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posted by Dopefish on Sunday February 23 2014, @08:00AM   Printer-friendly [Skip to comment(s)]
from the where's-carl-sagan-when-you-need-him? dept.

pjbgravely writes:

"Scientists use gravity lensing measurements to determine mass of galaxy clusters. Anja von der Linden, an astrophysicist at the Kavli Institute for Particle Astrophysics and Cosmology at Stanford University in California, is using the Subaru telescope and the Canada-France-Hawaii telescope, both on Mauna Kea in Hawaii. The results are 40% higher than the measurements done by the Planck collaboration.

I guess there goes Douglas Adams' theory that the missing mass was in the packing material of the scientists' equipment."

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  • (Score: 5, Funny) by Anonymous Coward on Sunday February 23 2014, @08:07AM

    by Anonymous Coward on Sunday February 23 2014, @08:07AM (#5116)

    Yes, in Hawaii we have lots of missing mass. Mostly attached to our residents, but none the less. . .

    • (Score: 0) by Anonymous Coward on Sunday February 23 2014, @08:37AM

      by Anonymous Coward on Sunday February 23 2014, @08:37AM (#5121)

      Yeah but do they have higher results?

      • (Score: 0) by Anonymous Coward on Sunday February 23 2014, @08:46AM

        by Anonymous Coward on Sunday February 23 2014, @08:46AM (#5123)

        Yes when you measure their height when lying down.

        • (Score: 1) by ls671 on Sunday February 23 2014, @08:58AM

          by ls671 (891) Subscriber Badge on Sunday February 23 2014, @08:58AM (#5128) Homepage

          Why? Tidal forces on the missing masses make their body stretch somehow?

          --
          Everything I write is lies, read between the lines.
    • (Score: 1) by evilviper on Sunday February 23 2014, @10:42AM

      by evilviper (1760) on Sunday February 23 2014, @10:42AM (#5143) Homepage Journal

      Yes, in Hawaii we have lots of missing mass. Mostly attached to our residents, but none the less. . .

      "The mass of an adult human brain is about 1,300 to 1,400 g. The brain makes up about two percent of the human"s mass."

      http://hypertextbook.com/facts/2003/RachelScottRos enbluth.shtml [hypertextbook.com]

      --
      Hydrogen cyanide is a delicious and necessary part of the human diet.
    • (Score: 3, Funny) by mcgrew on Sunday February 23 2014, @04:46PM

      by mcgrew (701) <publish@mcgrewbooks.com> on Sunday February 23 2014, @04:46PM (#5216) Homepage Journal

      Yo' momma's galaxy is so massive that when it sits around the house, it sits around the solar system!

      --
      Free Martian whores! [mcgrewbooks.com]
  • (Score: 5, Interesting) by stormwyrm on Sunday February 23 2014, @08:49AM

    by stormwyrm (717) on Sunday February 23 2014, @08:49AM (#5126) Journal

    Note that the article doesn't say anything about what makes up the mass in the galactic clusters that has been measured. They used gravitational lensing to do the mass measurements that discovered this missing mass in the new study, and well, dark matter can act as a gravitational lens just as much as ordinary matter can.

    If the folks around here are pretty much those from the other site, well, I imagine that many are bothered by the theory of dark matter. The trouble is non-baryonic dark matter is central to the theory of the Big Bang as we know it today: if this missing mass is baryonic, the theory predicts very different proportions of elements from Big Bang nucleosynthesis than what we observe. If you want to get rid of the dark matter hypothesis, or want to say that the dark matter is ordinary baryonic matter, you need to come up with an adjustment to the theory of the Big Bang that will explain why the ratios of the elements are the way they are.

    --
    Numquam ponenda est pluralitas sine necessitate.
    • (Score: 5, Informative) by evilviper on Sunday February 23 2014, @09:33AM

      by evilviper (1760) on Sunday February 23 2014, @09:33AM (#5135) Homepage Journal

      It's not as if dark matter is settled science. While there's evidence that supports it (See Wikipedia), there's enough that also contradicts it:

      https://maximilianspeicher.wordpress.com/2013/03/0 5/the-evidence-for-and-against-dark-matter/ [wordpress.com]

      http://www.universetoday.com/94808/newly-discovere d-satellite-galaxies-another-blow-against-dark-mat ter/ [universetoday.com]

      http://www.technologyreview.com/view/516681/the-in credible-dark-matter-mystery-why-astronomers-say-i t-is-missing-in-action/ [technologyreview.com]

      http://scitechdaily.com/no-evidence-of-dark-matter -around-the-sun/ [scitechdaily.com]

      I consider "dark matter" a place-holder... A gap in the current equations that gets filled with a constant to better (but not perfectly) match actual observations.

