3 ms·

dark matter is pretty solid of an idea. it's been around for over a hundred years at this point. it isn't a band-aide fix for wonky math in an inaccurate theory

dark matter is pretty solid of an idea. it's been around for over a hundred years at this point. it isn't a band-aide fix for wonky math in an inaccurate theory. the foundations of the concept of dark matter are fairly reasonable.

Maursault 5y ago
> dark matter is pretty solid of an idea Not really. It is a hypothesized form of matter. There are competing hypotheses. Dark matter came to popularity in order to explain observations of galaxy rotation curves in the late 1930s. But these galaxies were observed in isolation, giving the illusion of gravitational isolation, which doesn't exist. Once accounting for the tidal effects of nearby galaxies, [1] dark matter becomes unnecessary to explain galaxy rotation curves, all that is needed is Newtonian physics. But in the period since dark matter was hypothesized, other observations that could not be readily explained were lumped into dark matter. Dark matter is nothing if not an amalgamation of unexplainable observations. So while dark matter is unnecessary to explain galaxy rotation curves, it is still somehow useful to explain unrelated observations. > it isn't a band-aide fix It really sort of seems like that: can't explain an observation, so invent something out of thin air to explain it. Honestly, an hypothesis that elves are causing the observations has just as much validity (or lack thereof). Now, elves have not been proven to be the cause of these unexplained observations, but neither has dark matter. > the foundations of the concept of dark matter are fairly reasonable. See above concerning galaxy rotation curves and endnote. Please understand it is quite possible that dark matter does not exist. The reason why it seems like accepted science has to do with scientific paradigms. Once a notion becomes an accepted part of the science paradigm, it takes years if not decades after disproving it beyond all doubt to dislodge it from the paradigm. If science has a problem, it is paradigms. [1] https://www.youtube.com/watch?v=PL0ewiwqoTw&t=6m11s https://www.youtube.com/watch?v=PL0ewiwqoTw&t=6m11s
- Keysh 5y ago
  The observations in the 1930s you allude to were of the motions of galaxies in galaxy clusters. The rotation-curve measurements for individual galaxies started in the 1970s and really took off in the 1980s. "Tidal effects" are a non-starter, and do nothing to explain galaxy rotation curves. Nor do they explain the excess motions of individual galaxies in galaxy groups and clusters, or the excess pressure of hot, X-ray emitting gas in groups and clusters -- all of which requires either some kind of dark matter, or some kind of alternate theory of gravity, or both. (I notice that I pointed out the ignorant nonsense of that video when you posted a link to it 7 months ago -- https://news.ycombinator.com/item?id=27085979#27090683 https://news.ycombinator.com/item?id=27085979#27090683)
  - Maursault 5y ago
    > The observations in the 1930s you allude to were of the motions of galaxies in galaxy clusters. The rotation-curve measurements for individual galaxies started in the 1970s and really took off in the 1980s. Nice catch. > "Tidal effects" are a non-starter, and do nothing to explain galaxy rotation curves. Nor do they explain the excess motions of individual galaxies in galaxy groups and clusters, or the excess pressure of hot, X-ray emitting gas in groups and clusters -- all of which requires either some kind of dark matter, or some kind of alternate theory of gravity, or both. What a well formed and well supported argument, and not just a matter of fact statement that you've left entirely unsupported. I'm totally convinced!

Maursault 5y ago

> dark matter is pretty solid of an idea Not really. It is a hypothesized form of matter. There are competing hypotheses. Dark matter came to popularity in order to explain observations of galaxy rotation curves in the late 1930s. But these galaxies were observed in isolation, giving the illusion of gravitational isolation, which doesn't exist. Once accounting for the tidal effects of nearby galaxies, [1] dark matter becomes unnecessary to explain galaxy rotation curves, all that is needed is Newtonian physics. But in the period since dark matter was hypothesized, other observations that could not be readily explained were lumped into dark matter. Dark matter is nothing if not an amalgamation of unexplainable observations. So while dark matter is unnecessary to explain galaxy rotation curves, it is still somehow useful to explain unrelated observations. > it isn't a band-aide fix It really sort of seems like that: can't explain an observation, so invent something out of thin air to explain it. Honestly, an hypothesis that elves are causing the observations has just as much validity (or lack thereof). Now, elves have not been proven to be the cause of these unexplained observations, but neither has dark matter. > the foundations of the concept of dark matter are fairly reasonable. See above concerning galaxy rotation curves and endnote. Please understand it is quite possible that dark matter does not exist. The reason why it seems like accepted science has to do with scientific paradigms. Once a notion becomes an accepted part of the science paradigm, it takes years if not decades after disproving it beyond all doubt to dislodge it from the paradigm. If science has a problem, it is paradigms. [1] https://www.youtube.com/watch?v=PL0ewiwqoTw&t=6m11s https://www.youtube.com/watch?v=PL0ewiwqoTw&t=6m11s

Keysh 5y ago
The observations in the 1930s you allude to were of the motions of galaxies in galaxy clusters. The rotation-curve measurements for individual galaxies started in the 1970s and really took off in the 1980s. "Tidal effects" are a non-starter, and do nothing to explain galaxy rotation curves. Nor do they explain the excess motions of individual galaxies in galaxy groups and clusters, or the excess pressure of hot, X-ray emitting gas in groups and clusters -- all of which requires either some kind of dark matter, or some kind of alternate theory of gravity, or both. (I notice that I pointed out the ignorant nonsense of that video when you posted a link to it 7 months ago -- https://news.ycombinator.com/item?id=27085979#27090683 https://news.ycombinator.com/item?id=27085979#27090683)
- Maursault 5y ago
  > The observations in the 1930s you allude to were of the motions of galaxies in galaxy clusters. The rotation-curve measurements for individual galaxies started in the 1970s and really took off in the 1980s. Nice catch. > "Tidal effects" are a non-starter, and do nothing to explain galaxy rotation curves. Nor do they explain the excess motions of individual galaxies in galaxy groups and clusters, or the excess pressure of hot, X-ray emitting gas in groups and clusters -- all of which requires either some kind of dark matter, or some kind of alternate theory of gravity, or both. What a well formed and well supported argument, and not just a matter of fact statement that you've left entirely unsupported. I'm totally convinced!