The Galapagos Penguin

One of the most-marvelous creatures that exhibits the ability of life to adapt to its surroundings is the Galapagos penguin. The Galapagos penguin is the most-northerly of all penguins, being native to the Galapagos Islands of Fernandina and Isabela. They are the smallest warm-weather penguins, standing about 40 to 45 cm high and weighing in at about 2 to 2.5 kg.
   This little penguin has a black head and topside, with a thin white line extending from the throat to the corner of the eye. They are white underneath, with two black bands extending across the breast. The Galapagos penguin has a long, skinny bill that is black on the upper part and the tip of the lower part. The rest of the bill and a bare surrounding patch is pinkish yellow. The female Galapagos penguin is usually smaller than the male. Juveniles have a dark head, and lack the dark bands across the breast that the adults have.
   These penguins are excellent divers. To reduce their buoyancy they only breathe in what they think they will need. They are 10 times better at storing oxygen in their muscles than other birds and can also store huge amounts of oxygen in their bloodstream. As they deplete this oxygen their unique blood chemistry avoids the acidic buildup that other animals would experience, which in turn lets them avoid muscle fatigue.
   Life near the equator is challenging for these birds. Penguins have many adaptations for surviving in very cold water. Insulating feathers, a thick, underlying layer of fat, and specialized blood heat exchange makes it difficult for them to deal with the tropical heat when on land. To survive the heat, they have evolved with special anatomical and behavioral adaptations. Their small size helps them to dissipate heat when on land. They also have shorter feathers than other penguin species which also makes heat loss easier. Galapagos penguins seek out shade when on land. They are able to dissipate heat by increasing the blood flow to their flippers, feet, and face. They have proportionately-larger flippers than Antarctic penguins, increasing the surface area for heat exchange. They are able to direct blood flow and bypass their heat-transfer system when in cold water.
   The Galapagos penguin has a very small breeding range and is the only penguin that lives entirely within the tropics. They prefer to breed in rock crevices, caves, or lava tubes that shade them and their chicks. They feed near shore in the cool, nutrient-rich Cromwell current, where there is an abundance of prey year-round. During El Niño years the current does not upwell and their population suffers as a result. The Galapagos penguin is considered endangered with numbers ranging from 1,000 to 1,500 individuals.

The Betelgeuse Supernova

Betelgeuse in the Orion constellation.

Betelgeuse, also known as Alpha Orionis, is the second-brightest star in the constellation of Orion. Betelgeuse could have a shock in store for us sometime in the next million years. It is classified as a red supergiant star, meaning that it’s enormous and very unstable. If it were our sun, it would extend out to the orbit of Jupiter. Betelgeuse is about to explode as a type II supernova. When it does it will shine like a second sun in our sky because it is relatively close, only 640 light years away. A star that goes supernova is one of the most-violent events in the cosmos and can briefly outshine a whole galaxy. 

  When a red giant has reached the end of its life and used up nearly all of its fuel, it can no longer counter gravity’s pull with heat pressure from it’s core. By this time, the core has fused hydrogen into helium, helium into carbon, carbon into oxygen, oxygen into neon, neon into silicon, and silicon into iron. Fusion stops with iron because it is so stable that no more energy can be achieved by fusing it. 
  By now the core is losing its desperate fight against gravitational collapse. Fusion of silicon into iron only takes about two weeks. When it runs out, the core collapses immediately and in less than a second it reaches the density of an atomic nucleus. This is like driving into a brick wall and bouncing off. The core rebounds and recollapses over and over, and the shockwave heats up the rest of the star to temperatures in the range of millions to billions of degrees. The outer layers of the star is blown away at speeds approaching 30,000 km/s, or 1/10th the speed of light. The total energy created is about 100 times more than the total energy our sun will produce in its 10 billion year lifespan, all within a few seconds. If it happened in our lifetime It would be one of the most-spectacular astronomical events ever.
  It is through the violence of a supernova explosion that elements heavier than iron are forged. That is because there is no net-energy gain when heavier elements fuse—they can’t be created in the hearts of stars. So the gold from your jewelry was formed by a supernova, then spread into space in the expanding shell of the supernova remnant where it mixed with other material in the Milky Way and this became the raw material for the next generation of stars and planets, including our own solar system.
  Betelgeuse is easy to spot in the night sky, as part of the famous constellation Orion and because of its distinctive orange-red color. In the Northern Hemisphere it can be seen rising in the east just after sunset during winter. By mid-March, Betelgeuse can be seen in the southern sky at night and is visible to virtually all the inhabited parts of the globe. The next time you are out stargazing, look for this amazing star—maybe it will put on the show of a lifetime for us some day.

