EDIT: Let’s cool it with the downvotes, dudes. We’re not out to cut funding to your black hole detection chamber or revoke the degrees of chiropractors just because a couple of us don’t believe in it, okay? Chill out, participate with the prompt and continue with having a nice day. I’m sure almost everybody has something to add.

  • @Treczoks@lemmy.world
    -3•11 months ago

    We observe patterns of behavior – orbits, movement, gravitational lensing – that are exactly what we would see if, for example, there were great clouds of matter or other galaxies in those places.

    Which would still not rule out anything else…

    But we don’t see the hydrogen gas. We see non-uniform distributions of dark matter mass that imply there is not simply some consistent calculation error, but rather that there is dark matter that is not uniformly distributed.

    That non-uniformity though, yes, this is a good point for a “dark matter exists” hypothesis. Although I would still word it differently: Not “We see non-uniform distributions of dark matter mass” but “We see a non-uniform mass-like effect”. I’ve learned that keeping the terms as neutral as possible, or it might exert too much pressure on the thought process to go in just one direction.

    We’ve also discovered things like ultradiffiuse galaxies – likely remnants from ancient collisions – that have apparently been stripped of their dark matter.

    Which is basically an extreme case on “not uniformly distributed”.

    MOND cannot explain these observations because these galaxies essentially behave in a Newtonian manner that would be impossible in a MOND framework.

    That is acceptable. I was not “selling” MOND here (or any other theory), btw, I’m just wondering what kind of possibilities are there to explain all those observations. “An invisible mass nobody has observed except for it’s gravity effect” sounded a bit thin of a leg to stand on there, while incomplete models are a rather widespread phenomenon.

    electromagnetism is the reason things clump. Absent electromagnetism, what would cause clumping?

    Gravity? I mean, we are talking about something that has gravity. Did planets form because of electromagnetism?

    Yep, and more than a handful Many that make specific predictions we can test for and so are testing for.

    Indeed. Try that with the wannabe-sciences like economics…

    For example, you could look at axions, which are a theoretical particle predicted by an entirely different theory that may be a good fit for the dark matter particle.

    Well, at least they share the common trait of not being found yet… ;-)

    • admiralteal
      5•11 months ago

      Did planets form because of electromagnetism?

      For myriad reasons, the answer to this is an emphatic yes.

      Gravity may attract particles towards each other, but the force that actually causes them to interact with each other is almost entirely electromagnetism. The collisions of grains of cosmic dust are caused by electromagnetic fields interacting with each other. As is the gradual loss of kinetic energy – the friction – that allows some amount of potential energy to get converted to heat, allowing the particles to slow down and, as you described it, clump.

      Absent electromagnetism, the actual particle nuclei would need to directly hit each other to cause an interaction via the nuclear forces, which is VERY improbable in the vastness of space. Improbable doesn’t mean it wouldn’t happen, but in this case it does mean the universe is way too big and young. Without electromagnetic interactions, particles just form orbits. Which again, that’s what a “dark matter halo” is. It’s all the dark matter stuff orbitting around a galaxy’s center of mass because it doesn’t get easily trapped in the center. It’s all the dark matter in a gravitational system constantly whizzing back and forth across the center of mass since there’s no electromagnetic force to rob them of the potential or kinetic energy and stop them from heading back out.

      And, conveniently, these halos are just what our observations seem to indicate dark matter is doing in a typical galaxy. The observations and theory align well

      • @Treczoks@lemmy.world
        -1•11 months ago

        The observations and theory align well

        OK, I can accept that. Good luck hunting down whatever this dark matter is made of, then.

      • @Treczoks@lemmy.world
        -2•11 months ago

        I don’t have a bias against new particles. For me as a non astrophysicist, just another theory having a big hole was simply more likely. And the theory of gravity breaks anyway when it approaches quantum theory, why shouldn’t it be broken elsewhere, too?

        But I can easily accept the information given here, primarily the case with uneven distribution, which is a good case for something being there. Now you just have to nail the particle down.