Heisenberg's Uncertainty Principle

One of the biggest problems with quantum experiments is the seemingly unavoidable tendency of humans to influence the situati­on and velocity of small particles. This happens just by our observing the particles, and it has quantum physicists frustrated. To combat this, physicists have created enormous, elaborate machines like particle accelerators that remove any physical human influence from the process of accelerating a particle's energy of motion.

Still, the mixed results quantum physicists find when examining the same particle indicate that we just can't help but affect the behavior ofquanta -- or quantum particles. Even the light physicists use to help them better see the objects they're observing can influence the behavior of quanta. Photons, for example -- the smallest measure of light, which have no mass or electrical charge -- can still bounce a particle around, changing its velocity and speed.

This is called Heisenberg's Uncertainty Principle. Werner Heisenberg, a German physicist, determined that our observations have an effect on the behavior of quanta. Heisenberg's Uncertainty Principle sounds difficult to understand -- even the name is kind of intimidating. But it's actually easy to comprehend, and once you do, you'll understand the fundamental principle of quantum mechanics.

Imagine that you're blind and over time you've developed a technique for determining how far away an object is by throwing a medicine ball at it. If you throw your medicine ball at a nearby stool, the ball will return quickly, and you'll know that it's close. If you throw the ball at something across the street from you, it'll take longer to return, and you'll know that the object is far away.

The problem i­s that when you throw a ball -- especially a heavy one like a medicine ball -- at something like a stool, the ball will knock the stool across the room and may even have enough momentum to bounce back. You can say where the stool was, but not where it is now. What's more, you could calculate the velocity of the stool after you hit it with the ball, but you have no idea what its velocity was before you hit it.

This is the problem revealed by Heisenberg's Uncertainty Principle. To know the velocity of a quark we must measure it, and to measure it, we are forced to affect it. The same goes for observing an object's position. Uncertainty about an object's position and velocity makes it difficult for a physicist to determine much about the object.

Of course, physicists aren't exactly throwing medicine balls at quanta to measure them, but even the slightest interference can cause the incredibly small particles to behave differently.

This is why quantum physicists are forced to create thought experiments based on the observations from the real experiments conducted at the quantum level. These thought experiments are meant to prove or disprove interpretations -- explanations for the whole of quantum theory.

Source : http://science.howstuffworks.com/innovation/science-questions/quantum-suicide2.htm

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Newton's Laws of Motion

The motion of an aircraft through the air can be explained and described by physical principals discovered over 300 years ago by Sir Isaac Newton. Newton worked in many areas of mathematics and physics. He developed the theories ofgravitation in 1666, when he was only 23 years old. Some twenty years later, in 1686, he presented his three laws of motion in the "Principia Mathematica Philosophiae Naturalis." The laws are shown above, and the application of these laws to aerodynamics are given on separate slides.

Newton's first law states that every object will remain at rest or in uniform motion in a straight line unless compelled to change its state by the action of an external force. This is normally taken as the definition of inertia. The key point here is that if there is no net force acting on an object (if all the external forces cancel each other out) then the object will maintain a constant velocity. If that velocity is zero, then the object remains at rest. If an external force is applied, the velocity will change because of the force.

The second law explains how the velocity of an object changes when it is subjected to an external force. The law defines aforce to be equal to change in momentum (mass times velocity) per change in time. Newton also developed the calculus of mathematics, and the "changes" expressed in the second law are most accurately defined in differential forms. (Calculus can also be used to determine the velocity and location variations experienced by an object subjected to an external force.) For an object with a constant mass m, the second law states that the force F is the product of an object's mass and its acceleration a:

F = m * a

For an external applied force, the change in velocity depends on the mass of the object. A force will cause a change in velocity; and likewise, a change in velocity will generate a force. The equation works both ways.

The third law states that for every action (force) in nature there is an equal and opposite reaction. In other words, if object A exerts a force on object B, then object B also exerts an equal force on object A. Notice that the forces are exerted on different objects. The third law can be used to explain the generation of lift by a wing and the production of thrust by a jet engine.

