Picture by joelwillis via Flickr (Creative Commons 2.0)

I usually don’t like making grandiose statements ahead of myself, like “Astrology is totally unscientific”, because I prefer leaving the benefit of the doubt until I check the claim. In the case of Astrology, however, there’s no use pretending.

Astrology isn’t science. It makes baseless predictions, relies on overly-generalized statements and has a false basic premise*.  You can read this online from various other sources, and there isn’t much use for me to reiterate the points made.

What I am going to do is test the basic premise.

* Phil Plait, “The Bad Astronomer”, has a great analysis of Astrology that goes over all the above, and more, as does the skeptic dictionary and the Astronomical Society of the Pacific among many, many others. You can also watch Australian Skeptics’ Richard Saunders brief live argument with an Astrologer.

Note: For your convenience (and due to popular demand), I added an automatic tool where you can measure the force applied by any object at any distance. Test it yourself!

Click here to open the Force Calculator!

(opens as a new window).

The basic premise of astrology

Astrologers claim that the positions of the planets and “Zodiac” signs (constellations of stars) at the moment of our birth – and generally throughout our lives – affect our personality, mood and affairs.

I will not get into the so-called  “metaphysical” effects, a mishmash of misunderstood physical theories (quantum physics, dark matter, dark energy, etc) with some pseudoscientific new-age unfalsifiable claims (from “fate” and “luck” to “planetary energies”, whatever that means). What I will do is treat the claim that astrology has merit in science. Many astrology-believers think that since the planets exert gravity, they might affect our brains, and therefore our moods.

Many people give the moon as an example. The moon’s gravity is known to affect tides – a powerful force we can witness. Many take this as proof that the planets’ gravity is affecting our bodies. On its face, the claim makes sense.

We are going to examine it.

Gravity, the force of masses

Any two objects with mass exert gravitational force on one another. That force is related to the masses of the objects and the distance between them by the formula:

Where G is the universal constant of gravitation, M and m are the masses of the objects and r is the distance between them.

Since we think of planets as incredibly big objects, the idea that their gravity affects our bodies sounds reasonable. But to a newborn, there are other “massive” objects around that exert the same type of force as the planets. They might be much smaller than the planets, but they are much closer, too. If the position of planets at the moment of our birth defines our personality, so should the positions of objects in the delivery room.

This is a testable claim.

The test: planets vs. delivery room

We are going to compare two forces, those coming from the planets and those coming from objects in the delivery room, to reach a conclusion:

• If the forces from the objects in the delivery room outweigh those from the planets, then astrologers should, at the very least, ask the weights and positions of the people in the delivery room when they calculate your chart.
• If, however, the forces of the planets are substantial, then astrology might have some scientific merit. This is what we are about to check.

OMG! Math! Panic!

Relax.

We are about to calculate physical forces so there is some math involved, but you can choose if you want to see it or not. Yes, I’m that considerate.

If you want to go over my math so you can repeat it yourself, add to it (items I missed?) or criticize me (peer-review away, mathematicians) you can reveal the calculations by clicking the “Show the Math” links.

Otherwise, just continue reading the solutions only. Those are useful too.

kthxbai!

One more note: Forces are directional (vectors), but in this case, since we want to calculate the maximum possible force, we will treat them as if they are “lined up”, and therefore calculate them numerically.

What about the mother?

Right, the mother is also in the room, and her body also exerts a gravitational force on the baby. However, The baby is inside the mother, and in her midsection. He is, almost literally*, in her center of mass. For all intents and purposes the mother’s gravity “cancels out” from all directions and there’s no use adding her into the calculation.

* Physicists, stay calm, think “spherical chicken in a vacuum” and bear with me here.

On we go.

The delivery room

Since my intent is to calculate the most basic hospital delivery room, I put in the most basic items that should be found in one. There are likely many more people and pieces of equipment in and outside the room, but the goal of these calculations is a “conservative estimation.”

Therefore, I will ignore the size of the hospital, other people walking by and other large machines that exist in the building. See “Conclusion” for more about those.

