I met so many cool people, made new friends and greeted some old friends again. I had a great time seeing Phil Plait, the Bad Astronomer (and president of the JREF) again (see picture above), schmoozed with Jamie from “The Cuter Side of Politics” (picture below, with Richard Saunders), watching the very talented Sarah Trachtenberg do her stand-up routine at the TAM Talent Show, and got to do an awesome audio recording with Richard Saunders from the Skeptic Zone that included beer, Australians and sound. Awesome!

The Think Tank Experiment

I had the great privilege to sit down with Richard Saunders, Brian Dunning (from the awesome skeptoid.com) Amanda Rose,  and others to record a special edition of the Skeptic Zone’s Think Tank at the sports bar in the hotel. We sat down with some beers and had a great time sharing a nice little demonstration about the different sounds you can make with half-filled beer bottles.

You are encouraged to listen to the entire episode, where Richard updates from The Amazing Meeting with some interviews and snippets from the different speakers, but if you want to jump straight off to the Think Tank experiment, it starts about an hour and fifteen minutes (1:15) into the show.

The different sounds bottles make

Richard drank all the liquid in his bottle, while I drank only a little bit. Mine was almost full, while his was almost empty. Tapping both bottles produced different sounds; the empty bottle produced higher pitched sound and the full one produced lower pitched sound.

However, when we blew air inside the bottles, the sounds were reversed. The empty bottle produced a low pitch sound and the full bottle produced a high pitch sound (You can see us in action in this great picture).

Why does that happen?

Tapping the bottle causes the glass to vibrate. When the bottle is empty, the glass moves more freely and produces faster vibrations (and higher pitched sound). When it’s full, the liquid prevents the glass from moving as much and the vibrations are slower (and lower pitched sound).

Blowing air into the bottle makes the air itself move around in the space inside the bottle. The sound is produced as the air molecules vibrate at the  bottle’s mouth . When the bottle is empty there’s more room inside for air to move around, and it escapes more slowly. When there’s liquid inside the bottle there’s less room for the air to move around, and it escapes more quickly. The quicker the air escapes the bottle’s opening, the faster the air molecules vibrate and create the sound.

Slow vibrations produce low pitch sound and high vibrations produce high pitch sound. This is one demonstration you can do anywhere where they serve drinks. Bottoms up!

The Awesomeness of TAM

I had a wonderful time in Las Vegas at The Amazing Meeting 7, and I just can’t wait for next year’s Amazing Meeting 8. Are you coming? You should, and if you end up there, walk around, make new friends, and hunt me down to say hello. It’s the best time of year!

Update: You can find more pictures of the great experiment with Richard Saunders at TAM7, in sc00ter’s TAM7 flickr album.

This was an awesome experiment in an already awesome convention. Don’t forget to check out the JREF website for the DVDs and extras from TAM6. Richard Saunders’ many projects can be checked out through the Australian Skeptics website and the Tank Podcast.

What’s Going On?

When you convert a 3-dimensional object (a face, for example) into a 2-dimentional surface (a page, for example), your end result is stretched and distorted. The reason lies in the curvature of the 3-d object you are trying to copy: The curvatures that give your face the shape it has (your nose, your mouth, your ears), will appear longer when stretched to a flat surface.

What is the Shroud of Turin?

The shroud of Turin is a piece of linen that seems to bear an image of a man lying with his hands in his lap. Some religious groups claim that the image is, in fact, the image of Jesus after his crucifixion.

Whether or not this shroud is real (Scientific examination of the fabric and impressions on it show it is dated much after it is supposed to exist to be authentic), the image that is transcribed on it is interesting. Missing the impression of the face on it is quite hard, and explaining it away with ’simple’ paraedolia doesn’t seem to do it justice.

But if we take our experiment to mind, this image seems to get a different perspective – literally. Take a look at the above drawing, for example, (by Giulio Clovio), depicting Jesus being wrapped in a shroud after his crucifixion. If, truly, this cloth covered the face and body of a man (any man, for that matter), then the impression should not have appeared as a face at all, it should have appeared distorted. A relatively simple test – print out the image, then fold it in half along the nose line – casts some doubt by itself on the existence of a human model for this image.

How are flat maps made?

The creation of a flat map is similar, but not exactly the same as what you have seen in the video. Since distorted maps are quite useless, the drawing of a flat map uses a technique called “Map Projection”. Essentially, the glove is divided into equal squares which are also drawn on a flat surface map. Each square is copied in exact details to the corresponding square in the flat map.

There are several types of such projections, depending on the type of map you need.

An “Equidistant” projection creates a map that has equal distances from the center (equator). A “Zenithal” projection is one that maintains accurate directions.

In general, a flat map is not the accurate depiction of the way our planet looks. It can’t be, because our planet is spherical. But a map projection, at least, makes the conversion slightly more accurate, and easier for our brain to calculate distances and shapes.

More information about the creation of flat maps out of the curvature of our planet can be found in this website (also on the ‘extra resources’ section at the bottom of this page).

Thanks (Original Idea Credit)

Thanks to Edtharan from ScienceForums.net for this idea!

