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Can someone who really knows this stuff clarify my understanding? I've been given to understand that black holes remain a physics theory that has not been dire

Can someone who really knows this stuff clarify my understanding? I've been given to understand that black holes remain a physics theory that has not been directly observed or proven. I thought that we had a fair amount of observational evidence that suggests their existence, but no "smoking gun" proof of it, and that these types of "observed a black hole" articles are a little misleading - that in reality, what was observed was much indirect, interpreted data that is consistent with black hole theory, but could also be something else. Am I off base here?

thehappypm 3y ago
Scientist recently got a good picture of one
- claytongulick 3y ago
  See, this is my beef with the reporting on this stuff and the source of my question. The "photo" you're referring to was constructed by a super computer massaging enormous amounts of data to fit a model and constructing an image from weighted averages of thousands of data images across the spectrum from an enormously complex array of detectors in an unfathomably noisy environment [1]. It was presented by the media as a "photo", but it seems to me like it's more similar to the "image" we get from reconstruction of wifi signals in a room to determine interior object's shape. Or maybe a better example would be the "photos" of atoms, which are not photos at all but a reconstruction of miniscule electromagnetic resistance readings from a STM whisker driven by a piezoelectric crystal. I think we're supposed to get the ability to have better "photos" with the activation of LISA in 2037 [2] but until then, claiming that we have photos of black holes seems a bit misleading (not by you, I mean the science reporting). [1] https://eventhorizontelescope.org/blog/astronomers-reveal-first-image-black-hole-heart-our-galaxy https://eventhorizontelescope.org/blog/astronomers-reveal-fi... [2] https://en.m.wikipedia.org/wiki/Laser_Interferometer_Space_Antenna https://en.m.wikipedia.org/wiki/Laser_Interferometer_Space_A...
  - Keysh 3y ago
    LISA is a scaled-up version of LIGO, and won't produce "photos" any more than LIGO does. Of course, LIGO has provided extremely good evidence that black holes exist (most of what it detects are the gravitational waves from two black holes merging), but if you don't buy that, then you won't buy LISA's observations, either.
    - claytongulick 3y ago
      > but if you don't buy that, then you won't buy LISA's observations, either. Because science is about "buying" it?
      - andrewflnr 3y ago
        Yes, in the real world. Even if it wasn't, you've made this conversation about you personally "buying" it, so yeah.
        claytongulick 3y ago
        > you've made this conversation about you personally "buying" it, so yeah When?
  - perrygeo 3y ago
    > It was presented by the media as a "photo", but it seems to me like it's more similar to the "image" we get from reconstruction of wifi signals Are you suggesting that emitting or reflecting visible radiation is required before we can prove something exists in objective reality? Your own point about Wifi signals proves you wrong - we can detect wifi in other wavelengths and thus learn a great deal about it. Just like we can with black holes. There is no distinction between "images" and "photos" - they're both electromagnetic radiation converted to a visual medium. There's nothing unique about radiation in the 380 to 700 nanometers wavelength range that makes it somehow more scientifically valid for remote sensing.
    - 3y ago
csours 3y ago
As far as I know, the existence of black holes is accepted by basically every astrophysicist. There are several smoking guns: https://en.wikipedia.org/wiki/Black_hole#Observational_evidence https://en.wikipedia.org/wiki/Black_hole#Observational_evide...
Larrikin 3y ago
There's been more than one picture of one
krukah 3y ago
The theoretical prediction of black holes dates back to 1916, when Karl Schwarzschild proposed a solution to Einstein's field equations that were part of his general theory of relativity. General relativity is arguably the most robust theory in physics - that being said, general relativity introduces some tension with the other most robust theory in physics, namely quantum mechanics and the Standard Model. These two theories are largely accepted to be accurate and correct, and since they predict different phenomena at different length scales, most scientists have no trouble subscribing to both. With respect to "direct observation" of a black hole, astronomers at the Event Horizon Telescope successfully reconstructed pictures of a black hole using light in the visible spectrum. But to be fair, this comes after decades of overwhelming experimental evidence of black holes + GR. The EHT result probably received the media attention it did because it is easily interpretable as nice lil JPEG, rather than a 12-page paper with dense plots and LaTeX. See https://en.wikipedia.org/wiki/Tests_of_general_relativity https://en.wikipedia.org/wiki/Tests_of_general_relativity
- claytongulick 3y ago
  I'm familiar with the indirect evidence, and there's a lot of it. This article [1] seems to affirm my understanding that this is still all indirect evidence until LISA becomes operational. [1] https://www.science.org/content/article/after-decades-effort-scientists-are-finally-seeing-black-holes-or-are-they https://www.science.org/content/article/after-decades-effort...
Zamicol 3y ago
Einstein didn't think black holes existed (1916) and it took until 1971 with Cygnus X-1 for serious consideration, which was the smoking gun. 55 years of being considered probably a math fluke and then observational evidence.
funnymony 3y ago
I’ve read something like: there are bunch of observations of extremely dense masses in various suroundings. Talented people can find explanations other than black holes in each case. But that feels adhoc, and black hole fits quite nicely for whole class of observations. Current consensus is that b holes exist.
- claytongulick 3y ago
  > Current consensus is that b holes exist. I don't think it works like that? My read from looking at the literature is that the feeling is more like "black holes are a mathematical theory that have not been falsified by observational evidence, and for which we have some compelling, but inconclusive data, reconstructed from intensely noisy and poor resolution sources. Seems likely, but more data needed."
  - andrewflnr 3y ago
    If you're sufficiently cynical, you can describe almost all astronomy results that way. Lots of alternate explanations for the observations have been proposed, and fail to match the full evidence. Just how much evidence are you going to demand of phenomena hundreds of lightyears away before you say, "yeah, that's probably what it is"? Anyway, do be sure to read the whole list of observations linked above by csours, as there are quite a few.
Chabsff 3y ago
I think you are confusing Black Holes with Hawking Radiation . The later's status is basically exactly as you describe.

