All about Science, continues...
When I was a child, my father was my Sunday School teacher. As you might expect, this meant that bible study was considered somewhat important. In particular, I recall to mind now a bible story about Doubting Thomas. Religiously, this Apostle seemed not highly regarded for his doubt.Science is different. In science, critical thinking and skepticism are good things. Much of scientific thinking can be thought of as similar to keeping your room or your person neat and tidy. One good way of keeping your room tidy, is to get rid of what you don't need. Critical thinking and a healthy dose of skepticism allows a scientist to determine what beliefs are rubbish and should be discarded.
Neat and Tidy Beliefs.
Anyone have a mess in their room that could be lessened by getting rid of things they don't really use anymore? What things might you get rid of to make your room or playroom more tidy?___________________________________________________________________________
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Critical Thinking Club?
Our club isn't about Critical Thinking and we don't want to get side tracked. For those who are curious, there is a nice set of kid-friendly videos that might help you understand why critical thinking is important for science. -> Critical Thinking in Six Kid-Friendly Animations (http://io9.com/5888322/critical-thinking-explained-in-six-kid+friendly-animations)
We are a Science Club, but in order to understand science, one must also understand what science is not. One way we can do this, is to look at where science comes from originally. From what seed did science grow?
We have minds that are curious about our surroundings. We look and we ask "why did this happen?" We want to know "what does it mean?" If we are in the middle of a jungle and we hear a rustling of leaves off to the side, we instantly assume "something" is making the noise. Something, that is, which might be dangerous. We would do this for a good reason. If we assume it is something.. say, a tiger.. and it turns out to be the wind we are still safe. Contrariwise, if we assume it is the wind and it turns out to be a tiger... well, not so good for us.
Argument from Ignorance with Neil Tyson
(Video) ( http://youtu.be/9BRDCxNEuyg )We also want to feel safe and secure. One way of achieving this is to have some control over our surroundings. Yes, we have shelter. Yes, our crops are growing. But, what makes the rain? How can we guarantee the rains will come?
Creating Rain?
Does anyone remember how I described a witch doctor trying to create rain? Does anyone know of a way we might be able to make it rain with science?
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(Cloud Seeding http://en.wikipedia.org/wiki/Cloud_seeding)
A Witch Doctor looks at the sky when it rains and sees lightning and hears thunder. Since flashes of light and crashes of thunder occur with a heavy rain, he assumes that making flashes of light and creating rumbles of noise like thunder will bring rain. This is magical thinking. It is also a fallacy (mistake) of reasoning (logic). In this case, confusing cause and effect. If the young "magician" performs his ceremony enough nights in a row, it might happen by chance to rain. He might then take this as validation (proof) of his ritual's effectiveness. This belief appeals to his emotions. Feeling he has some control over his environment, which is necessary for his comfort and survival, he is motivated to believe.
Once he believes his magic works, he will be subject to confirmation bias. He will want to confirm or support his existing belief. We do not like to surrender our beliefs easily. They become precious to us, like our children. Looking at evidence which weakens our belief can make us feel anxious, uneasy, nervous, and stressed. There is a term for those feelings we'd like to avoid, cognitive dissonance. A person who engages in motivated reasoning will distort evidence, deny observations, or entirely ignore data that seems to disprove their existing belief.
Magic doesn't work. If it did work, it would be reproducible. If it were reproducible, it would be testable. If it were testable, it would become Science. How did we move from Magical Thinking to the Scientific Method?
How did we get from Magical Thinking to the Scientific Method?
New people are born all the time. They are not born believing in the magic rituals, they must be taught to believe. Eventually, someone will come around who isn't convinced that drum-beating and torch waving produces rain. He, or She, will question the existing assumptions. History is not always kind to those who choose to question tradition. For example, if Sam the Savage were to suggest to the village Witch Doctor that his ritual wasn't bringing rain, the Witch Doctor might claim the ritual didn't work because Sam the Savage's doubt angered the weather spirits. The Witch Doctor might even convince the rest of the villagers that the only way to appease the anger of the weather spirits required Sam the Savage's untimely demise.
Look out, Sam!
What do you think about the Witch Doctor's suggestion? Is killing Sam the best action? What do you think the villagers can do? Is the Witch Doctor falling back on motivated reasoning to protect his precious belief? Playing by the Witch Doctor's rules, can the ritual be disproved?
