Friday, December 21, 2007

'Top 10' Famous Quotes

www.famous-quotes-and-quotations.com/
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Albert Einstein

I want to know God's thoughts... the rest are details.

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Wayne Gretzky

100% of the shots you don't take don't go in.

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Lewis Carroll, Alice's Adventures in Wonderland

'Would you tell me, please, which way I ought to go from here?'

'That depends a good deal on where you want to get to,'said the Cat.

'I don't much care where --' said Alice.

'Then it doesn't matter which way you go,' said the Cat.

'--so long as I get somewhere,' Alice added as an explanation.

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M.K. Gandhi

An eye for eye only ends up making the whole world blind.

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Dr. Napoleon Hill

Whatever the mind can conceive and believe, the mind can achieve.

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Wolfgang Amadeus Mozart

Neither a lofty degree of intelligence nor imagination or both together go to the making of genius. Love, love,love, that is the soul of genius.

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Zig Ziglar

You can have everything in life that you want if you just give enough other people what they want.

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Mark Twain

Keep away from people who try to belittle your ambitions. Small people always do that, but the really great make you feel that you, too, can become great.

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Samuel Johnson

Great works are performed, not by strength, but by perseverance.

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Blaise Pascal

I made this letter longer than usual because I lack the time to make it short.

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Larry Wilde, The Merry Book of Christmas

Never worry about the size of your Christmas tree. In the eyes of children, they are all 30 feet tall.

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Helen Steiner Rice

Peace on earth will come to stay,

When we live Christmas every day.

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www.1000ventures.com/business_guide/crosscuttings/mind_how-it-works.html

Limited Attention Span

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The limited attention span means that only part of your memory surface can be activated at any one time. "This limited attention span is extremely important for it means that the activated area will be a single coherent area and that single coherent area will be found in the most easily activated part of the memory surface. The most easily activated area or pattern is the most familiar one, the one which has been encountered most often, the one which has left most trace on the memory surface. And because a familiar pattern tends to be used it becomes ever more familiar. In this way the mind builds up that stock of present patterns which are the basis of code communication."

Mental Patterns

Mental pattern is a memory trace formed in your brain tissue to record something that you have experienced. As you see, hear, feel, smell, sense or taste something over and over, your brain builds a pattern of it.When you experience it again, or something like it, your brain activates the existing memory trace or patterned thinking and you go on autopilot.

Your Brain Can Process Only Positive Information

The language of brain are pictures, sounds, feelings, tastes and smells, i.e. inputs from your senses. Your brain cannot work with negative information, i.e. inputs you haven't experienced. It can work only with positive information, i.e. "information from the experiences of your five senses, which it then manipulates in the emotional blender we call the imagination."

Can You Reflect and Act at the Same Time?

Well... sort of. Reflecting and acting at the same time is very difficult as our mind can only hold one thought at a time. You can be going through periods of reflection and action at the same time but at any specific moment in time you are only spending energy in one of these two areas. You need to be focused on either reflection or action at one point and then be able to switch quickly and effortlessly to the other polarity when required. This is an important point to remember when you are considering focus and balance your life.

Left Brain / Right Brain

Research on brain theory helps you understand why some people are excellent inventors but poor producers or good managers but weak leaders. The research indicates that the brain is divided into two hemispheres, the left and the right, and that each hemisphere specializes in different functions, processes different kinds of information, and deals with different kinds of problems. The left brain works more with logic and analysis, the right works more with emotions and imagination. *As we apply brain dominance theory to the three essential roles of organizations, we see that the manager's role primarily would be left brain and the leader's role right brain. The producer's role would depend upon the nature of the work. If it's verbal, logical, analytical work, that would be essentially left brain; if it's more intuitive, emotional, or creative work, it would be right brain. People who are excellent managers but poor leaders may be extremely well organized and run a tight ship with superior systems and procedures and detailed job descriptions. But unless they are internally motivated, little gets done because there is no feeling, no heart; everything is too mechanical, too formal, too tight, too protective. A looser organization may work much better even though it may appear to an outsider observer to be disorganized and confused. Truly significant accomplishments may result simply because people share a common vision, purpose, or sense of mission.*

The Brain Likes to Race Ahead

Once your mind gets moving in a direction, be it a left-brain direction (logical, mathematical, judgmental, analytical activities) or a a right-brain one (creative, visual, spatial concepts), it tends to keep going. To illustrate this, try this easy test suggested by Timothy Foster:

What do you call a funny story? – joke

What are you when you have no money? – broke

What's another word for Coca Cola? – Coke

What's the white of an egg? --------------

It isn't yolk, it's albumen. Were you tricked? Most people are. The brain likes to race ahead, because it already knows the answer.

Divide Your Time Between the Left-Brain and Right-Brain Activity

If you keep bouncing back and forth between creative and analytical activities, you'll get a headache and won't produce your best results. Analysis, evaluation and judgment get in the way of creativity. That's why in brainstorming sessions we suspend judgment while we generate ideas. Similarly, radical innovation project managers apply the loose-tight leadership technique to divide time between divergent and convergent thinking by their team members at different project stages.

Your Brain Cannot Think While It Focuses on Two Sensory Inputs

Research shows that "when a person is thinking actively (as documented with EEG equipment) and then focuses on one perceptual happening such as sound, a tactile sensation, or an image, the brain waves remain basically the same and thoughts continue flow through the mind. We can expand our mind's attention to include one perceptual input and still keep thinking actively without loosing our concentration on our thoughts. However, when the human mind focuses on two distinct sensory inputs at the same time (a sound and an image, for instance, or breath and heartbeat), all thoughts almost immediately stop flowing through the mind."

