thick collection of it – one ringing the earth in a band 120 miles thick and 45,000 miles wide. Making elaborate claims in oral presentations, without nailing down all the variables that could keep a set of results from being twisted into something more interesting than the truth is a red flag for any scientific presentation, let alone one making audacious claims about the way dark matter behaves or weight of the Earth, according to an exasperated counterargument from Matthew R. Francis, who earned a Ph.D. in physics and astronomy from Rutgers in 2005, held visiting and assistant professorships at several Northeastern universities and whose science writing has appeared in Ars Technica, The New Yorker, Nautilus, BBC Future and others including his own science blog at Galileo's Pendulum."
This discussion has been archived. No new comments can be posted.

Is Earth Weighed Down By Dark Matter?

Comments Filter:
  • by thue (121682) on Monday January 06, 2014 @09:16AM (#45877261) Homepage

    "Any headline which ends in a question mark can be answered by the word no."

  • Readability (Score:5, Informative)

    by Anonymous Coward on Monday January 06, 2014 @09:19AM (#45877273)

    Making elaborate claims in oral presentations, without nailing down all the variables that could keep a set of results from being twisted into something more interesting than the truth is a red flag for any scientific presentation,

    It's standard not to write all the technicalities down in a scientific presentation. They usually last 30 to 45 minutes. There is no way, even for a scientific mind, to follow all the technicalities in 45 minutes when it took several months for the speaker to grasp the subject. Nobody in the audience would understand anything aside from the coauthors. Imagine your 20 hours advanced graduate course on physics condensed in 45 minutes with no simplification at all.

    Disclosure: I'm a mathematician, not a physicist.

    Let's wait for the proceeding or the full paper even though it's true we should be skeptical at this point.

    • by Sarten-X (1102295)

      Let's wait for the proceeding or the full paper even though it's true we should be skeptical at this point.

      This is Slashdot. That never happens.

    • Re:Readability (Score:5, Informative)

      by professionalfurryele (877225) on Monday January 06, 2014 @09:47AM (#45877399)

      Not to mention that this is a completely bullshit attitude to take to oral presentations. I often present preliminary data at conferences, part of the point of these things is to get feedback from colleagues about things like what variables might explain the results seen and to search for collaborators who have the expertise to help you pin down your result precisely. Most talks I go to are "I collected this data to test X, I saw Y, X either can or cannot explain Y but Z definitely can, comments?".
      The exception is some engineering conferences where you are presenting finished work and it is a peer reviewed paper which other can cite, then you should know your shit.

    • re: (Score:5, Informative)

      by Anonymous Coward on Monday January 06, 2014 @09:57AM (#45877449)

      The later link from Dr Francis points out that the calculation has yet to be adjusted for the gravitational contributions of the Moon or Sun, and that it also doesn't make any relativistic corrections.

      Those omissions puts the dark matter claim on par with "hey guys I haven't looked at it from far away but from right here it looks the Earth is pretty flat, yeah?"

    • by hubie (108345)

      They usually last 30 to 45 minutes

      It has been many years since I have presented at an AGU meeting, but back then at least, you were given about 12 minutes. This just the kind of thing to present at one of these meetings. You have preliminary work and have a working hypothesis, and you put it out in a brief talk to your colleagues for comments and criticism. Some of these talks are summaries of work that has been, or will be sent in, as a formal refereed paper, a lot of it are graduate students presenting their work in progress, and some

    • Of course, but just saying "What if it's dark matter?" without accounting for any of the many sources of errors I can think of off the top of my head (plus many more which I can't) is an indicator for grade-A bullshit.

  • by Anonymous Coward

    The excess mass is an invasion force of cloaked ships.

  • by Nevynxxx (932175)

    I thought we'd been using tiny variations in gravity to detect Oil for 20 or so years now, fly over an area and map the underground caverns based off gravity variation.

    • I thought we'd been using tiny variations in gravity to detect Oil for 20 or so years now, fly over an area and map the underground caverns based off gravity variation.

      Yea, this whole thing sounds really sketchy. Like the guy made a miscalculation when helping design the satellites, only discovered after reports of accuracy issues with the system, and now he's floating a balloon about some wild theory so he doesn't have to admit to making a stupid, multi-billion dollar mistake.

  • by rossdee (243626)

    " one ringing the earth in a band 120 miles thick and 45,000 miles wide."

