Regardless of the exact absorption mechanism, heat is heat. There’s no meaningful distinction between “indirect” vs “direct” heat.
This is determined not by the exact absorption mechanism, but by the thermal properties of the tissue, absorbance of the surface, and the penetrating depth of the radiation. And for most types of tissue, I think the penetrating depth of UV/visible/IR is so small as to be inconsequential for this discussion.
Of course the eye has many parts that are transparent to visible light, so that does change things. If anything, I think this makes visible light more dangerous for the retina than IR. Much of the far-IR will be absorbed by the cornea, lens and vitreous humour. But almost all visible light will transmit right through these parts and reach the retina.
According to lazybratsche’s cite, you are wrong. You are making statements perhaps based on your intuition without analysis or cite.
Again, you are just making statements, totally ignoring the explanations I have written which describe specifically what I am referring to. If you address those specifically, perhaps we can have a conversation in which you convince me I am wrong. I may very well be, but I have no way of knowing that based on un-explicated statements like the above which totally ignore the argument I have put forward.
The penetration depth is larger than 1mm for some frequencies in human flesh. (There is a graph inside here, fig 7-9). It is not at all inconsequential.
I did throw up a rather large wall of text. Trimmed down to the most relevant bits, bolding mine:
Which was against my intuition. I expected moderate heating which would be sufficient to cause damage. There is moderate heating, to about 41 C, but not to the 47 C threshold for retina damage. And even that threshold is low compared to the ~60 C needed to cause serious damage to the skin during a brief exposure.
Awesome cite, lazybratsche (I’ve selected out and bolded the most relevant part above)! So, I guess the answer to my question is that staring at the sun can slowly cause long-term problems due to photochemical processes. I am inferring that there is no clear ‘threshold’ for eye damage as I thought before – that a small amount of damage is even happening from your lights around the house.
ETA: You beat me to it, but I’ll leave the post as-is
In one experiment cited by the above review, which might answer your question, normal lab rats were exposed to a range of intensities of green and UVA light. Green light of similar intensity to direct sunlight (100 watt/m^2) would pretty much fry the retina in about 12 seconds. The amount of UV provided by direct sunlight (1 watt/m^2) took more than 40 minutes to cause similar damage. But, in the very long term, damage can accumulate from much lower UV exposures.
If you extrapolate that to humans, staring directly at the sun will fry your retina in a few seconds, regardless of UV protection. But every author cautions that such extrapolations might not be accurate at all. I think, however, that it’s safe to conclude that UV protection doesn’t make it safe to stare at the sun.
There is clearly a major problem with such extrapolations (or the study to begin with), given that many, including myself, have given the sun a good multi-second stare without any signs of trouble.
Have you had your eyes examined? I saw a documentary about sungazing, and the guy in the documentary had been sungazing for a few months. He noticed no difference in his vision, but photographs of his retina showed a very clear circular ‘burn’ in the center.
I have had my eyes examined (no problems), and I also have pretty good vision. It wouldn’t surprise me if I have accrued some small degree of long-term damage, but my retina is by no means “fried.” And while I’m not sure how much weight to give them, there are numerous accounts turned up via google of people who claim they have stared for minutes without problem (there are also some who report problems, however).
Hmm, actually I have to retract my earlier summary. I was reading too quickly and conflated two very different experiments that were in the same paper. The time and intensity of light that I mentioned above (12 seconds 100 watt/m^2 green light, or 40+ minutes 1 watt/m^2 UVA) was measuring the bleaching of retinal pigments in a test tube*, not ablation of an actual retina. These pigments are constantly being bleached at a low rate (which is why bright lights leave an after-image), but also produce toxic by products which can build up and eventually cause permanent damage.
That paper also did an experiment measuring physical ablation of the retina after a four hour** exposure at various intensities of green and UVA light. 100 w/m^2 of green light ablated 40% of the retina, and 50 w/m^2 ablated 10%. 1 w/m^2 of UVA light also ablated 10%. They use 10% as a (fairly arbitrary) threshold for serious damage. They did not test whether, say, 1% or 20% ablation was actually sufficient for blinding the rat.
So, if you stare at the sun for some sufficiently long period of time (minutes? hours?) you can quite literally fry your retina, even if you completely block UV light.
*confirmed by a smaller scale experiment measuring the pigment bleaching in an actual eye.
**actually they weren’t very clear about the exposure time in this experiment, but they clearly state that an initial experiment had a four hour exposure.
I have been sun gazing for more than 6 months now. My experience has been that my eyesight has improved to an extent that I no longer need to wear my glasses. I have not had my eyes checked so I cannot say whether or not the retina shows any damage.
Over the past several decades, I have lived in various parts of India for several months at a stretch. It was during one of my visits to India, several years ago, that I was introduced to a sadhu (holy man) at an ashram, who is an avid sun gazer and like many of them, he does not need to eat to sustain himself. This I have verified for myself since I shared a room at the ashram with this person and I was with him through the day for two whole weeks. I never saw him eat and as far as I could tell, he never took a dump in our bathroom. His eyesight was perfect.
Since then I have come into contact with many sun gazers who have been practicing sun gazing for long periods of time (several years). All of these people have perfect vision, very clear skin and no ailments, at least none that I could decipher.
I know that many on this forum believe that sun gazing can be injurious. My understanding is that there is a correct way to practice sun gazing, which if followed is safe. If you sun gaze at high noon then it is very likely that you will damage your eyes.
LOL. No I’m not a quadriplegic. I suggest that you follow HRM’s method. I followed a very similar method that was taught to me by a person who has been sun gazing for 30 years and one whom I have come to trust to teach me the method. Before HRM, successful sun gazers have never revealed the process except to select people.
The key is to start with a short time period and to increase it gradually. HRM suggests increments of 10 seconds per day. I was taught to use 15 seconds. Also, I would recommend that you gain clarity on what it is that you hope to derive from sun gazing - emotional health, physical health, inedia, spiritual, etc. and be mindful of that while you sun gaze. Express your gratitude to the sun for providing you with what you seek and believe that you will attain your goal. Each person has a different experience as a result of sun gazing and the time that it takes for a person to attain their goal varies greatly. Having said that, if you don’t see some positive results within 6 months, I will be very surprised.
Good luck and do let us know how you progress if you choose to undertake the practice.
So if I hope to derive weight gain from my sun gazing and I express my gratitude to the sun for providing me with what I need to attain my goal; will I gain weight from sun-gazing alone? And still not need to shit?