Memorization Problems: Solved!

Have you ever had problems in remembering names, numbers, grocery items needed, and other little details such as the location where you placed your car keys this morning? The truth is, we all have our moments of forgetting little bits of information that matters at the exact moment we need them. But did you know that memorization techniques boil down to two basic things?... More

Mediation

Meditation is the most powerful mind tool ever developed. Meditation has been scientifically proven to improve creativity, intelligence, memory, alertness, and to integrate left and right brain functioning. It has been shown to improve physical, mental, and emotional health... More

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www.answerbag.com/q_view/114342

If You Go Fast Enough, Does Time Slow Down?

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Yes. The closer you approach the speed of light, the slower time passes for you. This is a basic property of Relativity.

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This is a very complex question to answer, but I'll take my best shot at it. I will start, however, not by talking about time, but by talking about distances. Imagine you are holding a ruler and looking at its shadow. You're holding it in a plane parallel to the wall, and the shadow and ruler are the same length, which is one foot. Let's choose right and left as the "x-axis" and up and down as the "y-axis".You're holding the ruler parallel to the x-axis. The shadow of the ruler is now one foot along the x-axis, and just a point on the y-axis. If you rotate the ruler 45 degrees (still in the plane parallel to the wall), now the distance of the shadow along the x- and the y-axis is about 0.7. So, when rotated, the distance the ruler "projects" along x and y changes. But it doesn't just change randomly, it changes in a way that's related to the overall length of the ruler, specifically, according to the Pythagorean theorem: x^2 + y^2 = 1 foot.We are used to thinking about all three spatial dimensions being related in this way. In all three dimensions, no matter how it's oriented in space, if you take it's projection along x, y, and z, and sum the squares, you'll get 1 foot. The ruler's length is "invariant" with regard to its rotation or position in space.Einstein's insight with relativity is that this is *not* actually the case. In fact, Einstein figured out that the ruler's overall length is actually affected by its velocity relative to the observer!So, now imagine the ruler in empty space, floating around. If you are hovering next to it, and the ruler is not moving relative to you, you will observe its length to be one foot. However, at the very same moment you make your observation, if I come whizzing past you and the ruler at a constant velocity, I'll observe the ruler as being shorter than the 1 foot long ruler I'm holding. (Actually, I'll see compression of your ruler only if it is not perpendicular to my direction of motion--if it's perpendicular, then I'll still measure it to be one foot.)So what happened to that extra distance? How can *your* ruler be squeezed by *my* motion? And furthermore, how can it appear squeezed only to me, but not to you? Even more confusingly, from *your* perspective, it's *my* ruler that's squeezed and yours is 1 foot, same as its ever been!Let's go back to the wall and the shadow. You're holding your ruler it's in the plane parallel to the wall and at 45 degrees to the x-axis (and so is the shadow on the wall). Now, if you rotate it slightly *out of plane* so that it's no longer in the plane parallel to the wall, the overall length of the shadow is no longer 1 foot, it's shorter. This is because there's now some component unaccounted for in the z direction, perpendicular to the wall. The ruler shadow on the wall is a useful analogy because you can imagine you're a 2D shadow person looking at the ruler shadow with no comprehension of the z dimension perpendicular to the wall. If you're a 2D shadow person, you've lived on the wall all your life and have no idea that there's a world off your wall. To you, forward, backward, up, and down are the only directions that exist..."out" and "in" would not be comprehensible to you. In fact, you'd have no comprehension of the actual ruler itself, you would only be able to comprehend the ruler's shadow. So, when I, from my 3D view, rotate the ruler into the z dimension, to you, the shadow appears compressed.Back into space...when I'm whizzing past you and the ruler, Einstein says that your ruler is slightly "rotated", but in not in x, y, or z. Rather, it's rotated slightly in the fourth dimension of time. It turns out that if two things are moving relative to each other, those objects appear to each other as having a small component rotated in the unseen time dimension. The amount of rotation is proportional to the relative velocity.Now consider that z-dimension. Before the rotation out of wall's plane, the ruler had no component of distance perpendicular to the wall, but after, it has a slight distance in the z dimension. This is where the analogy breaks down a little bit, but not completely. The main point is this: the distance of the ruler's projection in z changed.So, from the 3D perspective trying to understand the 4D world of space-time the ruler is rotating into this unseen fourth dimension (the "time" dimension), what affect will that have? The answer: time will have slowed down. So, now if we imagine that our rulers have a little digital clock embedded in them (I got one of these once at a trade show and though, wow! A relativity measuring device!), the ruler I zip past will tick seconds slower than mine. Just like when I rotate my ruler in front of the wall, the shadow not only compresses, but there's now distance in z, when I "rotate" the ruler in space-time (by having a velocity relative to it), it has distance in that unseen dimension that manifests as slower seconds ticking by. It's very difficult to get more in-depth than this without getting into complex math, but I hope this gives you a good overview!

