astronomy

This magazine is from a federated server and may be incomplete. Browse more on the original instance.

teft, in The largest Black Hole compared to Our Solar System
@teft@startrek.website avatar

deleted_by_author

  • Loading...
  • jarfil, (edited )

    Supposedly.

    They can still rotate, so that means they’re not just unidimensional points in space.

    elavat0r,
    @elavat0r@mander.xyz avatar

    Technically couldn’t a ray emanating from a singularity rotate? Like, the point could have a sort of orientation without having any real measure?

    Not saying that’s the case here, but I think it could happen.

    jarfil,

    Let me stop you right there: a ray can’t emanate from a black hole, that’s why it’s a black hole, not even zero-mass light-speed photons can get out.

    We know about black holes rotating, because we can detect frame dragging around them, which means whatever mass is in there, has an average rotation.

    The thing is, an absolute “singularity” doesn’t even make sense for a black hole. From what we know of how they get formed, they’re just a bunch of star that gets compressed so tight that its own gravity doesn’t let anything escape… but that doesn’t mean every particle goes straight to the center of mass. Forming a singularity would require the initial star core to be kind of perfectly symmetrical, at absolute rest and 0K, which definitely is not the case. What’s more likely, is that at the center of a black hole, there is a star worth of particles “orbiting” the center of mass at speeds close to the speed of light, sometimes bumping into each other, but since not even mass-less photons can escape the black hole, nothing can get bumped out like it would in normal stars, atmospheres, and so on.

    From a mathematical point of view it makes sense to say there is a “singularity”, since for most purposes it behaves like one… but it really isn’t one. It’s also easier to think of the event horizon to be “empty” inside… but it also really is not, it’s going to be full of recently trapped particles on decaying orbits, with a lot of them being still right on the other side of the event horizon (more particles will be entering at a shallower than a steeper angle).

    Also, being an actual singularity would make evaporation due to Hawking radiation kind of impossible.

    elavat0r,
    @elavat0r@mander.xyz avatar

    When I said “ray” I just meant an imaginary line that could be drawn to extend in a given direction, not a literal particle escaping. It was mostly to think of a way you might conceptualize an orientation of an object that may not have any dimension. As in, if the matter just outside a singularity rotates, perhaps you could consider it to rotate? But I’m not sure that would be accurate to say anyway. My grasp of the physics of black holes is obviously pretty loose. :)

    Thanks for taking the time to explain!

    jarfil,

    an orientation of an object that may not have any dimension

    The thing is, if it had no dimension, then there would be no way for it to have any orientation in some dimensions, it would have to be perfectly identical regarding all dimensions.

    if the matter just outside a singularity rotates

    It’s a bit more fun, because it would be normal for matter to orbit around before falling in, but “frame dragging” means that not just matter, but also light outside it rotates with the black hole, and time gets stretched.

    jon,

    Normally black holes are considered to be everything up to the event horizon. E.g., from the Wikipedia page:

    The size of a black hole, as determined by the radius of the event horizon, or Schwarzschild radius, is proportional to the mass, M

    The term “black hole” derives from the fact that beyond a certain point light can’t escape, that point being the event horizon.

    Che_Donkey, in The largest Black Hole compared to Our Solar System
    @Che_Donkey@lemmy.ml avatar

    Is there a banana for scale or does Lemmy use a different model for scale? Beans?

    Calyhre,

    I think all the bananas (and beans) are already in the picture

    galilette,

    Well, even the picture is in the picture…

    FlyingSquid, in The largest Black Hole compared to Our Solar System
    @FlyingSquid@mander.xyz avatar

    That’s actually smaller than I would have thought. I wouldn’t have expected our solar system to even be visible in comparison.

    Zozano,

    What the hell are you talking about, that thing is beyond comprehension.

    RecursiveParadox,
    @RecursiveParadox@lemmy.world avatar

    We shouldn’t downvote people when they realize they have been thinking about something the wrong way and admit it.

    Zozano,

    Did I miss something? I didn’t down vote them

    RecursiveParadox,
    @RecursiveParadox@lemmy.world avatar

    Not you I’m sure, but they were at 0 when I posted, so thought I’d note it.

    Aimhere, in The largest Black Hole compared to Our Solar System

    How big is this, in real numbers?

    President_Pyrus,
    @President_Pyrus@feddit.dk avatar

    More than 1 AU.

    thepianistfroggollum,

    That’s technically correct.

    CrabAndBroom,

    About 1600 AU, according to wikipedia.

    Carvex, in Most planets in the Universe are orphans without parent stars

    Well yeah, planets get launched from their parent star gravity field during initial solar system formation all the time. There could be hundreds of small planet sized rocks slinging by each other in every direction before a stable disk formation forms. Bye bye, IceBall#768!

    notfromhere,

    Reminds me of the movie Dark City

    Sentau, in It Takes 26 Fundamental Constants To Give Us Our Universe, But They Still Don't Give Everything

    This article is like 8 years old. Please don’t post such old articles or at least add a small remark that it is an old article.

    Rozz, in It Takes 26 Fundamental Constants To Give Us Our Universe, But They Still Don't Give Everything

    Just where I like to go for my physics: Forbes.

    Also I didn’t read it yet. Does it make sense?

    argentcorvid, in See 17 Years of an Exoplanet’s Orbit in One Captivating GIF
    @argentcorvid@midwest.social avatar

    Crazy that it seems exacly edge-on to us.

    PancakeLegend,
    @PancakeLegend@mander.xyz avatar

    I’m going to take a swing at that being a function of how it was identified in the first place.

    can, in See 17 Years of an Exoplanet’s Orbit in One Captivating GIF
    Chadus_Maximus, in Something in space has been lighting up every 20 minutes since 1988

    Well as long as it keeps doing that we’re fine. If it randomly stops, just to restart after an arbitrary period of time, we should be concerned.

    emmanuel_car,

    Occasionally, a window will also go by without any bursts.

    It looks like it does that already.

  • All
  • Subscribed
  • Moderated
  • Favorites
  • random
  • uselessserver093
  • Food
  • aaaaaaacccccccce
  • [email protected]
  • test
  • CafeMeta
  • testmag
  • MUD
  • RhythmGameZone
  • RSS
  • dabs
  • Socialism
  • KbinCafe
  • TheResearchGuardian
  • Ask_kbincafe
  • oklahoma
  • feritale
  • SuperSentai
  • KamenRider
  • All magazines