Here’s a list of what should be the most basic elements in a delivery room:

People:

• A doctor (obviously)
• A nurse
• OB tech (whose job is to help the doctor and nurse during the actual birth)
• The partner (assuming the mother has one)

Objects

• Bed or birthing chair.
• The machine that beeps (heart monitor).
• Baby crib
• Scale (to weigh the baby, clean and check him or her up)
• Sphygmomanometer (blood pressure monitor) and stethoscopes.

The Calculation

In the following section I will calculate the force exerted on the baby from each of these elements by estimating their weight and mass and their relative distance.

I will assume average-sized staff (75-85 kg), leaning towards the thinner side, to keep my estimate conservative. I will also assume that the baby is level with their midsections (i.e., their centers of mass) which will allow me to ignore their height in my calculation.

Show the Math

Total Maximum Force

So, to summarize (and, for those of you who cared not for the mathematics, to state in the first place):

• The Doctor =
• The Nurse =
• The OB Tech =
• The Partner =
• The Bed =
• Heart Monitor =
• Scale =
• Other Small Objects =

Show the Math

Total Force:

The Planets

EDIT: I have recalculated the forces from the planets. It seems that during the initial calculations I made a rather small (but recurring) conversion error, and due to vigilant commentors, it was properly corrected. You should note, though, that the total force after this re-examination didn’t change. My calculation was fine, I just had a problem with how I wrote it out in the process (in the math part). Apologies.

Now, astrology claims that the planets exert a force on the baby, and their different locations change that force ever-so-slightly to somehow affect the baby’s personality traits.

The idea that the planets exert a force, even on the baby, is true. Whether or not it is canceled out or overwhelmed by other forces is a different issue.

Our next step, then, is to calculate the maximum force that can be exerted from the various planets, and combine them to get the maximum possible force exerted by the planets.

Show the Math

The force from all the planets combined

All of the forces above were calculated as if the planet is in its closest position to the Earth. The chances that all planets together will be in such positions are incredibly small. This doesn’t usually happen, and the resultant combined force is much smaller. However, we can still calculate the maximum theoretical force that can be produced by all planets combined on the newborn baby.

Here they are:

• Mercury =
• Venus =
• Mars =
• Jupiter =
• Saturn =
• Uranus =
• Neptune =
• Pluto =

(Before you protest about Pluto, read this: there are many problems with including Pluto in the calculation of gravity – the least of which is his “partner” Charon, who’s of similar mass. However, Astrologers calculate Pluto into their maps, and so I thought it would be appropriate to include the force it exerts, too.)

Show the Math

Total Force =

Comparison

So, what do we have?

• The combined forces of the delivery room =
• The combined forces of the planets =

Difference =

The forces from the delivery room are 8 times bigger than the combined force from the planets, and we have calculated a very conservative estimate.

Proponents of the claim might jump out of their seats and claim the forces are extremely close. They seem close (if a factor of 8 is considered close) but we have to remember a few important issues that show conclusively that the forces from the planets are minuscule compared to the forces exerted on the baby from his immediate surroundings:

• The planets do not, ever, line up where they are all as close to Earth as our calculation asserted. The realistic force from the planets is lower.
• Our estimates for both the distances, the amount of people and their weight was very conservative. In reality, hospitals have a lot more people and staff, much more equipment in the room and directly outside of it.
• Hospitals are huge places. If planets as far as a few billion kilometers exert force on our newborn baby, the MRI machine (that weighs 50-60 times the weight of the doctor, nurse and OB Technician combined) at some floor below, and the CT machines somewhere in the hospital should be taken into account as well. Those would dramatically increase the difference between the two forces.
• And, one of the most notable point of all: We ignored the Earth’s gravity!

We ignored the Earth’s gravity!

To be fair, I ignored the Earth’s gravity in both cases, for a very good reason: it absolutely trumps both. Since it is also coming from the ground, and the other forces are spatially distributed, my goal was to show that even without gravity, the difference exists, and is indeed noticeable.