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A simple "yes" does not suffice because time doesn't slow down for some observers. That's the point of my entire entry--if you read it and truly understand what I'm saying, then you should understand that time will only slow down only for clocks traveling at velocity relative to the observer. The faster the relative velocity, the more time slows in other reference frames. (It never slows in your own reference frame.)Sorry I couldn't be more concise with my answer, but relativity doesn't lend itself to short answers for the uninitiated. :-)

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Yes because the total speed of an object through the dimension of space and the dimension of time equals the speed of light. An object moving through space must subtract from its movement through time for the sum to remain at lightspeed. So an object at the speed of light has all its movement through space and its movement through time must equal zero. Inversly a stationary object has all its movement through time and none through space. Making the quickest way to travel into the future is to stop moving.

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Time is not slowing down when you go fast.In that case we would be doomed if another Olympic Champion runs again Oo

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You do realise you would have to be going very fast for this to work. Research the theory of relativity.

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No, time slow down is just a perception. For example,you leave the earth at a very high speed(neglect the process of accelerate). On one hand,you can observe the clock on the earth is slow down. While on the reference frame of yourself, there is no change of the time. On the other hand, people on the earth will also feel that the clock of yours has slowed down. Maybe you can take the following link as reference: http://en.wikipedia.org/wiki/Twin_paradox

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This is only correct if you neglect the process of acceleration, and neglecting acceleration is the basis of the twins paradox. However, one thing to note here is that, if you do take into account acceleration, then the traveller will age less than the Earth in the round trip out and back to Earth. So, that means people on Earth watching the clock on the ship will see it ticking slower, and even after they calculate the time it takes for the light to reach them from the ship, the ship's clock will stay behind a clock on Earth the entire duration of the trip.

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Actually even at fast speeds, just the difference is so tiny it is hard to notice.

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The perception of time slows down, but time itself doesn't slow down. It can't. It's not a physical entity that can be affected by speed. Our bodies, on the other hand, can be affected by great speed. If we were to travel extremely close to the speed of light for 20 regular, non-space traveling years, It wouldn't feel like that long. Our bodies would have only aged a short time. It's a hard concept to grasp, but very interesting when you think about it long and hard.

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Time does slow down- check einsteins theory. They put a clock on a speedy satellite and it was way behind in weeks.

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I'm sorry, but if you're only perceiving time to slow down, why would your body age more slowly by traveling close to the speed of light? Wouldn't time actually have to slow down to have that kind of effect? What I'm getting at is that you're right about what happens when you travel at speeds approaching the speed of light. But time actually DOES slow down for the object that is traveling at those speeds. It is not just a perception. It is something that actually has relevance in our daily lives, as well. GPS devices and satellite phones have to address this concern because of a very slight temporal lag that their linked satellites experience.

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Im afraid time does slow down and it may not be something physical you can touch, but it is effected by other physical properties such as speed an gravity.

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I’m not a physicist but my understanding is that time slows down for an object travelling at speed relative to other objects that are not moving or objects that are travelling slower. The passage of time is relative to the observer; this is difficult for me to explain with out using maths but basically it mean that if you were travelling on a super fast train approaching the speed of light, from your perspective time would be passing normally. You would not be able to tell that time was running slower because it is only running slower relative to an observer i.e. a man standing at the side of the rail tack watching you passing by. In principle this means time is passing faster for the man at the side of the railway track than for you travelling on the train, therefore the longer you stay on the train travelling at such high speed the greater time difference will occur between you and the observer. Theoretically you could get on the train in the year 2007 and travel at high speed before getting off the train in the year 2057. From you perspective only a short period of time will have past whereas relatively the world around you will have aged many years. I believe this theory has actually been proven and documented on a smaller scale by flying and aeroplane around the world at high speed with an atomic clock onboard. The atomic clock was perfectly in sync with another atomic clock on the ground; the experiment showed that the clock on the aeroplane had lost time by a few fractions of a second relative to the clock on the ground. Unfortunately it is currently thought to be impossible to travel even close to light speed due to many factors for example the energy requirement necessary for constant acceleration increases exponentially the closer to light speed you travel another factor connected to this is the fact the mass increases as speed increased (which means more weight) and more gravity, so any manmade craft travelling at such high speed would be implode under its own mass. I think the rate of acceleration necessary to reach light speed within the pilot’s lifetime without crushing the pilot under g-force is probably a consideration also along with other factor that I wont go into. M Eves

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I somehow don't believe this theory; If I am on a spaceship, travelling at light speed , then is my heart beat is going to slowdown? My heartbeat can be my clock. I can close my eyes while I am on the spaceship to avoid any perception-related illusions. I suppose my heart must keep beating for me to stay alive.

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The time in the spaceship would stay the same because everything in the spaceship is moving at the speed of light. Time around the space ship would slow down.

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By Chris Miller By Chris Miller
http://www.eclipse.net/~cmmiller/DM/
Copyright © 1995 by Chris Miller, all rights reserved.
This text may be freely redistributed among individuals in any medium so long as it remains unedited and appears with this notice. Any commercial or republication requires the written permission of the author.

Cosmic Hide and Seek: the Search for the Missing Mass

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Scientists using different methods to determine the mass of galaxies have found a discrepancy that suggests ninety percent of the universe is ma tter in a form that cannot be seen. Some scientists think dark matter is in the form of massive objects, such as black holes, that hang out around galaxies unseen. Other scientists believe dark matter to be subatomic particles that rarely interact with ordinary matter. This paper is a review of current literature. I look at how scientists have determined the mass discrepancy, what they think dark matter is and how they are looking for it, and how dark matter fits into current theories about the origin and the fate of the universe. In 1933, the astronomer Fritz Zwicky was studying the motions of distant galaxies. Zwicky estimated the total mass of a group of galaxies by measuring their brightness. When he used a different method to compute the mass of the same cluster of galaxies, he came up with a number that was 400 times his original estimate (1). This discrepancy in the observed and computed masses is now known as "the missing mass problem." Nobody did much with Zwicky's finding until the 1970's, when scientists began to realize that only large amounts of hidden mass could explain many of their observations (2). Scientists also realize that the existence of some unseen mass would also support theories regarding the structure of the universe (3). Today, scientists are searching for the mysterious dark matter not only to explain the gravitational motions of galaxies, but also to validate current theories about the origin and the fate of the universe.

