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Measuring the Speed of Light With Valentine's Day Chocolate

samzenpus posted more than 4 years ago | from the speed-of-the-sound-of-loneliness dept.

Idle 126

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."

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Darn you, slashdot! (0)

Anonymous Coward | more than 4 years ago | (#31159438)

Now I'm hungry.

Re:Darn you, slashdot! (1)

ls671 (1122017) | more than 4 years ago | (#31159670)

> Now I'm hungry.

Now I am *horny*. There must still be hope in my case...

Re:Darn you, slashdot! (4, Funny)

Red Flayer (890720) | more than 4 years ago | (#31159720)

Now I am *horny*. There must still be hope in my case...

If a microwave, chocolate, and performing an experiment make you horny...

Let's just hope you never learn what fondue is.

Re:Darn you, slashdot! (1)

ls671 (1122017) | more than 4 years ago | (#31160130)

I should have specified that I have a groovy orgy an every Valentine's day.

Did you miss the fact that we were talking about "Valentine's day" chocolates ?

Re:Darn you, slashdot! (1)

element-o.p. (939033) | more than 4 years ago | (#31161514)

In light of your sig, the rest of your post is actually quite funny ;)

Re:Darn you, slashdot! (1)

ls671 (1122017) | more than 4 years ago | (#31161688)

In light of your sig, I hope you do not live in South Korea ;-))

Re:Darn you, slashdot! (1)

omuls are tasty (1321759) | more than 4 years ago | (#31161892)

You mean like, both hands at once?

Re:Darn you, slashdot! (1)

ls671 (1122017) | more than 4 years ago | (#31162388)

Yep, I seem to remember that the girls both used their hands at once at some point...

Re:Darn you, slashdot! (1)

Locke2005 (849178) | more than 4 years ago | (#31162102)

If you're like the average slashdotter, there would be a lot more hope for you if you were just hungry... unless you've got an "American Pie" like fetish for warm chocolates!

Re:Darn you, slashdot! (1)

ls671 (1122017) | more than 4 years ago | (#31162432)

> If you're like the average slashdotter

Without regards for the groups I might be considered part of, I am never considered "average" in any case.

Slashdot doesn't recongnize this holiday! (0)

LostCluster (625375) | more than 4 years ago | (#31159446)

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?

Re:Slashdot doesn't recongnize this holiday! (5, Funny)

KharmaWidow (1504025) | more than 4 years ago | (#31159496)

Or even, what's this thing called "leftover chocolate?"

Re:Slashdot doesn't recongnize this holiday! (2, Interesting)

tomhudson (43916) | more than 4 years ago | (#31160118)

Definition: "Leftover chocolate"

See: Modern myths.

There are only two places in the entire planet where there's a chance of finding "Leftover chocolate."

  1. Soviet Russia, where Left-over Chocolate (also known as Chocolate-flavoured Exlax) leaves YOU!
  2. CowboyNeals ... because he got his chocolate truffles off the set of American Pie [youtube.com] .

Aslo, the article is wrong:

The demonstration works because microwave ovens produce standing waves -- waves that move "up" and "down" in place, instead of rolling forward like waves in the ocean.

Ocean waves don't "move forward".

The oven is designed to be just the right size to cause the microwaves to reflect off the walls so that the peaks and valleys line up perfectly, creating "hot spots" (actually, lines of heat).

Disproved by direct observation. Go into any store and you'll see microwaves in various sizes. The perfect microwave doesn't have "hot spots".

Re:Slashdot doesn't recongnize this holiday! (4, Informative)

Bakkster (1529253) | more than 4 years ago | (#31160402)

Aslo, the article is wrong:

The demonstration works because microwave ovens produce standing waves -- waves that move "up" and "down" in place, instead of rolling forward like waves in the ocean.

Ocean waves don't "move forward".

While the individual particles do not, the wave itself does.

He is mistaken on the meaning of a standing wave. It is not the same as a transverse wave (which seems to be why he is comparing them to a longitudinal wave).

The oven is designed to be just the right size to cause the microwaves to reflect off the walls so that the peaks and valleys line up perfectly, creating "hot spots" (actually, lines of heat).

Disproved by direct observation. Go into any store and you'll see microwaves in various sizes. The perfect microwave doesn't have "hot spots".

Again, he's wrong about it being 'designed' for the purpose of having hot spots, but the design does result in hot spots. These occur regardless of oven size, they will simply be located in different locations. This is caused by reflections off internal surfaces acting like two signal sources.

