The latest in tinfoil hat fashion.

April 27, 2007 12:29 PM

"Is Wi-Fi going to turn out to be the tobacco, asbestos or Thalidomide of the 21st century? It's looking that way." Woman choses to live in a Faraday cage to ameliorate the symptoms caused by electrosmog. It's funny that she looks so much like a beekeeper in her fancy hat, given the recent kerfuffle (from another UK paper) about mobile phones wiping out the bees. Coming soon: faraday undies. [via]
posted by scblackman (84 comments total)

I hear that cranially applied tin foil can help with that.

In other news fungus is the most likely cause of the bee die-off.
posted by Artw at 12:37 PM on April 27, 2007 [1 favorite]

The second one on that "electrosmog" link made my head ache, so there you go on that one.

But, who are these "concerned scientists" who say that this is going to be so horrible? The only reason it bothered me is because it was cranked up so loud. I've heard that before but not at that high of a level.
posted by Cyclopsis Raptor at 12:39 PM on April 27, 2007

From the 'electrosmog' link:
Some sensitive people, those whose bodies tend to have allergic reactions to the environment, will react to very low levels of audible microwaves.

Audible microwaves?
posted by Pastabagel at 12:39 PM on April 27, 2007

She doesn't need a Faraday cage. This guy needs a Faraday cage.

Also, where's the batshitinsane tag?
posted by Joe Invisible at 12:40 PM on April 27, 2007

Right now, my pc can see 19 different Wi-Fi networks, and I could see just 4-5 a year ago.
posted by bobo123 at 12:40 PM on April 27, 2007

0xFCAF on AskMe:

If WiFi were dangerous, the game would already be lost. As a reference point, the legal power limit for a WiFi antenna is 100 mW. A 100W light bulb is emitting 10,000 times more power, and is definitely not limited to the visible spectrum. Sunlight is multiple times more powerful that that, and includes all sorts of nasty things like cosmic rays and ultraviolet light.

posted by russilwvong at 12:40 PM on April 27, 2007 [2 favorites]

I love the appearance of Faraday cages in weird places; it's like fringe paranoia is becoming more mainstream.

Full disclosure: my wallet is a Faraday cage. Take that, RFID passport!
posted by Mayor West at 12:40 PM on April 27, 2007

It's a good job that someone has invented a detector so that these people can know when to feel ill.

(Oh, and I notice the first link is a Dialy Mail story - never a good sign. OMG THE MODERN WORLD WILL KILL YOU is a favorite story of theirs, though they'd prefer it if Labour or gypsies were involved. )
posted by Artw at 12:42 PM on April 27, 2007 [1 favorite]

Reference: the applicable Achewood.
posted by rush at 12:43 PM on April 27, 2007 [2 favorites]

This lady (and her doctors) would benefit greatly from the application of the double-blind test methodology.

Let's see how sensitive she is to EM fields when neither she nor her doctors are even sure when they're there or not.
posted by odinsdream at 12:45 PM on April 27, 2007 [2 favorites]

In the eternal words of our fearless leader: "Our childrens' bones hurt because you have wireless!"
posted by CitrusFreak12 at 12:46 PM on April 27, 2007

Is there some kind of Al Quaeda of rationality I can join?
posted by Divine_Wino at 12:47 PM on April 27, 2007 [7 favorites]

Once upon a time people like this drove me up a wall. Now I just love the for what they are -- a sort of postmodern clown that helps me better understand the peculiarities of human behavior.

They also give me faith that, if all else is lost, I can embark upon a career of hucksterism with the sure knowledge that there are legions of suckers waiting to be gently fleeced.
posted by aramaic at 12:49 PM on April 27, 2007 [6 favorites]

What a total load of *head explodes*
posted by brain_drain at 12:49 PM on April 27, 2007

People with Faraday cages: Richard Hammond, Doctor Megavolt.
posted by adamrice at 12:49 PM on April 27, 2007

I know a local guy who has spent every penny he has fighting against the company who owns the phone masts around here, claiming that they made his wife ill...
posted by chuckdarwin at 12:51 PM on April 27, 2007

Wow, that lady is exactly the woman from Safe.
posted by chococat at 12:53 PM on April 27, 2007

Technophobia, ignorance, hypochondria.