Mass and Weight.

What exactly is mass? Most people would say that mass is what you weigh. But to scientists, mass and weight are different things. Mass is the measure of a quantity of matter--how much stuff there is. Weight, on the other hand, is the effect that gravity has on that stuff. Weight is dependent on mass--the more mass you have, the more gravity pulls you down, and the more you weigh. When an astronaut floats in space, we say that the astronaut is weightless. But the astronaut still has a body, and so has mass.

Hide and Seek.

Scientists estimate that 90 to 99 percent of the total mass of the universe is missing matter (4). Actually, "missing matter" may be misleading--it's really the light that is missing (5). Scientists can tell that the dark matter is there, but they cannot see it. Bruce H. Margon, chairman of the astronomy department at the University of Washington, told the New York Times, "It's a fairly embarrassing situation to admit that we can't find 90 percent of the universe" (6). This problem has scientists scrambling to try and find where and what this dark matter is. "What it is, is any body's guess," adds Dr. Margon. "Mother Nature is having a double laugh. She's hidden most of the matter in the universe, and hidden it in a form that can't be seen" (5).

Determining the Mass of Galaxies

How do we measure the mass of the universe? Since the boundaries (if there are any) of the universe are unknown, the actual mass of the universe is also unknown. But scientists talk of the missing mass of the universe in percentages, not real numbers. Since the majority of the matter that we can see is clumped together into galaxies, the total mass of all the galaxies should be a good indication of the mass of the universe. Although it isn't possible to add up an infinite number of galaxies, scientists can infer the percentage of the universe's missing mass from estimates of the missing mass in galaxies and clusters of galaxies (7). And because scientists (like Fritz Zwicky) use different techniques to determine the masses of galaxies, they can perceive mass that they cannot see.

The Doppler Shift.

One of the tools that scientists use to detect the motions of galaxies is the Doppler Shift. The Doppler Shift was discovered in the 1800's by Christian Doppler when he noticed that sound travels in waves much like waves on the surface of the ocean (7). Doppler also noticed that when the source of the sound is moving, the pitch of the sound is different, depending on whether the source is moving toward or away from the observer. Take, for example, the horn on a train. As the speeding train passes by you, the sound of the horn changes to a lower pitch. This is the Doppler Shift. When the train approaches, the sound waves get pushed together by the motion of the train. As the train speeds away, the sound waves get stretched out. The Doppler Shift also works with light. When a light source is moving toward you, the light becomes bluer (called a blue shift). When a light source is moving away from you, the light becomes redder (called a red shift). And the faster something is moving, the farther the light is shifted. But the Doppler shift for light is very subtle and cannot be detected with the naked eye. Scientists use a device called a spectroscope to measure Doppler Shift and determine how fast stars and galaxies are moving (7).

Rotational Velocity.

Using the power of the Doppler Shift, scientists can learn much about the motions of galaxies. They know that galaxies rotate because, when viewed edge-on, the light from one side of the galaxy is blue shifted and the light from the other side is red shifted. One side is moving toward the Earth, the other is moving away. They can also determine the speed at which the galaxy is rotating from how far the light is shifted (7). Knowing how fast the galaxy is rotating, they can then figure out the mass of the galaxy mathematically. As scientists look closer at the speeds of galactic rotation, they find something strange. The individual stars in a galaxy should act like the planets in our solar system--the farther away from the center, the slower they should move. But the Doppler Shift reveals that the stars in many galaxies do not slow down at farther distances. And on top of that, the stars move at speeds that should rip the galaxy apart; there is not enough measured mass to supply the gravity needed to hold the galaxy together (7). These high rotational speeds suggest that the galaxy contains more mass than was calculated. Scientists theorize that, if the galaxy was surrounded by a halo of unseen matter, the galaxy could remain stable at such high rotational speeds.

Seeing the Light.

Another method astronomers use to determine the mass of a galaxy (or cluster of galaxies) is simply to look at how much light there is. By measuring the amount of light reaching the earth, the scientists can estimate the number of stars in the galaxy. Knowing the number of stars in the galaxy, the scientists can then mathematically determine the mass of the galaxy(1). Fritz Zwicky used both methods described here to determine the mass of the Coma cluster of galaxies over half a century ago. When he compared his data, he brought to light the missing mass problem. The high rotational speeds that suggest a halo reinforce Zwicky's findings. The data suggest that less than 10% of what we call the universe is in a form that we can see (8). Now scientists are diligently searching for the elusive dark matter--the other 90% of the universe.