The Equation That Changed the World

Sculpture of Einstein’s equation at the 

2006 Walk of Ideas, Berlin, Germany.

Albert Einstein is perhaps most-famous for his equation E = mc², yet many don’t understand its true meaning. Einstein described his equation this way: “It followed from the special theory of relativity that mass and energy are both but different manifestations of the same thing. A somewhat unfamiliar conception for the average mind. Furthermore, the equation E is equal to m c-squared, in which energy is put equal to mass, multiplied by the square of the velocity of light, showed that very small amounts of mass may be converted into a very large amount of energy and vice versa. The mass and energy were in fact equivalent according to the formula mentioned before…”
  This would be proven experimentally by Cockcroft and Walton in 1932, when they developed the first particle accelerator and used it to smash protons into a lithium target to produce alpha particles. They had split the atom. Six years later nuclear fission would be discovered.

The original Cockcroft and Walton experiment.
They bombarded a lithium target with protons,
splitting the atom to create two alpha particles
and converting some of its mass to energy.

  In 1939, the Austro-Hungarian physicist Leó Szilárd would approach his old friend and cohort Einstein with a letter which he intended to send to President Roosevelt. The letter was an attempt to convince Roosevelt that the U.S. should begin research on creating an atom bomb, fearing that the Nazis—who were trying to develop just such a weapon—would get the bomb first. Szilárd wanted Einstein to lend his fame and credibility to the proposal. Einstein signed the letter and it resulted in the creation of the Manhattan Project.
  Both Einstein and Szilárd would come to regret that letter. They were against using the atom bomb against civilians and thought that simply demonstrating the power of the bomb would be enough to force Japan’s surrender. After the war, Szilárd was so horrified by atomic weapons that he gave up physics for molecular biology.

The Einstein-Szilárd letter that was sent to President Roosevelt.

  In 1950, Szilárd proposed a new kind of bomb using cobalt. The proposal was not meant to be taken seriously as a weapon, but as a wake-up call to point out that it would soon be possible to destroy all life on Earth. Ironically, Szilárd was diagnosed with bladder cancer in 1960 and underwent cobalt therapy that he himself designed. The cancer returned two years later and he was forced to undergo a second round of treatments with an increased dosage. His doctors thought that the increased radiation would kill him, but he disagreed and thought that it was his only chance to beat the cancer. The increased dose did end up working and his cancer didn’t return. This became the standard treatment for many forms of cancer and is still used today when more modern methods are unavailable.
  Incidentally, E = mc² is just part of Einstein’s equation, and only describes the energy of an object at rest. The full equation is E² = (mc²)² + (pc)², where p is the momentum. If the object is at rest then it has zero momentum and the equation reduces to E = mc². If the object is a massless particle like a photon, then the equation reduces to E = pc, which means that the energy of a massless particle is equal to its momentum multiplied by the velocity of light.

String Theory (continued)

Let’s continue with our discussion of string theory from last week, which says that all matter can be broken down to a fundamental particle, called a string. Atom are made up of protons, neutrons, and electrons. Electrons aren’t made of anything smaller. Protons and neutrons can be broken down further into quarks, which also can’t be broken down any further. For this reason, quarks and electrons are referred to as fundamental particles. Even though quarks and electrons behave very differently, string theory says that they are actually very similar, and that the differences between them are due to these strings vibrating at different frequencies, similar to how a violin makes different sounds.

   The most interesting thing about string theory is that it requires extra dimensions of space. These curled-up dimensions are too small to see or experience. There are a great many ways of curling up these extra dimensions. String theory require seven extra curled up dimensions, so when added to our three familiar dimensions of space plus time we get a total of 11 dimensions.

   You can think of multi-dimensional space as a garden hose. If the hose is viewed from far away, it appears to have only one dimension—length. Now think of a ball small enough to enter the hose. Such a ball would move more or less in one dimension. However, viewed close-up, one discovers that the hose contains a second dimension—its circumference. For an ant crawling inside, it would move in two dimensions. This extra dimension is only visible when up-close, or if the ball we use is small enough compared to the hose.

