I agree with Phil about this conclusion. However, these questions of man-made objects seen in space is a long-time pet-peeve of mine, and I couldn’t just let this go.

There’s no doubt we can see man-made objects from space. Depending on your definition of space.

See, space is huge, HUGE, and the border between Earth’s atmosphere and Space is less clear-cut than many think. This renders the question itself – Are man-made objects visible from space? – moot. Is space 400km above the Earth, or is it 30,000km above the earth? Whether or not we can see man-made objects on the surface of the earth depends on how far away we are when we look.

Here vs. There

Case in point – the International Space Station is somewhere between 336 to 346 km above the surface of the Earth at any given moment. Some man-made communication satellites are about 30,000km above the equator. What’s visible from the space station might not be visible from our man-made communication satellites.

Notice the differences here: The ISS is proximately 400km above the Earth’s surface, and our communication satellites are around 30,000km above the Earth’s atmosphere. That’s almost 100 times farther away.

This means that the same area that we see from the International Space Station in this picture (taken by Soichi Noguchi):

Pyramids from the ISS

Will be almost 100 times smaller in a picture taken from 30,000km altitude:

Pyramids from 30,000km

So that’s what the pyramids look like from space. Hrm. The.. the pyramids.. wait.. uh.. the pyramids? Where did they go?

As you can see, it’s very hard (if at all possible) to see the pyramids in the second teeny tiny picture. And yet, that’s their relative size from a 30,000km altitude – about 1% size of the original picture.

So Can We See the Pyramids From Space?

We can see the pyramids in space, when space is around 400km above the Earth. Actually, we might be able to see the pyramids from 30,000km if we have better resolution in the picture, but the farther out you go, the harder it is to make up items on the Earth’s surface. That includes the pyramids, and the wall of china, and the super-dome. You can see neither of those from the Moon.

The same can be said about moving closer to the Earth’s surface. The border between the Earth’s atmosphere and outer space isn’t clear cut at all. The earth’s atmosphere becomes thinner and thinner as you venture outwards, and it doesn’t just end in a clearly discernible line.

At around 175km above the earth’s surface is where shuttles returning to earth begin feeling a discernible effect from the atmosphere, so we often take that limit to be the “edge” between the Earth and outer space.

If you go to that height, though (half the height from the ISS to the surface of the Earth), you could see much more than just the pyramids.

And it is still Space.

The Farther Away, the Less You See

When you’re in Battery Park, you can see the Statue of Liberty. When you’re on top of the Empire State Building, you will likely need binoculars.

We all know this simple fact: It’s harder to make out objects the farther away you are from them. We don’t need to go to space to see this, it’s enough that we board a plane and fly above our city. When we are on the ground, we can make out people and buildings. When we are on the plane, we can only make out buildings. When the plane is very high up in the air we can only see clusters that we recognize as cities.

The same goes with space:

• From the International Space Station, we can obviously see the pyramids. Does that mean the pyramids are visible from space?
• From the distance of communication satellites, we probably can’t see the pyramids. Does that mean that the pyramids aren’t visible from space?
• From the moon, it’s almost impossible to recognize any feature other than landmass on the surface of the Earth. Does that mean no man-made objects are visible from space?

It all depends on what you mean by “space”.

Here is a picture taken by the Apollo 8 astronauts, from the moon, of the Earth rise:

Apollo 8: Earth rise, Credit: NSSDC Photo Gallery Earth & Moon NASA

If you think you can make out any detail other than landmass (the wall of china? the pyramids? anything else?), then I’d love to get to know your optometrist. Is he taking new patients?

Conclusion

Space isn’t a finite point, it’s an unclear range that seems to start around 160km above the Earth (more or less) and ends … well… at the edges of the universe, some 46.5 billion light years away.

We can barely make out our own planet from the edge of our own solar system. Do you think we can see man-made structures from the center of our galaxy? Of course not. Does that mean they are not visible from space?