    Presumably that would be outside the planet, and therefore would be counteracting the force of gravity towards the centre of the planet.
    Or is there some other wierd geometry involved.

    • by E++99 (880734)

      If the ring was perpendicular to the orbit of the satellite, it would have an additive effect to the earth's gravity in proportion to how far out of the plane of the ring the satellite is. If the satellite is in the plane of the ring, it would have no effect, as it would pull equally in all directions.

      • by Dunbal (464142) *
        How could it be perpendicular to something that's going around in a circle, unless its a ring that is not only perpendicular but also spins at exactly the same rate as the satellite. Otherwise the force will only be perpendicular for an instant, and then be at some angle for the rest of the orbit. Kind of hard to expect from a dark matter ring especially since there are all kinds of satellite orbits.
    • by lgw (121541)

      A ring doesn't make any sense at all given existing ideas about dark matter. Rings and disks form as a result of friction gradually eliminating all rotation except along a single, common axis. Friction is exactly the sort of thing that makes matter non-dark. Where would a ring come from?

    • by AK Marc (707885)
      If it were a more uniform cloud around the Earth, not a "ring" like Saturns, then it would be hard to find. The effects wouldn't be fully visible until one was beyond it. And I don't know whether any of the probes sent out looked back at Earth for any gravitational changes.
  • by Anonymous Coward on Monday January 06, 2014 @09:27AM (#45877309)

    > geostationary GPS satellites

    A what now?

    • by EasyTarget (43516) on Monday January 06, 2014 @09:54AM (#45877429) Journal

      > geostationary GPS satellites

      A what now?

      Yeah, I had the same thought, if the summary cannot tell the difference between geostationary and lower earth orbits, what hope it there that it gets anything else right?

  • this sounds like a new religion. watch out Scientology!
  • How? (Score:2, Interesting)

    by Anonymous Coward

    How was the accepted mass of earth measured? It should at least be consistent with large-scale behavior of our solar system. Now satellites see a harder pull from earth. The same pull should be seen from the sun. It would make sense to me if satellites saw a lower pull than sun, implying that some mass is at earth, but further out than the satellites. This way, not so much.

    Is it drag induced by the outer parts (not perfectly vacuum) of the atmosphere?

    • Re:How? (Score:4, Informative)

      by Anonymous Coward on Monday January 06, 2014 @10:12AM (#45877521)

      For geostationary satellites, drag is unlikely. The upper altitude limit for atmospheric drag is considered to be 2000km, geostationary are at 36 thousands km high.

      The earth mass is computed from the semi axis and the (sideral) period of any satellite (including the moon) orbiting earth: http://en.wikipedia.org/wiki/Standard_gravitational_parameter which gives you the standard gravitational parameter. To get the mass, you need to measure the gravitational constant which is harder but can be done with Cavendish experiment: http://en.wikipedia.org/wiki/Cavendish_experiment.

    • by anegg (1390659)

      I think that accurately predicting the orbit of satellites requires more than just the mass of the earth as a point. I think that generally predicting the orbit requires less data (and maybe only requires a point mass estimate), but results in errors accumulating over time between where the satellite is predicted to be versus where it really is. Its my understanding that satellites intended for long-term use have mechanisms to correct for the error (i.e., discover the delta and alter the orbit).

      Accuratel

  • by pedestrian crossing (802349) on Monday January 06, 2014 @09:45AM (#45877393) Homepage Journal
    Yo mama!
  • You fools! (Score:5, Funny)

    by east coast (590680) on Monday January 06, 2014 @09:52AM (#45877417)
    You laugh at the power of Lord Cthulhu, the Great and Glorious One. You try to come up with "scientific" theories and fancy math but the truth will become apparent to you very soon.

    Your screams of terror will be like the song of angels to me.
    • by Wycliffe (116160)

      You laugh at the power of Lord Cthulhu, the Great and Glorious One. You try to come up with "scientific" theories and fancy math but the truth will become apparent to you very soon.

      Your screams of terror will be like the song of angels to me.

      How does this get rated +4 insightful? Funny maybe but insightful? I'm confused.

      • by zlives (2009072)

        the truth is always insightful?

      • Funny maybe but insightful?