Dark Matter

What do scientists look for when they search for dark matter? We cannot see or touch it: its existence is implied. Possibilities for dark matter range from tiny subatomic particles weighing 100,000 times less than an electron to black holes with masses millions of times that of the sun (9). The two main categories that scientists consider as possible candidates for dark matter have been dubbed MACHOs (Massive Astrophysical Compact Halo Objects), and WIMPs (Weakly Interacting Massive Particles). Although these acronyms are amusing, they can help you remember which is which. MACHOs are the big, strong dark matter objects ranging in size from small stars to super massive black holes (1). MACHOs are made of 'ordinary' matter, which is called baryonic matter. WIMPs, on the other hand, are the little weak subatomic dark matter candidates, which are thought to be made of stuff other than ordinary matter, called non-baryonic matter. Astronomers search for MACHOs and particle physicists look for WIMPs. Astronomers and particle physicists disagree about what they think dark matter is. Walter Stockwell, of the dark matter team at the Center for Particle Astrophysics at U.C. Berkeley, describes this difference. "The nature of what we find to be the dark matter will have a great effect on particle physics and astronomy. The controversy starts when people made theories of what this matter could be--and the first split is between ordinary baryonic matter and non-baryonic matter" (10). Since MACHOs are too far away and WIMPs are too small to be seen, astronomers and particle physicists have devised ways of trying to infer their existence.

MACHOs

Massive Compact Halo Objects are non-luminous objects that make up the halos around galaxies. Machos are thought to be primarily brown dwarf stars and black holes (2). Like many astronomical objects, their existence had been predicted by theory long before there was any proof. The existence of brown dwarfs was predicted by theories that describe star formation (7). Black holes were predicted by Albert Einstein's General Theory of Relativity (11).

Brown Dwarfs.

Brown dwarfs are made out of hydrogen--the same as our sun but they are typically much smaller. Stars like our sun form when a mass of hydrogen collapses under its own gravity and the intense pressure initiates a nuclear reaction, emitting light and energy. Brown dwarfs are different from normal stars. Because of their relatively low mass, brown dwarfs do not have enough gravity to ignite when they form (7). Thus, a brown dwarf is not a "real" star; it is an accumulation of hydrogen gas held together by gravity. Brown dwarfs give off some heat and a small amount of light (7).

Black Holes.

Black holes, unlike brown dwarfs, have an over-abundance of matter. All that matter "collapses" under its own enormous gravity into a relatively small area. The black hole is so dense that anything that comes too close to it, even light, cannot escape the pull of its gravitational field (11). Stars at safe distance will circle around the black hole, much like the motion of the planets around the sun (7). Black holes emit no light; they are truly black.

Detecting MACHOs

Astronomers are faced with quite a challenge with detecting MACHOs. They must detect, over astronomical distances, things that give off little or no light. But the task is becoming easier as astronomers create more refined telescopes and techniques for detecting MACHOs.

Searching with Hubble.

With the repair of the Hubble Space Telescope, astronomers can detect brown dwarfs in the halos of our own and nearby galaxies. Images produced by the Hubble Telescope, however, do not reveal the large numbers of brown dwarfs that astronomers hoped to find. "We expected [the Hubble images] to be covered wall to wall by faint, red stars," reported Francesco Paresce of the Johns Hopkins University Space Telescope Science Institute in the Chronicle of Higher Education (5). Research results are disappointing--calculations based on the Hubble research estimate that brown dwarfs constitute only 6% of galactic halo matter (12).

Gravitational Lensing.

Astronomers use a technique called gravitational lensing in the search for dark matter halo objects. Gravitational lensing occurs when a brown dwarf or a black hole passes between a light source, such as a star or a galaxy, and an observer on the Earth. The object focuses the light rays, causing the light source to brighten (13). Astronomers diligently search photographs of the night sky for the telltale brightening that indicates the presence of a MACHO. Wouldn't a MACHO block the light? How can dark matter act like a lens? The answer is gravity. Albert Einstein proved in 1919 that gravity bends light rays (13). He predicted that a star, which was positioned behind the sun, would be visible during a total eclipse. Einstein was right--the gravity of the sun bent the light rays coming from the star and made it appear next to the sun. Not only can astronomers detect MACHOs with the gravitational lens technique, but they can also calculate the mass of the MACHO by determining distances and the duration of the lens effect (13). Although gravitational lensing has been known since Einstein's demonstration, astronomers have only begun to use the technique to look for MACHOs in the past two or three years. Gravitational Lensing projects include the MACHO project (America and Australia), the EROS project (France), and the OGLE project (America and Poland). Preliminary data from these projects suggest the existence of lens objects with masses between that of Jupiter and the sun (9).

Circling Stars.

Another way to detect a black hole is to notice the gravitational effect that it has on objects around it. When astronomers see stars circling around something, but cannot see what that something is, they suspect a black hole. And by observing the circling objects, the astronomers can conclude that, indeed, a black hole does exist. In January of 1995, a team of American and Japanese scientists announced "compelling evidence" for the existence of a massive black hole at the American Astronomical Society meeting (14). Led by Dr. Makoto Miyosi of the Mizusawa Astrogeodynamics Observatory and Dr. James Moran of the Harvard-Smithsonian Center for Astrophysics, this group calculated the rotational velocity from the Doppler shifts of circling stars to determine the mass of the black hole. This black hole has a mass equivalent to 36 million of our suns (15). While this finding and others like it are encouraging, MACHO researchers have not turned up enough brown dwarfs and black holes to account for the missing mass. Thus, most scientists concede that dark matter is a combination of baryonic MACHOs and non-baryonic WIMPs.

