How A Candle Burns

People have been burning candles for thousands of years... and I know I, at least, have been taking the science for granted.  It wasn't until I listened to last week's "Science Friday" on NPR that I finally "got" why the candle works.

Host Ira Flatow and staffer Flora Lichtman talked about how Brigham Young engineers have been taking high-speed videos of flames in order to figure out how to reproduce one in digital 3-D. Lichtman spent some time with these engineers as they accomplished this task, and shared what she had learned with Flatow:

LICHTMAN: But - here's one that I thought was pretty amazing. A flame, a candle flame, for example, is just an envelope of fire around this sort of center area. So the wax, which is the fuel, goes up through the wick. It melts, goes up through the wick, and then evaporates into a gas. And that is - the part around the wick is actually not on fire. So the wick is actually not on fire. 

FLATOW: That's why it doesn't burn away, I guess. 

LICHTMAN: That's why. 

FLATOW: Yeah. Hey, you're right. You know, the wick is not on fire - so there's an envelope of gas around the wick, and it's the gas that's burning. 

LICHTMAN: And it's the gas that's burning, and it only burns when it hits oxygen. So the gas on the inside that doesn't have access to oxygen isn't burning, and it's actually cool inside the flame.

You can listen to the whole interview here. It's full of good stuff!

Why Are Diamonds Valuable?

I just read some disturbing information about the diamond industry and thought I'd share.  I have not seen the movie Blood Diamond, nor know its plot, so forgive me if this is all old news...

Diamond jewelry has come to symbolize love. We also think of diamonds as valuable investments, valuable because they are so rare. But we think both of those things -- because we've been conned. 

Diamonds only mean love, and cost more than gold, because one brilliant company convinced people that diamonds were special. 

The marketing strategy was born 100 years ago in the mines of South Africa, when huge deposits of diamonds were found... Before that the discovery of a diamond was so rare that diamonds had become status symbols among royalty. But with the South African discovery, diamonds were suddenly ordinary. Prices plunged. 

Then a smart Englishman, Cecil Rhodes, bought lots of the suddenly cheap diamond minds, and established a monopoly [through the company De Beers] on the diamond supply... [His dealings with diamond-producing countries] brought De Beers an astonishing... 80% of the market... 

To keep prices high, De Beers hoards diamonds. That makes diamonds seem more rare than they actually are. 

But that's only half of their strategy... De Beers played the market brilliantly. It launched an advertising and public relations campaign to manipulate the world into believing that diamonds were the proper way to express love.

At the beginning of the 20th Century, there was not a clear American marriage "tradition" since the country was made of so many different cultures. De Beers jumped on that opportunity and offered their solution: if you want to marry a woman, you put a diamond ring on her finger.  Movie studios jumped on the diamond bandwagon, and sales exploded.

De Beers seems to be able to set the diamond standards based on what's in their warehouses.  When they had an overflow of large diamonds, they advertised "The bigger the diamond, the more you love her." When they acquired many small diamonds from Russia, De Beers encouraged men to buy their wives "Eternity Rings" for their anniversaries, which happened to contain lots of smaller stones.

So now we're left with a conundrum -- De Beers may have started the diamond trend based purely on economic strategy that leaves diamonds chronically overpriced, but it now IS culturally "American" for diamonds (instead of other precious stones) to symbolize eternal love. How can we resolve this?

You are so pretty and so sparkly... but are you worth it?

[source: Myths, Lies, & Downright Stupidity by John Stossel]

Prevent Hearing Loss

Here's a handy guide from Reader's Digest to help you know when you're listening to music too loudly:

One in five adolescents now suffers from hearing loss -- a 30% jump from just two decades ago. The loss is mild, but it means more teens are hearing only about as well as a typical 40- to 60-year-old. 