        Funny? Your mockery will be met with the fury of The Great Cthulhu. Trying to stop Cthulhu would be like trying to stop the winds with your bare hands. Await your doom, meatbag.
    • You laugh at the power of Lord Cthulhu, the Great and Glorious One. You try to come up with "scientific" theories and fancy math but the truth will become apparent to you very soon. Your screams of terror will be like the song of angels to me.

      I'm not laughing. I, for one, welcome our new tentacle-faced overlords. Wait...that sounded weird.

  • More information complexity creates more entropic potential energy.

    http://en.wikipedia.org/wiki/Entropic_force [wikipedia.org]
    http://arxiv.org/abs/1207.4803 [arxiv.org]
    http://arxiv.org/abs/1001.0785 [arxiv.org]

  • by imjustmatthew (1164609) <matthewNO@SPAMroyhousehold.net> on Monday January 06, 2014 @09:56AM (#45877445) Homepage

    No, this research wasn't even published, it's a conference talk and a PR release. Go read the actual link, at the bottom of the long post, where Matthew Francis dishes it out. Here it is again in case you missed it:

    http://galileospendulum.org/2014/01/02/no-dark-matter-is-not-messing-up-gps-measurements/ [galileospendulum.org]

    • by Sockatume (732728)

      His calculations are nonrelativistic! Wouldn't that make the satellites seem to be going unphysically fast, implying his stronger-than-accepted value for the Earth's mass?

  • by ghack (454608) on Monday January 06, 2014 @10:02AM (#45877467)

    The dark matter ring is merely a hypothesis. In my field (or science, engineering, or mathematics generally) we should follow the scientific method when reporting results at a meeting.

    This guy was unfortunately presenting a hypothesis. He should have waited and tried to find more compelling evidence before presenting. New Scientist should be familiar enough with the scientific method to avoid publicizing a radical and unproven hypothesis.

    • by Hatta (162192) on Monday January 06, 2014 @12:50PM (#45878945) Journal

      What's wrong with presenting ideas to collegues who may be able to help you come up with ways to test that idea? That's what conferences are for. Papers in a peer reviewed journal are where you publish actual results.

    • by jfengel (409917) on Monday January 06, 2014 @01:31PM (#45879453) Homepage Journal

      It's not just a hypothesis. It's a hypothesis that fits some data, from GPS satellites and the Juno probe. It's solid enough to present as an idea to other scientists.

      It's not solid enough to present as an idea to the general public, but unfortunately that's what popular science publications do for a living. They want "news"; their readers want to be the first ones to hear about exciting new developments. So they publish highly speculative material without the kinds of caveats, qualifications, and context that other scientists in the field bring automatically.

      I have a love-hate relationship with them. They're helpful in drumming up public interest in science, playing up the romantic parts that help young proto-scientists engage with the field before the years of drudge work that go into actually becoming a scientist. And they help keep people feeling good about science and voting to fund it. But they mis-inform as much as they inform, and real scientists are continually having to provide the context that the magazines frequently refuse to.

      (New Scientist is better than most daily newspapers, but worse than Science News. Frequency of publication seems to make a big difference: the longer your readership is willing to wait for accurate information, and the less they demand to have it ten seconds before the next guy, the more informative they are. Web-only sources are generally the worst.)

  • This statement is inaccurate: "...predominant theories about the composition of the universe didn't assume 80 percent of it was made up of invisible dark matter" 80% of the universe is made up of with Dark Matter and Dark Energy. The theories suggests the universe is made up of about 27% dark matter (not 80%) which is the subject of the article. Dark energy is a sort of negative gravity and is the force pushing galaxies apart faster and not relevant to this article's topic. Dark energy makes up most of
    • 80% of the universe is made up of with Dark Matter and Dark Energy. The theories suggests the universe is made up of about 27% dark matter (not 80%) which is the subject of the article. Dark energy is a sort of negative gravity and is the force pushing galaxies apart faster and not relevant to this article's topic.

      The whole notion of "dark matter/energy" seems a little desperate to me. We have evidence that our models of gravity cannot account for certain observations. That means one of two things. Either A) the model is correct and there is something out there that has mass that we cannot presently see OR B) the we can see all the matter out there meaning the model is wrong and needs revision. So far I've seen no compelling argument that A is more likely than B. I understand the hesitation to revise our model

      • by Hafnia (590482)
        No one has ever come up with a theory of Modified Gravity that can explain the data we have , but Dark Matter does. http://scienceblogs.com/startswithabang/2013/01/18/why-the-universe-needs-dark-matter-and-not-mond-in-one-graph/ [scienceblogs.com]
        • No one has ever come up with a theory of Modified Gravity that can explain the data we have , but Dark Matter does.