These people seem to have little or no grasp of the mechanics of electromagnetism. It's like my aging mother-in-law worrying that microwaves are going to leak out of the little holes in the screen on the oven door, despite the disparity between the size of the holes and wavelength of microwaves.

It's malarkey.
posted by CheeseburgerBrown at 12:54 PM on April 27, 2007

I wonder if Sarah Dacre is related at all to Lord Dacre, who ran (runs?) the Daily Mail.
posted by parmanparman at 12:55 PM on April 27, 2007

So if we're at risk from WiFi, how much longer do I have to live as a direct result of my father's two story HAM radio tower in the backyard? Does it make a difference that all the radios are in his office in the basement, which is right next to my bedroom?

My bones hurt.
posted by CitrusFreak12 at 12:55 PM on April 27, 2007

Oh, and some actual tin-foil hat science. Come to think of it, would her beekeeper hat even absorb wifi/cell phone wavelengths to a significant degree? IIRC, to work best you would need parallel conductive rods spaced at the wavelength of the radiation, which is on the order of about 1 meter (I think). Or does she benefit from the placebo effect when she wears the hat?
posted by Joe Invisible at 12:56 PM on April 27, 2007

Thanks for the laugh scblackman.

Does this qualify as Luddite?
posted by nofundy at 12:57 PM on April 27, 2007

Magical underwear?

Wait a minute, I've heard this one before!
posted by nofundy at 12:58 PM on April 27, 2007

One one hand, this is so obviously bunk it's not worth commenting on.

On the other hand, a part of me appreciates the elegance of fully shielded systems. The "let's run lots of unshielded wires everywhere" thing strikes me as similar to the way we handled pollution and leaded fuels back in the day. Not that I'm, in any way, implying that the dangers to anything are similar, just the mentality. Don't worry about interference, we'll just twist the wires.

Humans are almost certainly unaffected by the em soup we live in, but it still strikes me as a hack. And it makes all of our systems vulnerable to EMI, natural or intentional.
posted by Skorgu at 1:00 PM on April 27, 2007

Wi-Fi is the tabasco of the 21st century.
posted by Artw at 1:05 PM on April 27, 2007 [1 favorite]

This is such nonsense. I've been using wifi for years, and I'm perfectly wifi.
posted by humblepigeon at 1:06 PM on April 27, 2007 [4 favorites]

Joe Invisible writes "IIRC, to work best you would need parallel conductive rods spaced at the wavelength of the radiation, which is on the order of about 1 meter (I think). "

The mesh spacing needs to be smaller than the wavelength of the radiation, which is about 10 cm for WiFi. So this would work.
posted by mr_roboto at 1:07 PM on April 27, 2007

I have the world's smallest emitter of audible microwave radiation in my hand, and it's playing just for you.
posted by psmealey at 1:07 PM on April 27, 2007 [6 favorites]

The amount of power emitted by WiFi is incredibly small; if it were visible light, you'd barely be able to see it in a dark room. And that wavelength is stopped by water, so it won't penetrate more than, what, 1/8th inch, maybe?

Another way of measuring the power of a signal is decibels; a typical WiFi signal is at about -60db or so. A human whisper is about +40. This isn't a direct correlation, because sound is vibrating air molecules and WiFi is photons, but the perceived 'loudness' of a signal drops by 1/2 for every reduction in 10db, where actual energy drops 10-fold. A -60db signal, if it were soundwaves, would "sound" about a thousand times weaker than a human whisper, and in terms of actual energy reaching you, would be one ten billionth as intense.