While it may be conceivable to create a 'perfect' microwave with no standing wave nodes, it would be pointless. Besides, he wasn't using an 'ideal' microwave, just a regular off-the-shelf microwave, which does have standing waves.

Re:Slashdot doesn't recongnize this holiday! (0)

Anonymous Coward | more than 4 years ago | (#31160486)

Seems to me that a prolate spheroid wouldn't have hot spots, assuming the emitter was at one focus (except for the distance squared from the direct rays from the emitter of course).
http://en.wikipedia.org/wiki/Prolate_spheroid

Re:Slashdot doesn't recongnize this holiday! (3, Informative)

Fish (David Trout) (923462) | more than 4 years ago | (#31161408)

She. Her name is Kathy Ceceri. She's a she, not a he.

Re:Slashdot doesn't recongnize this holiday! (1)

Bakkster (1529253) | more than 4 years ago | (#31161490)

My bad, I didn't read the byline. I assumed that an article on a blog called GeekDad was written by a geeky dad... ;-)

Re:Slashdot doesn't recongnize this holiday! (1)

Hognoxious (631665) | more than 4 years ago | (#31162098)

Ah. That explains it all.

Re:Slashdot doesn't recongnize this holiday! (1)

Red Flayer (890720) | more than 4 years ago | (#31160438)

Ocean waves don't "move forward".

False. Disproved by direct observation. Stand on a pier sometime and look at the waves. The spot where a maximal low is does not become the maximal high; instead a spot in front of it is the maximal high. There is, indeed, a rolling forward effect.

Disproved by direct observation. Go into any store and you'll see microwaves in various sizes. The perfect microwave doesn't have "hot spots".

Just because there are microwaves of different size does not mean that none of them were designed to produce heat lines. It's about multiples of the wavelength, not absolute size, anyway. Ever wonder why we can see many buildings that express the golden ratio, but they are not all the same size?

Re:Slashdot doesn't recongnize this holiday! (1)

tomhudson (43916) | more than 4 years ago | (#31160508)

They're no longer "ocean waves" at that point. In the mid-atlantic or mid-pacific the water stays in place.

Re:Slashdot doesn't recongnize this holiday! (1)

danbert8 (1024253) | more than 4 years ago | (#31160662)

The matter stays in place, but the wave energy passes on continuously. In a standing wave, the nodes are fixed. This is not the case in the ocean.

Re:Slashdot doesn't recongnize this holiday! (1)

Hognoxious (631665) | more than 4 years ago | (#31162124)

Is that why you can't hear anything except when there's a wind blowing?

Re:Slashdot doesn't recongnize this holiday! (1)

Monkeedude1212 (1560403) | more than 4 years ago | (#31159614)

I'm pretty sure I read about girlfriends in Popular Science...

Re:Slashdot doesn't recongnize this holiday! (1)

rubycodez (864176) | more than 4 years ago | (#31159802)

alas, if only most slashdotters were in Japan. There the women or girls give low cost chocolate to all the guys at work or in school class. It's called "obligation chocolate" or "pity chocolate", but if there is a guy they really like they give expensive or homemade chocolate with a gift "prospective winner chocolate".

So no male is without cheap chocolate from a female, at least.

you can use chocolate to measure speed of light (4, Funny)

circletimessquare (444983) | more than 4 years ago | (#31159476)

although its far more interesting to use chocolate to measure the speed of digestion

Re:you can use chocolate to measure speed of light (0)

Anonymous Coward | more than 4 years ago | (#31159546)

I'd say it's more interesting to use chocolate to measure the speed of fat.

Re:you can use chocolate to measure speed of light (1)

circletimessquare (444983) | more than 4 years ago | (#31159714)

I'd say it's more interesting to use chocolate to measure the speed of fat. ...and that explains why you are eating valentine's day chocolates by yourself

Re:you can use chocolate to measure speed of light (1)

ls671 (1122017) | more than 4 years ago | (#31159808)

I misread "the speed of FART".

The brain makes assumptions while reading, speed implicates something that we imagine moving by itself unless we talk about speed of growth, as it is the case for fat. That, along with the "digestion" topic GP, could explain this mistake from me.

Anybody else misread the same ?

