3 ms·

As another layperson with a background in finance, it always felt like the cosmological equivalent of making a Balance Sheet balance by plugging the difference

As another layperson with a background in finance, it always felt like the cosmological equivalent of making a Balance Sheet balance by plugging the difference in a model

ixaxaar 3y ago
"Goodwill"?
Sharlin 3y ago
Well not at all. If anything, that's the MOND theories. The proper almost exact analogue to dark matter is an accountant noticing something's wrong with the figures, trying to find an honest mistake somewhere, and failing to do so, starting to reasonably suspect that there's embezzlement going on and the missing money has not simply disappeared into the ether.
- airstrike 3y ago
  Except accounting is just fun with numbers, so by definition you know if something is off, whereas with cosmological models you can't ever know if the math is missing something or if the model itself is inaccurate I'm saying (as others seem to also be saying) that it feels akin to saying "trust me, the model is right, we just haven't been able to find the missing $1 million but I'm sure it exists somewhere" It's not a particularly innovative or insightful criticism of current models, but that's what it feels like from the outside looking in. Chalk it up to ignorance, if you'd like, but I still feel like asking "are you sure you can't fix the model instead of plugging it with some unobservable feature?"
  - tekla 3y ago
    Its ignorance. There are very good reasons why Astronomers haven't chucked out Dark Matter. And yes, they have thought of the 5 minute HN remarks and already dealt with them.
  - lonjil 3y ago
    But we do know where it is, to quite good precision. We know how much or how little dark matter is present in different galaxies, which matches quite well with the amount of dark matter that must've been present in the early universe to explain some of the anisotropy of the cosmic microwave background.
  - fatbird 3y ago
    If we're going to correct our metaphor, it's like saying "when we add up the balances of all accounts, we're missing a million dollars, but when we add up all the interest earned on those accounts, total interest only makes sense if that million dollars is somewhere in there. Therefore, there's a million dollars we can detect overall but can't locate specifically."
    - airstrike 3y ago
      I like that, thank you for humoring me and my ignorance It feels like TFA is arguing "the way we calculate interest in the current model is wrong, here's a new formula". The jury is still out on whether that new formula breaks other parts of the model, I suppose
      - fatbird 3y ago
        Yes, exactly. And carrying it just a little further, the missing million idea has been around a while and actually accounts for quite a few observed discrepancies. A new interest formula plausibly explains one, but then has to tackle the others as well or better before it'll be taken as seriously.
  - Sharlin 3y ago
    Someone investigating a potential financial crime doesn't have all the information. They only have a model of where the money is coming from and going to. It's not like it's always easy to prove that there's definitely something illegal going on if the perpetrators have been carefully hiding their tracks with shell companies and money laundering and so on. So the investigator must form hypotheses and then try to find evidence for or against said hypotheses. Another analogy: we find a person, shot, in his home. There's a bullet inside the body, calibre and rifling marks point to a particular type of firearm, powder burn marks indicate a point-blank shot, all the CSI stuff. But the murder weapon is nowhere to be found. Do we assume that the weapon – and the perp – does indeed exist, or should we "tweak the model" to include a way for bullets to spontaneously materialize out of thin air and kill people? > Chalk it up to ignorance, if you'd like, but I still feel like asking "are you sure you can't fix the model instead of plugging it with some unobservable feature?" I don't understand how people think there's a distinction between "introducing a particle" and "fixing the model". Doing the former is doing the latter! Anyway, yes I do chalk it up to ignorance, because that's still a strawman, assuming some kind of a Scientific Orthodoxy that has decided that Dark Matter It Is, Claiming Otherwise Is Heresy. It's tiring to repeat this in every thread about DM, but – everybody and their dog has been testing the dark matter hypothesis for several decades now, obviously, because finding definitive evidence against it could be worth a Nobel, and so would figuring out a way to detect dark matter particles in laboratorio. And thus far they've found zero contradictory evidence, but instead in several other subdisciplines of astronomy, observations have been made that just happen to fit exactly the same sort of dark matter model that was originally only devised to explain the galactic rotation curves, without any fiddling. All the new evidence has simply tightened some parameters of the model that used to be less well known. Meanwhile, no competing hypothesis has been able to explain all the different observations that the the single unified dark matter model does explain. Different non-dark-matter models may be finetuned to explain some pieces of evidence, but that makes them unable to match other evidence. Nobody is claiming that there couldn't be a nice elegant dark-matter-less model that explains everything neatly. Most astrophycisists and cosmologists would be elated if one were found, and people do keep on looking. But as long as no such thing exists, we must assume that something that walks like a duck and quacks like a duck is, indeed, a duck.