The CMB temperature fluctuations from WMAP data seen over the full 

sky. The average temperature is 2.725 degrees Kelvin, and the colors 

represent small temperature fluctuations. Red areas are warmer and 

blue areas are colder by about 0.0002 degrees.

   It might be possible to detect gravitons indirectly. Remember, gravitons are the hypothesized fundamental particles that carry the force of gravity. Experiments are in progress to detect gravitational waves and although these experiments cannot detect individual gravitons, they could provide information about gravitons. Gravitational waves were hypothesized by Einstein whenever two massive bodies are in tight orbit with one another, such as the binary white dwarf stars discusses previously in this column.

   At the Large Hadron Collider (LHC), scientists will soon be ready to run at energies high enough to allow for the testing of extra dimensions as predicted by string theory. The thinking is that if they can smash particles together at high enough energies, part of the collision debris might escape into an extra dimension. By calculating the total energy before and after such a collision, they can see if less energy is present after the collision. If so, it could mean that energy is flowing to an extra dimension.

   The Cosmic Microwave Background (CMB) radiation might also contain clues about strings. It is interesting to think that in the first moments after the big bang, all the matter of the Universe was contained in an extremely hot, dense stew of fundamental string particles. If so, we might be able to look for an imprint in the background radiation as the universe inflated.

   NASA’s Wilkinson Microwave Anisotrophy Probe (WMAP) has been gathering information about the nature of the Universe for nine years, finishing in September 2010, and has provided us with some fascinating information, mapping the CMB radiation to produce a map of the microwave sky, revealing what the Universe went through during the first trillionth of a second (inflation). The Planck space observatory, a project underway by the European Space Agency, will improve on this by a factor of three and is scheduled to deliver final results near the end of 2012.

String Theory

One of the toughest problems in physics is unifying Einstein’s theory of general relativity, which describes gravity on a large scale, with quantum mechanics, which describes the other three fundamental forces acting on the atomic scale. Finding this “theory of everything” has stirred great debate in the scientific community. Devising experiments to test it has been unsuccessful so far, but that may soon change.

   After Einstein finished his work on general relativity, he spent the next three decades of his life trying to expand his theory of gravitation to include electromagnetism (the strong and weak nuclear forces had not yet been discovered). This search left Einstein isolated from the main body of physics which was consumed by the emerging field of quantum mechanics, and which Einstein never fully embraced. In the early 1940s, Einstein wrote “I have become a lonely old chap who is mainly known because he doesn’t wear socks and is exhibited as a curiosity on special occasions.” In 1950, he described his unified field theory and although his work was ahead of its time, his efforts were ultimately unsuccessful. Einstein’s dream of unifying the fundamental forces of nature would have to wait for physics and mathematics to catch up.

The worldsheet on the left shows a string splitting apart and 

the worldsheet on the right shows two strings joining together. 

The arrows indicate the direction of travel through spacetime.

   Since then, theoretical physicists have taken up the challenge. The most successful theory thus far is string theory. At its essence, string theory is an attempt at describing gravity at the quantum level. In string theory, all fundamental particles are not point like, but instead made out of tiny, one-dimensional, vibrating loops of string—like incredibly small rubber bands. These strings use gravitons to exchange the force of gravity back and forth. A graviton is a hypothetical particle that is itself another little loop of string. You start with a loop of string and that string splits in half, creating a second string. If you have many strings doing this at the same time, every once in a while the split strings will get mixed up with one another and exchange back and forth, and that is the origin of gravity in string theory. This splitting and joining can be viewed diagrammatically as a worldsheet. A worldsheet is the name coined by Leonard Susskind for a two-dimensional surface which describes the embedding of a string in spacetime.

   Leonard Susskind is widely regarded as the father of string theory. In 1969, he and other physicists began to explore the possibility that particles were made up of strings. What they discovered, to their amazement, was that these particles behaved as if they had gravitational forces between them. Split off little pieces, exchange them, and they create forces very similar to gravity.

   Initially, string theory was intended to describe protons and neutrons. But the strings that physicists describe now are a billion billion times smaller than a proton. Much smaller than we can see with any kind of microscope that exists and smaller than anything that can be detected by the Large Hadron Collider. Because of this, graviton detection is impossible. Even if we could build a detector the size of Jupiter, we would only be able to observe one graviton every 10 years at best and it would be impossible to distinguish it from a neutrino. And a neutrino shield would be so massive that it would collapse into a black hole!