Extra Resources

• JREF Website (James Randi Educational Foundation): http://www.randi.org/
• Australian Skeptics: http://www.skeptics.com.au/
• The Tank Vodcast: http://tankvodcast.wordpress.com/
• The Shroud of Turin: http://www.shroud.com/ and http://en.wikipedia.org/wiki/Shroud_of_Turin
• How maps are formed (3D to 2D): http://www.nationalatlas.gov/articles/mapping/a_projections.html

Now, though, you too have something to do with your extra nickels and pennies you keep safe for future plans: You can do science with them! Yay!

So, this experiment is very simple and fun, and I wanted to do it a bit different than what you probably already know (and what I ended up doing eventually in the video). When I was roaming around the internet looking for more ideas and information, I saw this picture and decided I should try it out (even though I had no doubt, in this case).

Okay, so maybe I went a bit too far with my love for fun: after all, who knew those ice boxes fight back. I didn’t.

But we can learn a lot from this experiment, as well as this experience. We will start with the scientific principles. Then, we’ll go on to my flying metal clips. Pooooiiing.

What you need?

• Pennies.
• Nickels.
• Salt water (just mix water with about 2 table spoons of salt)
• Tissue paper.
• Voltmeter or LED or small light bulb – anything that will prove to you that there is voltage in this spare change tower.
• Depending on your tower-building skills, you may need copper wires.

What do you do?

To create a difference in potentials (which will lead to the existence of voltage and ‘power up’ your lightbulb/LED/voltmeter) you need to create a small tower, alternating a penny, a tissue paper soaked with saltwater and a nickel.

Penny -> saltwater -> Nickel -> saltwater -> Penny -> saltwater -> Nickel … and so on.

Easy!

Note: Make sure you have access to the bottom of the pile. By the time I finished building my little spare-change tower I found out I can’t reach the bottom of the pile to check for voltage, and had to squeeze in another bit of copper wire. If you need one, get it, but if you “play” it right (like, put the first penny sticking out a little) you can do it without any wires at all.

What’s going on?

When we put table salt in water we create a mixture that is electrically conductive. The saltwater mixture is an electrolyte. An electrolyte is a substance that has free ions and conducts electricity.

The electrolyte reacts with different metals, allowing for an exchange of electrons from the metal to the solution. But different metals react differently. A Nickel is made of approximately 75% Copper and 25% Nickel. A Penny has about 97% Zinc and 3% Copper. The difference between the metals causes a difference in reactions to the electrolyte.

This difference creates a difference in electrical potential, which is voltage. And it can light up your lightbulb, your LED or show the difference on a voltmeter.

A bit of History

This experiment, or something very close to it, was done by Alessandro Volta, who created the first cell battery.

In his experiment, he alternated plates of Zinc with plates of Copper, with an electrolyte substance between them (He used either saltwater or sulfuric acid), and created the first cell battery.

This type of battery, however, is short-lived. The voltage stops when the chemical reaction creates hydrogen bubbles that (initially help the procedure, but) later form a sort of ‘barrier’ to one of the metal electrodes. It is also not very safe (and not necessarily due to what you’ve wittnessed in the video) because sulfuric acid is quite dangerous, even when diluted.

But it was certainly the start for the batteries we have today, that operate on the exact same principle!

What happened in my first try?

Okay, so you’ve seen the video and you’re laughing. Great. Glad I could brighten your day with my mishaps. But now what? Does that mean you can’t do it? Probably not. The method of connecting the “electrodes” (spare change) to the walls of the ice box should work just fine, as long as you have enough time to mess with it. I was fighting against the clock, as the sun was setting and the lighting in my apartment is quite poor when dark.

But take your time, try this method out, and let me know if you got it, it seems like fun!

About Experimental Errors

We’re talked before about experimental errors, but I think this experiment (and the “blooper” that accompanied it) is a good chance to state one, very important, issue about science and experimentation:

Mistakes are very important.

We learn from our mistakes. It sounds so repetitive, I know, you’ve heard it from your kindergarden teacher a billion times, but it’s true, and it’s even truer for science. Experimental errors should be examined and analyzed. It may be the equipment, it may be the settings, it may be that it’s not an error at all but a brand new discovery you are going to win the Nobel prize for.

Mistakes happen. The important thing is to understand why they happen.

This is also why true scientists (in true labs) never settle for a single experiment. The experiments are always repeated, over and over, but multiple people. Then, they are analyzed – mistakes and all – and summarized. Then, other scientists from other labs look at the experiment and result and try to repeat them too. If the experiment can be repeated with similar (or same) results, then it is probably actually indicative. If other scientists cannot repeat the experiment, there is a big problem with the suggested conclusion.

This is part of the scientific method.

In my videos I am showing you simple demonstrations of scientific phenomena. This is, by no means, a replacement for actual scientific experiments in labs. I will probably never be able to get actual significat results that affect the scientific community (or the way we live and think) by recording a once-performed experiment at my house. But that’s also not my intended purpose.

I don’t mean to give you “new” radical answers, I mean to give a taste of waht science is about, and how you can check these principles and prove them for yourselves at your own home without going to a fancy lab, or spending lots of time for a PhD. Not that PhDs aren’t important..

Take these videos as examples of what and how things are done, and what the scientific method is all about. Other than being fun (and sometimes funny), these experiments can show you that if you can reach a relatively accurate conclusion at your own home, then true laboratories doing the same (or similar) experiments with much better and more accurate equipment can get much better and more accurate results. But at least now you know how they do it.