Re:you can use chocolate to measure speed of light (0)

Anonymous Coward | more than 4 years ago | (#31159770)

or in my case, indigestion

Re:you can use chocolate to measure speed of light (1)

RDW (41497) | more than 4 years ago | (#31159792)

'although its far more interesting to use chocolate to measure the speed of digestion'

Yes! Reserve the chocolate for this vital research. The microwave experiment is best performed with marshmallows (which aren't really food, anyway):

http://orbitingfrog.com/blog/2008/05/13/measure-the-speed-of-light-using-your-microwave/ [orbitingfrog.com]

Why bother? (1, Funny)

Anonymous Coward | more than 4 years ago | (#31159494)

It's approximately 300 000 km/h. 'Nuff said.

Re:Why bother? (2, Informative)

maxwell demon (590494) | more than 4 years ago | (#31159530)

299792458 m/s, to be exact.

Re:Why bother? (3, Informative)

ls671 (1122017) | more than 4 years ago | (#31160028)

Now this is very informative ;-)

Actually, not that much since you did not specify in which environment it has that "exact speed". Saying the speed of light is 194792442 m/s or any value is just as precise.

Now, saying that c is constant equal to 299792458 m/s is absolutely correct although, the speed of light is actually:

c/n where n is the refraction index.

In a microwave oven at sea level, the speed of light is *approximately* 299792458/1.0003 = 299702547 m/s

Re:Why bother? (2, Funny)

Anonymous Coward | more than 4 years ago | (#31160418)

Now this is very informative ;-)

Actually, not that much since you did not specify in which environment it has that "exact speed". Saying the speed of light is 194792442 m/s or any value is just as precise.

Now, saying that c is constant equal to 299792458 m/s is absolutely correct although, the speed of light is actually:

c/n where n is the refraction index.

In a microwave oven at sea level, the speed of light is *approximately* 299792458/1.0003 = 299702547 m/s

Nerd

Re:Why bother? (3, Insightful)

ls671 (1122017) | more than 4 years ago | (#31160652)

> Nerd.

Actually, using expression like "approximately" or specifying an error margin instead of using terms like "exact" like the GGP did is a pretty scientific standard and it is overall a good habit in all sphere of life.

In general, one should be doubtful about "absolute truths", "exact calculations", "100% efficiency" or the like ;-))

Re:Why bother? (1)

Bloomy (714535) | more than 4 years ago | (#31161012)

Does that make maxwell demon a Sith?

Re:Why bother? (1)

ls671 (1122017) | more than 4 years ago | (#31161228)

Nah, I do not have enough data to conclude that so I would assume he didn't do it on purpose. That's why I choose to enlighten him and I suggested to rethink about the fact that nothing is exact. ;-))

Re:Why bother? (1)

maxwell demon (590494) | more than 4 years ago | (#31161680)

Nah, I do not have enough data to conclude that so I would assume he didn't do it on purpose. That's why I choose to enlighten him and I suggested to rethink about the fact that nothing is exact. ;-))

Except for the speed of light in vacuum.
And the magnetic constant.
And the vacuum permittivity.

Re:Why bother? (1)

ls671 (1122017) | more than 4 years ago | (#31162034)

You are mixing up constant definitions and theoretical values with actual measurements/realty.

Einstein went through this before, I suggest to read what his theories say about "exact measurements". ;-))

For example, a perfect vacuum doesn't exist, so c is a theoretical value. Even outer space is not a perfect vacuum.

http://en.wikipedia.org/wiki/Vacuum [wikipedia.org]

Anything else I can do for you today ?

Re:Why bother? (3, Funny)

Locke2005 (849178) | more than 4 years ago | (#31162172)

Anything else I can do for you today ? My car _really_ needs to be washed... and it would also be nice if you could give the interior a "once over" with a perfect vacuum.

Re:Why bother? (1)

ls671 (1122017) | more than 4 years ago | (#31162274)

I am on my way, please post the location of your car.

I would have modded you funny if I hadn't already posted.

Re:Why bother? (1)

Hognoxious (631665) | more than 4 years ago | (#31162168)

Isn't one of those redundant, since you can calculate it from the other two? One over the square root, or something like that.

Re:Why bother? (2, Informative)

maxwell demon (590494) | more than 4 years ago | (#31161632)

Except that the speed of light in vacuum is exactly 299792458 m/s. Not approximately, exactly. By definition (of the meter).

Re:Why bother? (3, Informative)

garg0yle (208225) | more than 4 years ago | (#31159570)

I think you mean approximately 300 000 km/s, not km/h. You're only out by a factor of 3600, no worries!

Re:Why bother? (5, Funny)

Gerafix (1028986) | more than 4 years ago | (#31159582)

Are you sure? My Texas School Board Approved textbook says the speed of light is exactly the speed it takes God to wink. Coincidence? I think not.

