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I'm not seeing anything there that isn't a handwavey explanation for "reality doesn't match the models, so DARK MATTER!"

• laretluval 9y ago
  It's still a nontrivial observation that the equations can be corrected to account for reality most simply by adding a term for unseen matter (rather than some factor or some other mathematical operation). Maybe the term doesn't have a straightforward physical explanation but there's a long history of introducing math without any corresponding mechanistic explanation---this is what gravity itself was until general relativity, nothing more than an inexplicable inverse-square attractive force.
  • electrograv 9y ago
    If a Newtonian model of gravity doesn't "explain" gravity, then neither does general relativity. These are all different models of reality with different levels of model complexity and predictive accuracy, but there's no fundamentally binary difference between them in their power of "explanation" etc. So new models like "dark matter" or "MOND" are all just different models that model observations better than prior theories but currently have the problem of being difficult to unify with the rest of theoretical physics.
• hwillis 9y ago
  >One of the recent most convincing things was the bullet cluster as described here.[1] We saw two galaxies collide where the "observed" matter actually underwent a collision but the gravitational lensing kept moving un-impeded which matches the belief that the majority of mass in a galaxy is collisionless dark matter that felt no colliding interaction and passed right on through bringing the bulk of the gravitational lensing with it. How can you possibly even begin to explain that without dark matter? [1] http://www.preposterousuniverse.com/blog/2006/08/21/dark-matter-exists/ http://www.preposterousuniverse.com/blog/2006/08/21/dark-mat...
  • douche 9y ago
    We don't understand how matter acrually works on a large scale. Inventing imaginary terms that we can't observe to satisfy the equations in the models to match the observed reality seems a poor practice.
    • hwillis 9y ago
      We understand that when two galaxies hit each other, the visible mass gets all tangled up and suns and nebula smash into each other. Meanwhile the invisible mass continues onwards, oblivious to everything else. We CAN observe it and we have. Seriously this is basic object permanence. We can see hidden things moving around by themselves. Dark matter is still there even when there's normal matter on top of it.
    • Avshalom 9y ago
      No. When the model is wrong, you build a new model. A bunch of weakly interacting particles is the new model.
    • gaius 9y ago
      Right it's like when people say, I don't believe in Creation, that stuff is just nonsense. And you say, so what's your alternative theory then? And they reply, well there was a "big bang" and everything just sort of appeared, for no reason. Really, that's the alternative explanation?
      • hwillis 9y ago
        Well yes, if you ignore all the evidence of something then you can confidently say there is no evidence. Christian genesis: There was a garden of Eden, and a god. Evidence: No garden of Eden, no evidence of angels or god, no reason those things would suddenly stop being apparent. Direct contradictory evidence that YHWH[1] was a minor god in the original jewish pantheon rather than an actual creator god. Big Bang: The universe started for an unknown reason and rapidly expanded outward. Evidence: The universe is visibly expanding outwards and formed in a way consistent with an explosion. Did you think that the big bang theory was just something someone thought of, and then they looked for evidence? Evidence came first, then the big bang was proposed. [1]: https://en.wikipedia.org/wiki/Yahweh https://en.wikipedia.org/wiki/Yahweh