More References

• The Amazing Meeting 6: http://www.randi.org/joom/component/option,com_registrationpro/Itemid,33/func,details/did,1/
• James Randi Educational Foundation: http://www.randi.org/

• Alessandro Volta: http://en.wikipedia.org/wiki/Alessandro_Volta
• A Cent (Penny): http://en.wikipedia.org/wiki/Cent_(United_States_coin)
• A Nickel: http://en.wikipedia.org/wiki/Nickel_(United_States_coin)
• How batteries work: http://en.wikipedia.org/wiki/Battery_%28electricity%29#How_batteries_work
• This experiment at the US Mint (Dept of Treasury) site: http://www.usmint.gov/kids/teachers/lessonPlans/viewLP.cfm?lessonPlanId=138
• This experiment in “Make Magazine”: http://blog.makezine.com/archive/2006/11/pennypowered_le.html

Science magic! Okay, well, it’s not quite magic, it’s science magic, which means it has (as always) a perfectly good explanation to it. But – can you guess it?

This is a very straight forward demonstration about static electricity, and it is working so well, that it really is fun to do anywhere with a faucet (and a plastic comb..).

What Do You Need?

• A plastic comb or a nylon balloon.
• Dry hair.
• Dry environment (humidity is baaaad)
• A very thin flow of water (about 1 cm thick, or for all you metric-deniers, about 1/16th of an inch).

What’s Going On?

Well, the plastic comb is made of molecules (as is every other matter) that have electrons floating around them. Electrons have a negative charge, and just like a polarized magnet, they are repelled by other negative charges.

When I comb my (dry!) hair with the plastic comb, it collects electrons from the individual strands of hair to itself. About 10 strokes should be enough to make the charge strong enough for the demonstration. The electrons move from my hair strands to the comb and, therefore, lose negative charge. The individual hairs become positive (because they have lost negative charge), the comb becomes negative (because it gained negative charges, in the form of electrons).

The molecules in the water stream are neutral – they have both positive and negative charges, and all their electrons nicely floating around wherever they are supposed to be. When I move the (now negatively charged) comb next to the water stream, the electrons that are closer to the comb are being repelled away. The molecules that are closer to the comb, therefore, become positive, and away from the comb there is more negative charge (more electrons).

The side of the water flow that is closer to the comb is now positively charged, and the comb is negatively charged. Positive and Negative attract one another, and that concept allows the water flow to bend towards the comb.

Voila! instant science magic!

Practical Applications

Static electricity exists in nature, as you may well have noticed in a hot, dry day, trying to open a metal door knob and heard a tiny Bzzzz, followed by an inconvenient sting. Our body exchanges electrons with the surroundings all the time, gathering up and discharging static electricity. But there are more applications and phenomena that are attributed to static electricity:

• Electrostatic Percipitator: This invention is used to clean the air from other particles by inducing electrostatic charge. It’s quite useful, specifically for power plants or big industrial facilities.
• Xerography: this is a photocopying technique developed in the late 1930s. It distributes a uniform electrostatic charge on a surface of a drum. The image is then lit through (so wherever there is color, the surface remains unlit) on a grid on top of the charged drum. The light dissipates the charge, so the grid remains charged only where the image is printed. Then, carrier particles are mixed through the drum and “soaked” into the paper – so they “stick” where the charge exists, and therefore duplicate the image.

More References

• This demonstration on about.com: http://chemistry.about.com/od/chemistryexperiments/ht/bendwater.htm
• This demonstration on sciencebob.com http://www.sciencebob.com/experiments/bendwater.html
• This demonstration on SciFun@Wisconsin university: http://scifun.chem.wisc.edu/homeexpts/BENDWATER.html
• This demonstration on Science Made Fun: http://www.sciencemadesimple.co.uk/page30g.html
• Wikipedia entry on Static Electricity: http://en.wikipedia.org/wiki/Static_electricity

Well, this is going to be sweet, short and to the point: Fire in closed spaces can really suck.

Ha, I was dying to use that pun for a while now, and here I had the chance. This experiment is a really short and sweet one, and can join your mental arsenal of “party tricks” for the partying geeks. It can really impress anyone, and from now on – you are going to know what makes this happen.

Ready?

Air is a fascinating thing, but sometimes it can be an obstacle. We will see that in future experiments, where the existence of air (or, more precisely, of oxygen) can hinder an experiment and render it unexperimentable. … Right. I think I need a dictionary replacement.

Warning!

In case this isn’t completely clear, I am going to point out that since we are dealing with a live and exposed flame, the use of any high-percentage alcohol is absolutely not recommended.

I hope that is obvious, but in case it’s not – ALCOHOL IS FLAMMABLE. SO IS GASOLINE. Don’t do something very stupid, don’t use flammable liquids in this experiment!

(Thanks to RedShiftScience for pointing out people might not find this obvious.)

Corrections!

Before I go on to corrections, let me say a word about getting things wrong: Human beings are usually emotional entities, and as such, we tend to take things personally. Science is supposed to be empirical, void from emotions. How do you connect the two? Using the scientific method.

There is no shame in getting things wrong. We are only humans.