As another layperson with a background in finance, it always felt like the cosmological equivalent of making a Balance Sheet balance by plugging the difference in a model

ixaxaar 3y ago

"Goodwill"?

Sharlin 3y ago

Well not at all. If anything, that's the MOND theories. The proper almost exact analogue to dark matter is an accountant noticing something's wrong with the figures, trying to find an honest mistake somewhere, and failing to do so, starting to reasonably suspect that there's embezzlement going on and the missing money has not simply disappeared into the ether.

airstrike 3y ago
Except accounting is just fun with numbers, so by definition you know if something is off, whereas with cosmological models you can't ever know if the math is missing something or if the model itself is inaccurate I'm saying (as others seem to also be saying) that it feels akin to saying "trust me, the model is right, we just haven't been able to find the missing $1 million but I'm sure it exists somewhere" It's not a particularly innovative or insightful criticism of current models, but that's what it feels like from the outside looking in. Chalk it up to ignorance, if you'd like, but I still feel like asking "are you sure you can't fix the model instead of plugging it with some unobservable feature?"
- tekla 3y ago
  Its ignorance. There are very good reasons why Astronomers haven't chucked out Dark Matter. And yes, they have thought of the 5 minute HN remarks and already dealt with them.
- lonjil 3y ago
  But we do know where it is, to quite good precision. We know how much or how little dark matter is present in different galaxies, which matches quite well with the amount of dark matter that must've been present in the early universe to explain some of the anisotropy of the cosmic microwave background.
- fatbird 3y ago
  If we're going to correct our metaphor, it's like saying "when we add up the balances of all accounts, we're missing a million dollars, but when we add up all the interest earned on those accounts, total interest only makes sense if that million dollars is somewhere in there. Therefore, there's a million dollars we can detect overall but can't locate specifically."
  - airstrike 3y ago
    I like that, thank you for humoring me and my ignorance It feels like TFA is arguing "the way we calculate interest in the current model is wrong, here's a new formula". The jury is still out on whether that new formula breaks other parts of the model, I suppose
    - fatbird 3y ago
      Yes, exactly. And carrying it just a little further, the missing million idea has been around a while and actually accounts for quite a few observed discrepancies. A new interest formula plausibly explains one, but then has to tackle the others as well or better before it'll be taken as seriously.
- Sharlin 3y ago
  Someone investigating a potential financial crime doesn't have all the information. They only have a model of where the money is coming from and going to. It's not like it's always easy to prove that there's definitely something illegal going on if the perpetrators have been carefully hiding their tracks with shell companies and money laundering and so on. So the investigator must form hypotheses and then try to find evidence for or against said hypotheses. Another analogy: we find a person, shot, in his home. There's a bullet inside the body, calibre and rifling marks point to a particular type of firearm, powder burn marks indicate a point-blank shot, all the CSI stuff. But the murder weapon is nowhere to be found. Do we assume that the weapon – and the perp – does indeed exist, or should we "tweak the model" to include a way for bullets to spontaneously materialize out of thin air and kill people? > Chalk it up to ignorance, if you'd like, but I still feel like asking "are you sure you can't fix the model instead of plugging it with some unobservable feature?" I don't understand how people think there's a distinction between "introducing a particle" and "fixing the model". Doing the former is doing the latter! Anyway, yes I do chalk it up to ignorance, because that's still a strawman, assuming some kind of a Scientific Orthodoxy that has decided that Dark Matter It Is, Claiming Otherwise Is Heresy. It's tiring to repeat this in every thread about DM, but – everybody and their dog has been testing the dark matter hypothesis for several decades now, obviously, because finding definitive evidence against it could be worth a Nobel, and so would figuring out a way to detect dark matter particles in laboratorio. And thus far they've found zero contradictory evidence, but instead in several other subdisciplines of astronomy, observations have been made that just happen to fit exactly the same sort of dark matter model that was originally only devised to explain the galactic rotation curves, without any fiddling. All the new evidence has simply tightened some parameters of the model that used to be less well known. Meanwhile, no competing hypothesis has been able to explain all the different observations that the the single unified dark matter model does explain. Different non-dark-matter models may be finetuned to explain some pieces of evidence, but that makes them unable to match other evidence. Nobody is claiming that there couldn't be a nice elegant dark-matter-less model that explains everything neatly. Most astrophycisists and cosmologists would be elated if one were found, and people do keep on looking. But as long as no such thing exists, we must assume that something that walks like a duck and quacks like a duck is, indeed, a duck.