          Never mind the tiny, little, minor detail that we have NO idea if dark matter actually exists or what it might be composed of it it does exist. It's not an unreasonable theory to investigate but I'm pretty reluctant to invoke some new exotic form of matter as a go-to explanation. Remember it was 400 years between Newton and Einstein. If the math model needs adjusting (and dark matter turns out to not be the answer) it might be a while before we figure it out.

      • by mythosaz (572040)

        Either A) the model is correct and there is something out there that has mass that we cannot presently see...

        Like, I dunno, maybe dark matter?

        • Like, I dunno, maybe dark matter?

          Maybe but the point you ignored is maybe-not. With the evidence in hand, an incorrect model is a much cleaner explanation than some as yet undiscovered exotic form of matter than we aren't actually sure exists. I'm not saying dark matter doesn't exist, merely that I'm skeptical in light of the lack of evidence. It sounds like an effort to make the data fit the current model when there is a non-trivial chance the current model is wrong somehow.

    • 27 + 68 = 95. Our physical laws don't predict about 95% of the universe.

  • Weight Gain (Score:5, Interesting)

    by trongey (21550) on Monday January 06, 2014 @11:26AM (#45878007) Homepage

    planets can't gain weight over the holidays like the rest of us

    Actually they do. It's estimated that the Earth gains at least 164,000 kg per day from meteoric accretion. (Barker, J.L. and Anders, E. "Accretion rate of cosmic matter from iridium and osmium contents of deep-sea sediments." Geochimica et Cosmochimica Acta 32, 627-645 (1968))

  • Bullshit Flag (Score:5, Informative)

    by jasnw (1913892) on Monday January 06, 2014 @12:16PM (#45878579)
    I work with GPS a lot, and there are many MANY people around the world who spend their entire lives making sure that there are very precise measurements of where those satellites are and how good predictions of where they'll be going are. These orbit calculations take into account the pressure of light from the sun on the satellites along with several other very small effects, so if there was some large extra mass in a ring around the earth it would have been noticed many years ago. I think this guy needs to recheck his calculations.
    • by ediron2 (246908)

      I agree, this is likely a mistake. Most grand new discoveries fizzle when peers start falsifying (as in 'to test and prove false') them.

      Having said that, a matter type can be imagined whose 'drag' on GPS sats would be so rare and trivial as to be mistaken for part of the drag that near-atmospheric objects feel. Neutrinos fit this example. All we need here are massive nonreactive slow cloudy fat (but I repeat myself) particles that do gravitationally interact but don't bump into each other, don't coalesce,

    • by msobkow (48369)

      Well, the earth is certainly weighed down by a plethora of bullshit artists out there.

      The guy making the "observation" is himself the dark matter which weighs us down... :P

  • From New Scientist :

    "Harris has yet to account for perturbations to the satellites’ orbits due to relativity, and the gravitational pull of the sun and moon."

    That, alone, would make this fail peer review, not to mention that the GPS satellites (which are big and messy and do stationkeeping and get replaced) are not the satellites to use to do this with (the Lageos satellites fit both requirements, being both well monitored and with very low non-gravitational perturbations). The Lageos orbit at a lower

  • I wish I could have just written "Dark Matter" as the answer every time my math homework didn't add up to the correct number due to math errors. Obviously nobody knows precisely how much the Earth weighs...or the entire universe. In fact, how are they counting stars' mass from 10 million light years away by viewing 10 million year out of date light from it? And how are they counting mass that's already inside black holes from a not so viewer friendly distance away? Dark Matter is a myth.
  • Isn't the whole point of DM that we can't detect it except by the gravity distortion? Its basically "unfound matter"...

    And what means is what we really have is a distortion of gravity in a given area that we cannot count for... its therefore not dark matter but dark gravity.

    Or am I wrong? have we actually found dark matter? The actual stuff. Proven to exist? Or is it just what we write down when our math doesn't add up?

  • If the headline is a question the en answer is almost certainly "No", and the reporter unqualified for the topic.

Suburbia is where the developer bulldozes out the trees, then names the streets after them. -- Bill Vaughn

Working...