The best thing about science and experimentation is to have other people think about things, analyze them, and criticize your work. I not only enjoy that, I think it’s a necessary part of science.

In my video, I explained a few things incompletely, and some even seemed to have come across bluntly wrong (aaa! matter is not created out of nothing, and it does not disappear! in failing to mention that, I sounded like this experiment defies the laws of thermodynamics!). So, I am hereby correcting, adding and subtracting to what I said. I tried to do that well in this post — and then Shane Killian — who noticed this error first – posted a video reply.

So now I can just post it here instead of doing it all over again. Cheers, Shane, GREAT job, and thanks a lot for the correction!

Don’t ever be afraid to try just because you’re afraid to make a mistake.

What is a Vacuum?

A vacuum is a volume of space with no matter in it, and a zero atmospheric pressure. That is the formal definition. That said, there are no places in nature that have absolute vacuum.

We tend to call “Outer Space” a vacuum, but in reality, it is filled with particles, which makes it have some sort of matter, which means it’s not a complete vacuum. But it’s close enough.

Since a vacuum is supposed to have 0 atmospheric pressure (or as close as possible), it “sucks” into it anything that has a different – and higher – pressure. This is due to the tendency to have a balance of pressures — different pressures will try to balance one another, so the lower pressure environment will “suck” matter from the higher pressure environment until both environment are at a balance.

That’s why you see people get sucked out of the airlock in sci-fi movies. It’s one of those things movies got right.

In our experiment, we lowered the pressure and created a semi-vacuum inside the glass, and in turn, it sucked up the liquid around it. Or, more specifically -

What’s going on here?

With this cool little party trick, we are creating a “semi” vacuum inside the clear glass by consuming the oxygen inside it. When the fire consumes the oxygen molecules, it “vacates” a place for – well – whatever else. The pressure inside the glass rises, and since it isn’t sealed, it sucks whatever it is standing on

CORRECTION: The pressure inside the glass increases as the fire heats up the molecules. Oxygen is being “consumed” by the fire, that produces Carbon Dioxide (the matter itself remains, no matter is mysteriously ‘vanishing’ or ‘created’ out of nothing!). But now, the pressures are different and therefore the water outside the glass are pushed inwards — the lower pressure of the INSIDE ’sucks in’ the liquid around it under the pressure stabilizes.

Thanks to Shane Killian for the correction.

If I were to use a jar and sealed it well while the candle inside fed on the oxygen, the cap would have been “sucked” into the jar mouth, and the jar would have been sealed. Since I am not using a cap, but rather putting the glass on top of liquid (that can “pass through” the edge of the cup), the liquid is sucked inside the glass and stays there, until I release the pressure and allow air in.

This is a really sweet, cool and short experiment, but the best thing about it is that it will help us produce home-style vacuum setting for other experiments. And so, it’s good to know.

Plus, it’s fun. And edible. Woo hoo.

Practical Applications

• First, this is a cool and easy way of creating home-made semi-vacuum setting, for whatever other experiment you will need. We’ll use this in the future.
• Here’s a cool practical trick to preserve food for you to consider, though it isn’t precisely the same method, it uses a similar point: If you cook something and wish to save some for later in sealed jars, the best way of doing that is seal the jar while the food is still hot. Once sealed, whatever air inside the jar is trapped, and when the food cools, the air compresses and tightens the jar cap so that it is relatively sealed from the outside. Food will last longer this way, but you will have a bit of a harder time opening the jar.
• Impress people in parties, collect on bets, and dazzle your dates. What else do you want?

Resources:

• Another video with the same point: http://www.metacafe.com/watch/334272/physics_experiment_liquid_suction/
• And another: http://www.metacafe.com/watch/540641/bored_try_this_easy_experiment/
• Vacuum: http://en.wikipedia.org/wiki/Vacuum
• The Human Body in Space (Vacuum): http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/970603.html

There is one little piece of us, though, that holds the secret to our existence, and the history of our species: The DNA.

My main interest is usually physics and astronomy, but I have always been fascinated by that double-helix molecule and its meaning, both philosophically and realistically; since the beginning of Genetics the human race have progressed exponentially. It’s just, simply, amazing.

So when the “rogues” of “The Skeptic’s Guide to the Universe” Podcast debated the history of DNA discoveries, I decided it is time for some biology experiment.

I am about to show you how to extract your own DNA from your own bodies in your own kitchen. Yourselves.

It’s aliiiiiiiiiive!

The Experiment

This experiment allows you to extract DNA matter from cells from your mouth, and is very similar to what Friedrich Miescher discovered. His discovery was from pus, and this one is from your mouth. Physiology can be funny like that.

What do you need?

For this experiment,you will need the following tools:

• Two beakers.
• A glass or a cup. You can use one from the previous experiment.
• Liquid soap (NOT antibacterial. You shouldn’t use those at all anyways).
• 2 test tubes or clean and clear bottles. I used “travel-size”empty plastic bottles for the experiment. These work, just make sure they are properly cleaned with distilled water.
• Distilled water.
• Rubbing Alcohol.
• Sodium Chloride. Well, Salt.
  Sodium Chloride is a nice and fancy way of saying “Salt”. You don’t need anything other than table salt, or cooking salt, but for fun, I suggest going to your nearest pharmacy and try to ask for a small amount of Sodium Chloride.
  I did, and the nice lady replied it is a prescription drug. Worth the chuckling, I promise.
• Glass rod (I used wood, because I didn’t have glass, but wood isn’t as good at all.. try to get a glass rod).
• Anything that can be used to measure the liquids. The more accurate your solutions are formed, the better your results would be.
• Drinking water. Preferably bottled water, to avoid varying amounts of chloride or other contaminants.

