Entry #27. Paul Ginart, Philadelphia, Penn.
Paul is an MD/PhD student in medicine and biomedical engineering at the University of Pennsylvania.
A flame is a very special kind of transformation. It’s actually a way of turning most solids into air.
Think about burning wood by the fireplace. You start out with a nice brown log, and you light it on fire. It burns away, releasing smoke, light, and heat. After a while, the fire dies down, and you only have bits of ashes left.
But wait a second … Where did the log go? What happened to it? This is the cool part – it actually transformed from a solid wood log to a gas. It turned into the smoke you saw coming off the flames!
This transformation is very special. Turning a solid, touchable object into air sounds pretty hard, right?
That’s why flames require special conditions to start. A spark of energy, be it electricity, another fire, an explosion, or rubbing sticks together using friction, is necessary to start the transformation. That’s why things don’t usually start randomly burning on their own.
And when a flame is there, as the solid object turns into air, the energy inside that object is released, and we see and feel that energy as light and heat.
Some things can transform into air more easily than others depending on what they are made of, and solid parts that cannot transform are left over as ash or char.
So next time you want to feel like a wizard and make a solid object turn into thin air, you can just go light a candle. (With permission from your parents of course.)
Entry #154. Eric Olson, Waltham, Mass.
Eric is a senior lecturer in ecology at Brandeis University.
Have you heard the saying “red hot”? Maybe you have even seen something get so hot it glows? Like how about those wires inside a toaster — they are made of metal and when they get hot they turn bright red, right? So there’s clearly a connection between heat and light, for things made of metal. How about lava, have you seen pictures of goopy molten rock? Even rock stuff can glow if you make it a zillion degrees or almost a zillion, so hot it melts. So hot metal lets out light, it gets so hot it glows and hot lava is a liquid that’s so hot it lets out light and glows as it flows. Okay, ready now? Because if solids can glow and liquids can glow, what you need to know to understand a flame is that even gases can glow. There’s three kinds of matter, right? Solids, liquids, and gases. And when something is burning, like wax (sort of a solid) or wood (solid) or gasoline (liquid), as it burns some of the burning stuff is converted into gases from the intense heat BUT — some of those gases can themselves burn. And what you are seeing when you see a flame is gas that is so hot, it glows. It wiggles and dances around because a gas is not like liquids or solids, it’s not held so readily by gravity. Hot metal glows, hot molten rock glows, and now you know that certain flammable gases can also glow. A glowing gas is a flame.
Entry #437. Beth Yountus, Kansas City Mo.
Beth is an electrical engineer who works at Burns & McDonnell.
A flame is like you (a human) and needs oxygen to breathe and must eat to live, except a flame will eat almost anything (wax, wood, paper, etc.). After a flame eats its dinner, it “poops” out part of what it ate in the form of ashes or melted wax.
Entry # 479. Dan Putnam, Sherman Oaks, Cal.
Dan is a plant scientist at the University of California, Davis.
In order to understand a flame, you first have to know what energy is!
In a really basic sense, energy is the ability to do something — like push or pull something. When you have energy, you can kick a soccer ball about a million times, but when you’re low on energy, you can’t! You get hungry and tired instead, right?
Now, there are other kinds of energy. Did you know heat is energy? You might say “well, how can that push or pull something?” That’s a really good question!
If you were to get smaller and smaller and smaller, until you were so small that nobody could see you — and then get even smaller than that, you would find that the universe is made of teensy particles we call atoms. Heat is nothing more than these atoms bouncing around or vibrating! If an atom has no heat, it doesn’t move at all. If it has lots of heat, it bounces around like a toddler on a sugar high! If you touch something hot, the bazillions of atoms are banging into your hand over and over again!
So do you understand energy?
What’s really strange is that the universe HATES to have energy! If your body is left alone for too long, you’ll run out of energy – you’ll get tired and hungry. You won’t have the strength to lift anything or run or push anything. By the same token, things in nature are always trying to get rid of their energy as best they can. If cold food touches a hot plate, the hot plate will throw as much energy at the cold food as it can… until the food is warm and starts throwing ITS energy back at the plate, or up into the air!
What else does energy do? Well, it breaks stuff apart at a teensy weensy level! Have you ever gotten hit with something so hard that it left a bruise? It forced energy into your body so hard that it broke a blood vessel. Have you ever heated ice up so hot that it melted? You’re actually breaking the ice molecules away from one another!
