BLACK HOLES by Ted Bunn What is a black hole? --------------------- Loosely speaking, a black hole is a region of space that has so much mass concentrated in it that there is no way for a nearby object to escape its gravitational pull. Since our best theory of gravity at the moment is Einstein's general theory of relativity, we have to delve into some results of this theory to understand black holes in detail, but let's start of slow, by thinking about gravity under fairly simple circumstances. Suppose that you are standing on the surface of a planet. You throw a rock straight up into the air. Assuming you don't throw it too hard, it will rise for a while, but eventually the acceleration due to the planet's gravity will make it start to fall down again. Now imagine an object with such an enormous concentration of mass in such a small radius that its escape velocity was greater than the velocity of light. In general relativity, gravity is a manifestation of the curvature of spacetime. How big is a black hole?
Chaos Theory for Beginners; An Introduction Life finds a way beauty of the unpredictable and display it in the most awesome patterns. Nature, when looked upon with the right kind of eyes, presents herself as one of the most fabulous works of art ever wrought. What is Chaos Theory? Chaos Theory is a mathematical sub-discipline that studies complex systems. Complex systems are systems that contain so much motion (so many elements that move) that computers are required to calculate all the various possibilities. But there is another reason that Chaos Theory was born so recently, and that is the Quantum Mechanical Revolution and how it ended the deterministic era! Up to the Quantum Mechanical Revolution people believed that things were directly caused by other things, that what went up had to come down, and that if only we could catch and tag every particle in the universe we could predict events from then on. How Chaos Theory was born and why. Hold that thought (7): The Uncertainty Principle prohibits accuracy. Attractors
What is String Theory? For the past decade, physicists all over are focusing their attention on string theory. But what is string theory? A simple explanation to string theory is that it is the basic fundamental building block for everything. When all the matter in the universe is broken down to its most basic component, it will be tiny particles that look like strings; String Theory. That basically is the most simple answer to what String Theory is. But going one step further is where things get really complicated. When we look an object, we know it is made up of molecules. According to string theory, these quarks (including the electron) can still be broken up into smaller units. What string theory suggests is that the whole universe is made up of these strings. Based on the math, for these strings to exists, the universe has to be made up of not just three dimensions, but ten dimensions. Video: David Tong, a physicist at Cambridge University, explains String Theory Why is string theory important? Related Links
How can parts of Canada be 'missing' gravity?" For more than 40 years, scientists have tried to figure out what's causing large parts of Canada, particularly the Hudson Bay region, to be "missing" gravity. In other words, gravity in the Hudson Bay area and surrounding regions is lower than it is in other parts of the world, a phenomenon first identified in the 1960s when the Earth's global gravity fields were being charted. Two theories have been proposed to account for this anomaly. But before we go over them, it's important to first consider what creates gravity. One theory centers on a process known as convection occurring in the Earth's mantle. A new theory to account for the Hudson Bay area's missing gravity concerns the Laurentide Ice Sheet, which covered much of present-day Canada and the northern United States. To get a better idea of what happened, think about what happens when you lightly press your finger into the surface of a cake or a piece of really springy bread. So which theory is correct?
Codes Daniel Chandler Codes In 1972 NASA sent into deep space an interstellar probe called Pioneer 10. It bore a golden plaque. The art historian Ernst Gombrich offers an insightful commentary on this: The National Aeronautics and Space Administration has equipped a deep-space probe with a pictorial message 'on the off-chance that somewhere on the way it is intercepted by intelligent scientifically educated beings.' The representation of humans is accompanied by a chart: a pattern of lines beside the figures standing for the 14 pulsars of the Milky Way, the whole being designed to locate the sun of our universe. Gombrich's commentary on this attempt at communication with alien beings highlights the importance of what semioticians call . Some theorists argue that even our perception of the everyday world around us involves codes. Images such as this are ambiguous concerning figure and ground. The principle of can be demonstrated thus: The principle also applies in the illustration below.
Penn Gazette | Essays | Notes from the Undergrad By Andrew Newburg | Yawn. Go ahead: Laugh if you want (though you’ll benefit your brain more if you smile), but in my professional opinion, yawning is one of the best-kept secrets in neuroscience. Even my colleagues who are researching meditation, relaxation, and stress reduction at other universities have overlooked this powerful neural-enhancing tool. However, yawning has been used for many decades in voice therapy as an effective means for reducing performance anxiety and hypertension in the throat. Several recent brain-scan studies have shown that yawning evokes a unique neural activity in the areas of the brain that are directly involved in generating social awareness and creating feelings of empathy. For these reasons I believe that yawning should be integrated into exercise and stress reduction programs, cognitive and memory enhancement training, psychotherapy, and contemplative spiritual practice. Why am I so insistent? My advice is simple.
Features of the year Embryonic stem cells, dating rocks on other celestial bodies and controversies on human guinea pigs were some of the most popular in-depth stories of the year. Stem-cell research: Never say die With a history of public blunders, can Advanced Cell Technology make embryonic stem-cell therapies a reality? 11 January 2012 Human experiments: First, do harm In the 1940s, US doctors deliberately infected thousands of Guatemalans with venereal diseases. 8 February 2012 The split brain: A tale of two halves Since the 1960s, researchers have been scrutinizing a handful of patients who underwent a radical kind of brain surgery. 14 March 2012 Life-changing experiments: The biological Higgs Biologists ponder what fundamental discoveries might match the excitement of the Higgs boson. 28 March 2012 Neuroscience: The mind reader Adrian Owen has found a way to use brain scans to communicate with people previously written off as unreachable. 13 June 2012 Planetary science: The time machine 25 July 2012 5 December 2012