The Process

You can find the process I used for this experiment in the repository of About.com biology expert, but here’s a short summary:

1. Solution #1 (Negative-charge Ions to bond the DNA molecules together): 8% Sodium Chloride + 92% Distilled Water.
2. Solution #2 (Breaking apart the cell membranes and “freeing” the DNA from the nucleus): 25% Liquid Soap + 75% Distilled Water.
3. Wash your mouth thoroughly; you want DNA from the cells in your cheek and not from whatever animal (or fruit) you ate for lunch. Make sure your mouth is CLEAN.
4. Swirl about 10ml of water in your mouth. Use the bottled water and NOT the distilled water! If you want a larger amount of cells, do it a bit ’stronger’. Do that for about 30 seconds.
5. Spit the water into the cup. You have just gathered a bit of cells from your own body, congratulations.
6. Take 1ml of Solution #1 (Sodium Chloride) and add it into an empty, clean bottle (or test tube).
7. Add the cell-water mix you just spit out into the same bottle (or test tube).
8. Add 1ml of Solution #2 (Liquid Soap) into the same bottle (or test tube).
9. Close the cap or seal with a test tube stopper.
10. Twirl, swirl, and turn the bottle upside down and right side up gently. Do not shake. You’re not 007.
11. Add 5ml of Rubbing Alcohol into the bottle while tilting it slightly so the alcohol ends up floating on top of your mixed solutions.
12. Wait for about 5 minutes.
13. Watch. If you want, you can do what I did and move the DNA strand from the solution bottle to a clear bottle that contains alcohol only. I keep my little creation next to my computer screen.
    Make sure you do it very gently.

What’s happening?

Well, DNA exists inside the nucleus of a cell. So to see it, you need to first let it out of its confinement. But that isn’t enough – DNA molecules are positive charge, so they reject one another. In order to see the strand, we need to make sure a bunch of these molecules bond together. Finally, DNA melts in water but not in alcohol – we will use that to “trap” the strand so we can look at it.

So, here’s the summary:

1. Soap has detergent in it, that dissolves the membranes (the “skin” of the cell) and releases the DNA from the nucleus.
2. Sodium Chloride is negatively charged, so it bonds the DNA strands together to create a long strand we can see in the naked eye.
   Correction:
   Okay, I got this wrong again, so ailboles was kind enough to explain it and give links, too!:DNA is a negatively charged molecule. It is the positive ions (in the Sodium Chloride solution) that interact with the DNA (see http://ppge.ucdavis.edu/Equipment/Protocols/thymus_dna_extraction_03.pdf under the section, “Answers to Student Activity” number 5)
   
   Well, that makes more sense. Thanks again to ailboles for taking the time and effort to explain this again!
3. Alcohol “traps” the strand, because it doesn’t break apart in alcohol, only in water.

There you have it. Your own DNA in a bottle. Beats wooden boats any day.

About Scientific Discoveries

Usually, when we hear that someone a long long time ago made a very big discovery we tend to be skeptical. It’s understandable – I find it hard to see anyone getting along without a fast-paced computer, let alone working without an electron microscope, or a light bulb.

But the truth is, usually scientific discoveries don’t just “pop up” miraculously. We tend to remember the people who invented specific “gizmos”, or wrote a patent relating to a specific discovery (like Edison and the Light bulb, Bell’s telephone, and Morse’s telegraph), but they were rarely “the first”. The research started a long time before, and their discoveries were possible only due to past discoveries.

The same is true to DNA.

The 1869 Discovery

In 1962, James D. Watson, Francis Crick and Maurice Wilkins recieved the Nobel Prize for the discovery of the structure of DNA and its hereditary role. Because the Nobel Prize is a famous honor, we tend to remember them specifically, but their discovery was possible because of many prior researches, the first of which was done by a Swiss researcher called Friedrich Miescher in 1869.

Miescher researched the human cells, specifically white blood cells, by taking blood-stained bandages from a nearby hostpital. He noticed a microscopic substance inside the pus on the bandages – and identified the substance as coming from within a cell’s nucleus. He called this substance “Nuclein”.

The following dates mark the time line that lead to the famous discovery of the DNA structure in the 1950s:

• 1869 - Friedrich Miescher identifies a substance that came out of a cell’s nucleus and has a weak acidic properties. He calls it “Nuclein“.
• 1919 - Phoebus Levene identifies the base, sugar and phosphate nucleotide units. He suggests that DNA is made of strings of nucleotide units that are connected together through phosphate groups.
• 1928 – Frederick Griffith combined “smooth” and “rough” forms of Pneumococcus bacteria, showing that DNA plays a role in passing genetic information.
• 1937 - William Astbury produces an X-Ray diffraction pattern that shows DNA has a regular structure.
• 1943 – Oswald Avery, Colin MacLeod and Maclyn McCarty identify DNA as the transforming principle – showing that bacteria transfers genetic information through a process called “Transformation”.
• 1952 – Alfred Hershey and Martha Chase confirmed the heredity trait of DNA in an experiment.
• 1953 - The structure of DNA is suggested by James D. Watson and Francis Crick, based on X-Ray Diffraction images taken by Rosalind Franklin. This is the structure that is accepted today.
• 1957 - Crick lays out the “Central Dogma” of molecular biology, including RNA, DNA and proteins, and the relationships between them.
• 1963 - Watson, Crick and Wilkins receive the Nobel Prize in Physiology or Medicine.

