The one thing you can say with any certainty about quantum physics is that there is no certainty about quantum physics. During the first part of the 20th century, physicists and mathematicians turned their minds to the study of the unseen components of our world: atoms, elections and even subatomic particles. While the laws of physics worked reliably in the larger sphere -- a dropped object always falls down, two objects can't occupy the same space at the same time and so on -- these scientists were perplexed to discover that this new physics seemed to be a law unto itself. Physicist Max Planck called the tiny particles of light he was studying quanta, and he came to realize that light isn't a continuous wave, but exists with an arbitrary amount, or quanta, of energy. Thus the term "quantum physics" was born [source: PBS].

The baffling part about quantum physics is that unlike its inflexible forebear, classical physics, the rules keep changing and the results of an experiment or equation can't be predicted. Often, physicists are as shocked by the results as anyone. Sometimes, the theories can't be proved except by imaginary experiments. After more than a century, quantum physics continues to be a source of mystery and amazement.

In this article, we'll take a look at some of the questions most commonly asked about quantum physics. We'll explore some practical applications of this bizarre science and examine some of its more esoteric aspects -- the possibility that the universe exists only in our minds and the search for the "God particle."

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