
What If You Could See WiFi? - bmul17
http://www.mydeals.com/blog/what-if-you-could-see-wifi/post
======
noonespecial
Illustrations like these do more harm than good. It lets people imagine that
spaces are getting 'flooded' with 'stuff'. Radio is a light. A blinking light.
A transmitting antenna like a light bulb. If your receiver can see the light
blink (or a reflection of it) the signal gets through. Radio has the added
benefit that (especially at longer wavelengths) most of the material world
appears to be made of tissue paper.

~~~
toyg
Well, radio pollution is still under debate. In Italy they've supposedly found
significant discrepancies in cancer distribution near large radio transmitters
(i.e. higher rates of cancer). We're talking humongous power and extreme
proximity though, nothing like wifi.

~~~
afreak
Correlation is not causation. There has been no conclusive link between EM
radiation and human ailments other than hysteria. We creatures have throughout
history been bombarded with intense radio activity from outer space (such as
the emissions from the crab nebula), and we are still alive and plentiful.

Quit it with the fear mongering while ahead.

~~~
toyg
Upvoted despite the personal attack. Can we keep it civil ? I don't think I
was fear mongering, I just said what was reported over there.

~~~
afreak
It wasn't intended to be a personal attack and I do apologise for that, but I
do get bothered when I see baseless accusations that non-ionising radiation is
going to kill us all. Of course with enough intensity it could cause problems,
but there are sources of high-powered EM radiation that bombard us every day
that are from natural sources.

We won't be dying from this stuff any time soon.

~~~
Ackley
If radiations are strong enough that you can feel the heat, it means that your
are cooking.

------
lcedp
Doesn't seem very legit to me.

Firstly, if wi-fi would be visible, you still wouldn't be able to see it all
like we can't see visible laser ray unless there is dust/water/something in
the air. It should be reflected from something to be seen.

But let's suppose it's just visible per se.. Ok, colors represent waves, but
they don't look like 3-5 inches, more like meters on some photos.

Secondly, signal strength should dramatically decrease over distance. In two
meters it should be four times as dark as in one meter, in 10 meters it should
be 100 times darker.

Thirdly, on many pictures waves don't seem to disperse properly. Looks like
everybody's using a very advance ridiculously narrow-range antennas.

~~~
sp332
"In two meters it should be four times as dark as in one meter"

But our eyes compensate for inverse square laws, and have a logarithmic
response to light.

~~~
lcedp
Ok, point taken. It is vaguely a logarithm function. But what's the base of
this logarithm? How much is it curved?

Just try light up a big room which has no windows with a candle - you can see
pretty well at the distance of your hand, but in a few meters from you - it's
plain darkness. I expect wi-fi waves to be like this.

Using the grath "Perceived Brightness" at [1] we have roughly the following
table:

    
    
        Distance/Actual/Perceived Brightness
        1/100/100
        2/25/~55
        4/6.25/~30
    

[1] [http://hyperphysics.phy-
astr.gsu.edu/hbase/vision/bright.htm...](http://hyperphysics.phy-
astr.gsu.edu/hbase/vision/bright.html)

~~~
sp332
Luminous efficacy depends on wavelength, with the eye being most sensitive to
555nm (green) light at 683 lumens/Watt. Most wifi setups max out at 1W (I
think?), so if the eye were as sensitive to wifi signals as to green light, we
could get 683 lumens which is about the same as a 60W incandescent bulb.

~~~
lcedp
And?

~~~
sp332
Oh, so if we're trying to imagine how bright a wifi router's "light output"
would look if we could see it, we can just imagine a 60W (monchromatic, say
green) lightbulb. Of course the light would pass through walls more easily
which is a bit unusual :) But for attenuation over free space, I think the
analogy to a 60W light bulb is very useful.

------
bbwharris
It would look like light from a lightbulb.

We already see light in the specific frequency peak of the sun.

If we could see wifi, it would be like a lightbulb that dimly appears to pass
through walls.

------
tomstuart
See also Timo Arnall et al’s work on light painting wifi:
[http://www.nearfield.org/2011/02/wifi-light-
painting](http://www.nearfield.org/2011/02/wifi-light-painting)

------
nemo1618
I've been thinking about making a project out of this for a while. Lots of
people have already hacked themselves to gain a "sixth sense" \-- the ability
to detect electric fields via magnetic vibrations. In today's world, wouldn't
the ability to detect a strong WiFi signal be a bit more useful?

Realistically the result wouldn't resemble these illustrations at all; a
simple signal strength -> vibration intensity converter would be more
practical.

~~~
mhurron
> Lots of people have already hacked themselves to gain a "sixth sense" \--
> the ability to detect electric fields via magnetic vibrations.

What?