WIMPs

In their efforts to find the missing 90% of the universe, particle physicists theorize the existence of tiny non-baryonic particles that are different from what we call "ordinary" matter. Smaller than atoms, Weakly Interactive Massive Particles are thought to have mass, but usually interact with baryonic matter gravitationally--they pass right through ordinary matter. Since each WIMP has only a small amount of mass, there needs to be a large number of them to make up the bulk of the missing matter. That means that millions of WIMPs are passing through ordinary matter--the Earth and you and me--every few seconds (8). Although some people claim that WIMPs were proposed only because they provide a "quick fix" to the missing matter problem, most physicists believe that WIMPs do exist (4). According to Walter Stockwell, astronomers also concede that at least some of the missing matter must be WIMPs. "I think the MACHO groups themselves would tell you that they can't say MACHOs make up the dark matter" (10). The problem with searching for WIMPs is that they rarely interact with ordinary matter, which makes them difficult to detect.

Detecting WIMPs.

All hope of proving WIMPs exist rest on the theory that, on occasion, a WIMP will interact with ordinary matter. Because WIMPs can pass through ordinary matter, a rare WIMP interaction can take place inside a solid object. The trick to detecting a WIMP is to witness one of these interactions. Dr. Bernard Sadoulet and Walter Stockwell at the Center for Particle Astrophysics hope to do just that. Their project involves cooling a large crystal to almost absolute zero, which restricts the motions of its atoms. The energy created by a WIMP interaction with an atom in the crystal will then register on their instruments as heat (8). Because their research is still in progress, there are no results available. A similar WIMP detection project is under way in Antarctica. The AMANDA project (Antarctica Muon and Neutrino Detector Array) is a collaboration of the University of Chicago, Princeton University, and AT&T, which is partially funded by the National Science Foundation. AMANDA scientists are placing detection instruments deep within the Antarctic ice. Instead of using a crystal, like the Berkeley team, the AMANDA group is using the Antarctic ice sheet itself as a WIMP detector (16).

Dark Matter and the Universe

The search for dark matter is about more than explaining discrepancies in galactic mass calculations. The missing matter problem has people questioning the validity of current theories about how the universe formed, and how it will ultimately end.

The Big Bang.

In the mid 1950's a new theory of how the universe formed emerged. The Big Bang theory says that the universe began with a great explosion. The theory evolved from Doppler shift observations of galaxies (17). It seems that, no matter which direction astronomers point their telescopes, the light from the center of the galaxies is red shifted. (Doppler shift caused by rotational velocity can only be detected at the sides of a galaxy.) Observing red-shifted galaxies in every direction implies expansion in all directions an expanding universe. The Big Bang theory is a current model for the origin of our universe which says all the matter that exists was, at one time, compressed into a single point. The Big Bang distributed all the matter evenly in all directions. Then the matter started to clump together, attracted by gravity, to form the stars and galaxies that we see today. The expansion generated by the Big Bang was great enough to overcome gravity. We still see the effects of that force when we see red-shifted galaxies.

Clumping.

One of the problems with the Big Bang theory is its failure to explain how stars and galaxies could form in a young universe that was evenly distributed in all directions. What started the clumping? In a smooth universe, every particle would have the same gravitational effect on every other particle; the universe would remain the same (6). But something supplied the initial gravity to allow galaxies to form. Physicists suggest dark matter WIMPs as the solution. Since WIMPs only affect baryon matter gravitationally, physicists say this dark matter could be the "seed" of galactic formation (6). "We don't have a completely successful model of galaxy formation," explains Walter Stockwell, "but the most successful models to date seem to need plenty of non-baryonic dark matter" (10).

Closed, Open and Flat.

There are three current scenarios that predict the future of the universe (17). If the universe is closed, gravity will catch up with the expansion and the universe will eventually be pulled back into a single point. This model suggests an endless series on Big Bangs and "Big Crunches." An open universe has more bang than gravity--it will keep expanding forever. And the flat universe has exactly enough mass to gravitationally stop the universe from expanding, but not enough to pull itself back in. A flat universe is said to have a critical density of 1. What does the expansion of the universe have to do with the missing mass? The more mass, the more gravity. Whether the universe is closed, open, or flat depends on how much mass there is. This is where dark matter comes into the picture. Without dark matter, critical density lies somewhere between 0.1 and 0.01, and we live in an open universe. If there is a whole lot of dark matter, we could live in a closed universe. Just the right amount of dark matter, and we live in a flat universe. The amount of dark matter that exists determines the fate of the universe.

Many Theories.