But the Earth’s gravity is important here.

The Earth isn’t a perfect sphere; its radius varies from 6357 km to around 6378 km.

Assume the baby is 6360 km from the center of the Earth.

Show the Math

In this case, the force exerted on him by gravity would be

As you can see, this is times more than the forces exerted by the occupants of the delivery room, and times more than the force exerted by the planets together. It’s a powerful force, gravity.

And there’s more. The Earth’s gravity isn’t constant. It varies across the surface of the planet (as the radius varies). We usually use the average rounded number for the gravitational acceleration () but in different locations on the Earth, the number varies.

If the claim astrologers make is that the force from other planets affect a baby’s personality – and we’ve seen how small that force is! – then the change in the Earth’s gravitation should have an effect too. In this case, Astrologers should consider the location and elevation of your birth as well as the date and time, to calculate the variations in the Earth’s gravity.

The next time an Astrologer offers to calculate your chart, you should reminder them about that.

One more thing: The Labor Itself

We didn’t include this part in the initial calculation, but this is definitely something that we should take into account, since this is likely to be quite a powerful force.

A baby doesn’t just “walk out” of the womb, it is pushed out by the mother’s muscles. If you see any TV shows at all, you know that at the moment where the baby – and doctor – are ready, the doctor will ask the woman to “Push!!” resulting in the baby’s head being pushed out (if all is well) and the doctor assisting the baby the rest of the way.

This “push” and the movement out of the woman’s womb also exert force on the baby. On top of that, there is usually a large amount of time during which the woman’s body exerts force on the baby before it actually comes out. This would apply pressure on his body; obviously, it’s not enough to harm the baby, but it definitely exists. And labors can be long… long and tedious processes. Ask your mother how long she was in labor.

So for a large number of hours (36 is the average!) the baby is subjected to pressure from the mother’s contractions, and then to the force that pushes him or her out of the womb.

So.. why don’t Astrologers ask how long your labor lasted?

Conclusion

There are many things that are plain false in the claims that Astrologers make, and many blogs and sites covered the reasons why. Now, though, you could see for yourselves how the basic premise – that planets’ positions, affect the personality trait of a newborn baby – is just silly.

If the planets’ positions affect the baby’s personality traits, so should the Doctor’s position, the OB Technician, the position of the heart monitor, the CT machine down the hall and the size of the hospital and the amount of people in it.

So, unless Astrologers are willing to take these components into account when they produce your “Chart”, it seems their claims are plain silly.

And you should tell them that.

Do you have more objects to test?

Now you can. Due to popular demand, I’ve prepared a small tool to help you calculate the force from object at any distance. Play with it, and share your findings in the comments!

Click here to open the Force Calculator!

(opens in a new window).

Resources

• http://pregnancy.about.com/cs/laborbasics/a/aa021504a.htm
• Labor and Delivery Room (scribd): http://www.scribd.com/doc/6390726/Labor-and-Delivery-Room
• Monty Python’s Hospital Sketch http://www.youtube.com/watch?v=arCITMfxvEc
• Average fetal weight: http://www.babycenter.com/average-fetal-length-weight-chart
• http://nssdc.gsfc.nasa.gov/planetary/factsheet/
• http://www.universetoday.com/guide-to-space/venus/venus-distance-from-earth/
• http://www.universetoday.com/guide-to-space/mars/distance-from-earth-to-mars/
• http://www.universetoday.com/guide-to-space/jupiter/how-far-is-jupiter-from-earth/
• http://www.universetoday.com/guide-to-space/saturn/saturn-distance-from-earth/
• http://www.universetoday.com/guide-to-space/uranus/uranus-distance-from-earth/
• http://www.universetoday.com/guide-to-space/neptune/how-far-is-neptune-from-earth/
• http://www.spinlife.com/Drive-Medical-600-lbs.-Bariatric-Full-Electric-Frame/spec.cfm?productID=82578
• Stages of Labor: http://www.accd.edu/sac/nursing/rnsg2261/PDFWH/StagesOfLabor.pdf

Thanks

Once again, thanks goes to:

• Capn_Refsmmat, for some language issues, for his mastery of the LaTeX plugin and for his math peer-review.
• Daniel Grrrrrr for his English support and patience. Lots of it.
• UnintentionalChaos (from ScienceForums.net) for some math peer-review and clarity correction issues.

