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Mimicking sunlight without the sun

PostPosted: August 19th, 2017, 10:21 pm
by caters
I have posted on several forums about using LEDs to mimic sunlight on the generation ship. I basically got 2 responses depending on the forum. 1 response was to not focus on it unless necessary and this was from forums related to writing. Another response was "Come on, that is too simple for a civilization that has mastered artificial gravity. Quantum mechanics is better." and this was from forums about science.

But here is my reasoning on why I would use IR, Visible, and UV LEDs and not a quantum mechanical light source.

A wavelength in any part of the EM spectrum could come from a quantum mechanical light source. Radio waves and microwaves would just be a waste of energy that could be used for more infrared, visible, and ultraviolet.

UVC, X rays, and Gamma rays would be even more wasted energy but also dangerous.

Yes, 10-15 minutes of UVB exposure can produce up to 20,000 IU of vitamin D from cholesterol in your skin. And yes UVB and UVA both carry a risk of sunburn and skin cancer with UVB having a higher risk of sunburn and UVA having a higher risk of skin cancer.

UVC exposure has a maximum time of 8 hours before it is deemed unsafe due to skin and eye injuries. And this is for people who know how to use UVC as a disinfectant. For the average person, maximum safe UVC exposure is much less than that. UVC can cause rapid sunburn, skin cancer, and temporary or permanent blindness.

X rays as background radiation or as a plain X ray have a 1 in 1,000,000 lifetime cancer risk. But X rays produced from a quantum mechanical light source would have a lifetime cancer risk closer to that of a CT scan of 1 in 1,000.

Gamma rays are the worst of all. A bit ironically, high dose gamma ray exposure is easier for the human body to repair than low dose gamma ray exposure. But gamma rays, because they are so energetic, not only have a high risk of giving you cancer but they also have a risk of radiation poisoning.

Clearly radiation poisoning and cancer are 2 things you would want to try and avoid during space travel but radiation poisoning especially so. Even if you were to limit the amount of time that UV light is produced, it is inevitable that some fraction of the population is going to get cancer. But with sufficient technology and limitations on the wavelength of photons produced, radiation poisoning is avoidable.

But how could you limit the wavelength of photons produced to be in either infrared, visible light, UVA, or UVB? The easiest way to do this is to use LEDs. I don't see how using quantum mechanics in a way that limits the possible wavelengths to infrared, visible, UVA, and UVB is feasible.

Re: Mimicking sunlight without the sun

PostPosted: August 20th, 2017, 11:41 am
by Braininvat
LEDs that just provide solar-equivalent band (yellowish-white light) will provide the healthful effects of natural light. No UV bands needed, just some foods with vitamin D in them. I would also advise going with the recent approach of Microsoft, whose PC software offers a lower-blue-light option when using the PC in the evening. Lowering the blue end helps the body produce melatonin and gives better sleep. So shipboard lights could have a Circadian cycle in which a blue filter comes into play later in the day. Ideally, it would mimick the orange-ing of the sun in later afternoon.

Good luck with your novel writing. Glad you have moved on from the topic of people who can't poop. :-D

Re: Mimicking sunlight without the sun

PostPosted: August 20th, 2017, 12:24 pm
by caters
But, UVB produced vitamin D has been shown to be better than synthetically produced vitamin D. And there are other benefits to using UV light. Those are:

According to 1 study, 98% of people with obstructive sleep apnea have a vitamin D deficiency and the worse the sleep apnea, the worse the deficiency.

In fact, a swedish research team has recently warned that the avoidance of sun exposure has the same risk of death as smoking.

Vitamin D in sufficient amounts in the bloodstream reduces your risk of getting cancer by 67% and increases the chance that you will survive the cancer. And sun exposure in infants not only increases bone density but also increases muscle mass and decreases body fat% by age 3 so vitamin D helps prevent childhood obesity when in higher quantities than 400 IU per day. In fact obese indiviuals of all ages tend to have lower Vitamin D levels than those who are not obese.

Oral vitamin D does not increase nitric oxide production but UV produced Vitamin D does. This significantly lowers the risk of heart attack and stroke by helping to prevent hypertension. Sun exposure also decreases the gene expression of pro-inflammatory genes. It has also been found out that 10,000 IU of vitamin D has a 100% cure rate for tuberculosis because it restricts the growth of bacteria and makes it easier for the immune system to get rid of the bacteria. These benefits of UV light and Vitamin D are numerous, enough to fill several books.

And infrared light can be used as an alternative to X rays and gamma rays to get rid of or reduce the size of a tumor without damaging other cells. Infrared light also helps with mitochondrial disorders and muscle pain. And like vitamin D, infrared light lowers blood pressure by producing nitric oxide. And infrared light also helps heat things up so that would be crucial if the nuclear fusion engines somehow fail but battery power is high(so moving slow in space until the engines are fixed).

Re: Mimicking sunlight without the sun

PostPosted: August 20th, 2017, 6:45 pm
by Braininvat
I'm aware of what you say. I would say that if we are writing speculatively about a civilization that can build starships, then it seems plausible that they could boost nitric oxide levels or regulate inflammatory responses in other ways, and would develop a better oral form of vitamin D. This makes all the more sense, given that any individual's total UV exposure over the course of a day is unpredictable and may be affected by personal habits, sartorial preferences, haberdashery, etc. Just because a future society recognizes the health value of UV and IR light, doesn't mean they would want to incorporate it in all their ambient light sources. I think you do make a better case for having some IR frequencies in the lighting, since it is a non ionizing radiation. And the backup heat thing - that's clever.

As an aside, did you know that vigorous inhaling through the nose has also been shown to boost nitric oxide levels? (maybe those ancient yogis were onto something...)