The high power lines with vibrating magnetic fields could potentially be a problem. WiFi.... no freaking way.

If you have a router or a switch... the little flashing lights showing you traffic are like 10 times brighter than your WiFi signal.
posted by Malor at 1:11 PM on April 27, 2007

Maybe I'm just not getting it, but does she actually have a current running through that thing? My physics layperson self isn't clear on whether a Faraday cage needs a current or not.
posted by Pope Guilty at 1:13 PM on April 27, 2007

Skorgu : Humans are almost certainly unaffected by the em soup we live in,

I don't know about that. I think a better way to say it would be 'humans haven't appeared to be harmed by EM soup we've been living in thus far' but we are most certainly affected by it.

One obvious way is that we are made happy when our technology works.

More seriously, I'll be interested to see if they ever do successfully find a link between EM and illness. Considering that we've been walking around in it for the last hundred years, I'm going to guess the answer is 'no', but we've never seen it in the quantities that we are seeing today.
posted by quin at 1:15 PM on April 27, 2007

We've made a discovery. A breakthrough. Please, remove your pants.
posted by sebastienbailard at 1:19 PM on April 27, 2007 [1 favorite]

It's interesting that these people who claim to be affected by mobile phones and wifi don't complain about radio waves which are much more powerful...
posted by ob at 1:20 PM on April 27, 2007

Malor writes "The amount of power emitted by WiFi is incredibly small; if it were visible light, you'd barely be able to see it in a dark room."

This is a little disingenuous. WiFi transmitters are limited to 100 mW. Sure, you wouldn't be able to see a 100 mW incandescent lamp, but a 100 mW laser is potentially dangerous.

Pope Guilty writes "Maybe I'm just not getting it, but does she actually have a current running through that thing? My physics layperson self isn't clear on whether a Faraday cage needs a current or not."

It does not. It needs to be constructed from a conductive material, however.

ob writes "It's interesting that these people who claim to be affected by mobile phones and wifi don't complain about radio waves which are much more powerful..."

Again, this is a potentially misleading statement. Electromagnetic radiation falls off as 1/r^2, so even though the transmitter power is much higher for a radio station, your body is getting a much higher exposure from the cell phone in your pocket or next to your head.


I doubt there's anything to these health claims, but a lot of the arguments here are just as specious and misinformed as the claims they're attempting to debunk.
posted by mr_roboto at 1:28 PM on April 27, 2007

but a lot of the arguments here are just as specious and misinformed as the claims they're attempting to debunk

...which is one reason why it's so hard to debunk them. Lots of people know, roughly, why these beliefs are lunacy but getting into the nittygritty eludes most (like me).

After a few rounds of incorrect "debunking", it's not hard to see why even fully-reasoned scientific arguments might fail to sway them.

Of course, that's assuming the believers are vulnerable to logic. I think they're probably not, but perhaps that's just cynicism on my part.
posted by aramaic at 1:32 PM on April 27, 2007

Reminds me of all the brouhaha about "environmental sensitivity" so brilliantly captured in Todd Haynes' film Safe.
posted by kozad at 1:32 PM on April 27, 2007

Aluminum Foil Panties? (That sounds mighty uncomfortable...)
posted by Steven C. Den Beste at 1:38 PM on April 27, 2007

“This is a little disingenuous. WiFi transmitters are limited to 100 mW. Sure, you wouldn't be able to see a 100 mW incandescent lamp, but a 100 mW laser is potentially dangerous.”

This is more than a little disingenuous. A WiFi transmitter is not a maser. Doofus.
posted by Ethereal Bligh at 1:52 PM on April 27, 2007

Fair point quin, I was imprecise. I wonder, though, if future self-aware machines will treat EM pollution the way we treat air pollution.
posted by Skorgu at 1:55 PM on April 27, 2007

News bulletin: crazy lady wears tin foil hat. Rest of world gets scared and catches onto the craze. Wifi banned without any scientific data. More at 11.
posted by triolus at 1:55 PM on April 27, 2007

This is bunk. According to the iBook I'm typing on there's something like 10 wireless networks within range of my couch and all that has no effect on me whatsoever.

