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Asked by to Mark, Matthew, Mike, Paul, Sabina on 11 Mar 2014. This question was also asked by .
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Matthew Malek answered on 11 Mar 2014:
Light everything, light can be dangerous. High energy light like x-rays can cause cancer. Ultraviolet light can give you a sunburn. Looking directly into the sun can cause blindness. And concentrated sunlight can cause fires — both in the wilderness and also in cities! (See http://www.bbc.co.uk/news/uk-england-london-23948811)
Modern technology gives us more abilities to harness light, but these also have their own dangers. Laser light can burn your eyes, or your skin! This is true even when you cannot see the laser light, like with an ultraviolet laser. I used to work extensively with one and had to wear safety goggles to filter out the UV light.
I wouldn’t say that light is inherently dangerous, and we certainly need it to survive! But everything has certain dangers, and one just needs to use a little common sense (and personal protective equipment) when working with light.
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Paul Coxon answered on 11 Mar 2014:
At sufficiently high intensity light can be very dangerous. Looking directly at a bright source such as the sun or a laser can damage the retina in the eye. Normally if the damage is slight, it can repair itself, but if the damage is too great you can be permanently blinded.
UV light is particularly dangerous as we can’t see it, but it is still highly damaging. UV light damages the DNA within skin cells which can lead them to turn cancerous. The body knows UV is dangerous, and so has developed mechanisms to minimise its dangerous effects on us.
Exposing the skin to UV rays causes certain cells to produce a pigment called melanin, which darkens by oxidation. This pigment absorbs UV and stops it penetrating further into the skin tissue. If you spend a long time out in the sun, these cells will migrate closer to the skin’s surface and produce even more melanin, which darkens the skin making us appear sun-tanned.
Some people think suntans are healthy and use tanning beds to get a nice brown glow, but really sunbeds are very dangerous and suntans are nothing more than a sign that your skins has been damaged.
When working with high powered lasers or UV sources in my research I make sure to wear appropriate safety shields over my eyes
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Mark Jackson answered on 12 Mar 2014:
Light is actually just a wave of electromagnetic radiation. Like all waves, it has a wavelength. You actually already know this: different wavelengths correspond to different colors. The wavelengths that the human eye cannot see are radio waves, microwaves, and many other types.
Light’s danger comes from its ability to transmit energy. Sufficiently intense light of any wavelength is dangerous, especially if directed at something sensitive like your eye. But the energy of an individual photon is proportional to the inverse to its wavelength, so the shorter the wavelength the higher the energy. The shortest wavelengths, or Ultraviolet (because they are even shorter than the short wavelengths of the color violet), are particularly dangerous to humans. When they hit our skin they actually rip apart the DNA, possibly leading to cancer in the future.
But light can also be beneficial. Without exposure to the sun, the body itself cannot produce vitamin D, a substance that helps maintain normal blood levels of phosphorus and calcium. It’s possible to compensate for this by eating vitamin D in pill form, or preferably via the food we eat (oily fish, eggs, liver or fish oil). Daylight also affects the production of substances in the brain that affect moods. A lack of daylight causes the body to produce substances that make us sleepy and lethargic instead of substances that make us feel peppy and alert. Light is an active neurobiological agent that is crucial in regulating cortisol, serotonin and melatonin levels in the brain. When light hits the retina, it activates photoreceptors (light-sensitive nerve cells), which stimulates the production of serotonin and cortisol. These substances are important in determining our physical and mental health. Insufficient levels of serotonin can result in depression, lack of energy, sleep problems, mood swings and poor impulse control.
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Mike Lee answered on 12 Mar 2014:
I would say the lack of light is more dangerous as you more likely to walk into things.
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