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Does it bother anyone else when science reporters talk about some hypothesis endorsed by a lot of people as if it is just a plainly observable thing? A sentence

by guscost 12y ago

Does it bother anyone else when science reporters talk about some hypothesis endorsed by a lot of people as if it is just a plainly observable thing? A sentence like this > Dark matter comprises most of the mass of a galaxy. means just about nothing. It reminds me of when Richard Feynman was ranting about the science textbook with "energy makes it go" as the answer to some questions, and saying that you could just as easily substitute the word "wakalixes" and it would communicate exactly the same amount of information. Dark Matter is the popular name for a variable in some models of how fast galaxies of different sizes rotate. The current definition basically goes "maybe there is a lot of extra mass that we can't see and somehow doesn't interact with the visible matter in other ways." I'm sure it's a very sophisticated hypothesis and a lot of smart people have good reason to support it, but that's what it is. Why condescend to the general public by pretending that Dark Matter is some well-defined observable thing that scientists are simply trying to measure, instead of a proposed explanation for observations that we don't understand yet? Maybe it helps get funding, I don't know. This experiment looks neat because they're having a go at falsifying one model.

jordanpg 12y ago
It's a dirty little secret. There are two physics, the public-facing one and the actual one. The public-facing one is the one that builds and maintains public interest in physics in the name of maintaining the substantial amounts of money needed to conduct experiments and get research grants. This physics is very loosely based on the actual physics, which can't be understood beyond a superficial level without an appreciable amount of advanced mathematical training (nothing special: advanced undergrad/basic grad, but way, way, way beyond what 99.9% of people are conversant on). The result is metaphors that are barely, tangentially related to the math. They are evolved, tested talking points: black holes, string theory, warp drives, dark matter. Any one with any physics training at all has been to umpteen cocktail parties where they were pumped for information about the "God particle" or the movie Interstellar, and has bitten the bullet and done their best. It is a necessary side effect of a democratic society where funding for the sciences is tenuous, granted by scientifically illiterate half-wits, where the public could care less about anything not on BuzzFeed, and where the level of mathematical literacy maxes out somewhere south of Algebra I.
- stolio 12y ago
  If you can't talk about Interstellar with somebody who doesn't understand topology, I will gladly do it for you. Maybe they're below you, but they're my favorite people because they're the people who will get as excited as me about how stars form and what happens when they collapse and how friggin awesome it is that the computer simulations in a sci-fi movie were so accurate that Kip Thorne thinks he can publish a few articles about them[0]. This is SO MUCH BETTER than having to talk to people about What the bleep do we know? [0] - http://www.wired.com/2014/10/astrophysics-interstellar-black-hole/ http://www.wired.com/2014/10/astrophysics-interstellar-black...
  - jordanpg 12y ago
    I didn't mean to imply they're below me, but I do stand by the idea that those kinds of conversations are only a shadow of the real big picture. But I definitely raise a glass to preferring Interstellar over What the Bleep. :) Here, here.
    - guscost 12y ago
      That is a cool movie. I've posted a layperson's review: http://guscost.com/2014/12/23/review-interstellar/ http://guscost.com/2014/12/23/review-interstellar/
    - stolio 12y ago
      I apologize, I was being a bit presumptuous. When it comes to quantum physics I do see your point. For astrophysics I view the math as a stepping stone to understanding those things in the sky that we see at night. In that sense there's a bigger picture behind the big picture of the physics and we can all share in it. In QM, maybe not so much.
- guscost 12y ago
  While I can't say that I'm happy to hear this, it does make sense.
simplicio 12y ago
I don't think its correct to say "Dark Matter is the popular name for a variable in some models of how fast galaxies of different sizes rotate". The properties of Dark Matter are pretty tightly constrained, not just by galactic rotation properties, but also by CMB observations, gravitational lensing, galactic structure observations, big-bang nucleosynthesis populations and direct detection experiments. Obviously what one considers a "plainly observable thing" is up for debate. But the effects of dark matter are seen in a very wide range of astrophysical phenomena. Its not true that its just some fudge factor stuck in to account for galactic velocity curves.
- guscost 12y ago
  Would you care to enumerate these properties?
  - batbomb 12y ago
    There are four Fundamental Forces: Strong, Weak, Electromagnetic, and Gravity. In general, Dark Matter does not interact electromagnetically, and therefore does not emit nor absorb light. We can't see it. That's the defining property. There may be a few flavors of dark matter, each with it's own additional properties. However, Dark Matter probably interacts through gravity and the weak force: http://www.lsst.org/files/img/xxnyt.jpg http://www.lsst.org/files/img/xxnyt.jpg http://en.wikipedia.org/wiki/Weakly_interacting_massive_particles http://en.wikipedia.org/wiki/Weakly_interacting_massive_part...
    - guscost 12y ago
      So perhaps we can say (to a layman) that the properties of Dark Matter are: - It interacts via Gravity - It interacts via the Weak Nuclear Force But has any experiment ever observed something that fits this description? The galaxy rotation and gravitational lensing stuff must only indicate a gravity interaction, and as far as I can tell the attempts to observe WIMPs in isolation have not yet succeeded[0]. It looks like there might be some information gained from this PICASSO experiment mentioned in the wiki, but I would be grateful for some help decoding this one: > The obtained limits restrict recent interpretations of the DAMA/LIBRA annual modulation effect in terms of spin dependent interactions. Anyway, it seems like PR nonsense when folks ignore Popper and list "confirmations" that tend to support the SUSY model. I was careful not to use the phrase "fudge factor" because that's unfair, but there is a wide gulf between a fudge factor and a well-defined observable thing. [0] http://news.discovery.com/space/lhc-discovery-maims-supersymmetry-again-130724.htm http://news.discovery.com/space/lhc-discovery-maims-supersym...
tjradcliffe 12y ago
I don't disagree with jordanpg's reply, but it's even deeper than that. Physicists think about theories and talk about theories as if they were reality. It's a huge convenience. Remember, we can only keep five or ten things in focus at once (the "magic number seven, plus or minus two). By adopting the trick of treating a theory as reality we gain a huge cognitive convenience. The problem comes when we talk to non-scientists about this, who want to maintain a far less contingent view of the world. Knowledge isn't like that, though. Knowledge is contingent and uncertain (faith is certain.) The situation is far more complex than you suggest, in fact. "Dark Matter" is a name for a range of diverse phenomena that don't necessarily have anything to do with each other. We keep this in mind when talking amongst ourselves, but have never been able to get it clear to journalists. Galactic dark matter is what we use to explain rotation curves of spiral galaxies. It may be baryonic. As we go to larger scales there are different kinds of dark matter required--we know the baryon density of the universe and it isn't enough to explain what we see. We don't know if there is just one kind of exotic particle or many, and don't get me started on the cosmological constant. We talk about all this stuff as if it was real--and keeping in our heads models that are far more complex than the rough sketch of the idea you've presented as "the current definition"--because there's no reason not to. We know that it may be wrong. We know how radically contingent it all is. It's only when it gets to the general public, who have a very distorted view of how contingent our understanding of the world is, that people get upset, because they take the scientific discourse for something that it is not. In any case, this is absolutely not about funding. It's about epistemology and psychology.
- guscost 12y ago
 Thanks for the clarification. I'm something of an orthodox skeptic so these simplifications tend to come across as a modern version of "Zeus throws the thunder because that's what Zeus does" but it makes sense.

