10 comments

  • FilosofumRex 8 days ago
    > One question that’s still unresolved is whether the supermaze versions of fuzzballs fully satisfy all the requirements scientists have for black holes

    The only question about supermaze fuzzballs blackholes, still unresolved, is what do string theorist smoke these days.

    • strogonoff 8 days ago
      Do you choose one model over the other if your basis for it is along the lines of “it sounds weird and unfamiliar to me” or “it sounds less like things I deal with in daily life” or “I cannot imagine what it looks like”? Should you do it?

      Surprisingly, in some ways, yes. A model is ultimately an attempt to lossily explain something in terms of (map it to) something else, more familiar. If it fails to do that, maybe it is not a good model.

      However, you cannot stop at the term. Yes, we all have seen a black hole (hell, I have one in my bathroom) and none of us have seen IRL a multi-dimensional anything, much less a supermaze fuzzball—but if you consider what the black hole model actually is, with things like event horizon, Hawking radiation, etc., it quickly loses its intuitiveness.

      Finally, of course, I’m not a string theorist, but I reckon if your model for something includes singularity as one of its main features then you obviously need some better model.

    • metalman 8 days ago
      As to black hole theorising, it is fair game for silliness , so, keeping in line with the joke they would be smoking "shatter", which is held in a kind of awe, even by the most hard core smokers as the densist and most refined form of cannabis availible, and casual observation of the effects and fall out from it's use suggests that it can precipitate life altering situations, also these days it would be very advisable for anyone trying such substsances to exercise extream caution, as 1 the actual stuff is powerfull, and 2 there are many reports of other things bieng added, that are outright deadly bieng thrown in. 3 hence the people I know who were indulging, made there own. And personaly I dont smoke anything, or, even though I do theorise about ,gravity, and black hole, I never expound upon those things, lest I realy get a greater reputation for oddity, and speculations as to what I am smoking.
    • aurareturn 8 days ago

        is what do string theorist smoke these days.
      
      What's with HN commenters, who are likely very unqualified to comment on string theory details, hating on people working in string theory?

      Is Sabine Hossenfelder's anti-string theory propaganda working that well?

      • raverbashing 8 days ago
        It's not SH, it's the last 20? 30? years of lack of experimental evidence for it
        • aurareturn 8 days ago
          Is 20-30 years a lot?

          Are there experimental evidence for an alternative quantum gravity theory?

      • Blahagun 8 days ago
        Naah, even that hack Brian Greene is distancing himself from String theory.
      • piva00 8 days ago
        [dead]
    • deepfriedchokes 8 days ago
      They smoke DMT, obviously.

      I, for one, really enjoy the ideas they come up with. Super creative!

  • unsnap_biceps 8 days ago
    > Black holes, the densest objects in the universe

    My mind was blown when I found out that mean density of black holes inside the event horizon can be quite low.

    > a super supermassive black hole with the mass of 4.3 billion Suns would have a density equal to one i.e. the same density as water.

    https://physics.stackexchange.com/a/218816

    • mytailorisrich 8 days ago
      This is purely based on the definition of "density" here, which is the mass of the black hole divided by the volume inside the event horizon (which is the invisible/black sphere).

      However the event horizon does not represent the extent of the mass of the black hole, but rather the point where gravity becomes so strong that nothing can escape it, even light (hence "black" hole/sphere).

      We don't really know what's inside the event horizon or how the mass if actually distributed. The concept of singularity is that all the mass is located in a zero volume with infinite density.

      • AnimalMuppet 8 days ago
        > We don't really know what's inside the event horizon or how the mass if actually distributed.

        Is that entirely true? We can tell if the black hole is rotating because of the frame dragging that happens outside the event horizon. Could we tell anything about the radial distribution of mass from the shape of space outside the event horizon? (I'm asking; I don't know enough GR to know.)

        • mytailorisrich 8 days ago
          Well we do reasonably know that the mass must be very densely packed at the centre but we do not know exactly how, we do not know if there is a singularity or not.
          • AnimalMuppet 8 days ago
            If a rotating black hole was not just a point, if it had a radial distribution, would the frame dragging be different? Could we tell that way?
    • FilosofumRex 8 days ago
      just like most fat people have lower density than skinny ones
  • piokoch 8 days ago
    I am surprised that String Theory is still alive, as it is a complicated mathematical structure (even quite elegant), but it is not clear how to verify it experimentally.

    For long year Particle Physics is hunted by the search of the "new physics", but it does not want to show up, my gut feeling is that if something interesting will be found, it will be coming from the space, as over there we have still unsolved mysteries, like "dark matter", which is observed, but does not have a good theoretical explanation.

  • 0xbadc0de5 8 days ago
    Unfalsifiable claims are uninteresting. Just Google the phrase "string theorists claim" and prepare to scroll through vast swaths of discarded theories.
    • chneu 8 days ago
      My understanding is that string theory has basically been tossed aside by most of the field.

      It's one of those things that got public support as it fell out of favor in academia. Now it won't go away because the public likes it.

      • raverbashing 7 days ago
        What I think happened is that this is probably one of the biggest "speculative steps" physics has taken without enough experimental evidence

        Sure, it's fine to think about and theorize, but I think they got way ahead of themselves than what the experimental results allowed them.

      • sshine 8 days ago
        The public likes Sheldon Cooper.
    • bruhthuh 8 days ago
      [dead]
  • asplake 8 days ago
    Potentially a testable hypothesis for string theory? I.e. that it might predict something observable that isn’t accounted for otherwise?
    • mnky9800n 8 days ago
      You are asking too much.
    • orwin 8 days ago
      No, still no.
  • bananapub 8 days ago
    seems pretty safe at this point to not care what string theorists have to say about anything, unless they’re paying for dinner?
  • qnleigh 8 days ago
    I'm confused; is this a proposed string-theoretic model of a black hole? Or is this a new object that they propose to form instead of a black hole when a star collapses?
  • mocenigo 7 days ago
    So they are essentially cosmic multi-dimensional yarn-balls. I wonder what cosmic multi-dimensional cats think of them.
  • simplesort 8 days ago
  • AnimalMuppet 8 days ago
    My daughter heard a little bit about string theory in physics class, and got freaked out. "11 dimensions? How am I supposed to understand that?" I told her that all the experimental evidence that supports string theory could fit on one sheet of paper, without using ink.

    So, string theorists say this. OK, and? That's kind of interesting, I suppose, but... make a testable prediction.