Practical Applications

Wow. That’s going to be a huge huge list. The discovery of Genes, structure of DNA and Genetics in general has led to countless advancements in medicine and technology. From discovering diseases earlier to devising vaccines. The list is just too great, too big, and too important to summarize in a single post. If you look at the resources, however, you could find many places to start.

• Forensic Medicine.
• Interpol’s Attempt – DNA Profiling.
• The study of Human evolution (many more resources, including this one from National Geographic, and Berkley’s “DNA, the Language of Evolution“).

Resources:

• The Experiment Instructions can be found here: http://biology.about.com/c/ht/00/07/How_Extract_DNA_Human0962932481.htm
• Extracting DNA From Fruit:
  • http://www.funsci.com/fun3_en/dna/dna.htm
  • http://www.csiro.au/resources/ps1tp.html
• Great Clip about DNA Structure: http://www.youtube.com/watch?v=qy8dk5iS1f0
• Friedrich Miescher: http://en.wikipedia.org/wiki/Friedrich_Miescher
• Albrecht Kossel: http://en.wikipedia.org/wiki/Albrecht_Kossel
• History of Electricity Discoveries: http://www.code-electrical.com/historyofelectricity.html
• Griffith’s Experiment: http://en.wikipedia.org/wiki/Griffith%27s_experiment
• Hershey-Chase Experiment: http://en.wikipedia.org/wiki/Hershey-Chase_experiment

Well, this is more of a “Show off your geektitude” physics trick that will amaze and enchant your buddies anywhere! Okay, well, maybe not anywhere. Or anyone. But it is geeky, I promise. And will get you some attention.

And it’s cool.

And it’s useful. For parties.

I can switch the contents of two glasses without using a third glass. Yes, I can. Don’t believe me? Well – When in doubt, try it out!

So. Anyone who asks a bartender for anything “on the rocks” knows that alcohol and water do not mix. Not properly, anyways. Not without insistent help. The alcohol always ends up floating on top of the excess water that melted off of the ice. But why?

Well, that has to do with the density of both liquids. Dense materials sink, and less-dense materials float. Water is denser than alcohol, so the alcohol floats on top of the water.

Density also changes with temperature. Water is denser when it’s cold. In higher temperature, the density is lower. Hotter water will always “want” to rise up above colder water. And we’re using this property in this nifty trick. Did I say it was cool?

What is Density?

Density is the measurement of mass per unit of volume. Put simply, it is the amount of particles within a specific space in the material used. A bar of gold will have a lot of particles within 1cm cube volume, while water fume will have very few in the same space. So gold is denser than fume. Which is why we choose to wear it as jewelry.

In physics, the general formula is represented by p=m/v, which means that density is mass per volume. If you know the mass and you know the volume (both quite easy to figure out), you can find the density of objects. This is another cool experiment that will be coming up in the future, and you can try it out yourselves with anything, really, as long as you know its volume (size) and weight (and can figure out the mass). Just be careful who you ask..

Why leave a small hole between the cups?

We don’t want our two liquids to mix, we want them to “switch”. When you leave a tiny hole between both cups, a stream of liquid from the bottom cup is flowing upwards, because it’s lighter, and is replaced by a stream of liquid from the top cup (the ‘heavier’ liquid). If we completely discard of our separator, the liquids will simply mix, and we will have diluted alcohol. Or room-temperature water.

When the process is allowed to happen slowly, after a few minutes, both cups are completely filled with the opposite liquids.

Maaaaaagic! Well, no. Physics.

I mean… Phyyyyyyyyyyyyyyyyyysics!

Materials needed for the Experiment

• Two cups of the same size.
• Alcohol
• Water.
• Credit Card / MTA Card / Cardboard.

Don’t drink and drive.
We will go over momentum in future experiments, but this is one thing you all should know.

Practical Applications

You mean other than being the star of a party? Oh, okay okay, here are a few practical applications for knowing the density and buoyancy of liquids:

• Buoyancy! The density of liquids affect their buoyancy. The lowest dry point on earth, for example, the Dead Sea, has a very high salinity, which makes its density a lot higher than regular ocean water. As a result, people (and other objects) float. Without trying.
• Distant Stars: Astronomers can calculate the density of stars from their mass and volume, and understand better about the process that is “running” the star.

