4 ms·

I always wonder if dark matter isn't simply made of wrinkles in space-time that just don't go back to flat after some weird event happens

• jfengel 4y ago
  It would have to be a galaxy sized, smooth spherical wrinkle that happened to coincide with practically every galaxy. And also to fail to interact with other galaxies when they collide. While we don't know the details of dark matter, we do know a lot of things about it. Putative explanations have to cover a lot of ground.
  • candiodari 4y ago
    That wouldn't be so weird as it sounds. From simulations we know that it was dark matter that came first, then came the galaxies. So if these wrinkles (they don't have to be very smooth) simply had a (large) preferred size and clumped up faster than normal matter in the early universe, that would be enough. Neither of those would be particularly weird. When dark matter clumped up normal matter was essentially a very low density hydrogen cloud, devoid of stars, much less dense than a cloud in the sky, which would take (without dark matter) some 15-50 billion years to clump up by itself. As for the size of the dark matter structures, well we don't know what they are, so you can postulate any size for them.
• throwawaymaths 4y ago
  In the case that dark matter doesn't interact via any force other than gravity, then there will be an epistemological crisis in physics as your model will be indistinguishable from one in which dark matter is a particle.
  • XorNot 4y ago
    It's the classic failing of everyone's casual "alternative to dark matter". It's not X because we can't detect it, what if instead it's an undetectable form of Y? Far too many people get hung up on the idea that in science what things "are" matters: because it doesn't. What matters is predictive power for future observations - if whatever you're proposing doesn't predict anything different to "invisible matter" then it's exactly as bad an explanation as "invisible matter" which so far is a perfectly good explanation for current observations.
    • tabtab 4y ago
      Then you just get fancy regression formulas. With enough layers and "bars", epicycles "work" in terms of predictive power. It's usually better to find out the underlying mechanism rather than merely satisfy prediction. Otherwise we'd still be using epicycles. Plus, gravity theory has Occam's Razor over epicycles.
      • XorNot 4y ago
        Right but that's the point: there's nothing wrong with "invisible matter" as an explanation if it explains everything. Even if it's actually not invisible matter, provided it behaves like it at all times, then that's good enough until it doesn't. The universe has no requirement to satisfy the day-to-day intuitions of African-plains originated upright apes, with senses optimized to spot large predators, in how it works. Quantum mechanics is a great example of that.