thehappypm 3y ago

Scientist recently got a good picture of one

claytongulick 3y ago
See, this is my beef with the reporting on this stuff and the source of my question. The "photo" you're referring to was constructed by a super computer massaging enormous amounts of data to fit a model and constructing an image from weighted averages of thousands of data images across the spectrum from an enormously complex array of detectors in an unfathomably noisy environment [1]. It was presented by the media as a "photo", but it seems to me like it's more similar to the "image" we get from reconstruction of wifi signals in a room to determine interior object's shape. Or maybe a better example would be the "photos" of atoms, which are not photos at all but a reconstruction of miniscule electromagnetic resistance readings from a STM whisker driven by a piezoelectric crystal. I think we're supposed to get the ability to have better "photos" with the activation of LISA in 2037 [2] but until then, claiming that we have photos of black holes seems a bit misleading (not by you, I mean the science reporting). [1] https://eventhorizontelescope.org/blog/astronomers-reveal-first-image-black-hole-heart-our-galaxy https://eventhorizontelescope.org/blog/astronomers-reveal-fi... [2] https://en.m.wikipedia.org/wiki/Laser_Interferometer_Space_Antenna https://en.m.wikipedia.org/wiki/Laser_Interferometer_Space_A...
- Keysh 3y ago
  LISA is a scaled-up version of LIGO, and won't produce "photos" any more than LIGO does. Of course, LIGO has provided extremely good evidence that black holes exist (most of what it detects are the gravitational waves from two black holes merging), but if you don't buy that, then you won't buy LISA's observations, either.
  - claytongulick 3y ago
    > but if you don't buy that, then you won't buy LISA's observations, either. Because science is about "buying" it?
    - andrewflnr 3y ago
      Yes, in the real world. Even if it wasn't, you've made this conversation about you personally "buying" it, so yeah.
      - claytongulick 3y ago
        > you've made this conversation about you personally "buying" it, so yeah When?
- perrygeo 3y ago
  > It was presented by the media as a "photo", but it seems to me like it's more similar to the "image" we get from reconstruction of wifi signals Are you suggesting that emitting or reflecting visible radiation is required before we can prove something exists in objective reality? Your own point about Wifi signals proves you wrong - we can detect wifi in other wavelengths and thus learn a great deal about it. Just like we can with black holes. There is no distinction between "images" and "photos" - they're both electromagnetic radiation converted to a visual medium. There's nothing unique about radiation in the 380 to 700 nanometers wavelength range that makes it somehow more scientifically valid for remote sensing.
  - 3y ago

csours 3y ago

As far as I know, the existence of black holes is accepted by basically every astrophysicist. There are several smoking guns: https://en.wikipedia.org/wiki/Black_hole#Observational_evidence https://en.wikipedia.org/wiki/Black_hole#Observational_evide...

Larrikin 3y ago

There's been more than one picture of one

krukah 3y ago

The theoretical prediction of black holes dates back to 1916, when Karl Schwarzschild proposed a solution to Einstein's field equations that were part of his general theory of relativity. General relativity is arguably the most robust theory in physics - that being said, general relativity introduces some tension with the other most robust theory in physics, namely quantum mechanics and the Standard Model. These two theories are largely accepted to be accurate and correct, and since they predict different phenomena at different length scales, most scientists have no trouble subscribing to both. With respect to "direct observation" of a black hole, astronomers at the Event Horizon Telescope successfully reconstructed pictures of a black hole using light in the visible spectrum. But to be fair, this comes after decades of overwhelming experimental evidence of black holes + GR. The EHT result probably received the media attention it did because it is easily interpretable as nice lil JPEG, rather than a 12-page paper with dense plots and LaTeX. See https://en.wikipedia.org/wiki/Tests_of_general_relativity https://en.wikipedia.org/wiki/Tests_of_general_relativity

claytongulick 3y ago
I'm familiar with the indirect evidence, and there's a lot of it. This article [1] seems to affirm my understanding that this is still all indirect evidence until LISA becomes operational. [1] https://www.science.org/content/article/after-decades-effort-scientists-are-finally-seeing-black-holes-or-are-they https://www.science.org/content/article/after-decades-effort...

Zamicol 3y ago

Einstein didn't think black holes existed (1916) and it took until 1971 with Cygnus X-1 for serious consideration, which was the smoking gun. 55 years of being considered probably a math fluke and then observational evidence.

funnymony 3y ago

I’ve read something like: there are bunch of observations of extremely dense masses in various suroundings. Talented people can find explanations other than black holes in each case. But that feels adhoc, and black hole fits quite nicely for whole class of observations. Current consensus is that b holes exist.

claytongulick 3y ago
> Current consensus is that b holes exist. I don't think it works like that? My read from looking at the literature is that the feeling is more like "black holes are a mathematical theory that have not been falsified by observational evidence, and for which we have some compelling, but inconclusive data, reconstructed from intensely noisy and poor resolution sources. Seems likely, but more data needed."
- andrewflnr 3y ago
  If you're sufficiently cynical, you can describe almost all astronomy results that way. Lots of alternate explanations for the observations have been proposed, and fail to match the full evidence. Just how much evidence are you going to demand of phenomena hundreds of lightyears away before you say, "yeah, that's probably what it is"? Anyway, do be sure to read the whole list of observations linked above by csours, as there are quite a few.

Chabsff 3y ago

I think you are confusing Black Holes with Hawking Radiation . The later's status is basically exactly as you describe.