## Monday, June 09, 2008

### Physicist Debunks Cellphone Popcorn Viral Videos

It is really sad that we now have to address all kinds of crackpotteries that appear on YouTube. This is one such example.

YouTube videos that show a group of friends apparently cooking kernels of popcorn with their cellphones have been viewed more than a million times since they were uploaded last week.

The parlor trick (see embedded clip) looks amazing enough, but there's a hitch: It's not physically possible, according to University of Virginia physics professor Louis Bloomfield.

The problem here isn't these yoohoos who made the video. There will always be bored people like this who'd do one thing or another just to get attention. The problem is the people who view these things and would put some credibility into it. We then have to take some effort into debunking such crap. Even then, how many people who saw the video would actually see this response?

Zz.

Anonymous said...

Yet, you didn't spend one word to actually say why it's isn't possible. Talk is cheap.

ZapperZ said...

.. and why do I have to? I would only be repeating what that article has written? Or did you bother to even read it?

I'd say your "comment" was worthless.

Zz.

Anonymous said...

I borrowed this from somewhere else

--Matt

Popcorn pops because the water in it turns to steam and a kernel is about 14% water. So, if we assume a kernel of popcorn weighs 1 gram, it has 0.13 grams of water. Heat that water from 30�C to 100�C would take:

(0.14g)*(100�C-3 to turn the water to steam requires he latent heat of vaporization, which is 2259J/g.

2259J*0.14g= 316J
for a total of 316J 41J = 357J.

Wattage = Joules/seconds. If it took about 5 seconds to turn the water in the popcorn kernel to steam, then the wattage required was:

357J/5sec = 71W assuming all power from the cell phone transmitter went into the kernel.

Cell phones typically have 0.75W-1W transmitters in them. With a 1W transmitter, it would take,

334J/1W = 334secs, if all power is transfered to the kernel.

stevie said...

Yeah, except those calculations are wrong.

Supposedly the video isn't real, but the math doesn't prove it's fake.

•A single kernel of corn weighs somewhere around 200-300 mg not 1g. Which means the energy requirements are 3-5 times lower than their given estimates.

Many cellphones operate between 1.5w to 2w, Not the .5w or in "extreme cases 1w" that these guys are touting. Cell phones have other frequency bands up to 2 GHz, and they typically peak at something more like 5 W, but only when they are working at max power, which would be when you are at the very limit of being able to communicate with the base station.

Microwaves work best at around 2.4ghz, and mobile phone frequencies are not too far off that.

And what kind of 'scientist' would say this: "Ringing the phones doesn't help because they're interfering with each other and receiving a signal -- not transmitting it."
The whole purpose is to combine the waves and he doesn't even understand that a mobile phone is a transceiver, so it would be transmitting too.

Popcorn, anyone?

ZapperZ said...

Forget about the math. Almost EVERYONE has a cell phone. Why don't someone at home get together with a few buddies and REPRODUCE this thing?

Considering how popular this thing is already, and how people are copycats, how come we don't hear someone else saying that they did this and got the same result? I mean, it is not as if this is some highly controlled proper scientific experiment that requires expensive and difficult apparatus.

So try it already! I bet many of you did and it didn't work, did it?

Zz.

Anonymous said...

Stevie is wrong on most of his points. No digital mobile phones (certainly none of the ones shown) transmit 5W. 23-26 dBm (around 200-500 mW) is the max Tx power for most devices.

Also, the original author was correct in stating that the phones weren't transmitting in the video. During paging very little power is emitted from the mobile. In order to get max Tx power out of the phone the call needs to be accepted and audio input is required.

Anonymous said...

The frequency cell phones operate at is not appropriate for resonating water molecules and heating the popcorn kernel.

I tried to explain as much to a local morning radio show, but the clearly dim-witted hosts (their response, "What if you used 100 cell phones?") did not air the call.