If that force truly affects your mood or character, then you should be going totally berserk every time your computer reboots, or when you sit in the movies among a few dozen people. Their mass affects you much more than remote planets, that’s for sure.

I’ve been planning to write a full blown analysis of astrology for SmarterThanThat with some actual calculations (because I know how much you all like calculations!) but the subject was discussed ad nauseam all over the net already. A SmarterThanThat analysis (and, possibly, an experiment) will come in the near future, but for now, if you wish to learn more about astrology and its premises, here’s a good place to start.

But apparently, people like believing in astrology -- it’s vague assessments are comforting. And it can be fun, in a useless kinda way.

But if you’re still under the impression that astrology has some merit to it, maybe you should watch this video where Richard Saunders (Australian Skeptics, Skeptic Zone podcast, and more) brings the astrologer back to Earth and away from fantasy. Far away. Welcome to reality, Astrology.

I wonder if the astrologer would take on Richard’s invitation. That would make for an interesting (though, I suspect, quite predictable) experiment. I have a feeling that Richard would keep us all updated if this happens.

Don’t hold your breath.

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.

The “losing weight” trend is one of the better outcomes of reality TV, and it encourages people to take charge of their lives and live a healthier life.

But there’s one thing that bugs me about this trend: The terminology.

Folks, you lose weight every time you go down a fast elevator. What you actually want is to lose mass. Since your weight is affected by your mass, it will mean that your body will weigh less on the scales the less massive it is, but the goal is not your weight, the goal is your mass.

“Burning fat” and getting rid of excess calories along with training in the gym will make you leaner, thinner, and less massive.

The force that a leaner body exerts on the floor is less than the force a big body exerts on the floor, but what you work on when you want to “lose weight” is, in fact, shaping your body’s mass: losing the mass of fat and/or gaining the mass of muscle.

I can lose weight without touching my mass by simulating a “weightlessness” situation, or by getting close to it.

For example, try riding up and down an elevator while standing on a scale.

When the elevator accelerates downwards, it is moving away from your feet and your body is, essentially, in a condition of “falling”. That decreases the force it exerts on the floor, and you experience a state of semi-weightlessness, depending how strong the elevator’s acceleration is.

When the elevator accelerates upwards, the force your body exerts on the floor is now increassed, because the floor goes up faster than your body can chase it, and your feet are pushed down towards the floor.

Congratulations, you just gained and lost weight in a few minutes.

If you want to be lighter, jump off a plane (with a parachute, please). The state of a ‘free fall‘ your body will be in for the first moments will simulate weightlessness. In these situations your weight is zero, but your mass -- the particles that make you “you” didn’t go anywhere.

And though you just lost weight, that does not make you thin.

The term “Weight Loss” is so engrained in our society, that it will be futile of me to try and get you to stop using it. That does not mean, however, that you can’t understand the physics behind those terms.

So, remember: If your goal is to lose weight, ride down an elevator or jump off a plane with a parachute.  If your goal is to be leaner, excercise and eat right, and get rid of that mass of fat that surrounds your muscles.

Alternatively, you can go live on the International Space Station, where weight is not an issue.