So, when I am asked this question – “Can we see the wall of china from space? Can we see the pyramids from space?” my answer is simple: Sure we can! It just depends how far out you go.

Smartassy, maybe, but more accurate.

Picture Credits

• Soichi Noguchi, twitpic: http://twitpic.com/170ftn
• NSSDC Photo Gallery, Earth & Moon, NASA ID: AS08-14-2383, 68-HC-870: http://nssdc.gsfc.nasa.gov/photo_gallery/photogallery-earthmoon.html

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.

A little while ago, the Israeli Museum in Jerusalem opened an exhibit featuring some of the torn, slightly burned pages of Col. Ilan Ramon’s personal diary from the shuttle Columbia. Ramon was the payload specialist onboard STS-107 (the spaceshuttle “Columbia”) that disintegrated during re-entry from space, killing all 7 crewmembers onboard. The diary survived the re-entry and subsequent crash, and was found in a field next to Palestine, TX.

Ramon’s personal diary fell close to 37 miles (almost 60 km) through the extreme conditions of re-entry. Unlike its human owner, it has survived the process and is now being restored and presented to the public in the Israeli Museum in Jerusalem.

During the weeks and months after the Columbia disaster, pieces of the debris were still being collected from wide areas in Texas. small pieces of insulation that detached from the outer parts of the shuttle to pieces of the Astronauts’ space suits. In an article covering the subject on “Universe Today”, The Israeli Museum curator is quoted as saying that “There is no rational explanation for how it was recovered when most of the shuttle was not.” It is no wonder, then, that many are awe-struck at such an apparent miracle.

But is there, really, no rational explanation for the survival of the diary? None at all? I doubt that. And when I doubt, I check it out, which is exactly what I am about to do.

A thought (or two) about Hypotheses

The information about the Columbia disaster is available in many online and offline sources, but it is still very limited. We can guesstimate what happened to certain parts of the shuttle based on facts on the ground and what we already know from previous manned missions to space using the Columbia shuttle.

The general investigation I am about to embark on in this post is based on the material I have found online and my own personal knowledge, strengthened by facts from other missions and physical concepts. It is by no means complete, and I had no time (or resources, sadly) to do a full blown investigation into the full train of events that Col. Ramon’s diary went through. If you have any thoughts on the matter, or if you hold any factual data that will help hypothesize what it “went through” in the moments before hitting the ground, please share them in the comment section. I am very much willing to update and upgrade this hypothesis in light of new information or ideas (just make sure you base those on valid data, of course).

I try to support my guesstimates with valid data when I can, and use ‘extremes’ to get us a rough idea of how this discovery (and this ’survival’ of such an item) is possible.

The Space Shuttle – Crew Quarters

The space shuttle is built to sustain its crew for days (and sometimes weeks) in space. It has sleeping bunks, restroom and shower, all located in the crew area in the “Mid Deck” (picture is taken from Space Shuttle News Reference (NASA), p 5-5):

According to ex-astronaut R. Mike Mullane, the mid deck also holds the crew personal lockers (“Do Your Ears Pop in Space”, R.  Mike Mullane, pg 135). We will remember this fact when we consider the process in which the Columbia disintegrated (keep reading).

Where was the Diary Located?

No one can know for sure (at least not from the published data that I’ve read) where the diary was located before the Columbia’s disastrous descent. However, there are a few facts we can be sure of:

• The crew was about to come home; their personal items were, most likely, locked away in their personal lockers, that are located in the Mid Deck.
• According to astronauts who were active in previous missions, a diary is sometimes put in the lower pocket of the flight suit. If the diary wasn’t locked away in Ramon’s personal locker, it is logical it was safely tucked into his flight suit pocket.  Flight suits are very durable and tolerate extreme heat and cold conditions.

Either way, it seems logical to assume that the diary was placed somewhere that kept it safe from the initial processes of re-entry and descent.

