4 ms·

Nothing. The event horizon is an absolute limit on observability and literally means “the threshold beyond which nothing ever happens”.

• mirimir 8y ago
  Yes. But TFA is all about what's happening there. So (and I apologize, if this seems rude) how is this different from talk about angels dancing on pins? Is it just that, somehow, this became a discussion of mathematics? I am, obviously, a hard-core experimentalist ;)
  • branweb 8y ago
    As I understand it, the ever-increasing interior volume of a black hole is deduced from the equations that support general relativity theory, which itself is supported by experimental evidence, so I think that's how it differs.
    • jostmey 8y ago
      The scientific process requires experimental observation and is the gold-standard for determining truth. But the scientific process has limits and does not work on every problem. It is important to understand that not all research uses the scientific method--a lot of research does not. I think that's okay provided the authors do not try to dress up their research to make it seem like it is science when it is not.
      • ordu 8y ago
        Do you think, that scientific process cannot work with black hole interior? If it so, I believe it is a premature belief. For experimental method was able to prove or disprove something, you need first some theoretic statement, based on which we can devise an experimental setup. Theoretic statements, which you can test experimentally, are not easily available in a countless quantities, theorists are searching for them, finding a lot of statements that can be drawn from paradigm, and some of this statments, happen to be reachable by an experiment. This statement maybe is not can be proved by observation, but who knows maybe if one think a little more, he would be able to draw some conclusions from this statement, that would be possible to check experimentally? How can we know if it possible to reach such a conclusions or not? The only way is to discuss angles dancing on pins. The only way is to find a lot of statments and see if some of them can be proved or disproved experimentally. And you would never know, did you had found all of such statements, or just small part of them. See? Scientific method is not just experimenting, scientific method is more about speculating and discussing dancing angles. Scientific method fully inherited such discussions from scholastics, but it differs from them because it added an experiment as a required tool. Scientific method is not negation of scholastic method, scientific method is an improved scholastic method. So, nothing wrong with discussing dancing angles, while we do not dismiss any opportunity to get an atomic miscroscope to count angels on a pin. If we do not see any opportunity, then we continue to discuss angels, until we see one. I don't know if it will be possible in a future to measure a volume of a black hole. But who knows... Scientists are very inventive when it comes to an experiment, and sometimes they can find some clues, that can be counted as observational evidence. Maybe they'll create experimental setup where all the conditions would be right to volume grow endlessly, but without creating a black hole? Or, maybe they create a gravitational-wave laser, point it at a black hole, and draw some evidence from observing results? I don't know. Generally we cannot know future before it happened. If we could then future was already here.
      • matthewdgreen 8y ago
        I disagree with this characterization. A crucial part of the scientific method is hypothesis formation. Nearly all of theoretical physics (or theoretical any field) can he slotted into that part of the method. Unguided experimentation can sometimes produce unexpected results, but many of our best scientific results come as a result of theoreticians proposing complete theories in advance, and then using these theories to generate new experiments. Since you can’t exactly pick up a black hole at the corner store, this type of theory development is even more critical — since it might produce ideas for experiments that we could actually conduct. [\rant]
  • mannykannot 8y ago
    I don't know if this is what is going on here, but I get the impression that these sort of discussions are ways to probe theories for inconsistencies. That seemed more clearly the case in this recent commentary by Sabine Hossenfelder on a paper invoking negative mass[1]. You don't have to experimentally observe a posited contradiction before thinking about whether it really is one, and if so, how it might be resolved. For one thing, you might find a way to investigate the issue experimentally. [1] http://backreaction.blogspot.com/2018/12/no-negative-masses-have-not.html http://backreaction.blogspot.com/2018/12/no-negative-masses-...
    • mirimir 8y ago
      Thanks. I do agree that generating testable hypotheses is a good thing, and that exploring contradictions, implications, etc re existing theory plays an important role. Still, it bugs me when these ideas get popularized, and people talk about them as if they were known. But I'm pretty sure that experts in the field keep it straight.
    • solotronics 8y ago
      Observing/measuring a quantum state affects it, I always wondered if thinking about possibilities similarly could affect quantum mechanics.
      • mirimir 8y ago
        So what? Observing a black hole could affect it? But because of the event horizon, we couldn't observe any such effect, right? I suppose that someone could drop in to check. And maybe then they'd know. But what about the rest of us? I gather that Hawking eventually agreed that black holes preserve information, and could leak it (somehow, eventually). Rajaniemi exploited the idea that information could be encoded in Hawking radiation. But that's just SF, I think.