~~~
6d0debc071
Some people implant, I believe it's a small neodine, magnet under their skin
with the idea that they can feel electrical fields.

~~~
VLM
Its almost as effective, much cheaper, faster, zero risk of infection, and
easier to reverse to just stick a magnet in the end of a
latex/nitrile/whatever glove and wear it for awhile.

I'd strongly encourage trying it. Been there done that. The glove thing, not
the implant thing. Cheap and fun. You will "stick" yourself to chunks of steel
and much simpler to fix that with a glove. It gets boring/annoying after a
couple hours, at which point you're pretty happy to peel off the glove; I
imagine implants are less convenient.

And its magnetic fields not electrical. Over a couple hundred volts/cm you can
feel electrical fields without any implants or whatever, assuming you have arm
hair. I'm talking about something distinct from feeling current flow, a
totally different scenario.

You can feel CHANGING magnetic fields if they're immense, like in a MRI.

~~~
TeMPOraL
I actually spent some time walking around the streets with a neodymium magnet
stuck to my finger with a piece of duct tape. What I realized after few hours
is that the sensations I had were not coming from magnetic fields - I could
just feel my own pulse. i.e. it worked equally well with a similarly-shaped
piece of metal instead of a magnet.

(Not questioning the implanted magnets; I just want to point out that one has
to be careful when doing the non-implant version of this experiment with
jumping to conclusions about what one feels.)

------
TomGullen
I don't know if these pictures make much sense really. Radio waves are part of
the light spectrum but not part of the visible light spectrum, so it doesn't
make much sense to represent it visually in this way.

If an artist pictured grass as if it reflected radio waves and not visible
light waves, we'd have a interesting/weird picture but one without much value.

~~~
roc
> _" If an artist pictured grass as if it reflected radio waves and not
> visible light waves, we'd have a interesting/weird picture but one without
> much value."_

It wouldn't even be necessarily interesting or weird. It would only need to
look like grass that has another set of lights shone on it, which is pretty
pedestrian. The 'weirdness' of these images comes from the fairly arbitrary
assignment of colors to these wavelengths-we-can't-normally-see. Which is
utterly unrelated to the original spectra.

One could 'false color' a scene by arbitrarily shifting color assignments for
_normally visible_ wavelengths and achieve something just as visually
'interesting/weird'.

~~~
lukeschlather
We actually do have a general understanding of what materials
absorb/transmit/reflect radio waves, so if you said "What would this scene
look like if you moved the visible light spectrum to where WiFi is" you could
actually create a meaningful and even potentially useful picture.

------
incision
I was hoping for something more than an RF crime sketch.

This recent EM visualization was pretty cool and a bit more substantial.

 _" Through a series of experiments in photographic and lighting techniques
followed by customising an Android phone to act as an EMF indicator and then
coding our own app in Processing we were able to visualize how these fields
change over objects."_

[http://vimeo.com/65321968](http://vimeo.com/65321968)

------
kineticfocus
While on the topic... [http://thecreatorsproject.vice.com/blog/who-knew-radio-
waves...](http://thecreatorsproject.vice.com/blog/who-knew-radio-waves-could-
look-this-good)

[http://www.popsci.com/gadgets/article/2009-10/rfid-waves-
viz...](http://www.popsci.com/gadgets/article/2009-10/rfid-waves-vizualized-
and-demystified-using-led-wand)

~~~
VLM
Very creative pictures, but if you want the real thing, merely visit:

[http://www.ansys.com/](http://www.ansys.com/)

and bring a thick wallet (like, don't bother unless you've got 4 to 5
figures). And a lot of patience because the real tools have a dwarf fortress
shaped learning curve.

A fine idea would be an open source-ish replacement for these type of tools.
Good luck avoiding the patent minefield.

Its interesting that there are lots of really good and popular and "famous"
computer algebra manipulation programs competing with mathematica type
proprietary software, but not much free good, popular and "famous" finite
element analysis and electromagnetic modeling type stuff.

------
Dirlewanger
Now throw in all the radiation coming from everyone's cell phones
communicating with the WAP, the numerous radio waves in the atmosphere, UV
light from the sun, other sources I'm probably forgetting, etc...that'd be a
much more impressive representation.

------
ANH
Ignoring the images, the physical descriptions in this seem badly wrong. For
instance, can any WiFi modulation scheme be described as, "The crests of waves
is [sic] translated to a 1 by a computer, and the troughs equal a 0."?

------
superpanic
The Wifi Camera
[http://www.ntticc.or.jp/Archive/2008/Light_InSight/Works/wif...](http://www.ntticc.or.jp/Archive/2008/Light_InSight/Works/wificameraobscura.html)

------
timini
It's very strange that the facebook comments on the Vice article are more
critical of the project than the comments here. What's up hacker news?

Can't you see how juvenile this work is?