Re:Why bother? (3, Funny)

cheftw (996831) | more than 4 years ago | (#31159842)

God takes speed to wink... :|

Re:Why bother? (1)

svtdragon (917476) | more than 4 years ago | (#31160020)

News of the hour: God takes speed! Claims it's "heavenly delicious".

And on the note of "heavenly delicious," weren't we talking about chocolate?

Re:Why bother? (0)

Anonymous Coward | more than 4 years ago | (#31159594)

Because it's fun and an interesting way to teach kids both math and science. You know, you don't have to be an asshat every day.

Too late (4, Insightful)

P-Nuts (592605) | more than 4 years ago | (#31159514)

That was two days ago. Give us some pancake science!

Re:Too late (0)

Anonymous Coward | more than 4 years ago | (#31159556)

chocolate pancakes?

Re:Too late (1)

garg0yle (208225) | more than 4 years ago | (#31159612)

Okay, how's this [scienceblogs.com] ? A mathematical formula for perfect pancakes...

Re:Too late (1)

Red Flayer (890720) | more than 4 years ago | (#31159810)

Pancakes are great tools for teaching math. Fractions, geometry, trigonometry...

They are good for teaching some chemistry (NaHCO3 + H+ Na+ + CO2 + H2O).

But what they are best at, in terms of science, is proving the universal truths of bacon and maple syrup supremacy.

Re:Too late (1)

Red Flayer (890720) | more than 4 years ago | (#31159832)

Damn slashdot for eating unicode arrows. That should be NaHCO3 + H+ --> Na+ + CO2 + H2O

This experiment is imprecise and delicious. (5, Funny)

Chris Burke (6130) | more than 4 years ago | (#31159600)

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*

Re:This experiment is imprecise and delicious. (4, Insightful)

bughunter (10093) | more than 4 years ago | (#31160080)

More problems than that, even. The article does nothing to address the puzzled questions that my son (or even my wife, who is smart but no techie) would ask if I showed them this. That's where the REAL lessons are:

1 - "How does this measure the speed of light when we are using the microwave and not a flashlight?" (Answer: because microwaves and visible light are both forms of electromagnetic radiation... so is infrared, what you feel on your face when you stand by the campfire, and radio waves that bring music to our car stereos.)

2 - "Why does this experiment mean anything about speed? We are measuring a distance, not a speed." (Answer: because the wavelength is related to frequency by the speed of propagation. Think about shaking one end of the rope and watching the waves travel down it. Frequency is how many times per minute you shake. Each shake makes a peak and the space between peaks is how far the previous peak moved down the rope before the next shake. That's how wavelength and frequency are related by propagation velocity.)

If your child is still paying attention at the end of that thought experiment, you know he's a scientist. Buy her a model rocket or a microscope. If not, give her a set of watercolors or a video camera.

If your child just eats the chocolate and asks for more, then just buy him a guitar.

Re:This experiment is imprecise and delicious. (1)

blueg3 (192743) | more than 4 years ago | (#31160460)

You seem to be confusing a complete lesson on electromagnetic radiation with an experiment to determine the speed of light. An experiment only does the one thing, and the instructions are just for how to perform the experiment. (It is lacking in theoretical hints, but does tell you to look into standing waves.)

Re:This experiment is imprecise and delicious. (1)

maxwell demon (590494) | more than 4 years ago | (#31161746)

An experiment is worthless if you don't know enough of the theory to interpret the results. Without that knowledge it's not an experiment to determine the speed of light, but just an experiment to determine the wavelength of the microwave.

Re:This experiment is imprecise and delicious. (1)

danlip (737336) | more than 4 years ago | (#31160674)

You also have to know the frequency for this to work, which involves trusting either TFA or your microwave manual, which makes it much less interesting as a pure science experiment. But still delicious.

Re:This experiment is imprecise and delicious. (1)

corbettw (214229) | more than 4 years ago | (#31160854)

If your child is still paying attention at the end of that thought experiment, you know he's a scientist. Buy her a model rocket or a microscope.

And put a lock on the plutonium in the cupboard.

Re:This experiment is imprecise and delicious. (1, Funny)

Anonymous Coward | more than 4 years ago | (#31161972)

Bu bu but... That's the secret ingredient in auntie Curie's "soul warming" chicken casserole!

It warms you up inside, helps you lose weight, AND makes you the brightest one at school, all at once!

Re:This experiment is imprecise and delicious. (1)

tool462 (677306) | more than 4 years ago | (#31160890)

You got your son and wife to ask you insightful questions about physics? How is that a problem?

