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It's not actually clear that there is any problem with current theory - it may just be that our understanding and application of it is incorrect. You can have a

It's not actually clear that there is any problem with current theory - it may just be that our understanding and application of it is incorrect. You can have a perfect mathematical model, but if just one of your premises is incorrect, the output can be nonsensical. I am a physicist (well, I studied as one, before going technology entrepreneur), and have always sat in the "dark matter is bullshit" camp - so my opinion is likely tainted. I think a far more likely explanation, as this paper could suggest, is that something far more mundane is happening. For instance, we already understand tidal forces - that bodies can become tidally locked, that there is an inertial frame shear that drags bodies along around a rotating centre of mass, and exchanges energy between an orbiting body and the centre.... So why is it infeasible that galaxies are tidally locked, and the lack of fall-off in radial velocity is down to the gravitational shear from the galactic core being far more intense than we anticipate, causing the behaviour we see. It doesn't require a rewrite of relativity, "just" of galactic evolution. Either that, or galaxies are sprites, and lazily rendered ones, at that.

dnautics 10y ago
I've half joked that dark matter might be cumulative IEEE floating point rounding errors.
- adrianN 10y ago
  I hope God doesn't use IEEE floats.
  - aminorex 10y ago
    A Catholic one would.
kmm 10y ago
> For instance, we already understand tidal forces - that bodies can become tidally locked, that there is an inertial frame shear that drags bodies along around a rotating centre of mass, and exchanges energy between an orbiting body and the centre.... So why is it infeasible that galaxies are tidally locked, and the lack of fall-off in radial velocity is down to the gravitational shear from the galactic core being far more intense than we anticipate, causing the behaviour we see. It doesn't require a rewrite of relativity, "just" of galactic evolution. Because someone has indubitably already ran the numbers. The tidal force only has a non central, orbit changing influence on spatially extended bodies, and its effects even on objects as large as our solar system are completely negligible, as it doesn't seem to have a measurable effect on the orbits of the planets. The rotation curves are way off, which is a huge chunk of excess angular momentum that no tidal force can conjure. Where would it even come from, the rotational angular momentum of component stars?
- madaxe_again 10y ago
  You're aware that mercury is tidally locked, as is our moon, mars' moons, and others? I would call those real, physical effects, not negligible. As to running the numbers - agreed - but one can get an answer which is correct but incorrect if your premises are incorrect. At a galactic scale the perturbations are likely tiny, but a tiny force applied over enough time adds up. Anyway. It's a poor example that's almost certainly wrong but my point was more about how a single incorrect assumption can wreck a model.

dnautics 10y ago

I've half joked that dark matter might be cumulative IEEE floating point rounding errors.

adrianN 10y ago
I hope God doesn't use IEEE floats.
- aminorex 10y ago
  A Catholic one would.

kmm 10y ago

> For instance, we already understand tidal forces - that bodies can become tidally locked, that there is an inertial frame shear that drags bodies along around a rotating centre of mass, and exchanges energy between an orbiting body and the centre.... So why is it infeasible that galaxies are tidally locked, and the lack of fall-off in radial velocity is down to the gravitational shear from the galactic core being far more intense than we anticipate, causing the behaviour we see. It doesn't require a rewrite of relativity, "just" of galactic evolution. Because someone has indubitably already ran the numbers. The tidal force only has a non central, orbit changing influence on spatially extended bodies, and its effects even on objects as large as our solar system are completely negligible, as it doesn't seem to have a measurable effect on the orbits of the planets. The rotation curves are way off, which is a huge chunk of excess angular momentum that no tidal force can conjure. Where would it even come from, the rotational angular momentum of component stars?

madaxe_again 10y ago
You're aware that mercury is tidally locked, as is our moon, mars' moons, and others? I would call those real, physical effects, not negligible. As to running the numbers - agreed - but one can get an answer which is correct but incorrect if your premises are incorrect. At a galactic scale the perturbations are likely tiny, but a tiny force applied over enough time adds up. Anyway. It's a poor example that's almost certainly wrong but my point was more about how a single incorrect assumption can wreck a model.