da foist pictures of a black hole

déjà vu

Hi Nick,

Certainly not a dumb question, but also one that I want to avoid having turn rabbinical.  So I have to be careful how I answer.  I imagine I am remembering posts in which you have said something like “ALL statements are metaphors”, and in that kind of reductio, there is no distinction left with which I can reason.  So I want to argue at a kind of practical-man’s level that some things can be regarded as literal, and relative to the former, other things are metaphorical in greater or lesser degree.

So, to set the rules of the game by which I will play:

1. If I point and say “There is a goat”, and the thing I am pointing at really is what we have agreed is a goat, then I will call that a literal statement.
2. If I point at a man who behaves badly around women and say “He is a real goat”, then I am speaking metaphorically.

Now, the role of pictures and instruments.

1. If I am looking across a room at you and say “I see Nick”, and it really is you, then I will call that literal.
2. If I am looking at the viewfinder of my phone to take a picture of you, and I say “Wave, Nick; I see you!”, then if I want to be didactic, I am being either metaphorical or sloppy.  What I literally see is a rendered image of you in the viewfinder.  However, to the extent that the picture presents a pattern of light that is pretty similar to the pattern of light that would emanate from the material you, and since my eye and my brain handle the light image in pretty similar ways, it’s a fairly minimal metaphor by my classification of such things.

Telescopes and other instruments; when does augmented seeing become a secondary image?
1. As Frank rightly says, pretty much any telescope gathers more brightness than the naked eye can gather, in addition to providing finer angular resolution by taking light rays separated by narrow angles and delivering them to the eye in wider angles that the eye can discriminate.  The “actual photons” (whatever that means, since formally their states are changed by refraction, but we think of a redirected photon as somehow a continuation of the “original” photon) are still entering my eye.  I would usually lump that in with literal seeing, and just comment that I have a telescope to help.
2. What do we do when we time-integrate, as Frank says?  Now it is not only the aperture, but also the exposure, that the machine augments.  The only way one could compress the delivery of energy to the eye in time, to accommodate its limited sensitivity, analogously to refracting to accommodate its limited angular resolution, while still using the same “literal” photons, would be to somehow store them and deliver them in a pulse.  Basically, since it is so easy to make viewfinders, I can’t imagine anybody’s designing a telescope to time-compress the photons (though I know a woman at Harvard who has the ability to do such things, if I could remember her name), so you could receive the “original” photons; we are all happy to look at pictures in a viewfinder and let the amplifier do the work.  If I call that “seeing”, it is however metaphorical or sloppy it would be with the cell phone.  

What I take away from this is: there is a whole field of images to which one could actually respond with literal sight, but they are too dim, or too small, or the wrong color, etc., so we let machines refract or amplify, and barely-metaphorically see with viewfinders.

“Seeing” space and things in it.  Sorry if the above was belaboring the obvious, and your question wasn’t meant to actually start until what comes next.  I didn’t mean any of that to be insulting. 
1.  Did you mean “is it a problem to “see” a black hole since it isn’t emitting any light?”
2. I would say “seeing” in the ordinary sense is to receive a pattern of more or less or different light, and to interpret that pattern as a geometric image, using both the light pattern and the rest of ways the mind constructs or handles geometric concepts.  In that usage, the places that don’t deliver light are still part of the literal seeing experience, by contrast to the other places that do.  
3. We certainly can look out into (mostly, through) space, and can see the objects in space, and the darkness where there are not objects emitting anything.  For me that would still be literal seeing.
4. A black hole with various stuff around it is a region in space that can be looked at, and it has a real geometry, which controls the patterns with which light is delivered, so in that sense can be seen as literally as any other visual field in space.
5. Of course, there are all these practical problems, of vast distances, and special wavelengths, and small angles, and faint brightnesses, etc., which we solve with telescopes of more or less complexity, to produce an image on a viewfinder.  (For the Event Horizon Telescope, it was one hell of.a viewfinder.). However, once all that work is done, the image on the viewfinder is as literal a rendering as can be managed, of the way the actual image would come from the visual field, if we were close enough to resolve the angular separation, and could see in the required wavelengths to see through the dust, etc.  Apart from vast technical refinement, we haven’t done anything conceptually different from using the viewfinder of the cell phone.

