Archive for May, 2011

About Eggs

Tuesday, May 17th, 2011

eggs.jpgWe eat them cooked any one of half a dozen ways in the morning.  We use them in cakes and cookies and as a meringue on lemon pies.  The particularly ambitious cook may use them in a mousse or a soufflé.  (For eggs in cooking, revisit Physics in the Kitchen.)  But have you ever stopped to think about how amazing the egg really is?

We all know that eggs should be handled carefully because their shells are incredibly thin.  Drop an egg a short distance and you have a gooey mess to clean up.  One simple tap on the edge of the counter is enough to crack open the shell.  But try this experiment: hold an egg in the palm of your hand and curl your fingers around it.  Now squeeze with all your might.

Did it break?  If you didn’t believe me and didn’t squeeze with all your strength, go back and try again.

What on Earth…?  The key to an eggshell’s strength is the fact that its whole surface is curved.  The strongest shape is a sphere, and an egg is a close approximation of this.  (The reason it’s not exactly a sphere in just a moment.)  With no corners or flat sides to weaken it, the forces you apply to the egg by curling your fingers around it are distributed equally over the egg rather than concentrating at any one point. 

This works even in the following way. Hold the top and bottom of the egg with your thumb and forefinger and squeeze.  Did it break this time?  In physics terms, we say that the egg has a high “compression strength” — you’re compressing the egg, but it doesn’t break!  In fact, an egg has such high compression strength, that (with the proper setup) it can support the weight of a small person without breaking.

So why aren’t eggs spherical?  The oval shape is created as the bird lays it, and this turns out to be an advantage for the hen.  The shape prevents the eggs from rolling away!  Spherical eggs would roll and roll and roll… and never return.  For birds like ostriches that nest on the ground, this isn’t an issue, and their eggs are generally more spherical.  But birds that nest on cliffs often lay very conical eggs, which roll in a tight circle around the narrow end and remain on the ledge.

What else?  How can you tell if your egg is fresh?  Eggs contain an air pocket that forms when its contents shrink as it cools after being laid.  As the egg ages, moisture evaporates and the air cell grows larger, reducing the average density of the egg.  An object floats in a liquid if it is less dense than the liquid and an object denser than the liquid sinks.  We can therefore use the egg’s density as a handy measure of the egg’s freshness!  Here’s how it works.  Place your egg in a container of water.  A fresh egg with a small air pocket will rest horizontally on the bottom.  The air pocket in a 1-week-old egg is slightly larger — its density is less — and the end will hover slightly off the bottom, and an egg that’s 2-3 weeks old — even less dense — will rest vertically on the bottom.  Don’t eat any eggs that float!

Now that you know so much about eggs, here’s a bonus question: what do eggs and Roman arches have in common? 

PS. When squeezing your egg: don’t wear any rings, and make sure your egg doesn’t have any cracks already.  My “research” egg was blessed with a crack and I ended up with a handful of broken shell and raw egg oozing between my fingers and onto the floor!

Numbers and Nature

Wednesday, May 11th, 2011

banana2.jpgDid you know that bananas have five sides?  Not sure?  Pick up a banana and count the sides.  Bet you there are five.

How many one- or two-petalled flowers have you ever seen?  Probably not many.  They are relatively rare in nature.  Flowers with three petals are more common, those with five petals more common still.  But flowers with four or six petals are few and far between.

What’s the deal?  The answer lies with Fibonacci.

Leonardo Fibonacci was born in Pisa, Italy, around 1170 and spent several years in Algeria with his father, a wealthy merchant.  Roman culture had spread widely in Europe by the Middle Ages and the Roman numeral system was commonly used for arithmetic.  While addition and subtraction are relatively easy with the system, anything more advanced — even multiplication or division — is difficult; the lack of zero poses a particular problem.  In Algeria, Fibonacci learned of the Hindu-Arabic numeral system and recognized the simplicity and efficiency of mathematics in this system compared to the Roman system.  He traveled throughout the Mediterranean, studying under many leading Arab mathematicians, and returned to Pisa around 1200.  The publication of his book Liber Abaci (Book of Calculation) two years later helped to popularize the Hindu-Arabic numeral system in Europe, becoming the numeral system we still use today.

In Liber Abaci, Fibonacci introduced a number sequence that solved a problem relating to the growth of a population of rabbits generation by generation assuming some idealized constraints.  This number sequence had been known to Indian mathematicians since the 6th century, but after publication of his book, it became known as the “Fibonacci sequence.”

