[yor_on]

In a way I think so. It seems as if we indeed are genetically programmed to 'know' some things, it must be that way considering small critters as bugs etc interacting (as I think:). But when it comes to larger brains we seem to use logical overlays that helps us simplify our senses, although I'm not sure on it of course. But I did discern it as salt after a short while though. So maybe we all really 'know' what salt is.

[Voxx (OP)]

Thank you for your thoughts Yor_on, it was an interesting conversation.

Although, it got a little off topic it was still interesting.

[damocles]

There is another phenomenon that seems to have been overlooked in this conversation -- fluorescence. X-rays are capable of breaking down chemical bonds in any material they pass through before reaching the eye. Some of this material will be in "excited states" and release its excess energy in the form of visible light. Intense x-rays would certainly break down in the material of the eyeball itself, but that would produce an unfocussed bluish glow.

But what about atmosphere and dust and objects in the path of an intense x-ray beam to the eye? X-rays might easily produce significant (but moch lower than the X-ray source) intensities of visible light in the directions of intense beams and none in regions where x-rays did not penetrate -- this would lead to a form of directional distribution of visible light that would be focussed in the usual way into a directionally resolved pseudo-image by the lens of our eyes.

[ScienceIsSquishy]

I can see X-Rays. I don't know if this is normal, but the CT scan techs didn't seem to be aware of it, and no one else I've told has noted it. I've Googled it and couldn't find any references.

During CAT scans, with my eyes open or closed I see hollow oval rings as the scanner position passes my eyes. I see the scan moving opposite of the actual scanner movement. e.g. I see the oval ring moving up from bottom when scan starts at the top - I'm seeing the X-Ray directly on my retinas, not adjusted by my lenses.

If anyone else sees this let me know.

[alancalverd]

Proteins in the lens can fluoresce, and the intensity increases with age. If you've had enough CT scans to notice an effect, you are probably old enough for the effect to be real! It's also possible if you have had several eye examinations or cataract surgery that there is some residual fluorescein in your eyes that is activated by x-radiation. 

[evan_au]

I see the scan moving opposite of the actual scanner movement. e.g. I see the oval ring moving up from bottom when scan starts at the top - I'm seeing the X-Ray directly on my retinas, not adjusted by my lenses.

I had to read this a few times before it sank in....
- The lens in our eyes inverts the image on our retina, so "high" things (above eye level) appear on the neck-side of your retina
- With the X-Rays, they are not refracted by the eye's lens, so they appear to be moving in  the opposite direction to the  CAT scanner beam!

I see hollow oval rings as the scanner position passes my eyes

I am not sure what a "hollow oval" is...
- I am having trouble imagining how a the fan-shaped X-Ray beam of a CAT scanner beam produces a "hollow oval".
- Could you post a diagram of what it looked like, please?

See: https://en.wikipedia.org/wiki/Operation_of_computed_tomography

[alancalverd]

If the interior of the lens were to fluoresce, the light would be dispersed by the concave rear surface. Nevertheless I'm baffled by the "movement"  as irradiation by the rotating fan beam would be pretty uniform and the beam width in a head-to-toe spiral or multislice scan may be as wide as the entire lens. 

[Bored chemist]

I presume that a hollow oval looks like this  0.
But I can't see how the eye could get any sense of "shape" for X rays unless the Xray bean was rather narrow and also very uneven in intensity.

However, if we consider Alan's idea that what you see may be fluorescence a possible explanation for the "shape" is that the distribution of fluorescent stuff is uneven.
As a throwaway idea, imagine that the lens doesn't fluoresce but the other components of the eye do- you would "see" a darker bit in the middle of the field of view, with a lighter area round it. You could get a similar pattern if the centre of the eye was (paradoxically) less sensitive to x-rays than the rest of the retina.


entre of A problem with that is that it wouldn't "track" the pate of  the scanner but there's possible reason for that effect too.

I once has the misfortune, while gardening,  to scratch the surface of my eye (I recommend not doing this).
Essentially, the treatment is to close the eye, sprinkle it with antibiotics to stop infection, and wait a few days for it to heal.
The problem is that, if you are doing anything- like making a cup of coffee or whatever, your eyes move and, when they did, the damaged but rubbed on the inner surface of the eyelid and that hurt.
So I spent a fair bit of time lying in bed.

I got bored, so I put the radio on.
I soon realised that I had to set it to play in mono.
Because, while it was giving a stereo sound image, my eyes would, instinctively, track the position of the loudest sound- ouch.

I can easily imagine something similar happening in a CT scanner.
You have your eyes shut, but they still automatically track the noisy scanner so a fixed blurry glow would seem to move.
What I'm not sure is which direction it would go.