Resources and References

• Weightlessness in Wikipedia: http://en.wikipedia.org/wiki/Weightlessness
• “The Biggest Loser” show: http://www.nbc.com/The_Biggest_Loser/

Credits

• Music from http://www.freeplaymusic.com
• “Houston” Mission Control voice: Daniel

Picture Credits (used in the video)

• I heart Nerds T Shirt http://www.flickr.com/photos/elvissa/880588709/
• (Featured photo) Scale http://www.flickr.com/photos/restlessglobetrotter/2929270640/
• Hamburger http://www.flickr.com/photos/jesswebb/2633566137/
• Obese dog http://www.flickr.com/photos/34428760@N03/3202436425/
• Lean dog http://www.flickr.com/photos/draplin/912213752/
• Pyramid http://www.flickr.com/photos/swamibu/2223726960/
• Sky scraper http://www.flickr.com/photos/nogood/220232524/
• Jumping off the roof http://www.flickr.com/photos/paulbence/93988862/
• Elevator free fall http://www.flickr.com/photos/bass_nroll/2215862793/
• Rollercoaster http://www.flickr.com/photos/mprinke/1139986131/
• Gym http://www.flickr.com/photos/abraj/181196330/
• Veggies http://www.flickr.com/photos/valjk/634696442/
• Obesity http://www.flickr.com/photos/combinedmedia/3067501298/
• Iron man http://www.flickr.com/photos/sscusp/242103879/
• Big man with coke http://www.flickr.com/photos/fatmandy/165144643/
• Weight loss http://www.flickr.com/photos/vernonwhite/3327754571/
• Baby cringe http://www.flickr.com/photos/craigforsyth/2384364393/
• Skydiving http://www.flickr.com/photos/gogap/423485388/
• Leaner http://www.flickr.com/photos/christinielsen/97438813/
• Exercise http://www.flickr.com/photos/n8kowald/1467191600/

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

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

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

Of course, it only takes a few years and a drivers license to understand that a car that actually sounds like that while standing is not quite the car you would like to buy. Or rent. Or.. get into.

So why are we all using this sound to describe the moving car? What happens to the sound of a car when it is moving to get it to change so dramatically? I wonder.

No more.

No more wondering, that is. Cars will stick around. At least for a bit, until we start with the hovercrafts… and everyone knows they go “fffffffffffffffffffffzzzzzzzhhuuuuuum!” anyways.

The next experiment explains the phenomena called “The Doppler Effect“, where waves (not just sound waves, mind you. Doppler welcomes waves of all kinds, shapes and frequencies), seem different in movement.

A ‘Wavy’ Reminder:

Just so we’re all in the same level, here’s a reminder: We can describe waves with a few main characteristics: Amplitude, Wavelength and Frequency.

• Amplitude defines the “strength” of the wave. In sound waves, it is the factor that determines how loud the sound is.
• Wavelength is one full cycle the wave ‘completes’ from 0 to 180 (or, from ‘peak to peak’).
• Frequency is determined by the amount of cycles (wavelengths) per second.Hight frequency will result in many cycles per second, and therefore a very small wavelength. Low frequency means few cycles per second and a long wavelength.

Formula for the Doppler Effect:

f is the original frequency in movement, and f’ is the “resulting” frequency (the one the mommy duckie actually hears).

V is the speed of the wave itself. Sound waves in air, for instance, have a speed of approximately 330 meters per second.

Vs is the speed of the moving object that is creating the sound – for that matter, the speed of my duckie. Solving that equation gives the resulting frequency (the “pitch”) that the stationary listener receives.

Preparations:

I didn’t have a lot of time to prepare, and I didn’t want to spend too much money on materials, so instead of working on properly connecting the buzzer to a battery, I just hooked up something very.. uhm.. amateurish. Anticipating the comments some of you will probably post, I must state, in advance, that I know it’s amateurish. I just don’t care. It worked.

Here’s the buzzer before:

I bought it for $1.60 in one of the main electronics shops (you could probably find it for a lot cheaper in a non-franchise (or just outside of Manhattan).

For whoever’s interested, the original (non moving!) specified frequency for it is 2700+- 500Hz.

After I tweaked with it a bit and used paper clips (because that’s what I have here), it took the shape of this lovely piece of art (though an incredibly annoying one):

That unconnected red line – when connected to the batteries – closes the circuit and activates the buzzer. I had to unhook it for fear of my sanity. Handle with care.