In the Fibonacci sequence, each number is the sum of the two preceding numbers, starting with 0 and 1:

0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, 377, 610, …

(In mathematical terms, we can write this as Fn = Fn-1 + Fn-2, with F0 = 0 and F1 = 1.)

The amazing thing about the Fibonacci sequence (aside from rabbit populations, of course) is that numbers in the sequence occur regularly in nature.  Look at your banana again.  Five sides – a Fibonacci number.  The most common flowers have 3, 5, 13, 21 petals – again, Fibonacci numbers.

In other cases, pairs of consecutive Fibonacci numbers determine the pattern of seeds in a sunflower, fruitlets on a pineapple, or scales on a pinecone.  Let’s look at the chamomile flower as an example.

fibonaccichamomile.png

To get the most compact arrangement, the florets are arranged in a spiral pattern, and — surprise! — the number of spirals corresponds to Fibonacci numbers!  Highlighted in turquoise in the picture are the florets spiraling counterclockwise.  Count the spirals, and you get 13.  Now count the number of spirals circling in the opposite direction.  Another Fibonacci number!

The next time you have a pinecone or pineapple in hand, look for the Fibonacci numbers.  (Hint: the pineapple has three.)  Where else do you find the Fibonacci numbers in nature?  We’d love to hear from you!

Merging Art and Science

Saturday, May 7th, 2011

Do you paint, write, dance, sing or sculpt?  Are you an artist who is inspired by science?  CERN may be the place for you.

The science that goes on at the laboratory has long been an inspiration for artists.  One current artist you may have heard of is Kate McAlpine, otherwise known as the rap artist Alpinekat.  She rose to fame with her hit Large Hadron Rap, which describes the Large Hadron Collider and its related science at CERN.  Check out that video and others here.

CERN, the French acronym for the European Organization for Nuclear Research, is a high-energy physics laboratory located mostly in Switzerland.  It is here that the largest accelerator in the world, the Large Hadron Collider, is located.  It spans the Swiss-French border about 330 ft (100 m) underground.  This instrument is essentially a ring, 88 ft (27 m) in diameter, consisting of a series of superconducting magnets.  The magnets serve to accelerate subatomic particles that are then smashed together in one of several detectors, each the size of a house.  The result is a spectacular computer display of brightly colored lines that look something like this:

atlas-minbias-event-300×2971.gif

It’s easy to see why science here can inspire artists.

Just look at the movie Angels & Demons.  Dan Brown was inspired by science at the lab when he wrote his book.  In it, the bad guys steal a canister of antimatter from a secret underground lab at CERN, and portions of the movie were filmed at the ATLAS experiment at the lab (check out the multimedia tab on the website).

Now, with ever increasing interest in merging art and science, a new experiment is taking place at CERN.  Called Great Arts for Great Science, the goal is to bring artists to the lab where they can connect with scientists and, through their art, bring science into a broader cultural setting.  And broad it is.  The gallery on the website shows examples of sculpture, music, photography, and dance.  The organization behind the project is due to Ariane Koek, a cultural specialist dedicated to arts development at CERN.  As part of the initiative, a residency program for artists at the lab is expected to launch this year, which is predicted to ease the flow of information between artists and scientists.  Artists will have the opportunity to visit the lab and talk with scientists, and support their artistic work with scientific knowledge.

But do you think this inspiration moves only from scientist to artist?  Surprisingly, the cultural exchange happens in both directions.  Great scientists often use creative thinking in solving a particularly difficult problem.  Just think of Leonardo da Vinci.  During the Renaissance, there were no strong divisions between art and science as there are today.  In spite of his work as an artist, da Vinci used his creativity to design various barricades, bridges and flying machines.  Or consider the names of the moons orbiting around Uranus.  Astronomers were inspired by the names of characters in the works of William Shakespeare and Alexander Pope.  By bringing artists to CERN, scientists will have the opportunity to tap into their artistic side and think more creatively about their projects and science in general.

As the advising scientist for Great Arts for Great Science, Michael Doser says, “Science can provide understanding, while art can provide meaning to the human enterprise.” 

By bridging art and science, we can more easily see the relevance of basic research to society and science can be allowed to engage within the larger cultural context.  There is a tight relationship between art and science in that both are ways of exploring our existence: what it means to be human and where we are in the universe.