Temperature Variation

Unlike common belief, the intense heat on the wings and body of a space shuttle as it descends from Space is not caused by friction, but rather by ‘compression’. The big body of the shuttle compresses air molecules downwards so strongly that the air around the shuttle becomes dense and packed like plasma. At this point, the wing-edge temperature naturally rise, and can reach a temperature of about 1,400° Celcius (2,500° Fahrenheit).

After the initial temperature rises, the Columbia initiated a roll to the right, a maneuver that decreases its speed and the heat on its body. This maneuver was successfully performed, and following it were 10 minutes where the heat on the body of the shuttle reached its peak. From there, it started to cool down.

The temperature at these heights is extremely low, and the heat from the shuttle can dissipate relatively quickly.

Explosion vs. Disintegration

About 15 minutes after the Columbia entered the Earth’s atmosphere, pieces of debris were visibly shedding out of its body. But the Columbia did not explode, it disintegrated, and this difference is very important to understand what happened to the parts inside the shuttle.

Explosion and Disintegration are two very different processes.

• Explosion (from Merriam Webster Dictionary):a large-scale, rapid, or spectacular expansion or bursting out or forth.
• Disintegration (from Merriam Webster Dictionary): 1 : to break or separate into constituent elements or parts 2 : to lose unity or integrity by or as if by breaking into parts.

Explosion is quick and “dirty”, resulting in a lot of damage to the individual parts. Disintegration is the breaking apart of the whole into individual, smaller, parts. It is usually slower, and gradual. The Columbia’s disintegration began about 10 minutes after re-entry and lasted until the massive body crashed on the surface. The various parts and debris were scattered over an enormous area, from eastern Texas to Western Louisiana.

The fact that the Columbia disintegrated, rather than exploded, has two main meanings for our investigation:

1. The Columbia did not ‘explode’ all at once; it took time for the various parts to separate away from the main body while the shuttle was cooling down in descent.
2. In an explosion, the parts heat up due to the exerted energy. When a body disintegrates, the parts separate away from the body without experiencing any sort of extra heat. If a piece was deep inside the shuttle, it wasn’t subjected for the intense heat from the plasma (during re entry). It would take it longer to be thrown-away and out of the body of the shuttle. It would, therefore, “spend” less time free-falling.

The objects inside the Columbia slowly broke apart and began a gradual free-fall to the ground, from varying heights, the largest of which is approximately 60 km above the surface of the Earth.

Disintegration = Change in Shape

The shuttle is designed and built for aerodynamic movement. From the nose, to the wings and tail, the purpose is to make sure its movement in the air is smooth and with as little drag as possible. This is meant to decrease drag and allow the pilot better control over the movement of the shuttle once it’s back inside the atmosphere.

Aerodynamic objects move very quickly through the air because of their shape. But Columbia began disintegrating about 40 minutes after initiating the ‘de-orbiting’ maneuver. Parts tore off its body, probably starting with the wings and tail (that ’stick out’ of the body and are subjected to more heat and pressures). Once those pieces – and pieces of the outer hull – tore off, the Columbia lost its aerodynamic shape. From this point on, it will slow down dramatically.

Terminal Velocity of an Object

In reality, when an object falls from a certain height down to the ground, its velocity increases because of the pull of gravity. Air resistance, however, exerts a force upwards – “fighting” the downward acceleration. When both forces are equal, they both negate one another, and the object falls in a constant speed (without the effect of any acceleration). That speed is called ‘terminal velocity‘.

For example, a sky diver falling from 12,000 feet would stop accelerating (hence, would move at a constant speed) at about 200 kph (124 mph). If his parachute didn’t open, he would hit the ground at the same force that a motorcyclist going at 200kph would hit a cement wall in case of a head-on collision (don’t try this at home). The height, in the case of the speeding diary, is not a very good indicator as to the force it hit the ground with.