Must..kill..Papsmear...
posted by jonmc at 1:56 PM on April 27, 2007

Ethereal Bligh writes "This is more than a little disingenuous. A WiFi transmitter is not a maser. Doofus."

It's like a laser in that it emits a very narrow frequency band; it's unlike a laser in that it's uncollimated. These factors would both be expected to effect how the radiation interacts with matter. Either way, the power of the device in and of itself tells you very little about its potential danger, which seemed to be the claim Malor was making. You're right; the comparison to a totally different category of device is inappropriate. I was merely pointing out that inappropriateness in Malor's comparison.
posted by mr_roboto at 1:58 PM on April 27, 2007

Or: It's not a lightbulb, either. Dork.
posted by mr_roboto at 2:03 PM on April 27, 2007 [2 favorites]

She doesn't need a Faraday cage. This guy needs a Faraday cage.
posted by Joe Invisible

That was beautiful.
posted by Termite at 2:04 PM on April 27, 2007

Artw writes "Wi-Fi is the tabasco of the 21st century."

I have no idea what that means, but I'm going to be using it often.
posted by krinklyfig at 2:10 PM on April 27, 2007

“Or: It's not a lightbulb, either. Dork.”

Yes, but you're comparing wattages which has everything to do with where that energy goes. In that, a WiFi transmitter is far more like a light bulb than it is a laser. Dingleberry.
posted by Ethereal Bligh at 2:15 PM on April 27, 2007

Didn't that woman post to AskMe about a month ago?
posted by pieoverdone at 2:23 PM on April 27, 2007

This is actually an interesting question. A laser beam is more intense than an incandescent lamp of the same power for two reasons: it's coherent, and all of the energy is concentrated in a narrow frequency band. It's possible to take all the energy from an incandescent lamp and put it all in one place: you just need a parabolic mirror and a couple of lenses to get it focused down to a diffraction-limited point. You can get the collimated laser beam down to the same point using just lenses. Now, the total energy being delivered to this point is probably greater for a 150 W halogen lamp than a 50 mW laser. But a lot of physical processes depend on the wavelength. And if you have a process that's only sensitive to the laser's wavelength, they'll be much more power in that particular wavelength when you use a laser.

In this respect, the WiFi transmitter is more like the laser.
posted by mr_roboto at 2:24 PM on April 27, 2007

mr_roboto, I think you're very confused. You correctly state that a 100mw laser can be dangerous, but the reason is because the entire 100mw is going into a tiny pinpoint.

WiFi signals are generally radiated omnidirectionally; it's not *quite* like a lightbulb, because they tend to be strongest in two planes, but they're much, much closer to being a lightbulb than a laser.

The closest visible approximation would probably be a 100mw LED, which is visible in a dark room, but which no reasonable human would ever consider dangerous.
posted by Malor at 2:47 PM on April 27, 2007

I meant collimated, not coherent, in this comment. And I maintain that the total power of the device says little about its safety.
posted by mr_roboto at 2:52 PM on April 27, 2007

She doesn't need a Faraday cage. This guy needs a Faraday cage.
Posted by Joe Invisible

Thanks for the link - that was excellent!
posted by rush at 3:02 PM on April 27, 2007

Michael Faraday on the twenty pound note looks like Mike Myers.
posted by Marla Singer at 3:02 PM on April 27, 2007

I have one word for that woman.. psychosomatic.
posted by MrLint at 3:05 PM on April 27, 2007

I don't know about all this. I get a lot of porn through my wifi and my reproduction system still works really well.
posted by paulinsanjuan at 3:08 PM on April 27, 2007

Again, this is a potentially misleading statement. Electromagnetic radiation falls off as 1/r^2, so even though the transmitter power is much higher for a radio station, your body is getting a much higher exposure from the cell phone in your pocket or next to your head.

