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Sunday, January 20, 2008

Interesting, weird, and unusual physical theories

10 Interesting and Weird Physical Theories

There are a lot of interesting theories in physics. Matter exists as a state of energy, while waves of probability spread throughout the universe. Existence itself may exist as only the vibrations on microscopic, trans-dimensional strings. Here are some of the most interesting theories, to my mind, in modern physics (in no particular order, despite the enumeration).

1.Wave Particle Duality
Matter and light have properties of both waves and particles simultaneously. The results of quantum mechanics make it clear that waves exhibit particle-like properties and particles exhibit wave-like properties, depending on the specific experiment. Quantum physics is therefore able to make descriptions of matter and energy based on wave equations that relate to the probability of a particle existing in a certain spot at a certain time.

2.Einstein's Theory of Relativity
Einstein's theory of relativity is based upon the principle that the laws of physics are the same for all observers, regardless of where they are located or how fast they are moving or accelerating. This seemingly common sense principle predicts localized effects in the form of special relativity and defines gravitation as a geometric phenomenon in the form of general relativity.

3.Quantum Probability & the Measurement Problem
Quantum physics is defined mathematically by the Schroedinger equation, which depicts the probability of a particle being found at a certain point. This probability is fundamental to the system, not merely a result of ignorance. Once a measurement is made, however, you have a definite result. The measurement problem is that the theory doesn't completely explain how the act of measurement actually causes this change. Attempts to solve the problem have lead to some intriguing theories.

4.Heisenberg Uncertainty Principle
The physicist Werner Heisenberg developed the Heisenberg Uncertainty Principle, which says that when measuring the physical state of a quantum system there's a fundamental limit to the amount of precision that can be achieved. For example, the more precisely you measure the momentum of a particle the less precise your measurement of its position. Again, in Heisenberg's interpretation this wasn't just a measurement error or technological limitation, but an actual physical limit.

5.Quantum Entanglement & Nonlocality
In quantum theory, certain physical systems can become "entangled," meaning that their states are directly related to the state of another object somewhere else. When one object is measured, and the Schroedinger wavefunction collapses into a single state, the other object collapses into its corresponding state ... no matter how far away the objects are (i.e. nonlocality). Einstein, who called these influences "spooky action at a distance," illuminated this concept with his EPR Paradox.

6.Unified Field Theory
Unified field theory is a type of theory that goes about trying to reconcile quantum physics with Einstein's theory of general relativity. The following are examples of specific theories that fall under the heading of unified field theory: Quantum Gravity String Theory / Superstring Theory / M-Theory Grand Unified Theory Loop Quantum Gravity Theory of Everything Supersymmetry

7.The Big Bang
When Albert Einstein developed the Theory of General Relativity, it predicted a possible expansion of the universe. Georges Lemaitre thought that this indicated the universe began in a single point. The name "Big Bang" was given by Fred Hoyle while mocking the theory during a radio broadcast. In 1929, Edwin Hubble discovered a redshift in distant galaxies, indicating that they were receding from Earth. Cosmic background microwave radiation, discovered in 1965, supported Lemaitre's theory.

8.Dark Matter & Dark Energy
Across astronomical distances, the only significant fundamental force of physics is gravity. Astronomers find that their calculations & observations don't quite match up, though. An undetected form of matter, called dark matter, was theorized to fix this. Recent evidence supports dark matter. Other work indicates that there might exist a dark energy, as well. Current estimates are that the universe is 70% dark energy, 25% dark matter, and only 5% of the universe is visible matter or energy!

9.Quantum Consciousness
In attempts to solve the measurement problem in quantum physics (see above), physicists frequently run into the problem of consciousness. Though most physicists try to sidestep the issue, it seems that there is a link between the conscious choice of experiment and the outcome of the experiment. Some physicists, most notably Roger Penrose, believe that current physics cannot explain consciousness, and that consciousness itself has a link to the strange quantum realm.