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Assuming, Sam the Savage manages to avoid a grizzly fate, his skepticism subjects the rain ritual to a test.The great advance of the Scientific Method lies simply in understanding a need for subjecting a hypothesis to skepticism and testing before accepting it as belief. If the ritual is proven false, then Sam's skepticism has uncluttered his village's beliefs. Rejecting false beliefs makes room for the discovery of truths.
Let us imagine a group of people in a distant age who have discovered metals. There are different types of metals. If we mix some metals together, we get an alloy with certain properties. Mixing others results in other alloys. For existence, brass is a mixture of copper and zinc. Bronze is copper and tin. Steel is iron alloyed with carbon. Copper, zinc, tin, iron, and carbon (which is not a metal) have their own properties but if you mix them in certain amounts you get something that looks like a metal but has different properties.
Brass is good for use in decorations because it looks golden. It is also useful for things like locks, gears, bearings, and ammunition casings were low friction is desired. Bronze, meanwhile, is harder than brass and was once useful for armor and weaponry like swords. More currently, bronze is often used for cymbals and bells. Steel, of course, is harder than bronze and commonly used in buildings and machinery.
Alchemists thought all metals were alloys of different materials and supposed gold to be the most pure metal. They sought for what they called the Philosopher's Stone in the hopes of learning how to transmute lead into gold.
"The alchemist maintained that all the metals are compounds; that the baser metals contain the same constituents as gold, contaminated with various impurities." ~~ Fairy Tales of Science by John Cargill Brough 1859 ( http://www.archive.org/stream/fairytalesscien00brougoog#page/n104/mode/2up )They were mistaken, but we should not treat too harshly the alchemists of old. We cannot clearly draw a line separating the alchemist from the chemist. "Alchemy is ancient chemistry, and chemistry modern alchemy." ~~ John Cargill Brough. Over time, people with questioning and skeptical minds (like Sam's) pruned away false beliefs. In some ways, this is like the philosopher stone.. by removing impurities you wind up with a far more valuable product. In this case, reliable knowledge as opposed to gold.
Air, Earth, Fire, and Water
Alchemists divided the world into four elements. Three of these we might call the phases of matter. Solid, Liquid, and Gas. Then they also had fire. Today, we would like to talk about this "element." Let us allow John Cargill Brough explain things from his perspective (as of the 1800s) : Fairy Tales of Science (Audio) ( http://archive.org/download/fairytalesofscience_1203_librivox/fairytalesofscience_03_brough.mp3 ) (The discussion of fire ceases at about the 8 minute mark.)
Experiment: Fire's oxygen dependence
Materials:* Large Pot (deeper than jar candle)
* Jar Candle
* Lid closely fitting pot.
Procedure: Place the jar candle in the stock pot. Light the wick. The spark of heat is sufficient to melt the wax. The liquid wax is drawn up the wick to the flame. The heat of the flame vaporizes the wax which can then burn freely. The heat liberated by this burning is sufficient to maintain the reaction.. that is, keeps the fire burning. The gasses of combustion are hot and will tend to rise. As the hot gasses rise, cool (fresh) air falls into the pot to replace it. This cool air brings new oxygen.
If the lid is placed on top of the pot, the candle will burn for a time and then be suffocated by the build up of carbon dioxide from the flame.
Experiment: Carbon Dioxide Gas to smother flame.
Materials:* Large Pot (deeper than jar candle)
* Jar Candle
* Vinegar
* Baking Soda
Procedure:
Place the jar candle in the stock pot. Light the wick. Pour vinegar into the pot around the base of the candle. Slowly add baking soda to vinegar and watch reaction. The bubbles produced are carbon dioxide gas. Carbon dioxide gas is heavier than air and will collect at the bottom of the pot. The level of carbon dioxide gas will build up until it rises above the level of the jar candle. The carbon dioxide gas will then pour over the sides of the jar candle and smother the flame.
From these two simple experiments, we see that fire needs three things. These are collectively called the fire triangle. Fuel, Heat, and Air (Oxygen) are needed to maintain the chemical reaction we call fire. You can put out a fire by removing any of the three components. For example, a lighter only remains lit so long as your finger is on the button. When you lift your finger off the button, a sort of valve closes and the fuel (a combustible gas) is no longer provided to the fire, which goes out. A candle which consumes all the wax also goes out. We've seen how a fire can be suffocated by preventing fresh air (and oxygen) from reaching it. You can also put out a fire with water. Water cools the fire, robbing it of the heat necessary for ignition.