Yeah I'll admit that I have no idea what I'm talking about, but she's complaining not about using a cell phone but anyone around using a cell phone (and getting an electric surge from picking up the receiver of a land line etc.) and thus insulating her house from cellphone signals and wifi, so it struck me that she should also be concerned about radio and tv signals for that matter.
posted by ob at 3:17 PM on April 27, 2007

Thanks Joe Invisible... where did that clip come from?
posted by anthill at 3:34 PM on April 27, 2007

mr_roboto wrote: It's like a laser in that it emits a very narrow frequency band

No, it's not even like that. A WiFi transmitter transmits across a channel about 22MHz wide. It uses spread spectrum, like a CDMA cell phone, only with much less power and a much larger spreading factor, leading to a much smaller power level at any given frequency.

By contrast, CDMA2000 uses 1.25MHz channels, while UMTS uses 5MHz channels, which is considered to be a very wide channel.

By the way, most WiFi APs are set, by default, to transmit at 28 milliwatts or so, and have dinky antennas that have 4 to 6 dB of gain. The ERP of that system is still well under 100mw. It's a truly miniscule amount of energy.
posted by wierdo at 3:39 PM on April 27, 2007

Why worry when the problem has already been solved. Just wear a pendant.





There are even some supposed to protect your entire house ffrom radiation. One wonders if you can still receive radio and TV with these in your house.
posted by Merlin at 4:02 PM on April 27, 2007

mr_roboto: the only way 100mw is going to be dangerous is if you use it to generate a tightly focused laser and aim it directly at someone's retina.

WiFi is just standard radiant EM. It works very much like a light bulb. It's not collimated or coherent or nothin'. Just regular old radio frequency photons, emitted just like every other antenna since the dawn of radio. The power output is more efficient than an incandescent bulb (more input power becomes photons instead of heat), but it's the same basic thing. And it's a tiny signal, incredibly 'quiet'.

It's just not an issue. And the power level IS a pretty strong indicator of safety, most of the time. You'll have to really dig to find many dangerous applications of a tenth of a watt of power. And, as wierdo points out, most consumer WiFi isn't even THAT strong. Generally, it's set to just 28mw... 1/35th of a watt.

If you're not afraid of FM radio, you really shouldn't be worried about WiFi.
posted by Malor at 5:27 PM on April 27, 2007

To paraphrase Lord Melbourne's famous remark, I wish I were as certain of anything as you all (with the notable and notably brave exception of mr_roboto) are of the safety of every kind of EM radiation below the threshold of visibility.

All that would be necessary to find a solid, not psychosomatic basis for this woman's illness would be to construct a model whereby EMR could stimulate the immune system the way almost infinitesimal amounts of peanuts can the immune systems of the sufferers of an allergy to that delicious nut 98% of us experience as perfectly benign-- with fatal results for 50-100 Americans per year, and severe illness for many, many more.
posted by jamjam at 5:54 PM on April 27, 2007

The student newspaper here devoted 2 pages to this foolishness this week, I can't believe it.
posted by Mitheral at 5:58 PM on April 27, 2007

anthill: Apparently from an Omni film called "Helicopters, up up and away."
posted by Joe Invisible at 6:12 PM on April 27, 2007

this thread needs cat pictures.
posted by casconed at 6:17 PM on April 27, 2007

If you're not afraid of FM radio

You bastard. I have to sleep tonight.
posted by dreamsign at 6:41 PM on April 27, 2007 [1 favorite]

this thread needs cat pictures.

Voici mes chats -- Muriel et Priscilla
posted by ericb at 6:43 PM on April 27, 2007

jamjam, I suggest strongly suggest you gain further understanding of the way the human body's immune system functions. EM fields pass harmlessly through the body, or at worst, are absorbed by water molecules in the outer layers of your skin, heating it ever so slightly. The comparison to peanut allergies is not only patently ridiculous, but is based on a complete ignorance of both how RF energy works and how the human body works.

