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Measuring the Speed of Light With Valentine's Day Chocolate
Cytotoxic writes "What to do with all of those leftover Valentine's Day chocolates? — a common problem for the Slashdot crowd. The folks over at Wired magazine have an answer for you in a nice article showing how to measure the speed of light with a microwave and some chocolate. A simple yet surprisingly accurate method that can be used to introduce the scientific method to children and others in need of a scientific education."
Now I'm hungry.
What is this Valentine's Day Chocolate thing? This mythical concept called a "girlfriend" seems strange around here. Do we have any proof such people exist?
although its far more interesting to use chocolate to measure the speed of digestion
intellectual property law is philosophically incoherent. it is your moral duty to ignore it or sabotage it
It's approximately 300 000 km/h. 'Nuff said.
That was two days ago. Give us some pancake science!
This experiment has lots of problems. *nom nom nom* First, microwave ovens don't always precisely match the given frequency. *chomp chomp* Second, and more importantly -- *chew chew swallow* -- identifying the hotspots and measuring the distance between them is difficult and error prone. *nom nom* And that's even when the chocolate is fresh! It's worse after it's already been partially melted. *stuff face* So I had to perform many experiments, using fresh chocolate each time, to get an accurate measurement.
In conclusion, this experiment rules. *nom nom nom nom*
The enemies of Democracy are
Yup, I think I've got some of that sitting beside my over-unity generator and my copy of Duke Nukem Forever.
I wonder if this works with that nasty fake stuff that Palmer makes. You know the stuff, made with vegetable oil instead of cocoa butter, and labelled "Milk Chocolate flavored candy"? It may change the melting dynamics just enough to invalidate the whole experiment. I bet that stuff isn't even good enough for science experiments.
Is this what Dr. Sheldon Lee Cooper do on Valentines Day?
Not what I would call completely transparent, eh?
While I have some Valentines chocolate remaining uneaten, none of it is 'left over'.
It's far too valuable to melt (thus destroying many of it's finer qualities), a) because it's quality chocolate rather than crap picked up at the convenience store, and b) my wife handpicked the assortment for me catering to my tastes.
Microwaves send the field to a rotating reflector in the top of the microwave... This randomizes the wave like light bounding of a bunch of rotating mirrors...
That is normally listed on the back of the microwave, and is almost always in the 2.4GHz range. You also don't need the figure that precise, given that your result is basically likely to have only about 1 sig fig anyhow. That's fine, since light is extremely close to 300,000,000 m/s. You need 4 sig figs before a discrepancy starts to show up, and you aren't getting that out of an experiment like this.
Nobody is claiming this is USEFUL, like you are finding out something amazing. After all, we know the speed of light to 9 figures already. This is just a fun type of experiment to show someone the practical application of wave related calculations. You could also run it the other way and calculate the frequency based on the measured wave length and known speed if you like.
Basic science experiments are always rather worthless in terms of true scientific knowledge. They don't tell you anything you couldn't look up. What they are worth while is in terms of personal knowledge. They show people how science work, they show them that these formulas don't come from nowhere, that they work on real, actual data.
OK, so you get the wavelength from the melted chocolate hot spots, but what's an easy way to verify that the frequency is really 2,450,000,000 hertz, from first principles?
Spin the turntable at 2,450,000,000 revolutions per second and look for stroboscopic effects on the chocolate?
"How to Do Nothing," kids activities, back in print!
The fastest rate your girlfriend can cram them into her mouth when she doesn't think you're looking.
I swear to God...I swear to God! That is NOT how you treat your human!
Though as far as I'm concerned it's cheating looking up the frequency of the microwave. It should be measured, which isn't as easy.
If only Ole Rømer had had a microwave oven ;-)
These posts express my own personal views, not those of my employer
It's a neat trick, albeit an old one. But it's not quite a real measurement of C. The problem is that you're given the frequency to start with, and a smart high school student will tell you that means you also know the wavelength. So if you trust the frequency rating of the microwave then the only thing you're really doing is verifying that the ruler you're using is accurate.
Building Better Software
Unless you provide a mechanism for calculating/confirming the frequency of your microwave, we have done no calculations at all. We have just done algebra... just simple manipulation of the arrangement of the numbers.
If we simply read the value off the label on our microwave's... then similarly we may as well just read the value for the speed of light from text of a science textbook and proclaim: "I just calculated the speed of light".
Furthermore, the frequency labeled on your microwave is calculated by the manufacture using techniques which assume the speed of light already. Meaning that the speed of light is not calculated by them or us. But rather, we can extract this assumption using this technique. ie: we end up with a number closely matching the speed of light, but with entirely nothing proven.
* this is slight of hand. bad science. should not be referenced or used in relation to speed of light calculations. does not demonstrate the scientific process.
But still... maybe fun for the kids to see/eat. And does demonstrate wave features... like troughs and peaks. Entertaining I guess.
"Valentine's Day chocolates? a common problem for the Slashdot crowd."
What is this Valentines Day? What does it have to with chocolate? ?
I think your new here, as that not on the list of IT holidays...
And there is NEVER left over chocolate, err.. REAL chocolate.. not that crap Hershey stuff (AND NO I don't buy Cadbury in the US! I know its licensed to be made by Hershey.. I have importers bring in the REAL CADBURYS!)
Just like beer if its made in the US, its junk. Same goes for chocolate.
Want cheap chocoloate, purchase all the Hershey you want.
1311393600 - Back to Black
... but those chocolates did disappear pretty darn fast at our house.
#DeleteChrome
Actually, it is measuring the wavelength of the microwave radiation, and assuming the stated frequency is correct, calculating the speed of light from that. However, this is circular, sense the frequency was most likely also calculated by measuring the wavelength!
I've abandoned my search for truth; now I'm just looking for some useful delusions.
I am really surprised that I could not find one comment that avoided the Emperor's Clothes effect.
They all assume that measuring the wavelength or frequency tells us about speed.
Think on this: Across the visible spectrum the colours have different frequencies (450 to 750 THz) but all travel at the same speed, 299792 km/s in a vacuum.
--Loki3
In a "real" experiment to measure the speed of light, we wouldn't know the frequency. Hence, we have 2 unknowns (frequency and speed) and only 1 equation, which is insufficient for determining a unique speed.
400-790 THz
In terms of frequency, this corresponds to a band in the vicinity of 790-400 terahertz.
http://en.wikipedia.org/wiki/Visible_light
Saw this some years back on the Christmas Lectures that the Beeb run... They did it wih a tray of marshmallows... Can't find a link to that though, but did find this one: http://www.physics.umd.edu/ripe/icpe/newsletters/n34/marshmal.htm
This is a pretty crappy experiment. I've done this before, but covered the bottom of my microwave with water soaked sheets of paper (which allows a constant height and full coverege) instead of chocolate. You do get a number of hot spots (where the paper completely dries), but they appear to be randomly spaced. The only way this experiment "works" is when you identify two spots that happen to be somewhat close to 12.5 cm apart (the value you're expecting -- 3e8/2.4e9) and ignore all of the other possible spacings. Microwave propagation in a microwave oven isn't nearly as simplistic as this experiment would require.
The two hotspots should both be nodes, surely. So, the experiment actually gives the wrong answer, if you use the calculation given.
All further computations shall be done by judges and attorneys, but you'll have lots of time to spare for writing great code afterwards.
BTW, the safety instructions miss the warning:
Remove all items such as knives, forks and frying pans she might feel an impulse to stab or hit you in the head with..."
What to do with all of those leftover Valentine's Day chocolates? — a common problem for the Slashdot crowd
Bullshit