Resources

• Water Density: http://www.4physics.com/phy_demo/Galileo_thermometer/galileo-thermometer-d.html
• Water’s Density and the Relation to Temperature: http://www.simetric.co.uk/si_water.htm
• Oil floats on Water: http://www.physlink.com/Education/AskExperts/ae105.cfm

Today we have a lot of sophisticated (and simple) methods of calculating the curvature and size of the earth. But how did humanity figure this out in the first place? I mean.. it’s so easy, without the help of satellites, airplanes and Jules Verne, to look at the flat horizon and mistake the earth for a flat table top. How could anyone figure out not only that the world is not flat, but also calculate the size of its radius?

Well, when in doubt, try it out. Hey.. I think I like that motto. It’s rhyming, and rhymes are usually true. Just ask Dr Seuss.

Plus.. it works!

So, a long time ago, people believed the earth was flat, and that if someone was to go away off to the horizon, he (or she) would fall off the end of it.

We look at this ancient concept as ridiculous today. We al know that the flatness of the horizon is an illusion. We have more than enough proof today to see absolutely that the world is definitely curved, but it is for the ingenuity of people like Erastosthenes of Cyrene that humanity knew about this so long ago.

Eratosthenes was a greek scholar that lived in 275-194 B.C. in Alexandria (Egypt). Some even say he was the curator of the library of Alexandria. One day, he had a bright idea. Actully, it wasn’t just any day, it was the summer solstice, and it wasn’t just any idea, it was a brilliant experiment. But, let’s not dwell on the tiny details. He was very smart and he acted on it.

He received word that on that summer solstice day the sun is reflected perfectly in a deep well in Syene. But at the same time and same day, in Alexandria, the sun wasn’t reflected perfectly in the same type of well. Why?

It occured to him that the only way that could have happened is if the earth was not flat. Using simple trigonometry, he managed to calculate the radius and diameter of the earth. In this experiment, we do the same, only we use a Pummelo. Because it’s easier. And tastier.

Materials Needed for the Experiment:

• Any type of round, big, (preferably tasty) fruit. I used a Red Pummelo, but a Watermelon will work too.
• Small sticks to simulate Eratosthenes’ big sticks.
• One bright and focused lamp.
• A ruler.
• A sharpie.

The pummelo represents the earth. Nevermind it isn’t perfectly round – the earth isn’t either, and we are only trying to see the method, not actually calculate the radius of the fruit.

Error Margin

Wow, there’s a lot of reasons to have that, but they are less important than you would have thought. If our goal was to accurately calculate the circumference of the earth (or the fruit) then our method is not perfect at all.

The fruit was far from being spherical. It was almost cubic at some pionts, flat at others, and had lots of bumps on it. The radius on one small section of it is not necessarily the radius on another point on it. So, error margin in that matter is quite obvious.

But Eratosthenes’ method is important not necessarily because of the numerical result, but for its significance in discovering the world is a sphere. Remember, Galileo Galilei almost lost his head over this idea (among others), and that was about 2000 years after Eratosthenes.

Not to mention many of us learned the (sadly, very common) misconception that Christopher Columbus is the explorer who discovered the world is round.

Wrong!!

Humanity was Smarter Than That a long time ago, and Eratosthenes’ ingenious way of estimating the circumference verifies it completely.

Resources:

Eratosthenes:

• http://outreach.as.utexas.edu/marykay/assignments/eratos1.html
• http://scienceworld.wolfram.com/biography/Eratosthenes.html
• http://www.eranet.gr/eratosthenes/html/eoc.html

Earth Radius:

• http://nssdc.gsfc.nasa.gov/planetary/factsheet/earthfact.html
• http://en.wikipedia.org/wiki/Earth_radius

Trigonometry Reminder:

• http://www.clarku.edu/~djoyce/trig/right.html
• http://oakroadsystems.com/math/trig10.htm

Flat Earth (not!):

• http://www.badastronomy.com/bablog/2007/09/19/how-wrong-is-the-flat-earth/
• “Flat Earth Society” (from “The Skeptic’s Guide to the Universe” blog: http://www.theskepticsguide.org/sgublog/?p=115

Red Pummelo is good for you:

• http://www.all-creatures.org/recipes/i-pummelo-red.html

My mom always told me never to play with my food, but in this case, I think even she will agree to make an exception. Not only am I going to play with this food, you should too. It’s way too fun to pass on.

This type of matter is called a “Non Newtonian Fluid”. Why? Well, because it is an exception to the rule Newton devised about the flow and viscosity of fluids.

Newton observed that fluids have a ‘tendency’ to resist flow; he called that tendency “viscosity”. If you have a water-pistol, for example, and you want to splash a target, the harder you press the trigger, the faster water come out. Pressure affects viscosity.

Ketchup is another example. It has very strong ‘resistance’ to flow – its viscosity is high. If you just tilt the ketchup bottle onto your fries plate, it takes a while for it to pour out of the bottle – and onto your plate. Honey is the same. You need to apply pressure on the bottle to force it out.

Newton’s theory was that the only way to change a liquid’s viscosity is to change its temperature. Honey, in that example, flows much more readily when it’s hot. I am not sure if Ketchup follows that example, but you’re welcome to try and let me know. I personally hate warm tomatoes; sauce or no.

Non Newtonian fluids, as their name suggest, are the exception of this rule. They, too, change their viscosity in different temperatures, but they also change viscosity when force is applied on them. And there lies the cool part.

Press down on a glop of honey, and your hands fill with honey. Press down on a glop of oobleck (corn starch and water, for example) and it’s solid.