      There's always the old equivalence principle problem... We only ASSUME that the laws of physics we observe locally, apply to the rest of the universe as well. A simple assumption to make, but we have been unable to observe the effects of dark matter and dark energy inside our solar system, yet it's necessary for the equations to work out in inter-stellar space. We could well find that dark matter / dark energy is actually evidence that this cornerstone of physics is flawed:

      http://thetechjournal.com/science/laws-of-nature-m ay-not-be-the-same-everywhere-revolution-in-physic s.xhtml [thetechjournal.com]

      --
      Hydrogen cyanide is a delicious and necessary part of the human diet.
      • (Score: 5, Informative) by maxwell demon on Sunday February 23 2014, @12:30PM

        by maxwell demon (1608) Subscriber Badge on Sunday February 23 2014, @12:30PM (#5164) Journal

        Thanks for the links. However the scitechdaily article is contradicted by a later one:

        http://scitechdaily.com/new-measuring-technique-su ggests-plenty-of-dark-matter-near-the-sun/ [scitechdaily.com]

        Relevant quote from there:

        In this latest study, the authors are much more confident in their measurement and its uncertainties. This is because they used a state-of-the-art simulation of our Galaxy to test their mass-measuring technique before applying it to real data. This threw up a number of surprises. They found that standard techniques used over the past 20 years were biased, always tending to underestimate the amount of dark matter. They then devised a new unbiased technique that recovered the correct answer from the simulated data. Applying their technique to the positions and velocities of thousands of orange K dwarf stars near the Sun, they obtained a new measure of the local dark matter density.

        --
        The Tao of math: The numbers you can count are not the real numbers.
      • (Score: 5, Informative) by kebes on Sunday February 23 2014, @02:58PM

        by kebes (1505) on Sunday February 23 2014, @02:58PM (#5187)
        The science of dark matter is indeed not settled (in particular, even if our measurements of its distribution are correct, we don't know what it is made of; e.g. what particle(s) are responsible). Although nothing in science can ever be considered 'settled', the evidence for dark matter is actually quite strong.

        With respect to the counter-evidence, I should note that the MIT Technology Review [technologyreview.com] article is flawed. It basically says that measurements of Dark Matter influence on the orbits of the planets in our solar system are negligible, and then claims that this is a blow against dark matter as an explanation. However, if you calculate the magnitude of the effect we expect [scienceblogs.com], it is indeed small and would be nearly impossible to measure at the scale of the solar system. The density of dark matter that we measure (by motion of galaxies, fitting the CMB [scienceblogs.com], etc.) is really quite low (at this point in the history of the universe). It adds up to large amount of mass over large-scales, but it's highly diffuse and so imperceptible over short distances.

        Alternative explanations (MOND [wikipedia.org]) also do not fit [scienceblogs.com] as much of the data as the dark matter explanation. (Sorry to keep linking the same blog-author; but he does a good job of summarizing the state-of-the-art in astrophysics.) Of course, it's possible that with further study, an alternative gravitational theory that fits the data will be found. But one has not yet been found.

        There's always the old equivalence principle problem... We only ASSUME that the laws of physics we observe locally, apply to the rest of the universe as well.

        This is indeed a central philosophical issue in science more broadly. And difficult to ever settle. In the case of modern cosmology, our best theories (which include dark matter) are able to very accurately fit data from the very early universe (the Cosmic Microwave Background [wikipedia.org]) under the assumption that the laws of physics are the same at those times as they are now. This gives us confidence that we're on the right track...

        • (Score: 3, Interesting) by evilviper on Monday February 24 2014, @12:42AM

          by evilviper (1760) on Monday February 24 2014, @12:42AM (#5400) Homepage Journal

          In the case of modern cosmology, our best theories (which include dark matter) are able to very accurately fit data

          Well OF COURSE it fits observations. It was a theory created to fit the discrepancy between accepted theories and actual observations. That just shows the discrepancy is uniform, but not really proof of anything by itself.

          I wasn't trying to suggest MOND or some other existing theory is accurate, just that dark matter and dark energy are a "fudge factor" without a firm theoretical basis, nor any evidence or observations seen on a local scale.

          I'm not opposed to it being found and quantified, but in the mean time, it's just a bit of a stretch to assume that a fudge factor is a real, physical object floating around in space, even if it might be.

          --
          Hydrogen cyanide is a delicious and necessary part of the human diet.
          • (Score: 1) by khchung on Monday February 24 2014, @01:52AM

            by khchung (457) on Monday February 24 2014, @01:52AM (#5435)

            In the case of modern cosmology, our best theories (which include dark matter) are able to very accurately fit data

            Well OF COURSE it fits observations. It was a theory created to fit the discrepancy between accepted theories and actual observations. That just shows the discrepancy is uniform, but not really proof of anything by itself.

            You wrote this as if our current theories are just a bunch of curve-fitting functions with a whole bunch of free parameters we can tune. The truth cannot be farther than that!

            What makes the current physical theories "beautiful" is the fact that these theories often start with very simple and clear premises, and then much of everything flows logically from them, with almost no room for tuning or "fudging".