Science is about questions, not answers.

Re:This experiment is imprecise and delicious. (1)

bughunter (10093) | more than 4 years ago | (#31161082)

You misunderstand me. The problem isn't with the child asking questions, it's with the article not arming the parent with the answers.

The questions AND the answers bring enlightenment, and it's the joy of enlightenment that creates a scientist out of a curious child.

Re:This experiment is imprecise and delicious. (1)

element-o.p. (939033) | more than 4 years ago | (#31161710)

The problem isn't with the child asking questions, it's with the article not arming the parent with the answers.

That's what Google is for <grin> Then, not only can you provide a physics lesson, but you can teach your child how to research, as well.

Re:This experiment is imprecise and delicious. (0)

Anonymous Coward | more than 4 years ago | (#31161162)

If your child is still paying attention at the end of that thought experiment, you know he's a scientist. Buy him a model rocket or a microscope. If not, give him a set of watercolors or a video camera.

FTFY.

Women aren't interested in science (for the most part -- there are obvious rare exceptions). Science is risky, boring, and doesn't involve constant in-person interaction. It requires systemization of knowledge and understanding of things you can't directly see. It has constant, obvious checks for when you are Just Plain Wrong, or Not Even Wrong.

Men tolerate that, women don't. (It's an open question which one is wiser for doing so!)

Posting anon because it's an unpopular truth that someone has to say.

Re:This experiment is imprecise and delicious. (0)

Anonymous Coward | more than 4 years ago | (#31161204)

Good job on the sexism. Apparently in this day and age, we need to call women smart and men stupid so we can be equal.

Not to say that guitarists are dumb. I happen to be a guitarist and a physicist. However, the tone of your statement implies so.

Re:This experiment is imprecise and delicious. (1)

element-o.p. (939033) | more than 4 years ago | (#31161694)

What about freaks like me who built/flew model rockets *and* played guitar?

Re:This experiment is imprecise and delicious. (1)

HeadlessNotAHorseman (823040) | more than 4 years ago | (#31162712)

Red Symons [wikipedia.org] has a Bachelor of Science degree (studied pure mathematics and computer science) but is perhaps best known for his role as lead guitarist for Aussie glam rock band Skyhooks [wikipedia.org] , as well as as a tv / radio presenter with an acerbic wit.

Re:This experiment is imprecise and delicious. (1)

mathfeel (937008) | more than 4 years ago | (#31160372)

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*

Yes, that's why there is such thing as uncertainty. If she propagated the uncertainty both in the frequency and the "eye-balling" part correctly it will probably include a large enough error bar pass the actual speed of light, making this an accurate, but imprecise experiment.
Oh wait, are we talking about a fun project to be doing with you kid, or a collage physics lab.

Leftover Valentine's Day chocolates? (0)

Anonymous Coward | more than 4 years ago | (#31159604)

Yup, I think I've got some of that sitting beside my over-unity generator and my copy of Duke Nukem Forever.

I wonder... (1)

zero_out (1705074) | more than 4 years ago | (#31159636)

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.

Re:I wonder... (1)

natehoy (1608657) | more than 4 years ago | (#31159778)

Very important reasons to use Palmer's:

1. You aren't running the risk of burning perfectly good chocolate to perform the experiment.
2. You are more likely to have leftovers of Palmer's, assuming you had some in the house in the first place, since no one in their right mind would actually eat it.

Remember, even Twinkies are good enough for science experiments. It's simply a matter of choosing the right experiment.

Sheldon Cooper?? (3, Funny)

kai_hiwatari (1642285) | more than 4 years ago | (#31159650)

Is this what Dr. Sheldon Lee Cooper do on Valentines Day?

You have to assume you know the frequency.... (1)

cpotoso (606303) | more than 4 years ago | (#31159710)

Not what I would call completely transparent, eh?

Re:You have to assume you know the frequency.... (1)

vlm (69642) | more than 4 years ago | (#31160266)

Well, so you've got two unknowns, the frequency, and the speed of light.

So, you go to google to get the speed of light, and thus calculate the frequency using the wavelength

Now, you know the experimentally determined frequency and the wavelength, so calculate the speed of light, which should be suspiciously near the previously google'd value.

Tada! Where's my Nobel prize in physics?

Seriously though, you probably aren't getting over 2 sig figs on the wavelength, and you have to take somebodys word for it on the free-running magnetron frequency, at best 2 sig figs (theres a reason the ISM bands are very wide). Combine two low accuracy numbers, one of which is a "trust us" number, and get the speed of light to maybe 1 sig fig, that being "really freaking fast".