Why can you put out a flame by blowing on it? Which of the three sides of the fire triangle explains why the candle flame goes out?
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Experiment: Campfire Basics
Materials
* Tender (Drier lint, sawdust)
* Kindling (Twigs)
* Fuel (Logs)
* Fire pit or portable grill.
Procedure: Using the Fire Pit or Portable Grill, try to light the logs (Fuel) with a match. Try to light the twigs (Kindling) with a match. Now try to light the drier ling or sawdust (Tender) with a match. Observe which one lights most easily. Why do you think this is so?
Reaction speed, why is it harder to light the Log than the Tender?
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If my car weighs 4,000 lbs and a young girl can lift 10 pounds, then 400 girls acting together could lift my car. The limiting element in this scenario, is getting all 400 girls where they can place their hands on the car and lift at the same time. The same thing happens with starting a fire. Only the outside of the wood is exposed to air. Only at the outside of the log can the match be pressed. So there is a very small area where fire can happen. (Any wood beneath the surface can't burn because oxygen can't get there and the heat of the match can't penetrate the physical layer of wood very well either.)
Surface area is important for a reaction to take place. In the case of the tender and even the kindling, there is more surface area exposed to the air whereby the reaction we call fire can take place. Therefore, it is easier to light tender than logs.
Tender, however, has a high surface area and burns up quickly. If we want a cook fire, we do not want to be constantly piling leaves into the fire. The tender can create enough heat to ignite the kindling. The kindling can create enough heat to light the logs. The logs can burn for a good long time.
Experiment: Campfire Building
Materials* Tender (Drier lint, sawdust)
* Kindling (Twigs)
* Fuel (Logs)
* Fire pit or portable grill.
Procedure:
When building a campfire, start by gathering the wood you will want to use. You will need a little tender to get the fire started; Some twigs for kindling to get the fire going; Then large logs to use a consistent fuel. To be on the safe side, you should have three times the fuel you expect to use.
The site for the fire needs to be prepared. A prepared campsite might have a ring of stones. If you are going to be starting a fire on the dirt, you will want to clear away vegetation to a fairly good distance. Ten feet is a reasonable suggestion, but if the weather has been particularly dry greater precautions might be justified. Grass is flammable, depending on how dry. Sparks can also be wind-blown up into trees, which are another cause for concern.
Fire is a good servant, but a terrible master. ~~ ProverbCampfires are like children; it is best to have clear and established limits. Fire, not well tended, can grow quickly out of control. Once this happens, it is you that must run around to contain the fire instead of the fire that meekly cooks your food.
For our purposes, we will use a portable grill as this greatly simplifies matters.
Benefits of a Portable Grill.
For purposes of starting a fire, a portable grill has some advantages. What advantages to you think are to be found in using a portable grill as opposed to starting a fire on bare ground or within a ring of stones laid upon the ground?
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A portable grill simplifies the process of preparing the site for a fire. As the legs of the grill lift it off the ground, the impact on the campsite would be minimized. Furthermore, some fire pits also allow air to come up from underneath the fire as well, improving ventilation and thereby allowing more oxygen to reach the site of ignition.
When laying out the fire, you are arranging the tender, kindling, and fuel in a way that allows convenient access to the tender while also allowing good air flow. Tender does not burn long, but it quickly catches flame and provides heat. A teepee arrangement of sticks helps by allowing room for air to reach the tender but also trapping the heat produced by the tender's flame to ignite the kindling which will in turn perform the same service for the fuel.
Another arrangement which is sometimes used when lighting a fire is a "log cabin" fire where the branches are laid out in layers each running parallel to the layer before. Which arrangement do you want to try?
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Links for Further Reading:
Volcano Experiment http://chemistry.about.com/cs/howtos/ht/buildavolcano.htm
What is a Char-Cloth? How do you make a Char-Cloth?
What is Charring? What is Charcoal? How do you make Charcoal? Why do we use charcoal instead of wood?
Marshmallows:
Why do they ignite easily?
Does the wooden stick ignite as easily?
Why do Marshmallows puff when you cook them?
Why doesn't metal ignite?
Can you ignite metal?
How to Roast a Perfect Marshmallow.
Marshmallow Science
Flames to Ashes
EPA: Burnwise Wood Combustion
NPR: How to Build a Campfire
Smokey the Bear: How to Build a Campfire
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