Dancing to the Same Score

One of the most famous experiments in physics is a simple yet profound example of the dual nature of light. It is called the “two-slit experiment.” It was first conducted by English polymath, Thomas Yong around 1800 and validated the wave theory of light, overturning Newton’s corpuscular ideas. Neils Bohr used it to develop the Principle of Complementarity showing that light was both a particle and a wave and no description of light was complete without referencing both. It was also at the heart of Einstein’s famous thought experiment called the EPR Paradox, designed to show the incompleteness of quantum theory. One of the most intriguing aspects of the experiment is that you find exactly what you expect to find. It validates light as both a particle and a wave. How can this be? Well, that is the very question physicists have been trying to answer for over 200 years.

The experiment is very simple. A steady laser beam of light is aimed at a target. Two devices with slits which can be individually opened or closed are placed side by side in the path of the light beam. When only one slit is open, all of the light travels through it and hits a target on the other side of the slit in a bullet fashion. This demonstrates the particle nature of light. When both slits are open, the pattern on the target looks exactly like waves which are interfering with one another. The most puzzling thing is that these same patterns emerge when the light is sent in a steady stream or when one photon is released at a time.

There are two main conclusions which physicists have drawn from this experiment. The first is that you find what you are seeking. If you set up the experiment with one slit to detect particles, that’s what is produced on the target. If you set up the experiment to detect waves, that will be the pattern produced regardless if it is a steady stream of light or one photon at a time.

As physicists attempted to come to grips with these results, some exotic theories arose. Some called into play the hidden variables found in entanglement experiments. Others suggested that each particle somehow “knows” beforehand which path to take so that it mysteriously cooperated with all of the other particles yet to be fired. Einstein even suggested a pilot wave ahead of the particle that served to guide it.

Physicist David Bohm developed a most intriguing theory. He described the two-slit experiment as photons dancing to a musical score. The score came from what he called the Seamless Whole which acted as a pool of information. This Whole included the physicist, the laser, the photons within the laser beam, the slits and the target, or measuring device. After the experiment was set up by the physicist, all elements of it became known to the Whole. For example, the conditions under which the experiment would be conducted was one element in the overall pool of information in the entire system. If the experiment were set up with one slit open to detect particles, that condition became a “known” element in the entire system. The photons then, simply went along with that information. In other words, they danced to that music. When the experimental conditions were changed, i.e., when the music changed, the photons simply did another dance in accordance. The photons didn’t have to have prior knowledge of anything nor was an observer necessary.

Prior to the introduction of Bohm’s theory, all of quantum physics had been absorbed in determining the state of a system in the present and the prediction of how that system would be in the future. This description was muddled in murky probabilities. Bohm’s theory described the genuine motion of particles over time, not just the probability of where any one would be at any one time. This solidified the idea that the universe must be seen as a whole system and that anything which can be said of its individual elements at any one instance is only a partial description at best. Bohm’s theories eventually came to be referred to as Bohmian Mechanics.

One of the interesting features of the two-slit experiment is that it allows a thing to be realized in two different ways. But, our daily experience would lead us to believe the words of Gertrude Stein in that “A rose, is a rose, is a rose.” We can accumulate different sensations of it by looking at it, smelling it and even touching it, but alas, it remains a rose. But, the two-slit experiment demonstrates a thing becoming a wave. That’s like a door knob turning into a sound depending on how you observe it. The entire concept is mind-boggling. Of such things, Heisenberg said, “What we learn about is not nature itself, but nature exposed to our methods of questioning.” Perhaps someday we will have a broader concept of nature that will give the two-slit experiment a fitting context so that we can better understand the question we are asking of it.

Some content excerpted from The Sage Age – Blending Science with Intuitive Wisdom
© 2008 MaAnna Stephenson
Content may be used freely with proper credit and a link to www.SageAge.net

The Power of a Curved Line Known as Gravity

Since ancient times, many people have theorized why things fell toward the Earth. The ancient Greeks, Newton and Einstein have all dramatically expanded our understanding. Even today, it is still a subject of debate as new experiments may shed light on a topic that is as old as the universe itself. Gravity is usually described as an attractive force. But, that force is actually a by-product of the power in a curved line.

Ancient geometers were aware of curved line effects but, the significance of this concept wasn’t attached to gravity until the time of Einstein. The writings of Aristotle stated that all things fell to Earth because everything was made of earthly substances and they were attracted to their natural home. Galileo substantiated this claim by stating that the center point of a pendulum’s swing always pointed toward the Earth, which provided its source of attraction.

Newton also subscribed to this view of attraction, but he expanded it in significant ways. He is credited with giving the affects of gravity a mathematical foundation and directly associating gravity with the mass of an object. For example, an apple has mass. So does the Earth. Since the planet is bigger than the apple, it has more mass and thus, more attraction or gravity. So, an apple falls toward the ground because the Earth’s attractive force is the larger. He applied this idea on a cosmological scale to account for why the planets in our solar system orbited the sun and why moons orbited planets. Because of Newton’s combined knowledge in ancient geometry, alchemy and the use of Calculus to determine acceleration along a curved line, it is amazing that he did not relate this concept to gravity. But, eventually, someone did.

Einstein’s first paper was found to be a special case over a limited range of circumstances, hence its common name of Special Relativity. It did not take into account the affects of gravity. He then developed a more general theory which did. It took him a decade to complete and it revolutionized the model we use to understand what gravity is and how it works.

Einstein stated that mass was not necessarily attractive, it simply bent or curved the space around it and that curve provided the means to move one body toward another. In Special Relativity he showed that spacetime is actually a fabric. In General Relativity he showed how it is bent or deformed by mass.