Re:You have to assume you know the frequency.... (1)

batquux (323697) | more than 4 years ago | (#31160394)

You can solve for the frequency using the speed of light and the wavelength. OH! Hmm....

Re:You have to assume you know the frequency.... (2)

blueg3 (192743) | more than 4 years ago | (#31160422)

It's stated on the microwave (or in its documentation). They don't get that by knowing the speed of light, but rather by the construction of the device. You could build your own microwave generator to be sure, but assuming that the manufacturer is giving you the correct value is good for an estimate.

Re:You have to assume you know the frequency.... (1)

vlm (69642) | more than 4 years ago | (#31160936)

They don't get that by knowing the speed of light, but rather by the construction of the device.

Actually, knowing the speed of light figures rather prominently in the design of the resonators in the magnetron.

Its hard to do RF design stuff that doesn't at some fundamental level involve Maxwells equations, which pretty unavoidably has a solution for light velocity...

That's not hard (1)

Sycraft-fu (314770) | more than 4 years ago | (#31160550)

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.

Re:That's not hard (1)

Nevynxxx (932175) | more than 4 years ago | (#31161356)

After all, we know the speed of light to 9 figures already.

Technically it's defined as those 9 figures, and the meter and second are defined in terms of that definition. So really the experiment is badly measuring a defined quantity....

Your last point though, that's a good valid one.

Re:You have to assume you know the frequency.... (1)

PPH (736903) | more than 4 years ago | (#31160800)

We're at work designing an experiment to measure it using cold pizza and warm beer.

Waste of good chocolate (1)

DerekLyons (302214) | more than 4 years ago | (#31159790)

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.

Re:Waste of good chocolate (0)

Anonymous Coward | more than 4 years ago | (#31160506)

Good for you. Too bad no one cares.

Re:Waste of good chocolate (1)

amRadioHed (463061) | more than 4 years ago | (#31160842)

Dude, the crap at the convenience store is the left over chocolate. You can pick up a box for dirt cheap.

This is BS... (0)

Anonymous Coward | more than 4 years ago | (#31160298)

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...

But how do you count the cycles? (3, Insightful)

dpbsmith (263124) | more than 4 years ago | (#31160636)

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?

Re:But how do you count the cycles? (1)

drsquare (530038) | more than 4 years ago | (#31161232)

Have someone throw the microwave at you so fast that the blue shift turns the microwaves into visible light. By observing the colour, and using the speed of the microwave, you can calculate the frequency.

Re:But how do you count the cycles? (1)

revengebomber (1080189) | more than 4 years ago | (#31161254)

It melts the chocolate, so it's gotta be reverberating with the water? I assumed that's how you know the frequency.

Easy calculation (1)

GodfatherofSoul (174979) | more than 4 years ago | (#31160920)

The fastest rate your girlfriend can cram them into her mouth when she doesn't think you're looking.

Seen it done with cheese too... (1)

syousef (465911) | more than 4 years ago | (#31161188)

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 ;-)

Not quite the measurement you're looking for (1, Insightful)

__roo (86767) | more than 4 years ago | (#31161302)

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.

Re:Not quite the measurement you're looking for (2, Insightful)

Namarrgon (105036) | more than 4 years ago | (#31162280)

A smart high school student will tell you that you can only calculate the wavelength from the frequency if you already know the speed of light (the formula is C = Wavelength x Frequency).

this is not scientific at all (0)

Anonymous Coward | more than 4 years ago | (#31161436)

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.

New here? (2, Informative)

rec9140 (732463) | more than 4 years ago | (#31161648)

"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.

I don't know about "the speed of light"... (1)

93 Escort Wagon (326346) | more than 4 years ago | (#31161712)

... but those chocolates did disappear pretty darn fast at our house.

Not measuring speed of light at all (2, Insightful)

Locke2005 (849178) | more than 4 years ago | (#31162078)

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!

Re:Not measuring speed of light at all (1)

ls671 (1122017) | more than 4 years ago | (#31162612)

> However, this is circular

Every measurement is. The conclusion that Einstein came to is that nothing is absolute, everything is relative.

You already replied to that post, but here is the link for the others:

http://slashdot.org/comments.pl?sid=1552160&cid=31162034&art_pos=4 [slashdot.org]

Nothing to do with the speed of light (0)

Anonymous Coward | more than 4 years ago | (#31162134)

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

Too many unknowns (0)

Anonymous Coward | more than 4 years ago | (#31162200)

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.

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