Wednesday, June 17, 2009

Nature's Symmetry

We referred to the laws of nature in a previous post, somewhat lightly, as “rules of the game.” These laws, or rules, have their basis in a more fundamental, but less familiar concept called “symmetry.” Nature’s symmetry may be described with terms such as balance, predictability, regularity, invariance, and repeatability. When we refer to nature’s symmetry, therefore, we are referring to nature’s coherent orderliness. Symmetry implies conservation laws.

Our recent post on the law of conservation of mass reminds us of a corollary--the law of conservation of energy. Albert Einstein connected mass and energy, and scientists now also refer to the law of conservation of mass/energy. The term energy sometimes refers to a fossil fuel product such as oil or gas. We refer to the “energy crisis” as a situation where supply and demand for these products are not in balance, causing shortages and price inflation.

The textbook definition of energy is different. Energy is the capacity or ability to do work. When work is done, a push or pull force moves an object. No work is done unless an object is moved, regardless of how much force is applied.

Energy takes many forms. Kinetic energy is energy present due to the motion of an object. A moving object can accomplish work, because it may move some other object. Potential energy takes two forms--gravitational potential energy and chemical potential energy. A large boulder hanging on a cliff has much potential energy due to its position: it could do a lot of “work” (destructive damage in this case) if it fell. A gallon of gasoline has chemical potential energy: burned in an automobile it could move your vehicle 20 miles. There are other types of energy capable of accomplishing work, such as electromagnetic energy (light or infrared waves), sound energy (voices or music), and heat energy (molecules in motion).

Each day of our lives, energy changes form many times during the course of our activities. If we start our car, the burning of fuel--chemical energy--is converted ultimately to motion of the car, heat of the engine, and sound of the motor. As the vehicle travels along, it transfers motion to the air. The swirling air, in turn, causes the leaves and grass to wave in the breeze, creating a gentle rustling sound. Where did the engine’s heat go? It is still in the air, but now widely diffused. All the other forms of energy are also present in a different form, perhaps as a very slightly higher air temperature. No energy is lost; rather, it has merely changed form. It may be less useful now because it is more diffused, but the total quantity of energy still exists. Einstein saw the relationship between mass and energy. We say the total mass/energy of any isolated system is conserved no matter what other changes occur.

As we recognize the coherent orderliness, the symmetry of nature’s laws, we might also logically and rationally deduce the existence of the Author of the symmetry which governs our universe. Scientists are discovering more and more about the macro- and micro-functioning of our universe. They acknowledge that nature’s symmetry is more and more apparent with each new discovery.