by guscost 12y ago

jordanpg 12y ago

It's a dirty little secret. There are two physics, the public-facing one and the actual one. The public-facing one is the one that builds and maintains public interest in physics in the name of maintaining the substantial amounts of money needed to conduct experiments and get research grants. This physics is very loosely based on the actual physics, which can't be understood beyond a superficial level without an appreciable amount of advanced mathematical training (nothing special: advanced undergrad/basic grad, but way, way, way beyond what 99.9% of people are conversant on). The result is metaphors that are barely, tangentially related to the math. They are evolved, tested talking points: black holes, string theory, warp drives, dark matter. Any one with any physics training at all has been to umpteen cocktail parties where they were pumped for information about the "God particle" or the movie Interstellar, and has bitten the bullet and done their best. It is a necessary side effect of a democratic society where funding for the sciences is tenuous, granted by scientifically illiterate half-wits, where the public could care less about anything not on BuzzFeed, and where the level of mathematical literacy maxes out somewhere south of Algebra I.

stolio 12y ago
If you can't talk about Interstellar with somebody who doesn't understand topology, I will gladly do it for you. Maybe they're below you, but they're my favorite people because they're the people who will get as excited as me about how stars form and what happens when they collapse and how friggin awesome it is that the computer simulations in a sci-fi movie were so accurate that Kip Thorne thinks he can publish a few articles about them[0]. This is SO MUCH BETTER than having to talk to people about What the bleep do we know? [0] - http://www.wired.com/2014/10/astrophysics-interstellar-black-hole/ http://www.wired.com/2014/10/astrophysics-interstellar-black...
- jordanpg 12y ago
  I didn't mean to imply they're below me, but I do stand by the idea that those kinds of conversations are only a shadow of the real big picture. But I definitely raise a glass to preferring Interstellar over What the Bleep. :) Here, here.
  - guscost 12y ago
    That is a cool movie. I've posted a layperson's review: http://guscost.com/2014/12/23/review-interstellar/ http://guscost.com/2014/12/23/review-interstellar/
  - stolio 12y ago
    I apologize, I was being a bit presumptuous. When it comes to quantum physics I do see your point. For astrophysics I view the math as a stepping stone to understanding those things in the sky that we see at night. In that sense there's a bigger picture behind the big picture of the physics and we can all share in it. In QM, maybe not so much.
guscost 12y ago
While I can't say that I'm happy to hear this, it does make sense.