Scientists are tossing theories back and forth. Some are skeptical of WIMPs; particle physicists say MACHOs will never account for 90% of the universe. Some, like H.C. Arp, G. Burbage, F. Hoyle, and J.V. Narlikan claim that discrepancies like the dark matter problem discredits the Big Bang theory. In Nature they proclaim, "We do not believe that it is possible to advance science profitably when the gap between theoretical speculation becomes too wide, as we feel it has . . . over the past two decades. The time has surely come to open doors, not to seek to close them by attaching words like 'standard' and 'mature' to theories that, judged from their continuing non-performance, are inadequate" (18). Others say there is no missing mass. In his book, What Matters: No Expanding Universe No Big Bang, J.L. Riley claims that galactic red shift is just the effect of light turning into matter as it ages, and not the universe expanding (19). But most scientists like Walter Stockwell have faith in the Big Bang. "The theorists will come up with all sorts of reasons why this or that can or cannot be and change their minds every other year," he says. "We experimentalists will trudge ahead with our experiments. The Big Bang theory will outlive any of this stuff. It works very well as the overall framework to explain how the universe is today" (10). Now the missing mass problem is threatening humankind's place in the universe again. If non-baryonic dark matter does exist, then our world and the people in it will be removed even farther from the center. Dr. Sadoulet tells the New York Times, "It will be the ultimate Copernican revolution. Not only are we not at the center of the universe as we know it, but we aren't even made up of the same stuff as most of the universe. We are just this small excess, an insignificant phenomenon, and the universe is something completely different" (20). A dark matter discovery could possibly affect our view of our place in the universe. If scientists prove that non-baryonic matter does exist, it would mean that our world and the people in it are made of something which comprises an insignificant portion of the physical universe. A discovery of this nature, however, probably will not affect our day-to-day process of living. "It's hard for me to imagine people getting bothered by the fact that most of the universe is something other than baryonic. How many people even know what baryonic means?" comments Walter Stockwell, "Most of the universe is something other than human. If their philosophy already accepts that humans are not the center of the universe, then saying protons and neutrons aren't the center of the universe doesn't seem like much of a stretch to me" (10). Perhaps the only thing a dark matter discovery will give us is some perspective.

Works Cited

1. West, Michael J. "Clusters of Galaxies." The Astronomy and Astrophysics Encyclopedia. New York: Van Nostrand Reinhold, 1992.
2. Griest, Kim. "The Search for the Dark Matter: WIMPs and MACHOs." Annals of the New York Academy of Sciences. vol 688. 15 June 1993: 390-407.
3. Gribben, John. The Omega Point: The Search for the Missing Mass and the Ultimate Fate of the Universe. New York: Bantam, 1988.
4. Chase, Scott I. "What is Dark Matter?" physics-faq/part2. sci.physics Newsgroup. 5 Dec. 1994.
5. McDonald, Kim A. "New Findings Deepen the Mystery of the Universe's 'Missing Mass'." Chronicle of Higher Education. 23 Nov.1994: A8-A13.
6. Wilford, John Noble. "Astronomy Crisis Deepens As the Hubble Telescope Finds No Missing Mass." New York Times. 29 Nov. 1994: C1-C13.
7. Zeilik, Michael., and John Gaustad. Astronomy: The Cosmic Perspective. New York: John Wiley & Sons, Inc, 1990.
8. Trefil, James. "Dark Matter." Smithsonian. June 1993: 27- 35.
9. Mateo, Mario. "Searching for Dark Matter." Sky and Telescope. Jan. 1994: 20-24.
10. Stockwell, Walter K. E-mail interview. 1 Feb. 1995.
11. McIrvin, Matt. "Some Frequently Asked Questions About Black Holes." physics-faq/part2. sci.physics Newsgroup. 5 Dec. 1994.
12. Asker, James R. "'Missing Mass' Enigma Deepens." Aviation Week & Space Technology. 21 Nov. 1994: 31.
13. Falco, Emilio and Nathaniel Cohen. "Gravity Lenses: A Focus on the Cosmic Twins." Astronomy. July 1981: 18-22.
14. Wilford, John Noble. "New Galactic Evidence of Black Holes." New York Times. 12 Jan. 1995: B9.
15. Miyoshi, Makoto., et al. "Evidence for a Black Hole from High rotation Velocities in a Sub-parsec Region of NGC458." Nature. 12 Jan. 1995: 127-129.
16. National Science Foundation. 1995 Center for Astrophysical Research in Antarctica: Amundsen-Scott South Pole Station. In Library of Congress LC Marvel [Online].
17. Abell, George O., and Marc Davis. "Cosmology." McGraw-Hill Encyclopedia of Science and Technology. 7th ed. New York: McGraw-Hill, 1992.
18. Arp, H.C., et al. "Big Bang contd . . ." Nature. vol 357. 28 May 1992: 287-288.
19. Riley, J.L. What Matters: No Expanding Universe No Big Bang. Plano TX: No Big Bang Publishing Co., 1993.
20. Wilford, John Noble. "Physicists Step Up Exotic Search for the Universe's Missing Mass." New York Times. 26 May 1992: C1-C11.
21. Miller, Christopher M. "Cosmic Hide and Seek: the Search for the Missing Mass" online in Chris Miller's Home Page, 1995.

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History of Refractive Surgery

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Nearsightedness has plagued humanity for centuries, probably since Cave Man days. Attempts to correct it have mostly been the engine driving refractive surgery experiments and leading to our modern LASIK procedures. Ancient Chinese people are said to have slept with sandbags on their eyes, to flatten the corneas and correct for nearsightedness. Leonardo da Vinci in fifteenth century Italy doodled diagrams of the eye and ways vision might be impaired. Nineteenth century Europe came up with a procedure using a spring-mounted mallet to flatten the cornea. Another procedure used a strong rubber band. Luckily for us, eye surgery has become more subtle in recent years. In the U.S., eye drop anesthetics appeared in the mid 19th century, and after the Civil War, some surgeries were done to treat cataracts. They developed a device to measure the cornea’s curvature after cataract surgery (called a keratometer). Also in the 19th century, Dr. Snellen in Holland came up with the vision chart which eye doctors still use today, with the large E at the top. The idea that the shape of the cornea is central in good eyesight has been around for a long time, but no effective action was taken until after a late 19th century Dutch doctor, Leendert Jan Lans, wrote a treatise on how astigmatism could be corrected with certain cuts in the cornea. He did some experiments on rabbits and before long, people in Italy and Germany were doing similar work. Experiments were done in many countries for about fifty years.