You might also be alarmed to know that there is a significant amount of background EM "radiation" (an awful term, since people often confuse it with nuclear radiation), which is much more powerful than you get from a WiFi transmitter at any reasonable distance.
posted by wierdo at 6:55 PM on April 27, 2007

That little Priscilla has a mixture of orange and gray background with stripes the like of which I've never previously seen, ericb.
posted by jamjam at 6:57 PM on April 27, 2007

To resort to yet another famous remark, wierdo, "listen to the calumny of fools, it is high praise."

Thank you very much, therefore.
posted by jamjam at 7:09 PM on April 27, 2007

Priscilla -- truly a feral cat -- was rescued after her fall from a Boston rooftop. A close friend who is a vet estimated that she was 4-6 weeks of age at the time. She survived and eventually recovered/flourished.

These days she's a handful -- energetic and very destructive (as I refuse to declaw^* her). I love her, whole-heartedly.

^* -- please see other COMETO's ("Controversial MeFi Topics") which include Abortion, the Bush Family, Circumcision, the Clintons, Karl Rove, Terrorism, Trolls, the War in Iraq and YouTube.
posted by ericb at 7:18 PM on April 27, 2007

Sealing your home in a Faraday cage is certainly overkill - any EM radiation coming from an outside source is probably really low by that point.

However, I can swear that the last cell phone I had gave me a headache every time I used it for more than 10 minutes or so. My new cell phone doesn't do that; I can talk for hours without feeling anything. So, unless it was some other factor of the phone - speaker noise, heat, etc. - it seems plausible to me that the radio waves had something to do with it.

The old phone also caused clicking noises on any unshielded speakers that were nearby whenever it received a call or checked in with the system, so it likely had a pretty high-powered transmitter for something you hold next to your ear.
posted by purple_frogs at 7:22 PM on April 27, 2007

jamjam, I'm too stupid to understand your fancy writings.
posted by wierdo at 7:44 PM on April 27, 2007

Ericb, you got her in early May when she was about 4-6 weeks old?

That would put her birth date back into March wouldn't it? That's awfully early for a place like New England; in Olde England there are all kinds of stories and superstitions about early spring cats. They are called Maycats and were rare and most often killed as unlucky. I've got a story somewhere about a little British girl born in May whose mates teased her about her birthday and said her parents should have drowned her. She ran home crying. God knows what they would have said about a Marchcat!
posted by jamjam at 7:56 PM on April 27, 2007

The same author said "if a fool would persist in his folly, he would become wise" wierdo, so carry on.

I do indeed have a lot to learn about the immune system, and I will do my best to take your suggestion to heart.

As far as EMR background is concerned, I assume your are referring to the radio output of the Sun. As I recall from one of Carl Sagan's discussions of detecting extraterrestrial life, human activities give the surface of the Earth a radio brightness of ~10 million deg. K ( I couldn't find confirmation online); the Sun, by comparison, has a surface temperature of around 10,000 K.
posted by jamjam at 8:15 PM on April 27, 2007

Ericb, you got her in early May when she was about 4-6 weeks old?

Yes ... to be exact -- the morning of May 2, 2004. I will read up on Early Spring Cats aka May Cats. Such may account for her devious ways!
posted by ericb at 8:24 PM on April 27, 2007

Why your speakers buzz when your cellphone is about to ring - and it's not harmful to people. It just happens to hit a harmonic thats picked up by amplifiers (in your speakers).
posted by porpoise at 8:30 PM on April 27, 2007

I was talking about the cosmic background radiation. (largely light from long ago ages red shifted so far that it's no longer what we consider light, and is instead EM noise)

Regardless, the power output of a default WiFi AP is something like 1 milliwatt per MHz. By contrast, a GSM cellphone is closer to 150 milliwatts per MHz (average, multiply that by 8 to get an instantaneous reading). As someone mentioned upthread, the energy dissipates as you get farther from the source.