Source : http://www.grc.nasa.gov/WWW/k-12/airplane/newton.html

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Theory of Relativity

The Theory of Relativity, proposed by the Jewish physicist Albert Einstein (1879-1955) in the early part of the 20th century, is one of the most significant scientific advances of our time. Although the concept of relativity was not introduced by Einstein, his major contribution was the recognition that the speed of light in a vacuum is constant and an absolute physical boundary for motion. This does not have a major impact on a person's day-to-day life since we travel at speeds much slower than light speed. For objects travelling near light speed, however, the theory of relativity states that objects will move slower and shorten in length from the point of view of an observer on Earth. Einstein also derived the famous equation, E = mc², which reveals the equivalence of mass and energy.

When Einstein applied his theory to gravitational fields, he derived the "curved space-time continuum" which depicts the dimensions of space and time as a two-dimensional surface where massive objects create valleys and dips in the surface. This aspect of relativity explained the phenomena of light bending around the sun, predicted black holes as well as the Cosmic Microwave Background Radiation (CMB) -- a discovery rendering fundamental anomalies in the classic Steady-State hypothesis. For his work on relativity, the photoelectric effect and blackbody radiation, Einstein received the Nobel Prize in 1921.
Theory of Relativity – The Basics
Physicists usually dichotomize the Theory of Relativity into two parts.

• The first is the Special Theory of Relativity, which essentially deals with the question of whether rest and motion are relative or absolute, and with the consequences of Einstein’s conjecture that they are relative.
  
• The second is the General Theory of Relativity, which primarily applies to particles as they accelerate, particularly due to gravitation, and acts as a radical revision of Newton’s theory, predicting important new results for fast-moving and/or very massive bodies. The General Theory of Relativity correctly reproduces all validated predictions of Newton’s theory, but expands on our understanding of some of the key principles. Newtonian physics had previously hypothesised that gravity operated through empty space, but the theory lacked explanatory power as far as how the distance and mass of a given object could be transmitted through space. General relativity irons out this paradox, for it shows that objects continue to move in a straight line in space-time, but we observe the motion as acceleration because of the curved nature of space-time.

Einstein’s theories of both special and general relativity have been confirmed to be accurate to a very high degree over recent years, and the data has been shown to corroborate many key predictions; the most famous being the solar eclipse of 1919 bearing testimony that the light of stars is indeed deflected by the sun as the light passes near the sun on its way to earth. The total solar eclipse allowed astronomers to -- for the first time -- analyse starlight near the edge of the sun, which had been previously inaccessible to observers due to the intense brightness of the sun. It also predicted the rate at which two neutron stars orbiting one another will move toward each other. When this phenomenon was first documented, general relativity proved itself accurate to better than a trillionth of a percent precision, thus making it one of the best confirmed principles in all of physics.

Applying the principle of general relativity to our cosmos reveals that it is not static. Edwin Hubble (1889-1953) demonstrated in 1928 that the Universe is expanding, showing beyond reasonable doubt that the Universe sprang into being a finite time ago. The most common contemporary interpretation of this expansion is that this began to exist from the moment of the Big Bang some 13.7 billion years ago. However this is not the only plausible cosmological model which exists in academia, and many creation physicists such as Russell Humphreys and John Hartnett have devised models operating with a biblical framework, which -- to date -- have withstood the test of criticism from the most vehement of opponents.Theory of Relativity – A Testament to Creation
Using the observed cosmic expansion conjunctively with the general theory of relativity, we can infer from the data that the further back into time one looks, the universe ought to diminish in size accordingly. However, this cannot be extrapolated indefinitely. The universe’s expansion helps us to appreciate the direction in which time flows. This is referred to as the Cosmological arrow of time, and implies that the future is -- by definition -- the direction towards which the universe increases in size. The expansion of the universe also gives rise to the second law of thermodynamics, which states that the overall entropy (or disorder) in the Universe can only increase with time because the amount of energy available for work deteriorates with time. If the universe was eternal, therefore, the amount of usable energy available for work would have already been exhausted. Hence it follows that at one point the entropy value was at absolute 0 (most ordered state at the moment of creation) and the entropy has been increasing ever since -- that is, the universe at one point was fully “wound up” and has been winding down ever since. This has profound theological implications, for it shows that time itself is necessarily finite. If the universe were eternal, the thermal energy in the universe would have been evenly distributed throughout the cosmos, leaving each region of the cosmos at uniform temperature (at very close to absolute 0), rendering no further work possible.

