How dangerous are photons?

[nexium]

There is some evidence that certain radio and microwave frequncies damage living tissue, but generally damage occurs only when the kilowatts per square meter is high enough to warm the tissue several degrees. Humans and photo synthesis plants can tolerate several kilowatts per meter of visable light, except for sun glasses being prudent. A bit higher frequency produces sun burn, and double blue light frequency, destroys flesh quickly at one kilowatt per square meter = 0.1 watt per square centimeter. The higher frequency Xrays and gamma rays pass clear though the human body and thus do little damage, unless they are at more than one kilowatt per square meter for hours. At one megawatt per square meter, tolerance is less than one second for all or most frequencies.<br />Little is known about photon frequencies below about ten hertz, but we believe gigawatts at millihertz to picoherz are produced in super nova and some other deep space events. Please correct, refute and/or embellish. Neil

 

[a_lost_packet_]

Not my specialty, but the material that is being subjected to the rays has a lot to do with it. Ex: In humans, UV rays are absorbed by melanin, spurring them to produce a "tan." They also cause damage to the skin. Also, UV-B interacts with DNA, damaging the normal processes and causing mutations leading to cancers. I can't answer to the energy requirements needed to produce these results. But, just the information on UV rays would seem to indicate that the material being effected is very important. <div class="Discussion_UserSignature"> <font size="1">I put on my robe and wizard hat...</font> </div>

 

[yevaud]

Certainly so.<br /><br />Ever wonder why, say, leaves look green? That's simply because leaves absorb almost all of the incoming insolation - but reflect strongly in the green. <br /><br />(You can continue that progression across all materials) <div class="Discussion_UserSignature"> <p><em>Differential Diagnosis:  </em>"<strong><em>I am both amused and annoyed that you think I should be less stubborn than you are</em></strong>."<br /> </p> </div>

 

[siarad]

UV rays are very dangerous & can blind you, ask any ski-er.<br />My eyes were badly burned from a deep UV light, for EPROM blanking, after a few seconds & it was only a 4W lamp!<br />Unnoticed at the time, I was making a 'safe' housing, but the next day it was like razor blades in my eyes & very painful to open them to see.<br />UV & above are high energy therefore dangerous.

 

[MeteorWayne]

But the cosmic rays (protons and neutrons) are not photons. <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[wurf]

When I was a kid, there was such thing as getting a "healthy tan", nowadays everybody says to avoid sunlight as much as possible. Sunlight helps with producing or metabolizing certain vitamins, but is it necessary? Just a silly hypothetical, but would a human body operate properly if it got good food, air and exercise, but was never exposed to direct sunlight? Does man-made light produce the same effects as sunlight?

 

[CalliArcale]

<blockquote><font class="small">In reply to:</font><hr /><p>But the cosmic rays (protons and neutrons) are not photons. <p><hr /></p></p></blockquote><br /><br />Actually, some are -- gamma rays, for instance. <img src="/images/icons/wink.gif" /><br /><br />It is an unfortunate bit of semantics, but the term "radiation" was invented before anyone knew the difference between electromagnetic radiation (photons) and particle radiation (protons and electrons -- alpha and beta particles). <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[billslugg]

Go to any of the Nordic countries for the first warm sunny spell in the spring. After a long dark winter, the folks are craving sunlight. I did a machine inspection in Karlstad, Sweden in the May of 1992. We arrived just as the winter chill evaporated and an unprecedented two week spell of sunny weather in the 70's and 80's set in. The local engineers took us out for lunch in the town square. I was sitting on a park bench eating a sandwich. A tall, blonde, attractive woman in a business suit walked over, set her briefcase and sack lunch down next to me, stripped to the waist, leaned back to get the sun at just the right angle, and proceeded to eat her sandwich. I was caught completely by surprise. The Swedish guys were cracking up. It was normal to them. <div class="Discussion_UserSignature"> <p> </p><p> </p> </div>

 

[wurf]

"Go to any of the Nordic countries..."<br /><br />I might have to do that, in the interest of science of course.

 

[yevaud]

Oh, assuredly. <div class="Discussion_UserSignature"> <p><em>Differential Diagnosis:  </em>"<strong><em>I am both amused and annoyed that you think I should be less stubborn than you are</em></strong>."<br /> </p> </div>

 

[a_lost_packet_]

Ok.. "May".. gotcha.. now, what was the name of that restaurant again? <div class="Discussion_UserSignature"> <font size="1">I put on my robe and wizard hat...</font> </div>

 

[nexium]

Hi wurf: Most man made light has very little near ultaviolet, which does have some health benefits and produces a sun tan on most people. Grow lights, and sun lights and tanning lights behave pretty much like sunlight except for being low in the harmful B type ultraviolet, but too much near ultra violet is also likely to cause cancer. Neil

 

[billslugg]

<font color="yellow">I am from Norway...here the girls do not act like that in the middel of the town. Must be a Swedish phenomenon. </font><br /><br />Perhaps I overstated the case. I have been to Sweden, Finland, and Denmark but not to Norway.<br /> <div class="Discussion_UserSignature"> <p> </p><p> </p> </div>

 

[vandivx]

"there was such thing as getting a "healthy tan", nowadays everybody says to avoid sunlight as much as possible."<br />--<br /><br />that's because people overdo it as they overdo everything fashionable as a rule and then its not healthy I recon<br /><br />btw one gets lots of 'sunlight' in indirect fashion - reflected scattered light which gets to you even if you are carefull sun never hits you directly and even if you stay inside houses, I think that's enough for proper healthy functioning, on the other hand if you made a point of shielding even such radiation, likely you would be very much unhealthy I imagine, after all mankind developped mostly outdoors for many thousands of years as well as animals who spent much longer adjusting to sunlight<br /><br />observe that animals aren't suntanning and we as humans could learn something from them methinks<br /><br />vanDivX <div class="Discussion_UserSignature"> </div>