The sun is far, far more intense. If it wasn't, you wouldn't get a sunburn after its energy travels 93 million miles through free space and through the atmosphere as well.

Perhaps it would take someone with a real scientific calculator to prove this to you.

Oh, and for what it's worth, our radio output into space has been decreasing dramatically as we adopt more advanced methods of communications (fiber, spread spectrum radio, etc)
posted by wierdo at 8:44 PM on April 27, 2007

You are all missing the point.

WARDRIVING KILLS!!!!
posted by bigbigdog at 9:05 PM on April 27, 2007

I can swear that the last cell phone I had gave me a headache every time I used it for more than 10 minutes or so

Never gotten a headache from cell phone use, though my ear sure hurts after holding any phone receiver to it for too long.

What I have experienced, though, I thought was pretty idiosyncratic until I later found several people (MeFites included) who experience the same thing, surprisingly. And that is muscle twinges in my leg near my cell phone when I'm carrying it in my pocket. No incoming call. No expectation of a call -- I often don't even realize I'm carrying it until this happens. Whereas it never happens when I'm not, nor in the opposite leg from where it is being carried (and I don't keep to a regular pocket). Strange. Not ruling out that it may be explained simply by something else; just don't what. Not ready for the cage yet!
posted by dreamsign at 10:38 PM on April 27, 2007

Eh, or maybe I am. MeFites, hope me! Likely explanations?
posted by dreamsign at 12:45 AM on April 28, 2007

bigbigdog: We'd better declare a war on wardriving.
posted by wierdo at 12:54 AM on April 28, 2007

And you think this is something new? A 21st century fear?

Doesn't anyone read James Thurber any more?

"... mother lived the latter years of her life in the horrible suspicion that electricity was dripping invisibly all over the house."

Talking about his grandmother living in their Columbus, Ohio home in the early 20th - he was writing nostalgically in 1933 in "My Life and Hard Times".
posted by cptnrandy at 5:51 AM on April 28, 2007

Wi-fi turns me into The Incredible Hulk. ...and Yes, I do
have an everlasting supply of purple pants.
posted by doctorschlock at 7:08 AM on April 28, 2007

purple_frogs it was most likely the plastic in the phone out gassing that was giving you head aches.

dreamsign it could be the phone is placed such that it is putting pressure on a nerve or the muscle or possibly is messing with your gait. I've heard about guys having similar problems caused by wallets.
posted by Mitheral at 4:50 PM on April 28, 2007

In the whole laser/wifi/lightglobe argument, you're ignoring the fact that both lasers and wifi are quoted in output (optical or RF) power whereas lightbulbs are in terms of the electrical power that heats them. They're pretty damn inefficient.

And the wavelengths are very different in each case: (10cm) (wifi), near infrared (1um) and whatever IR/visible/UV for each laser. Water and therefore people absorb each band quite differently; hell, look at how much atmospheric absorption varies - there's any number of peaks and troughs due to the various gases.

But yeah, the sun. 1 to 2kW.m^-2 at the earth's surface; that's a lot of power. I'm surprised she doesn't turn to ash in sunlight, like a vampire :)

jamjam: degrees kevin is a measure of spectral distribution assuming blackbody radiation, NOT emitted power or brightness. You heat something up, it glows; the colour it glows depends on the temperature, hence the use of temperatures to describe spectral distributions.

The earth and our communications aren't in a continous spectrum like that, they're at specific bands. You cannot therefore assign a blackbody temperature to it all, even if a pop-sci person made up a number. What he should have said is that we'd look very distinctive because of the narrowband (not to mention high information content!) emissions, particularly compared to the boring glow of the sun.

If you want to measure brightness... watts is the go. Radiated power, perhaps radiated power per solid angle (W.sr^-1).
posted by polyglot at 12:20 AM on April 29, 2007