An easy way to imagine this process is to picture a bowling ball, which represents a planet, at the center of a trampoline, which represents the fabric of spacetime. Since the ball has mass, or weight, it curves the surface of the trampoline a great deal near the center and only a little at the edge. If we set a golf ball near the edge, it has very little mass, so it doesn’t bend the surface very much. If we give the golf ball a little push around the edge, it will circle in a spiral that draws ever closer to the bowling ball.

Here’s the key point Einstein made. The golf ball is merely following a path determined by the curve of the trampoline. The bowling ball is not actively exerting an attractive force. As the golf ball nears the center, the curve is greater hence, the force is greater and it “falls” even faster toward the bowling ball. Einstein showed that the acceleration that one massive object “feels” when it approaches another is what constitutes gravity. In other words, acceleration and gravity are the same phenomenon. Gravity then, is an effect or by-product of the bending of space.

It is unfortunate that most dictionaries and text books still describe gravity as an attractive force, which is often misunderstood to be akin to other types of attractive forces such as magnetism. This concept is misleading in that it attributes the force to the massive body, not to the curve.

There are several reasons to update this notion of attraction. You are not kept on the face of the Earth because it is pulling you down. You stay in place because space is pushing down on you. The moon has less mass than the Earth therefore it curves the space around it less. So, you weigh less on the moon simply because space is pushing on you less there. Einstein’s model also shows how everything in the universe is connected to, and affected by, everything else in the universe.

There is no way to over-emphasize the importance of understanding the nature of gravity to our future knowledge of how the universe came to be, what it is, and how everything in it works. Gravity is, by far, the weakest of the four known forces. This disparity is the monkey wrench that
keeps physicists from being able to generate a Grand Unified Theory. It is hoped that experiments at the new Large Hadron Collider will help identify why the forces aren’t equal and whether gravity could be leaking out of our universe into others, as suggested by Lisa Randall, Professor of theoretical physics at Harvard University.

Some content excerpted from The Sage Age – Blending Science with Intuitive Wisdom
© 2008 MaAnna Stephenson
Content may be used freely with proper credit and a link to www.SageAge.net

Einstein and His Famous Equation

When most people hear the name Einstein, the next thought is usually his famous equation, E=mc2. Believe it or not, Einstein’s Nobel Prize was not awarded for this revolutionary discovery, but for his lesser known paper on the Photo-Electric Effect also published in the same year. A good deal of the confusion about Relativity Theory is that most folks think it is one theory. It is actually three different ideas submitted in three different papers. The equation showing the relationship of energy to mass can be found in an addendum he submitted three months after publishing the Special Theory of Relativity in 1905. He began work on the General Theory of Relativity in 1907 and finished it in 1915. With it, he added the effects of gravity to his original equations and revolutionized how we view the makeup of the universe. And then there’s the confusion about that light speed squared business. What’s that all about?

Einstein’s first paper was titled “On the Electrodynamics of Moving Bodies.” This eventually became known as the Theory of Special Relativity. It dealt primarily with how space and time were related, showing that they were actually two descriptions of the same phenomenon known as 4D spacetime. (A description of spacetime and how it differs from 3D space with an added element of time can be found in my article titled “Dimensions.”) It also explained the time dilation between objects which were moving near the speed of light and those that were moving very slow compared to the speed of light.

The paper showed time to be relative to its frame of reference. For example, if you and a buddy are standing in the aisle of a moving jet and tossing a ball back and forth, the two of you seem to be still and the ball seems to be moving at a normal, slow rate of speed. But, to an observer on the ground the ball, you, your friend, and the jet are all moving at 200 mph. The plane provides you with a different frame of reference than the one the observer on the ground has. Both Galileo and Newton understood this concept and called it an “inertial frame.” Einstein enlarged the inertial frame by stating that everything including you, the jet and the observer on the ground were all moving at speeds far below that of light. When one of the objects in the scenario gets ramped up to light speed, everything changes.

Because of this, no one observer had a privileged frame of reference. In other words, if an event happened and was observed in two different spatial locations, the event might appear to have happened simultaneously to one observer and as two separate events to another observer. The different perspectives were due to each observer’s motion in relation to the event. Therefore, both observations would be correct to each observer respectively. It would be impossible for either observer to claim they saw the event the “right” way.

Just as Einstein’s first paper showed that space and time were two descriptions of one phenomenon, similarly, the addendum to this paper showed that energy and mass were also two descriptions of one phenomenon. Energy and mass are not equal, as is often misquoted. They are intra-convertible. A very small amount of mass can be exchanged for a very large amount of energy, as demonstrated by experiments in atomic and nuclear physics. It’s considered one of the most elegant formulas in all of physics because a few characters demonstrate the complex concepts found in the original equation which is big enough to fill a blackboard.

Einstein applied this equation to whether or not an object of mass, any mass, could be accelerated to the speed of light. That’s also were the c2 part of the equation comes into play. The whole thing is about speed, not light. Let’s roll a rock to see how that works. It’s a rather large rock, so it takes a good deal of energy to get it rolling. The energy from that initial push is now stored in the rock as kinetic energy, which it dissipates as it rolls. Any additional pushes just store more kinetic energy than the can dissipate and now it has velocity. So, when we want to stop the rock from rolling, we have to absorb the extra energy it contains. The kinetic energy is proportional to the speed squared. So, if you give the rock twice the energy it can disperse, it will take four times as much energy to stop it from rolling (twice the energy squared is four times the energy). In Einstein’s equation, c represents the speed of light, emphasis placed on the word “speed.” His famous equation then, is the ratio of the energy required to move a mass proportional to the speed of light squared.

Some content excerpted from The Sage Age – Blending Science with Intuitive Wisdom
© 2008 MaAnna Stephenson
Content may be used freely with proper credit and a link to www.SageAge.net