9 ms·

> that has been falsified more than once What has been falsified more than once?

zamalek 8y ago
We haven't observed any of the predicted WIMPs at the LHC, as one example. They were subsequently relegated to a higher energy level.
- acqq 8y ago
  That doesn’t disprove the “matter-like” observed behavior, it just shows that the particular assumptions under which exactly these non-found WIMPs were imagined were false.
  - dnautics 8y ago
    If you have an infinite space of particle parameters and a series of tests keeps eliminating large swaths of this space, at some point it feels like you're playing a god of inbetweens game a la creationists arguing using gaps in the fossil record. There is a categorical difference, of course, but as a practical matter the parallels are useful, at what point do we table (for now) the search for the populist position and break for alternatives?
    - acqq 8y ago
      It's not "populist" anything. It's the best science that can be done: https://medium.com/starts-with-a-bang/five-reasons-we-think-dark-matter-exists-a122bd606ba8 https://medium.com/starts-with-a-bang/five-reasons-we-think-... "Five Reasons We Think Dark Matter Exists: No other idea explains even two of these." "1.) Galaxy Clusters" "2.) Galactic Rotation Curves" "3.) The Cosmic Microwave Background" "4.) The Bullet Cluster" "5.) Large-Scale Structure Formation" From these 5, only dark matter matches all. Whereas MOND theories match only one, the "item number 2" and only as an attempt to after-the-fact-explanation of what's anyway observed, not as any prediction of anything new. As I've quoted in my another message here: "the predictions of dark matter were first made in the 1970s and 1980s, and were observationally confirmed later. This is not a case of tweaking the model to fit the data; this is a case of the best kind of science you hope for: where you make predictions, make the observations, and what you see validates and confirms the predictions you had made." Moreover, there's nothing "large" of the possible space that is now excluded. The possible space includes everything that "behaves like matter". What's (still just "probably") eliminated is just what were for us, humans, in this particular moment of our history very convenient to happen: that the energies needed are exactly such that WIMPs that were conveniently postulated to be such can be generated by the device which design and maintenance costs less than 2% of the total cost of the F-35 fighter planes (the money invested and planned to be invested in F-35 is 75 times bigger than the international investment in LHC). It would have been luck if it had happened, but the possibilities are much bigger and include such which are going to remain physically unreachable to be produced by our technologies. That we, humans, can't produce some particles doesn't disprove that dark matter exists when we have precise observations that can only be explained by dark matter and effectively by nothing else.
      - nonbel 8y ago
        >"only dark matter matches all." Dark matter can be placed arbitrarily so it can match pretty much anything. I remember recently there was a galaxy with negligible deviation of the GR-predicted rotation curve and that was taken as evidence for dark matter too (even though MOND was still the better fit for that case). "Dark Matter" started out ok but has become a "god of the gaps" argument, I expect eventually MOND or similar solutions will be developed for all those issues. Also, I gather that while MOND does seem not predict these observations exactly, it is not fully developed yet and often the presence of some "normal" cold gas (undetectable via light) could make it fit. Also, to get dark matter to fit the observations requires post-hoc assumptions and parameter adjustments. Eg: "The amplitude of the third peak observed by WMAP merely falsifies the simple ansatz I used to make the prediction, not MOND itself. Indeed, I pointed out in the original papers that the ansatz must fail at some level, so I am hardly surprised that it does. All this means is that there are degrees of freedom (like a