Remember: when things get broken apart, they NEED energy. Conversely, when things come together, they GIVE AWAY energy! Some combinations give away more energy than other things — like vinegar and baking soda. That combination is pretty energetic (go ahead, try it), but potassium metal and water is EVEN MORE energetic — have an adult research it and try it for you!
So now that you get energy, let’s talk about your flame!
Pick something to burn. How about a stick? Yes, let’s use a stick. How do we start it on fire?
Well… we can:
– put already-burning fire on it
- use a spark (like lightning!)
- rub it on another stick super duper fast
Let’s think! What are you doing? If you put fire on the stick, you’re heating the stick up… giving it energy! If you use a spark, you’re also giving it energy! If you rub it on another stick super hard — well, rub your hands together super hard. Feel that? It’s heat! Energy!
In order to set something on fire, you have to give it a hard burst of energy. To set a stick on fire, you give it a hard burst of energy, which breaks the molecules of the stick (that’s chunks of atoms stuck together) apart! It also breaks some of the oxygen atoms in the air apart from one another!
HERE’S THE COOL PART!
Remember how I told you that things in nature HATE to have extra energy? Well, now leftover molecule chunks of this stick have all this extra energy. The best way for them to get rid of it is like this:
1. A chunk of stick molecule finds an oxygen atom that has also been broken apart.
2. The chunk of stick molecule grabs the oxygen atom.
3. It turns out that oxygen plus stick-molecule-chunks combine to turn into ash… and that particular combination gives away TONS of energy, WAY more than when baking soda and vinegar combine!
4. All that extra energy goes into breaking the molecules of the stick and the oxygen a little bit more, which starts the whole thing over again from step 1!
In step 3, so much energy was thrown out that the rest of the stick and the air gets super hot – that’s the “heat” part of a flame!
Now, sometimes parts of the stick get super hot, but for some reason they combine with the wrong thing — not stick plus oxygen, but stick plus more stick. This results in a combined chunk of “something” that’s super hot, but can’t break as easily as regular stick. This super hot “something” has to get rid of its energy somehow (because nature hates extra energy, remember?) And it does so by giving off light! That’s where the LIGHT of the flame comes from!
Some things in nature can get rid of their energy by throwing out light – tungsten lightbulbs do this!
A flame is actually really simple — it’s just the heat and light coming from a whole bunch of crazy chemical reactions, that all got started because of a teensy burst of energy!
Entry #541. Kenneth Power, Bowling Green, Ohio.
Kenneth is a family physician at Wood County Hospital.
A flame is something unique to every single one of us! When was the last time you secretly got close and watched a flame flickering in front of you?
Let’s pretend by closing your eyes, and trying to slow down your breathing,
so you can concentrate on a candle; you can see your flame clearly in your mind, can’t you?
Imagine now carefully getting really close. Can you feel the heat?
The flame is one thousand two hundred degrees hot!
Isn’t that crazy? Why doesn’t everything around it just burst into more flames?
Like a fierce tiger locked in a cage, your flame is tied to its wick. It roars and dances and tries to get away, but it can’t. And notice how your flame never stays still, (almost) as if it too is alive.
Your flame feeds on oxygen, burning into colors of yellow & orange, even red, white & blue; all of which radiate upwards toward the sky. Sometimes the flame gives off smoke and soot, which float back down eventually due to gravity.
Did you know that if you were in space (where there is no gravity) your flame would look totally different, like a perfectly round ball?
So do you consider your flame beautiful, or dangerous? Probably both.
I think the most amazing thing about your flame is that it is “all or none”:
This means its appetite is never ending!
It must be allowed to grow bigger and bigger or it must be destroyed, extinguished.
You have to choose to either keep feeding it with carbon and oxygen, or choke it with carbon dioxide… One or the other must prevail.
But when your time with the flame is up, don’t worry. Fire has been a part of nature since the time the Earth was born. And for somebody else — somewhere right now — in under a millisecond, a spark is transforming into the same, but different, flame…
Entry #724. Andrew Zwicker, Princeton, N.J.
Andrew is a physicist at the Princeton Plasma Physic Laboratory.
Entry #763. Jeanne Garbarino, Deborah Berebichez, and Perrin Ireland.
Jeanne is a postdoctoral scientist in biochemistry at Rockefeller University, Deborah is a physicist who works in financial risk analysis, and Perrin is a graphic science communicator at Alphachimp Studio.
Entry #771. George Hademenos, Richardson, Texas.
George is a physics teacher at Richardson High School.