Terminal Velocity and the Falling Diary

Assuming the diary was protected during the initial stages of the disastrous descent (as I’ve already explained), it shouldn’t have fallen as fast as it may sound like. When we hear the height “60 km above ground”, it sounds as if the falling object would hit the ground at enormous speed (and force). That, however, isn’t the case, because of the terminal velocity.

It is very much possible that the diary was packed or partially protected during parts of the fall, stopped accelerating at the terminal velocity. The pieces continued to disintegrate as they fell, and at some point whatever ‘protected’ the diary disintegrated and exposed it to the full force of the fall. But by that time the conditions that existed at the beginning of the fall were considerably lessened.

Conclusion

• Based on past missions and the structure of the Space Shuttle, we can safely assume the diary was encapsulated inside an item that protected it, either a closed locker or a sealed space suit pocket.
• Air resistance (and the laws of physics) makes the speed of falling objects limited.
• The diary was found in a damp field covered with soft leafs (provided a relatively soft landing).
• Other pieces of debris survived the long extreme fall to Earth (see next section).

Based on all the above, it is a bit easier to see a logical trail of events that could lead to the survival of a paper diary. This isn’t a miracle; it’s a surviving piece of history in light of a horrible, disastrous space mission.

A bit of Realism (Other objects made it, too..)

So we’ve examined the situation, and saw that it’s not as unlikely as we might have first thought for such an item to survive the Columbia disaster. A lot of other debris have survived, including ’sensitive’ materials such as CPU boards and pieces of cloth from the astronauts’ uniforms and rest area. But we also need to take into account the condition in which the diary was found.

According to the State of Israel Ministry of Public Security, which was responsible for the reconstruction and preservation of these pages, the diary was very hard to decipher. It was found wet, torn and crumpled in a muddy field (see picture). The efforts involved a lot of digitized reconstruction along with some measure of guesswork. Some of the text on the pages was simply incomprehensible.

That said, it is also important to remember that this is not the most “surprising” piece of debris that “survived” re-entry. If you want surprise, it is reported that a few worms survived re-entry and the fall to Earth. Yes, alive. A piece of crumpled, wet, torn paper, as emotional and touching as it may be (and I agree that it is), is hardly any competition to life forms surviving the fall to Earth.

This is no miracle.

Many thanks to Capn_Refsmmat for (again!) being the brevity King, and for asking questions that needed to be answered.

References and Resources

• The Physics of Space Shuttle Re-Entry: http://www.bbc.co.uk/dna/h2g2/A6381038
• Report of Columbia Accident Investigation Board, Volume I: http://www.nasa.gov/columbia/home/CAIB_Vol1.html
• Space Shuttle Orbiter Specifications: http://en.wikipedia.org/wiki/Space_Shuttle_orbiter#Specifications
• Columbia Accident Investigation Board (Official Site): http://caib.nasa.gov/
• STS107 Reentry Timeline:

  http://en.wikipedia.org/wiki/Space_Shuttle_Columbia_disaster#Destruction_during_re-entry

• Space Shuttle Blueprints: http://www.militaryfactory.com/blueprints/spaceshuttle.asp
• Space Shuttle Operational Book: http://spaceflight.nasa.gov/shuttle/reference/sodb/
• Columbia debris adds to re-entry research: http://www.msnbc.msn.com/id/5333706/
• Columbia Breaks Up During Reentry; NASA Fears Crew Lost: http://www.spaceref.com/news/viewnews.html?id=722
• Israeli Ministry of Public Security: http://www.mops.gov.il/nr/exeres/BD8C3AB6-6D05-462F-91B3-AA98E3986B24.htm

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Humanity has known the Earth to be round for a few millenia and I’ve been meaning to refine that video and show more of these methods of how we figured out the world is not flat. I’ve had a few ideas on how to do that, but recently got an interesting incentive, when Phil Plait (The Bad Astronomer) wrote about a recently published BBC article about “The Flat Earth” society. Phil claims it’s ridiculous to even bother rebutting the flat earth society – and I tend to agree. But the history of our species’ intellectual pursuit is important and interesting, and it’s very much well worth writing about. You don’t need to denounce all science and knowledge and believe in a kooky conspiracy theory to enjoy some historical factoids about humanity’s quest for space.