On electrons, for comparison:
1. Here I want to be careful.  Black holes are classical objects.  Their event horizons, and the various stuff that orbits around them, are all classical, and exist at definite places.  So they could be seen in conventional terms, and viewfinder images of them can be fairly literal.
2. Electrons are generally not classically-behaving objects.  Hence it is possible for them to be “somewhere” to fairly high precision, but it is also possible for them to be in states that are not any definite “where”, and in that sense, one could not see them in the same literal sense as one could see a face.  If an atomic force microscope makes a map of a surface, atom by atom, and the viewfinder shows us a picture of a lumpy surface which corresponds to some potential surface of the electron density in roughly-atomic orbitals, then those electrons are not “at” the tiny positions corresponding to pixels in the picture on the viewfinder.  In that sense, I would say that referring to the viewfinder image as “seeing” the electrons is _more_ metaphorical than a sloppy use of “see” for the viewfinder on the phone with your image rendered on it.

Other versions of seeing that are even more metaphorical:
1. There are (to suitable approximations) real spheres in real space, which we can see.
2. Once we have the mathematical representation of a sphere for spheres in space, we can use spheres in space as a visualization tool for other mathematical spheres that do not exist in space.  There is a whole domain of algebra/geometry called the theory of Lie groups (a man’s name), for which it is very helpful to use such visualizations to think about the group manifolds (see the manifold thread), which may be a sphere or related shape.
3. In physics, it turns out that those Lie groups represent dimensions for variation that are not spatial, but that we regard as being as physically real as the spatial ones, and we can understand quantum particles, and the vacuum, in terms of “positions” mathematically in both spacetime and in those other Lie-group dimensions.  If I speak of “seeing” some relation in the Lie group manifold, then I am not literally referring to a spatial field, and in that sense not directly extending the physiological use of the eye.  One could say that this use of “see” is a degree more metaphorical than the use of “see” for the electron field imaged by the atomic force microscope, since at least the electron distribution exists in space, even if there is no way to interpret each pixel of the image as corresponding to a “place where the electron `is’”.

I tend not to find these metaphors disturbing, and it is almost interesting to consider why.  Once I know how to see spheres in space, I rarely go find a sphere if I need to think something about spheres in space.  I can visualize one just fine for many tasks.  So there is some aspect of seeing that initially depends on objects in the world, and the eye-as-medium, to teach the mind how to form images, but once the mind has learned, it can do much of what seemed to constitute seeing without the medium of the eye or the thing in the world.  There are auditory versions of this too (see work of Paula Tallal and April Benesich on hearing remediation during child development, which you probably saw in an SFI public lecture 15 years ago that I moderated).  I am inclined to the view [a metaphor, but the only one English gives me] that seeing is a composite active neural/physiological process, and to the extent that the neural can often run on its own, in some important respects I am seeing Lie groups when I am visualizing, with or without using eyes and light. The role of the eye and the world is not trivial, of course: my mind can’t “see” on its own in 3 or 4 or n dimensions, presumably at least in part because it never had a world and eyes in those dimensions to teach it, and there was no other medium for it to autonomously teach itself as if they had done so.  

A final word on black holes:
1. Because the ray paths around black holes are pretty exotic, if we were to look at black holes, our usual habits of geometric interpretation would do a very poor job of interpreting the visual field we would receive.  At minimum, it is poor in the way we are poor at handling the distortions in a fun-house mirror, but once one realizes that this is relativity, so the space-time structure is not Newtonian, our mistakes are even bigger than fun-house mistakes, though our eyes give us no way to realize it.
2. There are so many magnificent mathematically-correct renderings of the visual fields around coalescing black holes, etc., on the internet right now, that you can get very literal renderings of what you could see if you were really there.  There is a lovely one about falling into a black hole, which does a lot of hard math and delivers the result to you as a valid image.
3. Are these interchangeable with the viewfinder, as sources of experience?  For me, no.  They are renderings of human-produced math.  They could be wrong if the math of general relativity were wrong (though GR is by now so constrained that it is hard to find ways it could be wrong, given all the other things it predicts accurately).  The image from the actual Event Horizon Telescope doesn’t include those assumptions about doing the math.  It just processes what is really coming in.  So it can’t make those errors of presumption.  To me, that makes these images “visceral” to a degree that is probably bigger than the remaining difference between a viewfinder and an optical telescope.
4. In the sense that we might want to think “seeing is understanding”, then the lack of light from inside the effective horizon of the black hole is different from the lack of light from a black felt disc.  We see both as black (within various limits and approximations that I won’t digress on), but the felt disc we understand correctly, whereas the black hole is something we have no way to comprehend without other mathematical renderings as a scaffold for thought.

Sorry for such a ramble.  I hope I haven’t completely missed the point in your posing the question.

Best,

Eric

da foist pictures of a black hole

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