You can purchase an already-built buzzer. I am just too cheap.

Also, a friend of mine gave me the idea of playing a continuous single-note mp3 file (if you can find, or record one) on your favourite mp3 player and fling around the earphones. (Nice idea, genius, next time you spend 10 minutes building a stupid buzzer.)

Materials Used in this Experiment:

• 2 Rubber Duckies with their Rubber Duckie Mommy.
• Any kind of bucket, tub or bowl. Preferably clean water.
• A buzzer or any type of annoying sound making device ($1.60 in Radio Shack). Do not use a baby.
• Batteries for your buzzer (or whatever else makes it go bzzzz).
• A Tennis ball.
• A stocking (don’t take a nice one, the owner of that stocking will not like it).
• A trusted (and trusting) friend.

So, What do you do? Simple. You turn the buzzer on, shove it into the tennis ball so that whatever happens it doesn’t break (and, also, if your hand gets slippery and it whooshes off to space, your friend’s face will have a nice round bump instead of a nasty battery-shaped one). You shove the now-very-annoying tennis ball into the stocking –

Note: This is the time to call your friend over to enjoy the wonders of this phenomenon. You, as the buzzer-slingshot performer, wont really notice any sound changes, but the person in front of you will, and your friend will thank you from the bottom of his heart.

Or his ear. Whichever will hurt less.

– start twirling the stocking around like a lasso above your head, or next to your body.

The buzzer moves quickly closer and farther from the person in front of you and the Doppler Effect kicks in. It might not sound as cool as a car ‘zhoooooooom’ing by but it certainly proves the point. Stop twirling the buzzer around and show your (hopefully appreciative) friend that the buzzer has a constant sound when it’s not brutally slingshot through the air.

Voila. You’ve created the Doppler Effect in your own house. Aren’t you proud?

Practical Applications

The Doppler Effect, as I stated before, does not discriminate on the type of waves it operates on. For that reason it has a lot of practical applications:

• Police Radar: Yup! When police officers measure the speed of a passing car using their nifty-looking radar-gadget, that’s how they’re doing it. Well, they’re not actually calculating it themselves, of course, the radar is doing it for them – but it is using the Doppler Effect. The device is sending a wave with constant frequency towards a passing car and expects the reflection. Since the car is in movement, the reflection is bound to come back distorted from the Doppler Effect. Using the formula, it then calculates the exact speed of the passing car and notifies the police officer if a ticket is needed.
• “Red Shift”: As we said, the Doppler Effect acts on waves of all kinds, including light. With light the effect is emphasized because different frequencies of light waves mean different visible colors. When astronomers look at the sky in search of new (and existing) galaxies, they measure the light frequencies from that galaxy. Galaxies that are shifted towards the “red” spectrum are lower frequency, and galaxies that are shifted to the “blue” spectrum are higher frequency. “Red Shift” is the term used on galaxies that move away from Earth, where their visible and invisible light frequencies are lower – shifted to the ‘red spectrum’. Measuring exact shifts can help astronomers understand how fast a stellar object is moving away (or towards) us.
• Airplanes: Since airplanes are moving, the ground always receives a distorted transmission. For that reason, airplanes never use frequency-modulations (FM) for their transmissions (even though FM transmission is considered to be of higher quality) but rather modulations that are based on amplitude (AM). That way the ground can decipher the messages quickly regardless of the distortion and changes in speed.
• Breaking the Sound Barrier:Moving airplanes get really fast. Really really fast, actually. If a plane moves faster than the spread of the sound waves, it is considered to “break” the sound barrier. A nice representation of it can be seen in this link from Kettering University.

Resources:

• http://www.seed.slb.com/en/scictr/lab/doppler/index.htm
• http://www.fearofphysics.com/cgi-bin/doppler.cgi?dir=a&vs=300&mode=wrap
• Doppler Effect and Red Shift: http://www.youtube.com/watch?v=Man9ulEYSgk
• http://www.space.com/scienceastronomy/redshift.html