simplicio 12y ago

I don't think its correct to say "Dark Matter is the popular name for a variable in some models of how fast galaxies of different sizes rotate". The properties of Dark Matter are pretty tightly constrained, not just by galactic rotation properties, but also by CMB observations, gravitational lensing, galactic structure observations, big-bang nucleosynthesis populations and direct detection experiments. Obviously what one considers a "plainly observable thing" is up for debate. But the effects of dark matter are seen in a very wide range of astrophysical phenomena. Its not true that its just some fudge factor stuck in to account for galactic velocity curves.

guscost 12y ago
Would you care to enumerate these properties?
- batbomb 12y ago
  There are four Fundamental Forces: Strong, Weak, Electromagnetic, and Gravity. In general, Dark Matter does not interact electromagnetically, and therefore does not emit nor absorb light. We can't see it. That's the defining property. There may be a few flavors of dark matter, each with it's own additional properties. However, Dark Matter probably interacts through gravity and the weak force: http://www.lsst.org/files/img/xxnyt.jpg http://www.lsst.org/files/img/xxnyt.jpg http://en.wikipedia.org/wiki/Weakly_interacting_massive_particles http://en.wikipedia.org/wiki/Weakly_interacting_massive_part...
  - guscost 12y ago
    So perhaps we can say (to a layman) that the properties of Dark Matter are: - It interacts via Gravity - It interacts via the Weak Nuclear Force But has any experiment ever observed something that fits this description? The galaxy rotation and gravitational lensing stuff must only indicate a gravity interaction, and as far as I can tell the attempts to observe WIMPs in isolation have not yet succeeded[0]. It looks like there might be some information gained from this PICASSO experiment mentioned in the wiki, but I would be grateful for some help decoding this one: > The obtained limits restrict recent interpretations of the DAMA/LIBRA annual modulation effect in terms of spin dependent interactions. Anyway, it seems like PR nonsense when folks ignore Popper and list "confirmations" that tend to support the SUSY model. I was careful not to use the phrase "fudge factor" because that's unfair, but there is a wide gulf between a fudge factor and a well-defined observable thing. [0] http://news.discovery.com/space/lhc-discovery-maims-supersymmetry-again-130724.htm http://news.discovery.com/space/lhc-discovery-maims-supersym...

tjradcliffe 12y ago

I don't disagree with jordanpg's reply, but it's even deeper than that. Physicists think about theories and talk about theories as if they were reality. It's a huge convenience. Remember, we can only keep five or ten things in focus at once (the "magic number seven, plus or minus two). By adopting the trick of treating a theory as reality we gain a huge cognitive convenience. The problem comes when we talk to non-scientists about this, who want to maintain a far less contingent view of the world. Knowledge isn't like that, though. Knowledge is contingent and uncertain (faith is certain.) The situation is far more complex than you suggest, in fact. "Dark Matter" is a name for a range of diverse phenomena that don't necessarily have anything to do with each other. We keep this in mind when talking amongst ourselves, but have never been able to get it clear to journalists. Galactic dark matter is what we use to explain rotation curves of spiral galaxies. It may be baryonic. As we go to larger scales there are different kinds of dark matter required--we know the baryon density of the universe and it isn't enough to explain what we see. We don't know if there is just one kind of exotic particle or many, and don't get me started on the cosmological constant. We talk about all this stuff as if it was real--and keeping in our heads models that are far more complex than the rough sketch of the idea you've presented as "the current definition"--because there's no reason not to. We know that it may be wrong. We know how radically contingent it all is. It's only when it gets to the general public, who have a very distorted view of how contingent our understanding of the world is, that people get upset, because they take the scientific discourse for something that it is not. In any case, this is absolutely not about funding. It's about epistemology and psychology.

guscost 12y ago
Thanks for the clarification. I'm something of an orthodox skeptic so these simplifications tend to come across as a modern version of "Zeus throws the thunder because that's what Zeus does" but it makes sense.