scalar field) that can oscillate separately from baryons in whatever the relavistic parent theory of MOND might turn out to be. The real test was for ΛCDM: the third peak had to be higher than predicted by pure baryonic damping. ΛCDM survives this test. It "wins ugly" in that, in order to obtain a fit, we have had to nearly double the baryon density over what it was so confidently known to be before it wasn't. That, and the no-CDM prediction for the second peak is still bang on. Amazing coincidence, that." http://astroweb.case.edu/ssm/mond/ http://astroweb.case.edu/ssm/mond/ >"the predictions of dark matter were first made in the 1970s and 1980s, and were observationally confirmed later." I'm afraid I have never seen this although I have looked into this topic (as a layperson). Can you give an example of this? It would make the dark matter idea much more convincing.
        acqq 8y ago
        > Dark matter can be placed arbitrarily so it can match pretty much anything. Quite the opposite, and that statement is obviously uninformed. The science behind dark matter is very precise and exact. That's why the alternative theories can't come even near: once the same rigor which was applied to test dark matter is applied to the alternatives, the alternative theories simply break. > I'm afraid I have never seen this ... Can you give an example of this? I've given you the link to the complete articles and also highlighted the major points. Try to read and understand them fully, then search for more. For example, even on the MOND page that you linked you can read: "2013: ΛCDM provides an excellent fit to the improved CMB data just as MOND provides an excellent fit to improved rotation curve data. As before, one's interpretation depends entriely upon which you find more impressive." Note: "rotation curve" from that quote is the "item 2" from my posts before. So, no, still the match of the single "item 2" is definitely not "more impressive." The "CMB" mentioned on your page is the "item 3" from all 5 which are explainable by ΛCDM (and specifically, ΛCDM is the model part of which the "dark matter" is: https://lambda.gsfc.nasa.gov/education/graphic_history/univ_evol.cfm https://lambda.gsfc.nasa.gov/education/graphic_history/univ_... see there 4 and 5). Edit: response to your later response below: > The claimed predictions from the 1970s and 1980s are not mentioned on that page. They are mentioned even on the very page that you linked to: that page, among other points, followed the history of the tests and effectively concludes that, yes, finally, in 2013 ΛCDM wins the "item 3". Read carefully. Learn what ΛCDM is. MOND can still only claim "item 2." Which actual "authority" can show anything else? Also, behind "darkmattercrisis" blog are just a few guys with very fringe positions.
    - dmurray 8y ago
      > If you have an infinite space of particle parameters and a series of tests keeps eliminating large swaths of this space, at some point it feels like you're playing a god of inbetweens game a la creationists arguing using gaps in the fossil record. Or you're getting closer to finding out what the real parameters are? If you eliminate all possibilities and have to make up some new parameters, sure, that feels like you're not doing science and might as well be a creationist. But what you describe, narrowing down the space of possible explanations from infinitely many to only a few, is the dream of every theoretical physicist.
      - zamalek 8y ago
        > Or you're getting closer to finding out what the real parameters are? By that metric, epicycles were rock-solid.
        deleted 8y ago
        [deleted]
syn0byte 8y ago
Lots, we just patch it and move on. Iron orb should glow blue unless this one variable is this one value? "patch it" by calling that one value plank's constant and see, the models still good! Our math says the universe comes up short on mass by over 3/4ths? Must be invisible matter we can't see or interact with see, the models still good! Over simplification in the extreme, but also a far cry from the rock solid foundations it claims to be.
- deleted 8y ago
  [deleted]