Though I have researched this subject, I am quite certain there will be much more to be said about it – feel free to add more in the comments. If all goes well, this might actually be a good post to refer to whenever anyone wants to discuss a bit of ancient science and the source of cosmological thought.

On we go to the top 10 ways to know the Earth is unequivocally, absolutely, positively, 100% not flat:

(1) The Moon

Now that humanity knows quite positively that the Moon is not a piece of cheese or a playful god, the phenomena that accompany it (from its monthly cycles to lunar eclipses) are well-explained. It was quite a mystery to the ancient Greeks, though, and in their quest for knowledge, they came up with a few insightful observations that helped humanity figure out the shape of our planet.

Aristotle (who made quite a lot of observations about the spherical nature of the Earth) noticed that during lunar eclipses (when the Earth’s orbit places it directly between the Sun and the Moon, creating a shadow in the process), the shadow on the Moon’s surface is round. This shadow is the Earth’s, and it’s a great clue on the spherical shape of the Earth.

Since the earth is rotating (see the “Foucault Pendulum” experiment for a definite proof, if you are doubtful), the consistent oval-shadow it produces in each and every lunar eclipse proves that the earth is not only round but spherical – absolutely, utterly, beyond a shadow of a doubt not flat.

Refer to the following image from Wikipedia for more details on what happens during a lunar eclipse:

Click for the Original

(2) Ships and the Horizon

If you’ve been next to a port lately, or just strolled down a beach and stared off vacantly into the horizon, you might have, perhaps, noticed a very interesting phenomenon: approaching ships do not just “appear” out of the horizon (like they should have if the world was flat), but rather emerge from beneath the sea.

But – you say – ships do not submerge and rise up again as they approach our view (except in “Pirates of the Caribbean”, but we are hereby assuming that was a fictitious movie). The reason ships appear as if they “emerge from the waves” is because the world is not flat: it’s round.

Imagine an ant walking along the surface of an orange, into your field of view. If you look at the orange “head on”, you will see the ant’s body slowly rising up from the “horizon”, because of the curvature of the Orange. If you would do that experiment with a long road, the effect would have changed: The ant would have slowly ‘materialized’ into view, depending on how sharp your vision is.

(3) Varying Star Constellations

This observation was originally made by Aristotle (384-322 BCE), who declared the Earth was round judging from the different constellations one sees while moving away from the equator.

After returning from a trip to Egypt, Aristotle noted that “there are stars seen in Egypt and [...] Cyprus which are not seen in the northerly regions.” This phenomenon can only be explained with a round surface, and Aristotle continued and claimed that the sphere of the Earth is “of no great size, for otherwise the effect of so slight a change of place would not be quickly apparent.” (De caelo, 298a2-10)

The farther you go from the equator, the farther the ‘known’ constellations go towards the horizon, and are replaced by different stars. This would not have happened if the world was flat:

(4) Shadows and Sticks

If you stick a stick in the [sticky] ground, it will produce a shadow. The shadow moves as time passes (which is the principle for ancient Shadow Clocks). If the world had been flat, then two sticks in different locations would produce the same shadow:

But they don’t. This is because the earth is round, and not flat:

Eratosthenes (276-194 BCE) used this principle to calculate the circumference of the Earth quite accurately. To see this demonstrated, refer to my experiment video about Eratosthenes and the circumference of the earth – “The Earth’s curvature is tasty!“.

(5) Seeing Farther from Higher

Standing in a flat plateau, you look ahead of you towards the horizon. You strain your eyes, then take out your favorite binoculars and stare through them, as far as your eyes (with the help of the binocular lenses) can see.

Then, you climb up the closest tree – the higher the better, just be careful not to drop those binoculars and break their lenses. You then look again, strain your eyes, stare through the binoculars out to the horizon.