20th century progress

• In 1936, Tsutomu Sato in Japan noticed that some people with eye injuries had flatter corneas. Having read Lans’ treatise, he followed it up with surgeries that placed tiny incisions in the cornea to flatten it, and thus laid the foundation for the procedure we know as Radial Keratotomy (RK).

• In 1948, an American Air Force physician noticed that when cockpit windscreens shattered and sent slivers of Perspex into the pilot’s eyes, it was not a great problem. In other words, the pilots’ eyes were able to tolerate the presence of Perspex. So he began designing plastic lenses that could be implanted in the eye. Thus we have the basis of cataract surgery and Intraocular Lenses (IOLs)

• In 1949, a Columbian doctor, Jose Barraquer, used a microkeratome (still used today) to create a corneal flap. He removed it entirely, rather than folding it back as eye surgeons do today. He froze it and then changed its shape with a device called a cryolathe, which precisely shaved a tiny portion of it off. Presumably that thawed-out flap was replaced on the eye and healed up, much as LASIK flaps heal up today.

• During the mid-twentieth century, several Russian eye doctors experimented with RK and determined that 16 incisions or less was enough to correct nearsightedness, and one of them, named Fyodorov, presented convincing evidence that this could be done with great precision to control the exact amount of correction. RK was begun in the U.S. in 1978.

• In 1980, still trying to correct nearsightedness, two American doctors tried using the heat of a carbon dioxide laser to shrink parts of the cornea and thus change its curvature. Now the progress speeded up. Throughout the 1980s and into the 1990s, various lasers were used in Germany and the U.S. and combined with use of a microkeratome to make the corneal flap. The name laser in-situ keratomileusis was coined for this procedure, abbreviated as LASIK. PRK was also developed during these years.

U.S. clinical LASIK trials in the 1990s led to FDA approvals of the excimer laser in LASIK procedures for nearsightedness, farsightedness and astigmatism between 1995 and 1999. Following the FDA approvals, LASIK surgeons hung their shingles out all over the country, and many people had LASIK who shouldn’t have had it. Patient screening has improved greatly, reducing side effects and giving better results for the good candidates. When choosing your
LASIK surgeon, check each doctor’s qualifications and background, and schedule a consultation. Ask how long he or she has been performing LASIK, and how many procedures have been done. With only one pair of eyes, it’s important to trust them only to responsible and qualified eye doctors.

Contact Hummel Eye Associates for more information about LASIK and if the treatment is right for you.

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October 2002
Technology Review
All record of our electronic age could be erased- unless we listen to the new digital preservationists.
Data Extinction

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What's So Hard About Digital Preservation? The naive view of digital preservation is that it's merely a question of moving things periodically onto new storage media, of making sure you copy your files from eight-inch floppy disks to five-and -a-quarter, to three-and-a-half, to CD, and on to the next thing before the old format fades away completely. But moving bits is easy. The problem is that the decoding programs that translate the bits are usually junk withing five years, while the language and operating systems they use are in a state of constant change. Every piece of software, and every data file, is at its heart written to instruct a given piece of hardware to perform certain task. In other words, it is written in the language of a machine, not of humans. Whenever you create a digital thing, be it a document, a database, a program, an image or a piece of music, it is stored in a form that you can't read. "It's like it was written in invisible ink," says jeff Rothenberg, a researcher at Rand, a think tank in Santa Monica, CA. "As soon as it's stored it disappears from human eyes, and you need the right resources to render it visible again, just like invisible ink needs some sort of solvent to be read." Yet rebuilding old hardware or keeping it around forever to interpret nearly extinct software or formats is economically prohibitive: when shippers dropped one of Feinstein's vintage arcade games, shattering it, its original manufacturer calculated the insurance costs to restore the cabinet alone at $150,000, while making new chips for the game- from dies that no longer exist-would have cost millions. Software companies confront the problem of digital preservation everyday as they update their code, making sure it works with the latest hardware and operating systems, while at the same time ensuring that customers can access old files for a reasonable amount of time. But without some sort of digital resusitation, every application-from the original binary codes written in the 1940s to WordPerfect to the latest million-dollar database application-eventually stops working, and every data file eventually becomes unreadable. Every application and every file. The evolution of operating systems- the programss that alllow other programs to run-provides yet another challenge. As Microsoft improves Windows, for example, it introduces new guildlines for programmers, know as application programming interfaces every few months, adding some features and taking others away. In each new release, some interfaces are "deprecaded," meaning that programmers are adviced to stop using them in the software they write. But what does that mean for programs written before the change? Most programs that use deprecaded features will work for a while but they access the underlying architecture in a less direct way than the newer interfaces do, and the program is likely to run more slowly. How long before it stops? Most people actively trying to keep old files and applications opera-tional say that five years is pushing it. "Interfaces change continually," says one Windows developer. "It's like asking how often the beach changes shape. Sometimes big storms come and nothing looks the same" But when programs are painstakingly rewritten to conform to new operating-system guildlines, they eventually become unable to access files created by their own precursors. "I frankly don't expect to have a version of Quicken in 10 years that will be able to read my tax files from today, " says Gordon Bell, who led the development of some of the first minicomputers as vice president of research and development at Digital Equipment, and who now works as a senior researcher at Microsoft's Bay Area Research Center. "Especially anything that is datatbase oriented, with a lot of complexity in the data structure, is difficult to move from one generation to the next"

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