            Take Special and General Relativity as example, the premises "Every observer is the same", "the speed of light is constant for everyone", "you cannot distinguish between an accelerating lift and a lift in gravity", etc, are all either measurable, or would make the universe quite incomprehensible if wrong ("every observer is the same"). Then you work out the math and got the equation, and if observation did NOT fit, BAM! the theory is wrong.

            If the precession of Mercury was not exactly what GR predicted, there is nothing else you can play with without causing it to fail in other areas.

            Sure, you can postulate that it was GR that was wrong instead of the existence of some dark matter. But until you can come up with another theory of gravity that worked as well as GR AND do away with dark matter, then having one workable theory (GR) + one unknown (dark matter) seems better than having no workable theory at all.

            • (Score: 1) by evilviper on Monday February 24 2014, @12:38PM

              by evilviper (1760) on Monday February 24 2014, @12:38PM (#5759) Homepage Journal

              the premises "Every observer is the same", "the speed of light is constant for everyone", "you cannot distinguish between an accelerating lift and a lift in gravity", etc, are all either measurable, or would make the universe quite incomprehensible if wrong

              It doesn't have to invalidate the entire theoretical basis of GR/SR, just because the equations need a fudge factor to work. Just consider the Cosmological Constant... Or consider how it falls apart with black holes or other quantum phenomena.

              But until you can come up with another theory of gravity that worked as well as GR AND do away with dark matter, then having one workable theory (GR) + one unknown (dark matter) seems better than having no workable theory at all.

              It's not an either-or. You can keep using it, but you should acknowledge that there seems to be something "wrong", rather than acting like it's an entirely solved problem. Think of Newtonian mechanics before GR... Nobody invented exotic new theoretical types of matter to make the equations match more closely than they do.

              Better yet, just TRY to consider the possibility that in the next couple decades there will be numerous experiments trying to identify and study dark matter / energy, and it's possible they'll all simply come back with a negative result. Then you still have numbers that work, but without the conceit that they might be theoretically sound.

              --
              Hydrogen cyanide is a delicious and necessary part of the human diet.
      • (Score: 1) by pjbgravely on Sunday February 23 2014, @06:40PM

        by pjbgravely (1681) <pjbgravelyNO@SPAMyahoo.com> on Sunday February 23 2014, @06:40PM (#5264) Homepage
        Your post proves this site is different than the other one. I have gotten troll mods and angry dark mater zealots claiming I am a heretic for suggesting that anything but dark matter explains the difference between observable light mass measurements and theoretical mass requirements of galaxies.

        This study shows that the mass of the galaxies are in the galaxies not something ringing them. That means to me dark matter should be seen in our own solar system.
        • (Score: 0) by Anonymous Coward on Sunday February 23 2014, @08:35PM

          by Anonymous Coward on Sunday February 23 2014, @08:35PM (#5306)

          You seem to have a different article from the one linked in TFS. I RTFA and didn't see it come up with the conclusion you have.

        • (Score: 1) by Daniel Dvorkin on Sunday February 23 2014, @10:06PM

          by Daniel Dvorkin (1099) on Sunday February 23 2014, @10:06PM (#5335) Journal

          I have gotten troll mods and angry dark mater zealots claiming I am a heretic

          No you haven't.

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          Pipedot [pipedot.org]:Soylent [soylentnews.org]::BSD:Linux
        • (Score: 2) by evilviper on Monday February 24 2014, @12:52AM

          by evilviper (1760) on Monday February 24 2014, @12:52AM (#5406) Homepage Journal

          Your post proves this site is different than the other one.

          /. was a very different and much nicer place when there were only a few thousand readers, too. I was there to see it. I hope this place will do better, but it's much too early to tell.

          --
          Hydrogen cyanide is a delicious and necessary part of the human diet.
        • (Score: 0) by Anonymous Coward on Monday February 24 2014, @05:50PM

          by Anonymous Coward on Monday February 24 2014, @05:50PM (#5990)

          That means to me dark matter should be seen in our own solar system.

          Isn't the whole point of dark matter that you cannot see it?

      • (Score: 3, Insightful) by Flying Turtle on Sunday February 23 2014, @07:25PM

        by Flying Turtle (1782) on Sunday February 23 2014, @07:25PM (#5287)
        All very true but there's a reason that, despite a lack of direct evidence, "dark matter" is usually considered part of a incomplete theory rather then just a placeholder. Alternate theories like MoND http://en.wikipedia.org/wiki/Modified_Newtonian_Dy namics [wikipedia.org] can't explain nearly as much, as well, as dark matter.
    • (Score: 1) by AnonTechie on Sunday February 23 2014, @09:54AM

      by AnonTechie (2275) on Sunday February 23 2014, @09:54AM (#5137) Journal

      What does this finding imply about the total amount of dark matter and dark energy ??

      --
      Albert Einstein - "Only two things are infinite, the universe and human stupidity, and I'm not sure about the former."
  • (Score: -1) by Anonymous Coward on Sunday February 23 2014, @09:55AM

    by Anonymous Coward on Sunday February 23 2014, @09:55AM (#5138)

    How could it be a-missing when it's a-found?