So, when forces are applied to the glop of Non Newtonian liquid, the forces of attraction between the molecules of the liquid increases, and the liquid becomes solid-like. When the forces decrease, the attraction between the molecules decreases as well, and the glop is again fluid.

Woohoo!

Materials needed for the Experiment

• A Bowl
• Corn Starch
• Mop – it’s necessity is proportional to the amount of fun you have with the glop.
• Plastic Bag (to dispose of the mixture)

Warning!!! Do not dispose of the fluid down the drain. It’s going to clog up your pipes, and that’s bad. Put it in a plastic bag and throw it with the garbage, instead.

Practical Applications

• Fun. I mean.. c’mon now. It really is. And since corn starch can be found in any food store for cheap, and the preparations take less than 5 minutes to make, you simply must try it yourself. Must.
• “Walking on Water” is probably the most famous fun application of Non Newtonian fluids. You can have examples in YouTube, just by looking up “Non Newtonian Fluids”. Or by watching the MythBusters episode about Ninjas. If only to see the blue corn starch fluid.
• Fluid Armor: Yeah, it sounds weird, but technically, if a fluid turns to solid when force is applied to it, then it makes much more sense to ‘wear it’ as an armor. I wouldn’t recommend using corn starch and water to stop a speeding bullet, but there are other fluids out there that can help in the matter. In fact, in many of the Kevlar armor suits today, there is a few extra layers of special Non Newtonian liquids that react strongly when force is applied. That application makes Kevlar suits lighter, because less layers of fabric are required.

Extra Resources:

• Non Newtonian Fluids: http://www.madsci.org/posts/archives/mar97/856396884.Ph.r.html
• General Chemistry Online FAQ:
  http://antoine.frostburg.edu/chem/senese/101/liquids/faq/non-newtonian.shtml
• Oobleck: http://en.wikipedia.org/wiki/Oobleck
• Dr Seuss’ “Bartholomew and the Oobleck”: http://en.wikipedia.org/wiki/Bartholomew_and_the_Oobleck
• “How Stuff Works” on Liquid Body Armor: http://science.howstuffworks.com/liquid-body-armor.htm
• “Army scientists, engineers develop liquid body armor”: http://www4.army.mil/ocpa/read.php?story_id_key=5872

I wonder what would their world look like if they knew that light can be bent. Well, in huge distances (like space) light is bent with gravit, which is pretty cool, but it takes a big body of mass and quite a large distance to do that. I am not going to travel light years to see light bend. I’m going to do it in my own bathroom. You can too. In your own bathroom.

So what actually happens with light to cause it to “bend”? In short distances, light travels in straight lines, and if they are otherwise undisturbed, they will go on forever. Or at least for a really really really really long time. That’s how we see distant stars, their light travels huge distances and reaches our telescopes (or eyes, if the night is clear).

Using the principle of refraction, we can simulate a situation where a light beam is ‘bent’. Think about a bunch of mirrors, each refracting the light in a slight angle towards another mirror – eventually directing a beam of light at a completely different angle. That seems easy enough, and – unsurprisingly – that is exactly what is happening within the flow of water.

Materials for the Experiment

• A Plastic Bottle – preferably clear and empty.
• Duct Tape. (I used blue, you can use whichever color you feel like).
• Laser Pen, or other directed light source.
• Water.

Preparations

Take the plastic bottle and poke a hole in it with a pin. I recommend expanding it a bit, the hole in my bottle was about 2mm in radius. The trick is to create a large enough hole to encompase the entire laser beam, but not large enough to have the water just pour out uncontrollably. It took me about 3 attempts to get this straight. Err.. bent.

Now, cover the hole with the duct tape and poke another hole through the not-for-long sealed hole. The duct tape is not absolutely necessary, but it will help directing the laser ray towards the hole. You would be amazed how difficult it can be to aim when water is pouring out on top of you…

Seal the hole with your finger and fill the bottle with water. When it’s full, close the cap. The pressure inside the bottle will prevent the water from coming out through the hole – as long as you are careful not to squeeze the bottle. Or drop it. Or tilt it too fast…. okay, maybe you should keep your finger on the hole anyway.

Put the bottle somewhere wet (or that you wouldn’t mind getting wet, like a bath tub), turn your laser beam on and point it at the hole. Release the cap.

Water should be coming out now, and if you aim your laser light properly, they should refract the beam towards the surface and appear slightly reddish (or.. whatever color your laser beam is).

Real Life Applications

• Optic Cables: Spread over the ocean and land, optic cables direct light from one point to another using this principle. No, they are not made of water, they’re made of a matterial that is, actually, better refracting (light beams don’t ‘come out’ of the cable mid-way, usually, only at its ends). This means that the light does not lose energy along the way, and reaches the destination in the speed of light. Which is fast. Very fast. Yay for optic cables.

Resources

• Light Refraction: http://www.ps.missouri.edu/rickspage/refract/refraction.html
• Refraction of Light: http://sol.sci.uop.edu/~jfalward/refraction/refraction.html
• Full Bottle, Hole, No Leak: http://www.newton.dep.anl.gov/askasci/phy00/phy00946.htm
• howtoons: http://www.instructables.com/id/Bending-Light/