The General Theory of Relativity demonstrates that time is linked, or related, to matter and space, and thus the dimensions of time, space, and matter constitute what we would call a continuum. They must come into being at precisely the same instant. Time itself cannot exist in the absence of matter and space. From this, we can infer that the uncaused first cause must exist outside of the four dimensions of space and time, and possess eternal, personal, and intelligent qualities in order to possess the capabilities of intentionally space, matter -- and indeed even time itself -- into being.

Moreover, the very physical nature of time and space also suggest a Creator, for infinity and eternity must necessarily exist from a logical perspective. The existence of time implies eternity (as time has a beginning and an end), and the existence of space implies infinity. The very concepts of infinity and eternity infer a Creator because they find their very state of being in God, who transcends both and simply is.


Source :http://www.allaboutscience.org/theory-of-relativity.htm

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Hawking's New Black Hole Theory

Famed astrophysicist Stephen Hawking said Wednesday that black holes, the mysterious massive vortexes formed from collapsed stars, do not destroy everything they consume but instead eventually fire out matter and energy "in a mangled form."

Hawking's radical new thinking, presented in a paper to the 17th International Conference on General Relativity and Gravitation in Dublin, capped his three-decade struggle to explain an elemental paradox in scientific thinking: How can black holes destroy all traces of consumed matter and energy, as Hawking long believed, when subatomic theory says such elements must survive in some form?

Hawking's answer is that the black holes hold their contents for eons but themselves eventually deteriorate and die. As the black hole disintegrates, they send their transformed contents back out into the infinite universal horizons from whence they came.

Previously, Hawking, 62, had held out the possibility that disappearing matter travels through the black hole to a new parallel universe — the very stuff of most visionary science fiction.

"There is no baby universe branching off, as I once thought. The information remains firmly in our universe," Hawking said in a speech to the conference.

"I'm sorry to disappoint science fiction fans, but if information is preserved, there is no possibility of using black holes to travel to other universes," he said. "If you jump into a black hole, your mass energy will be returned to our universe, but in a mangled form, which contains the information about what you were like, but in an unrecognizable state."

At that point, the audience of about 800 people, including many of his peers, laughed.

He added, "It is great to solve a problem that has been troubling me for nearly 30 years, even though the answer is less exciting than the alternative I suggested."

In a humorous aside, Hawking settled a 29-year-old bet made with Caltech astrophysicist John Preskill, who insisted in 1975 that matter consumed by black holes couldn't be destroyed. He presented Preskill a favored reference work "Total Baseball, The Ultimate Baseball Encyclopedia" after having it specially flown over from the United States.

"I had great difficulty in finding one over here, so I offered him an encyclopedia of cricket as an alternative," Hawking said, "but John wouldn't be persuaded of the superiority of cricket."

Later, Preskill said he was very pleased to have won the bet, but added: "I'll be honest, I didn't understand the talk." Like other scientists there, he said he looked forward to reading the detailed paper that Hawking is expected to publish next month.

Hawking pioneered the understanding of black holes — the matter-consuming vortexes created when stars collapse — in the mid-1970s. He has previously insisted that the holes emit radiation but never cough up any trace of matter consumed, a view that conflicts with subatomic theory and its view that matter can never be completely destroyed.

Hawking, a mathematics professor at Cambridge University, shot to international fame with his best-selling book "A Brief History of Time," which sought to explain to a general audience the most complex aspects of how the universe works.

Despite being virtually paralyzed and wheelchair-bound with amyotrophic lateral sclerosis since his mid-20s, Hawking travels the world on speaking engagements. He communicates by using a hand-held device to select words on his wheelchair's computer screen, then sending them to a speech synthesizer.



Source cbsnews.com

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