Comment by hbrav | Hacker News Reader

Comment by hbrav | Hacker News Reader

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I think there's some confusion on your part about what the image purports to show.

I shall put aside the parent comments concern about the signal analysis techniques. Those may be valid concerns, and I don't know enough to assess them.

> I'm not sure it's physically possible to take a visible light picture of a "naked" event horizon The event horizon telescope isn't purporting the image emission from the event horizon itself. While the theory of those emissions (Hawking radiation) is very persuasive, they would be incredibly weak for a black hole of even stellar mass, and even weaker for a supermassive black hole. What is being imaged here is hot around the black hole, which is heated due fluid dynamic effect (compression or viscosity, I'm not sure which dominates) as it spiral in to the black hole. The 'image' of the event horizon is the 'shadow' where the black hole blocks our view of the hot gas on the far side.

The fact that this shadow is compatible with the expected size given the mass of this black hole is a scientifically interesting result.

Thanks for your reply!

I also think it's scientifically interesting and appreciate the work.

But it should be called a model or illustration, because a human could never see this with bare eyes.

But our “bare eyes” are, too, merely instruments that the brain receives signals from; these signals have an electro-chemical nature, and in the brain they have to pass through a number of layers of interpretation before they reach the consciousness.

A picture is not reserved for something we can see with bare eyes - an infrared camera produces a photo, we don't call that an illustration - such cameras are used in military, geology, earth mapping and agriculture, etc. Most images in industry and astronomy could never be seen with bare eyes, because our eyes can see only 1% of what our instruments can.

Ofcourse each wavelength of light works a bit differently, like with the X-ray example, you need to understand how X-ray works to understand what you are looking at.

A model or illustration is something that would be product of our calculation or imagination, that was given visual form.

I agree that in science, as we extend our perception with instruments, it's difficult draw the line between an image and an illustration or diagram.

I'm maybe grumpy because this relatively featureless image of relatively massaged data is presented by mainstream news as "FANTASTIC new photo of a Black Hole! WOW! It looks just like in Interstellar!"

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