Sunday, January 29, 2012
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.
Monday, January 16, 2012
|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.
Thursday, January 5, 2012
Sculpture of Einstein’s equation at the
2006 Walk of Ideas, Berlin, Germany.
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.
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.|
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.