   Next week we will finish up our discussion of string theory by talking about why it requires extra spacial dimensions and what experiments are underway to test string theory.

White Dwarfs

Three illustrations showing white dwarfs 

orbiting each other and then colliding.

Our Sun is said to be a main sequence star, meaning that it fuses hydrogen to form helium. What happens when it exhausts its supply of hydrogen fuel? Once hydrogen fusion stops, there is not enough pressure on the star's core to create a fusion reaction with helium. Because there is no longer any outward push from fusion, the star begins to collapse from the crush of gravity. This collapse create more and more pressure in the core until helium fusion begins, while some of the remaining hydrogen burns outside of the core. The products of helium fusion is carbon and oxygen. The star expands and becomes a red giant. Its life as a red giant is brief on an astronomical scale—only a few million years. It will then eject its outer layers as it reaches the end of its burn cycle, leaving behind a collapsed core known as a white dwarf surrounded by a planetary nebula. 
  A white dwarf is the final evolutionary state of about 97% of all the stars contained in the Milky Way. White dwarfs are very dense—they pack a mass comparable to that of our Sun into a volume similar to the size of our Earth. A white dwarf is composed mostly of the fusion products of helium: carbon and oxygen. It is also surrounded by a thin layer of helium, and sometimes hydrogen. Fusion quickly stops so the white dwarf has no source of energy and will cool over many billions of years, eventually to the point where it no longer shines at all.
  Astronomers have recently found two white dwarfs stars orbiting one another once every 39 minutes. Binary white dwarfs are exceedingly rare. Out of the 100 billion stars in our galaxy, only a few dozen have been found. Located about 7,800 light-years away in the constellation Cetus, these two stars orbit each other at a distance less than that from the Earth to the Moon.
  The fate of these stars is already determined. Because they orbit one another so closely, they produces gravitational waves, ripple-like distortions in spacetime that were predicted by Albert Einstein in his theory of general relativity. The gravitational waves carry away orbital energy, which has put the stars in an ever-tightening spiral. In about 40 million years, they will crash into one another and merge to form a new star. If their combined mass were more they would collide and turn supernova, but since they aren't massive enough, they will be reborn and begin to shine once again.

The Mystery of Antimatter

Despite the apparent variety of materials in the world around us, we know that everything is made of one thing: matter. But when the universe was born about 14 billion years ago in the Big Bang, two types of matter were created: ordinary matter, which we and everything around us are made, and antimatter, a kind of opposite version of matter. The existence of antimatter was first predicted by the British physicist Paul Dirac in 1928. We know antimatter exists because we can find traces of it in cosmic rays and because scientists have made small amounts of it in particle accelerators. The universe is vast, but it seems to be made almost entirely of matter. So where did all the antimatter go?

Experimental area at CERN’s Antiproton Decelerator The actual antiproton decelerator ring is behind the concrete shielding seen on the left.

   When matter and antimatter come into contact, they annihilate each other, creating vast amounts of energy in the process. A reaction between on gram of matter and one gram of antimatter would release the same energy as exploding 43,000 tons of dynamite. We think that equal amounts of matter and antimatter were created in the Big Bang, but something happened in the first few minutes after the Big Bang to shift the balance in favor if matter so that when matter and antimatter destroyed each other, some matter was left over. This was the matter that went on to form the universe that we know today. Physicists don’t understand why there was an imbalance between matter and antimatter. In fact, this is one of the biggest mysteries in science today. What we do know is that antimatter is a mirror-like reflection of matter, but not quite. Antimatter is said to violate CP-symmetry (CP stands for charge and parity), meaning that there is not total cancellation between particles and their antiparticles. Understanding this process will help us understand why we live in a universe made of matter and not antimatter. But to really understand antimatter we need an experiment that can recreate the conditions just after the Big Bang. 

   Scientist at the European Organization for Nuclear Research (CERN) are attempting to do just that with several ongoing antimatter experiments. Antimatter is difficult to create but even more difficult to keep without it reacting. CERN’s Antiproton Decelerator holds the antiparticles before injecting them into one of several ongoing experiments. They can hold antiparticles for up to 1,000 seconds—a lifetime in the realm of particle physics. These experiments all have one thing in common: they want to pinpoint the differences in antimatter when compared to matter. It is their hope that someday this mystery of the universe will be solved.