10.Anthropic Principle
Recent evidence shows that were the universe just slightly different, it wouldn't exist long enough for any life to develop. The odds of a universe that we can exist in are very small, based on chance. The controversial Anthropic Principle states that the universe can only exist such that carbon-based life can arise. The Anthropic Principle, while intriguing, is more a philosophical theory than a physical one. Still, the Anthropic Principle poses an intriguing intellectual puzzle.

Popular Physics Myths By Andrew Zimmerman Jones,

Many legends have arisen over the years in regards to physics and physicists, some of which are quite false. This list collects some of these myths and misconceptions, and provides further information to try to clarify the truths behind them.

Quantum Physics Means the World is Completely Random.There are several aspects of quantum physics which easily lends it to misinterpretation. The first is Heisenberg's Uncertainty Principle, which very specifically relates to the proportional relationship of quantities - such as position measurement and momentum measurement - within a quantum system. Another is the fact that quantum physics field equations yield a range of "probabilities" of what the outcome is. Together, the two have led some postmodern thinkers to believe that reality itself is completely random. In fact, though, the probabilities go away when you combine them and expand the mathematics into our own macroscopic world. While the tiny world may be random, the sum of all that randomness is an orderly universe.

The Theory of Relativity Proves "Everything is Relative"

In the postmodern world, many believe that Einstein's Theory of Relativity says that "everything is relative" and it has been taken (along with some elements of quantum theory) to mean that there is no objective truth. In some sense this couldn't be further from the truth. While it does talk about how space and time change depending upon the relative motion of two observers, Einstein viewed his own theory as talking in very absolute terms - time and space are completely real quantities, and his equations give you the necessary tools to determine the values of those quantities no matter how you are moving.

Einstein Failed Mathematics.Even while he was still alive, Albert Einstein was confronted by rumours, both informal and published in the newspaper, that he had failed in mathematics courses as a child. This was patently not true, as Einstein had done fairly well in mathematics throughout his education and had considered becoming a mathematician instead of a physicist, but chose physics because he felt it led to deeper truths about reality. The basis for this rumour seemed to be that there was one mathematics exam required for admission into his university physics program which he'd not scored high enough on and had to retest ... so he had, in a sense, "failed" that one mathematics test, which covered graduate level mathematics.

Newton's Apple.There is a classic story that Sir Isaac Newton came up with his law of gravity when an apple fell on his head. What is true is that he was on his mother's farm and watched an apple fall from a tree onto the ground when he began to wonder what forces were at work to cause the apple to fall in that way. He eventually realized that they were the same forces which kept the moon in orbit around the Earth, which was his brilliant insight. But, so far as we know, he was never hit in the head with an apple.

The Second Law of Thermodynamics Disproves Evolution.The concept of entropy had been used, especially in recent years, to help support the idea that evolution is impossible. The "proof" goes:

1. In natural processes, a system will always lose order or stay the same (second law of thermodynamics).

2. Evolution is a natural process where life gains order & complexity.

3. Evolution violates the second law of thermodynamics.

4. Therefore, evolution must be false.

The problem in this argument comes in step 3. Evolution does not violate the second law, because the Earth is not a closed system. We gain radiated heat energy from the sun. When drawing energy from outside the system, it is in fact possible to increase the order of a system.

The Ice Diet

The Ice Diet is a proposed diet in which people say that eating ice causes your body to spend energy to heat the ice. While this is true, the diet fails to take into account the amount of ice required. Generally, when this is considered feasible, it does so by mistakenly calculating gram calories in place of the kilogram Calories which are what is talked about in reference to nutritional Calories.

Noise Travels in Space

Perhaps not a myth in the proper sense, because no one who thinks about physics for even a minute believes this happens, but still it's something which shows up in popular culture all the time. In the book Don't Try This at Home!: The Physics of Hollywood Movies by physics teacher Adam Weiner, this is listed as the biggest, most common physics error in movies.

Sound waves require a medium through which to travel. This means they can travel through air, water, or even solid objects, such as a window (though it gets muffled), but in space it is essentially a complete vacuum. There are not enough particles to transmit sound. So, no matter how impressive the space-ship explosion, it will be completely silent ... despite Star Wars.