The higher up you are the farther you will see. Usually, we tend to relate this to Earthly obstacles, like the fact we have houses or other trees obstructing our vision on the ground, and climbing upwards we have a clear view, but that’s not the true reason. Even if you would have a completely clear plateau with no obstacles between you and the horizon, you would see much farther from greater height than you would on the ground.

This phenomena is caused by the curvature of the Earth as well, and would not happen if the Earth was flat:

(6) Ride a Plane

If you’ve ever taken a trip out of the country, specifically long-destination trips, you could notice two interesting facts about planes and the Earth:

• Planes can travel in a relatively straight line a very long time and not fall off any edges. They can also, theoretically (and some do, though with stops along the way), circle the earth.
  Correction (Courtesy of Klaynos, from scienceforums.net): Apparently, planes can circle the Earth without stopping!
• If you look out the window on a trans-Atlantic flight, you can, most of the times, see the curvature of the earth in the horizon. The best view of the curvature used to be on the Concorde, but that plane’s long gone. I can’t wait seeing the pictures from the new plane by “Virgin Galactic” – the horizon should look absolutely curved, as it actually is from a distance.

(A picture of the curved horizon from a Concorde plane can be seen here).

(7) Look at Other Planets

The Earth is different from other planets, that much is true. After all, we have life, and we haven’t found any other planets with life (yet). However, there are certain characteristics all planets have, and it will be quite logical to assume that if all planets behave a certain way, or show certain characteristics – specifically if those planets are in different places or were created under different circumstances – our planet is the same.

In other words: If so many planets that were created in different locations and under different circumstances show the same property, it’s likely that our own planet has the same property as well. All of our observations show planets are spherical (and since we know how they’re created, it’s also obvious why they are taking this shape). Unless we have a very good reason to think otherwise (which we don’t), our planet is very likely the same.

In 1610, Galileo Galilei observed the moons of Jupiter rotating around it (click here to see a beautiful video reconstruction of his observations). He described them as small planets orbiting a larger planet – a description (and observation) that was very difficult for the church to accept as it followed a geocentric model where everything was supposed to revolve around the Earth. This observation also showed that the planets (Jupiter, Neptune, and later Venus was observed too) are all spherical, and all orbit the sun.

A flat planet (ours or any other planet) would be such an incredible observation that it would pretty much go against everything we know about how planets form and behave. It would not only change everything we know about planet formation, but also about star formation (as our sun would have to behave quite differently to accustom a “flat earth” theory), what we know of speeds and movements in space (like planets orbits, and the effects of gravity, etc). In short, we don’t just suspect that our planet is spherical. We know it.

(8) The Existence of Timezones

The time in New York, at the moment these words are written, is 12:00pm. The sun is in the middle of the sky (though it’s hard to see with the current cloud coverage). In Beijing, where Michael Phelps is likely getting ready for yet another gold medal, it’s 12:00am, midnight, and the sun is nowhere to be found.

In Adelaide, Australia, it is 1:30am. More than 13 hours ahead. There, the sunset is long gone – so much so, that it’s soon going to rise up again in the beginning of a new day. Here’s a list showing what time it is around the world when it is 12:00pm in New York city.

This can only be explained if the world is round, and rotating around its own axis. At a certain point when the sun is shining on one part of the Earth, the opposite side is dark, and vise versa. That allows for time differences and timezones, specifically ones that are larger than 12 hours.

Another point concerning timezones, the sun and flat/spherical Earth: If the sun was a “spotlight” (very directionally located so that light only shines on a specific location) and the world was flat, we would have seen the sun even if it didn’t shine on top of us (as you can see in the drawing below). The same way you can see the light coming out of a spotlight on a stage in the theater, even though you – the crowd – are in the dark. The only way to create two distinctly separate timezones, where there is complete darkness in one while there’s light in the other, is if the world is spherical.