We haven't observed any of the predicted WIMPs at the LHC, as one example. They were subsequently relegated to a higher energy level.

acqq 8y ago
That doesn’t disprove the “matter-like” observed behavior, it just shows that the particular assumptions under which exactly these non-found WIMPs were imagined were false.
- dnautics 8y ago
  If you have an infinite space of particle parameters and a series of tests keeps eliminating large swaths of this space, at some point it feels like you're playing a god of inbetweens game a la creationists arguing using gaps in the fossil record. There is a categorical difference, of course, but as a practical matter the parallels are useful, at what point do we table (for now) the search for the populist position and break for alternatives?
  - acqq 8y ago
    It's not "populist" anything. It's the best science that can be done: https://medium.com/starts-with-a-bang/five-reasons-we-think-dark-matter-exists-a122bd606ba8 https://medium.com/starts-with-a-bang/five-reasons-we-think-... "Five Reasons We Think Dark Matter Exists: No other idea explains even two of these." "1.) Galaxy Clusters" "2.) Galactic Rotation Curves" "3.) The Cosmic Microwave Background" "4.) The Bullet Cluster" "5.) Large-Scale Structure Formation" From these 5, only dark matter matches all. Whereas MOND theories match only one, the "item number 2" and only as an attempt to after-the-fact-explanation of what's anyway observed, not as any prediction of anything new. As I've quoted in my another message here: "the predictions of dark matter were first made in the 1970s and 1980s, and were observationally confirmed later. This is not a case of tweaking the model to fit the data; this is a case of the best kind of science you hope for: where you make predictions, make the observations, and what you see validates and confirms the predictions you had made." Moreover, there's nothing "large" of the possible space that is now excluded. The possible space includes everything that "behaves like matter". What's (still just "probably") eliminated is just what were for us, humans, in this particular moment of our history very convenient to happen: that the energies needed are exactly such that WIMPs that were conveniently postulated to be such can be generated by the device which design and maintenance costs less than 2% of the total cost of the F-35 fighter planes (the money invested and planned to be invested in F-35 is 75 times bigger than the international investment in LHC). It would have been luck if it had happened, but the possibilities are much bigger and include such which are going to remain physically unreachable to be produced by our technologies. That we, humans, can't produce some particles doesn't disprove that dark matter exists when we have precise observations that can only be explained by dark matter and effectively by nothing else.
    - nonbel 8y ago
      >"only dark matter matches all." Dark matter can be placed arbitrarily so it can match pretty much anything. I remember recently there was a galaxy with negligible deviation of the GR-predicted rotation curve and that was taken as evidence for dark matter too (even though MOND was still the better fit for that case). "Dark Matter" started out ok but has become a "god of the gaps" argument, I expect eventually MOND or similar solutions will be developed for all those issues. Also, I gather that while MOND does seem not predict these observations exactly, it is not fully developed yet and often the presence of some "normal" cold gas (undetectable via light) could make it fit. Also, to get dark matter to fit the observations requires post-hoc assumptions and parameter adjustments. Eg: "The amplitude of the third peak observed by WMAP merely falsifies the simple ansatz I used to make the prediction, not MOND itself. Indeed, I pointed out in the original papers that the ansatz must fail at some level, so I am hardly surprised that it does. All this means is that there are degrees of freedom (like a scalar field) that can oscillate separately from baryons in whatever the relavistic parent theory of MOND might turn out to be. The real test was for ΛCDM: the third peak had to be higher than predicted by pure baryonic damping. ΛCDM survives this test. It "wins ugly" in that, in order to obtain a fit, we have had to nearly double the baryon density over what it was so confidently known to be before it wasn't. That, and the no-CDM prediction for the second peak is still bang on. Amazing coincidence, that." http://astroweb.case.edu/ssm/mond/ http://astroweb.case.edu/ssm/mond/ >"the predictions of dark matter were first made in the 1970s and 1980s, and were observationally confirmed later." I'm afraid I have never seen this although I have looked into this topic (as a layperson). Can you give an example of this? It would make the dark matter idea much more convincing.
      - acqq 8y ago
        > Dark matter can be placed arbitrarily so it can match pretty much anything. Quite the opposite, and that statement is obviously uninformed. The science behind dark matter is very precise and exact. That's why the alternative theories can't come even near: once the same rigor which was applied to test dark matter is applied to the alternatives, the alternative theories simply break. > I'm afraid I have never seen this ... Can you give an example of this? I've given you the link to the complete articles and also highlighted the major points. Try to read and understand them fully, then search for more. For example, even on the MOND page that you linked you can read: "2013: ΛCDM provides an excellent fit to the improved CMB data just as MOND provides an excellent fit to improved rotation curve data. As before, one's interpretation depends entriely upon which you find more impressive." Note: "rotation curve" from that quote is the "item 2" from my posts before. So, no, still the match of the single "item 2" is definitely not "more impressive." The "CMB" mentioned on your page is the "item 3" from all 5 which are explainable by ΛCDM (and specifically, ΛCDM is the model part of which the "dark matter" is: https://lambda.gsfc.nasa.gov/education/graphic_history/univ_evol.cfm https://lambda.gsfc.nasa.gov/education/graphic_history/univ_... see there 4 and 5). Edit: response to your later response below: > The claimed predictions from the 1970s and 1980s are not mentioned on that page. They are mentioned even on the very page that you linked to: that page, among other points, followed the history of the tests and effectively concludes that, yes, finally, in 2013 ΛCDM wins the "item 3". Read carefully. Learn what ΛCDM is. MOND can still only claim "item 2." Which actual "authority" can show anything else? Also, behind "darkmattercrisis" blog are just a few guys with very fringe positions.
  - dmurray 8y ago
    > If you have an infinite space of particle parameters and a series of tests keeps eliminating large swaths of this space, at some point it feels like you're playing a god of inbetweens game a la creationists arguing using gaps in the fossil record. Or you're getting closer to finding out what the real parameters are? If you eliminate all possibilities and have to make up some new parameters, sure, that feels like you're not doing science and might as well be a creationist. But what you describe, narrowing down the space of possible explanations from infinitely many to only a few, is the dream of every theoretical physicist.
    - zamalek 8y ago
      > Or you're getting closer to finding out what the real parameters are? By that metric, epicycles were rock-solid.
      - deleted 8y ago
        [deleted]

syn0byte 8y ago

Lots, we just patch it and move on. Iron orb should glow blue unless this one variable is this one value? "patch it" by calling that one value plank's constant and see, the models still good! Our math says the universe comes up short on mass by over 3/4ths? Must be invisible matter we can't see or interact with see, the models still good! Over simplification in the extreme, but also a far cry from the rock solid foundations it claims to be.

deleted 8y ago
[deleted]