4 ms·

The picture is going to be a completely black rectangle.

by keketi 10y ago

lobster_johnson 10y ago
Black holes aren't necessarily dark. In fact, they usually emit a lot of light, especially in the x-ray spectrum. https://www.sciencealert.com/visible-light-emitted-from-a-black-hole-has-been-detected-for-the-first-time https://www.sciencealert.com/visible-light-emitted-from-a-bl...
- Y_Y 10y ago
  That's not what's in the article. The object falling into the black hole might emit a lot of light, but black holes can't emit from within, and Hawking radiation is very weak.
  - lobster_johnson 10y ago
    It's not the Hawking radiation, it's the friction caused by the gravitational forces (also thought to include magnetic fields) compressing and superheating the matter, which in turn causes it to emit light. It's apparently thought that the hole doesn't just immediately swallow up matter whole, and that it's not easy for matter to enter the hole at all. Rather the matter is sort of captured and slowly ground down by friction, leaving an accretion disc surrounding the event horizon. Black holes also emit "x-ray jets" that are thought to be observable. That said, I'm not a physicist. This is just what I've gleaned from articles and Horizon documentaries.
    - Y_Y 10y ago
      But I am a physicist, who works in this field. I know people in the article personally. You can't become an expert by watching documentaries, even though they thrive on making people feel like that. It's my personal opinion that popular science articles on new research (like this one), are ultimately unhelpful and are just an excuse for us to get funding. All that said it's great to see people interested in high-energy astro. If you wanted to know more I'd recommend Longair[0], even though it would be tough going for a non-scientist. [0] https://www.amazon.com/High-Energy-Astrophysics-Malcolm-Longair/dp/0521756189 https://www.amazon.com/High-Energy-Astrophysics-Malcolm-Long...
      - lobster_johnson 10y ago
        I went back to the article, which does say more or less what I wrote: What astronomers hope to finally see when they add up all the signals is a halo of light surrounding a dark circle -- the shadow of the black hole. The crescent of light comes from luminous gases, heated to hundreds of billions of degrees, that orbit just outside the black hole, tracing the region just beyond the event horizon. So when the grandparent said, "a completely black rectangle", that's probably not true. Which is was what I was responding to. Please feel to correct us non-experts (but it's not terribly useful to shut down discussion without explanation other than "I am a physicist").
        Y_Y 10y ago
        Stars are bright, we can see black holes that stars fall into because they interact with the star. Black holes all by themselves (almost) do not emit light and we observe them by seeing how they interact with light from further away objects. Jets are more complicated and have some open questions, but the conclusion is unchanged, if you really care then read the book. But if you want to think you know better then you can do that too.
      - lokedhs 10y ago
        I don't think anyone (at least I hope not) would claim to be an expert after watching some documentary. When reading your reply it does feel like you're suggesting that people shouldn't be allowed to watch light information on the subject that you work on. To me, that sounds similar to me suggesting that anyone interested in computing shouldn't be allowed to make a basic web page unless they read SICP first. If you are complaining about the state of science reporting, then I agree with you. It's really terrible. But, the solution isn't to get rid of it. The solution is to improve it. I think that people should be allowed to learn about the research they are paying for through their taxes. And it's the job of the scientists to share that information.
        Y_Y 10y ago
        There's no royal road.
gjkood 10y ago
> What astronomers hope to finally see when they add up all the signals is a halo of light surrounding a dark circle—the shadow of the black hole. The crescent of light comes from luminous gases, heated to hundreds of billions of degrees, that orbit just outside the black hole, tracing the region just beyond the event horizon. Probably some sort of ring image captured from the side or something like the artist's rendering in the article maybe.

The picture is going to be a completely black rectangle.

by keketi 10y ago

The picture is going to be a completely black rectangle.

Black holes aren't necessarily dark. In fact, they usually emit a lot of light, especially in the x-ray spectrum. https://www.sciencealert.com/visible-light-emitted-from-a-black-hole-has-been-detected-for-the-first-time https://www.sciencealert.com/visible-light-emitted-from-a-bl...

Y_Y 10y ago
That's not what's in the article. The object falling into the black hole might emit a lot of light, but black holes can't emit from within, and Hawking radiation is very weak.
- lobster_johnson 10y ago
  It's not the Hawking radiation, it's the friction caused by the gravitational forces (also thought to include magnetic fields) compressing and superheating the matter, which in turn causes it to emit light. It's apparently thought that the hole doesn't just immediately swallow up matter whole, and that it's not easy for matter to enter the hole at all. Rather the matter is sort of captured and slowly ground down by friction, leaving an accretion disc surrounding the event horizon. Black holes also emit "x-ray jets" that are thought to be observable. That said, I'm not a physicist. This is just what I've gleaned from articles and Horizon documentaries.
  - Y_Y 10y ago
    But I am a physicist, who works in this field. I know people in the article personally. You can't become an expert by watching documentaries, even though they thrive on making people feel like that. It's my personal opinion that popular science articles on new research (like this one), are ultimately unhelpful and are just an excuse for us to get funding. All that said it's great to see people interested in high-energy astro. If you wanted to know more I'd recommend Longair[0], even though it would be tough going for a non-scientist. [0] https://www.amazon.com/High-Energy-Astrophysics-Malcolm-Longair/dp/0521756189 https://www.amazon.com/High-Energy-Astrophysics-Malcolm-Long...
    - lobster_johnson 10y ago
      I went back to the article, which does say more or less what I wrote: What astronomers hope to finally see when they add up all the signals is a halo of light surrounding a dark circle -- the shadow of the black hole. The crescent of light comes from luminous gases, heated to hundreds of billions of degrees, that orbit just outside the black hole, tracing the region just beyond the event horizon. So when the grandparent said, "a completely black rectangle", that's probably not true. Which is was what I was responding to. Please feel to correct us non-experts (but it's not terribly useful to shut down discussion without explanation other than "I am a physicist").
      - Y_Y 10y ago
        Stars are bright, we can see black holes that stars fall into because they interact with the star. Black holes all by themselves (almost) do not emit light and we observe them by seeing how they interact with light from further away objects. Jets are more complicated and have some open questions, but the conclusion is unchanged, if you really care then read the book. But if you want to think you know better then you can do that too.
    - lokedhs 10y ago
      I don't think anyone (at least I hope not) would claim to be an expert after watching some documentary. When reading your reply it does feel like you're suggesting that people shouldn't be allowed to watch light information on the subject that you work on. To me, that sounds similar to me suggesting that anyone interested in computing shouldn't be allowed to make a basic web page unless they read SICP first. If you are complaining about the state of science reporting, then I agree with you. It's really terrible. But, the solution isn't to get rid of it. The solution is to improve it. I think that people should be allowed to learn about the research they are paying for through their taxes. And it's the job of the scientists to share that information.
      - Y_Y 10y ago
        There's no royal road.

gjkood 10y ago

> What astronomers hope to finally see when they add up all the signals is a halo of light surrounding a dark circle—the shadow of the black hole. The crescent of light comes from luminous gases, heated to hundreds of billions of degrees, that orbit just outside the black hole, tracing the region just beyond the event horizon. Probably some sort of ring image captured from the side or something like the artist's rendering in the article maybe.