(9) The Center of Gravity

There’s an interesting fact about mass: it attracts things to it. The force of attraction (gravity) between two objects depends on their mass and the distance between them. Simply said, gravity will pull toward the center of mass of the objects. To find the center of mass, you have to examine the object.

Consider a sphere. Since a sphere has a consistent shape, no matter where on it you stand, you have exactly the same amount of sphere under you. Imagine an ant (perhaps the same one from the previous point) walking around on a crystal ball. Assuming the crystal ball is polished, the ant’s only indication of movement would be the fact it’s moving its feet. The scenery (and shape of the surface) would not change at all.

Consider a flat plane. The center of mass of a flat plane is in its center (more or less – if you want to be more accurate, feel free to do the entire [shriek] integration [shriek] process), and the force of gravity will pull a person toward the middle of the plain. That means that if you stand on the edge of the plane, gravity will be pulling you toward the middle, not straight down like you usually experience.

I am quite positive that even for Australians an apple falls downwards, but if you have your doubts, I urge you to try it out – just make sure it’s nothing that can break or hurt you. Just in case gravity is consistent after all.

Further reading about the center of mass and about distribution of mass can be found here. And if you are brave enough to handle some equations (not involving integration), you can learn some more about Newton’s Law of Universal Gravitation.

(10) Images from Space

In the past 60 years of the space exploration era of humanity’s history, we’ve launched satellites, probes and people to space. Some of them got back, some of them still float through the solar system (and almost beyond it) and transmit amazing images over to our receivers on Earth.

Here’s a list of some of the pictures we’ve seen from space throughout the years:

October 24, 1946: A group of scientists in the New Mexico desert saw the first grainy photo of the Earth. The photograph was taken from a height of 65 miles (104.6 kilometers) by a 35-millimeter motion picture camera riding on a V-2 missile.

August 14, 1959: First crude photo of the Earth from the Explorer VI satellite. The photo showed a sun-lit area of the Pacific ocean and cloud coverage. It was taken from about 17,000 miles (27,350 kilometers) above the surface.

(Image Courtesy of the NASA GRIN Website)

June 5, 1966: Astronaut Eugene Cernan took this amazing picture of Gemini 9 and the Earth during his EVA (Extravehicular Activity). The spacecraft itself and Cernan’s “umbilical” (the cord that keeps him connected to the spacecraft’s systems) are visible on top of a beautiful background of the Earth.
(Image Courtesy of the NASA GRIN Website)

August 23, 1966: First view of Earth from the Moon. This picture was taken by Lunar Orbiter I when the spacecraft was on its 16th orbit and was just about to pass behind the Moon. (Image Courtesy of the NASA GRIN Website)

December 29, 1966: A spectacular view of the rising Earth from the Moon, taken by the crew of Apollo 8 after coming out from the other side of the Moon, approximately 239,000 miles (384,000 kilometers) from Earth.

(Image Courtesy of the NASA GRIN Website)

December 1, 1968: Photo of Earth from Apollo 8. This photograph was taken by an 80-mm lense, at a point very close to the Moon.

(Image Courtesy of the NASA GRIN Website)

More pictures from the NASA Missions throughout the years can be found at NASA GRIN Website: http://grin.hq.nasa.gov/index.html

Brief List of Manned Missions to Space

In the past 60 years humanity’s quest for Space has produced hundreds of pictures, videos and audio records from more than just the United States. Some of these countries used to be enemies. Some still are. The amount of proofs, from opposing countries and ’sides’, for the non-flatness of the Earth, if nothing else, should cast serious doubt on any possibility for the existance of “Global Conspiracy”. Here is an abbreviated list of some of the first missions to space:

• April 12, 1961 (USSR; Vostok-1): Yuri Gagarin, becomes first man in space.
• May 5, 1961 (USA; Mercury-3): Alan Shepard becomes first American in space.
• July 21, 1961 (USA; Mercury-4): Gus Grissom performs the second sub-orbital flight at an altitude of 126 miles (203 kilometers).
• August 6, 1961 (USSR; Vostok-2): Gherman Titov becomes the first man to spend an entire day in space.
• February 20, 1962 (USA; Mercury-6): John Glenn orbits the Earth at a distance of 100-162 miles (161-261 kilometers).
• May 24, 1962 (USA; Mercury-7): Scott Carpenter orbits the Earth three times.
• August 11, 1962 (USSR; Vostok-3): Andrian Nikolayev leads the first four-day flight, and first “group” flight with Vostok-4.
• August 12, 1962 (USSR; Vostok-4): Pavel Popovich mans the other half of the “group” flight with Vostok-4.
• October 3, 1962 (USA; Mercury-8): Walter Schirra orbits the Earth six times.
• May 15, 1963 (USA; Mercury-9): Gordon Cooper pilots the longest (and last) Mercury mission, lasting 34 hours in space.
• June 14, 1963 (USSR; Vostok-5): Valery Bykovsky is the first to stay 5 days in space.
• June 16, 1963 (USSR, Vostok-6): Valentina Tereshkova becomes the first woman in space, spending three days in orbit.

You can find a full list of the chronology of manned space missions at the University Corporation for Atmospheric Research.

More Methods Throughout History

• Abu Rayhan Biruni (sometimes known as “The Father of Geodesy“), has managed to calculate the circumference of the Earth using complex triangulation equations. I couldn’t find the actual calculation, or the method, so I can’t judge it this as a relatively easy “DIY” way to do it, but it’s still worth mentioning. If anyone has any more information about the method used, do post in the comments.
• Bedford Level Experiment: At the Bedford river in Norfolk, England. The experiments were done initially in order to prove that the Earth is flat. Though the first results of this experiment seemed to agree with the flat-earth contention, later attempts to repeat this experiment agreed with the fact that the Earth is, in fact, spherical.
• A Bit of History: Neil Armstrong narrating this video of the Earth as viewed from the Apollo 11 Command Module on its way to the Moon.

Extra Credits and Thanks

This is a very long post, but it was fun to write (and learn about!). There is some credit due to other people, and I am not one to hold out the cheers:

• Klaynos, from scienceforums, for his Physics mastery late at night.
• insane_alien from scienceforums, for directing me on the path of a good #9.
• Cap’n Refsmmat from scienceforums, for clarity issues, physics help, and saving you (the reader) some of my ramblings.
• Keren, for her editorial help and general (good) advice.
• Daniel and KerenG, for their mental and grammatical support.

Extra Resources

• Who figured out the Earth is round?

  http://starchild.gsfc.nasa.gov/docs/StarChild/questions/question54.html

• Earth from Space (from NASA)

  http://earth.jsc.nasa.gov/sseop/efs/

• First Photo from Space 1946: http://www.airspacemag.com/space-exploration/FEATURE-FirstPhoto.html
• History Channel’s “History of Space Exploration” interactive website (with Videos):
• http://www.history.com/minisite.do?content_type=Minisite_Generic&content_type_id=51655&display_order=5&mini_id=1438
• Non stop flight around the world: http://www.didyouknow.cd/aroundtheworld/flight.htm
• Foucault Pendulum (in Wikipedia)

  http://en.wikipedia.org/wiki/Foucault_pendulum

• Galileo Galilei (in Wikipedia): http://en.wikipedia.org/wiki/Galileo_Galilei
• Galileo’s Observations and Inventions: http://www.2020site.org/galileo/observations.html
• Spherical Earth (in Wikipedia)

  http://en.wikipedia.org/wiki/Spherical_Earth

• The Flat Earth: http://www.lhup.edu/~dsimanek/flat/flateart.htm
• Lunar Eclipse (in Wikipedia)

  http://en.wikipedia.org/wiki/Lunar_eclipse

• History of Geodesy (in Wikipedia)

  http://en.wikipedia.org/wiki/History_of_geodesy

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

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/

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