sin(3x)
Recently I happened upon this TradeMe auction (mirrored here), where someone was supposedly selling a chip that could be installed in your cell-phone and "neutralise" the electromagnetic waves transmitted, thus removing the harmful effects these waves supposedly have on your head. In the words of Penn & Teller: Bullshit!
How it works:
In this first paragraph I will be discussing the device in a theoretical sense, i.e., the theory behind how it works, and under the assumption that it will work.
This device utilises what is known as the superposition principle, the fact that as waves occupying the same physical space will sum together to form a resultant wave. This is easly demonstrated with some sine waves.
This is a graph of sin(3x). The x-axis scale is in radians (π radians = 180º). All the graphs use the same scale.
sin(3x)
Now, on the same scaled axes, is a plot of 0.5sin(3x), that is, a sine wave of the same period and phase but with half the amplitude of the above wave.
0.5 x sin(3x)
Notice that because these signals have the same phase, their peaks and troughs are in the same place. Now, if these signals are summed, we end up the resultant wave (in green, because yellow + blue = green, at least for paints.)
0.5sin(3x) + sin(3x)
Signals don't need to have the same frequency to be summed, here is a graph of 0.5sin(6x), a signal with twice the frequency of the previous yellow one, added to the blue wave, and the resultant wave (in green again).
0.5sin(6x) + sin(3x)
Adding signals in this way can produce interesting resultants, as above. In fact, any signal can be represented by an infite summation of sine waves (this is known as a Fourier series, and is far beyond the scope of this document).
If two out-of-phase waves (i.e. one wave has peaks where the other has troughs) are summed, the peaks and troughs will cancel each other out. Taking the first wave, sin(3x):
sin(3x)
And adding it with the same wave phase shifted by π (or 180º):
sin(3x+π)
Results in this wave (in green, again):
sin(3x)+sin(3x-π)
It is under this principle that the device operates: two opposite signals will sum to produce...nothing! So no "dangerous" waves will pass through your head, as they are neutralised. However, as we will find out, this device is bullshit.
"It doesnt need power."
Apparently, this mystical device can analyse a wave, generate its inverse, then transmit it without using any power. Obviously, the seller has forgotten about the first law of thermodynamics, which states that "the total inflow of energy into a system must equal the total outflow of energy from the system, plus the change in the energy contained within the system." Or, in other words, "energy can be converted from one form to another, but it cannot be created or destroyed."
Let's apply some logic here:
Wave transmission and generation requires energy.
AND
No energy goes into this device.
AND
Energy cannot be created,
THEREFORE
This device cannot transmit, as it uses no energy.
There, that there proves this device won't work. But I feel like playing Devil's advocate today. Let's pretend that this device runs without power, and transmits signals. It still won't work.
Omnidirectional antennae
Here's an illustration of a cell-phone communicating with a cell-tower, viewed from the front. I've drawn in the electromagnetic waves so you can see where they are. This cell-phone has an internal antennae, thus electromagnetic waves are radiated from within its body. Many modern cell-phones share this design.
Here is the same phone, viewed from behind:
And again, from the side:
You'll probably notice some similarlity between these three pictures: they're all horrible illustrations of a cell-phone. Okay, besides that, you'll notice the phone is radiating electromagnetic waves in all directions equally. Similarly, any device installed in the cell-phone will radiate inverse waves in all directions. This will lead to the following scenario:
And referring back to the superposition theory, the resultant will look something like this:
Where'd the waves go? Oh that's right, they were "neutralised". Well, I guess now your head is safe from those nasty waves... too bad your cell-phone can't talk to the cell-tower and has become a portable battery-powered paperweight.
But wait, maybe this device is smart enough to only block waves in the direction of your head. Then what happens in the un-rare event that the cell-tower is in the same direction as your head, and thus waves must pass through your head to contact a tower? Bang. Dead cell-phone, again.
Conclusion
Save your money, build yourself a tin-foil hat. You have the added bonus of protecting yourself from the nasty CIA, and save money, because folks, Cell-Phone Neutralisers are Bullshit! Heh heh I've always wanted to say that.
Rebuttal
The seller has finally provided me with some evidence that cell-phones can damage you:
Please let me know if you can read what this book says...
If you value your money too much to waste it on products that don't work, perhaps you woul be interested in some email spamming software instead.
More Updates
Someone likes porn (mirror). After pointing this out when he was trying to sell another one of these bullshit gizmos he blacklisted me from contacting him on TradeMe. If you see him please tell him to un-blacklist me so we may continue to trade together. View the third (at least) of these bullshit items he's tried to sell (mirrored here).
I have now written a page that will automagically take you to the seller's latest auction. This is probably buggy as hell, so if you don't get taken to a page trying to sell a cell-phone wave neutraliser the seller is either not selling one currently or the script is broken. Check this page if you're really interested in finding out.
Questions, comments? Email: ben AT beneboy DORT com