Playing music too loudly is partly to blame, experts believe. To avoid damage to your hearing, keep these numbers in mind:

• 60 : You can listen all day if you keep the volume at 60% of the max

• 80 for 90 : You can boost the volume to 80% for 90 minutes a day

• 100 for 5 : If you want to crank up the volume as high as it'll go, keep it short -- just 5 minutes a day

Here's to good hearing health!

Walking On Hot Coals

How can people walk barefoot on hot coals without getting burned?  Is it some mind trick?

Actually it's just science... and you can do it, too!

Physicist David Willey from the University of Pittsburgh physics department and 20/20 anchor John Stossel show how it's done:

Willey laid out 165 feet of lumber and set it aflame. As [they] waited for the lumber to turn into hot coals, he said that anyone can "fire-walk" in their bare feet, provided they keep moving, because when you touch burning wood or charcoal, the heat doesn't go instantly to your feet. You'd be burned if you walk on hot metal, but wood and charcoal don't conduct heat very well.

Hot coals can (slowly) roast a marshmallow and burn at a temperature of approximately 1000 degrees F. But it's a poor thermal conductor, so it takes a while to "conduct" (move) the heat from itself to whatever it's touching.  If you keep walking at an even pace on the coals your feet won't keep in contact with any coal long enough to burn them!  Plus, and this is pure speculation, the fact that the skin on your feet is so thick probably delays the heat transfer as well.

You're not so scary anymore, are ya?

Do Cats Only Meow At Humans?

My brother once told me that adult cats only meow to talk to humans, so I decided to see if he was right. And he seems to be!

What are you saying, kitty?

Here are the ways that cats communicate:

1. Meowing
They naturally meow just as kittens to get their mother's attention. But as a result of domestication, it appears that they have learned to meow at humans for the same reason!

2. Purring
Most of the time, cats purr because they are happy.  They sometimes purr when they are feeling sick or during stressful moments.

3. Hissing/Growling
Cats hiss or growl when they are angry or want to threaten other animals or humans. They typically will attack with their claws and paws if whoever they are hissing at doesn't back off.

4. Chirping/Chattering
This is a "bird-like" noise that cats can make while watching potential prey. Some have thought that the cats are imitating birds or mice, but the accepted theory is actually that they are simulating the biting motions they'd do if they actually caught the prey.

5. Caterwaul
Cats make this "crying baby" or howling noise to signal to other cats that they are in heat. In rarer occasions, cats will caterwaul to get their owner's attention, like if they are behind a door and need to be loud.

6. Body Language
There are so many ways cats use their body to communicate, I feel as though it may be their primary source of communicating, especially with other cats, who instinctively know what their bodies are saying.  Here are a few examples, some of which could be confusing to humans:

• Lying on their back: this could mean submission and trust, or that they want to attack with all four claws, or just that's how they feel comfortable
• Puffed tail: the cat is surprised or scared; they can also arch their backs and puff out their back hair to look bigger to whatever they feel threatened by
• Tail-twitching: this could mean they are hunting, or they are irritated, or they are excited, or they are playing
• Flattened ears: the cat is feeling threatened
• Nose-touching: this could just be a friendly greeting, or they are marking their territory
• Licking: the cat is trying to bond with another cat or sometimes with their human owner
• Pawing: this could mean they are showing affection or contentment or curiosity, or that they are comforting themselves, or that they are marking their territory

There are tons of other ways cats communicate to each other by whisker position, tail height, and other body movements.

7. Scent
Cats claim territory by territorial marking or by rubbing their scent on people or objects.

All that to say (since it seems I have strayed from the original question): it appears that past kitten-hood, cats mainly meow to humans, and use a variety of other methods of communication to deal with other cats and other animals.

It's pretty smart of them, actually. Cats must have figured out at some point that humans communicate well with noise... and don't always read their body movements correctly!

[source: wikipedia]

ps. Check out this cat who somehow learned to bark... yet didn't want their human owner know! I guess cats have a great ability to learn how to communicate the most effectively.