Quantum Physics For Dummies

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When you have the eigenvalues of angular momentum states in quantum mechanics, you can solve the Hamiltonian and get the allowed energy levels of an object with angular momentum. The eigenvalues of the angular momentum are the possible values the angular momentum can take. such that when you apply the lowering operator, L–, you get zero, because you can’t go any lower than At some point, your quantum physics instructor may want you to add time dependence and get a physical equation for a three-dimensional free particle problem. You can add time dependence to the solution for

That’s the solution to the Schrödinger equation, but it’s unphysical. Why? Trying to normalize this equation in three dimensions, for example, gives you the following, where A is a constant: These remedies, the quanta of solace, are called “interpretations.” At the level of the equations, none of these interpretations is better than any other, although the interpreters and their followers will each tell you that their own favored interpretation is the one true faith, and all those who follow other faiths are heretics. On the other hand, none of the interpretations is worse than any of the others, mathematically speaking. Most probably, this means that we are missing something. One day, a glorious new description of the world may be discovered that makes all the same predictions as present-day quantum theory, but also makes sense. Well, at least we can hope. For example, in an atom with a single electron, such as hydrogen or ionized helium, the wave function of the electron provides a complete description of how the electron behaves. It can be decomposed into a series of atomic orbitals which form a basis for the possible wave functions. For atoms with more than one electron (or any system with multiple particles), the underlying space is the possible configurations of all the electrons and the wave function describes the probabilities of those configurations. Deutsch argues that when two or more previously identical universes are forced by quantum processes to become distinct, as in the experiment with two holes, there is a temporary interference between the universes, which becomes suppressed as they evolve. It is this interaction that causes the observed results of those experiments. His dream is to see the construction of an intelligent quantum machine — a computer — that would monitor some quantum phenomenon involving interference going on within its “brain.” Using a rather subtle argument, Deutsch claims that an intelligent quantum computer would be able to remember the experience of temporarily existing in parallel realities. This is far from being a practical experiment. But Deutsch also has a much simpler “proof” of the existence of the Multiverse.

How Might Life Migrate Through the Universe?

Compatible with any classroom course -- study at your own pace and prepare for graduate or professional exams This article is excerpted from John Gribbin’s book “ Six Impossible Things,” a concise investigation of six interpretations of quantum physics.

For each l, there are 2l + 1 values of m. For example, if l = 2, then m can equal –2, –1, 0, 1, or 2. The power of the interpretation began to be appreciated even by people reluctant to endorse it fully. John Bell noted that “persons of course multiply with the world, and those in any particular branch would experience only what happens in that branch,” and grudgingly admitted that there might be something in it: Nearly every result [the quantum theorist] pronounces is about the probability of this or that or that … happening — with usually a great many alternatives. The idea that they may not be alternatives but all really happen simultaneously seems lunatic to him, just impossible. He thinks that if the laws of nature took this form for, let me say, a quarter of an hour, we should find our surroundings rapidly turning into a quagmire, or sort of a featureless jelly or plasma, all contours becoming blurred, we ourselves probably becoming jelly fish. It is strange that he should believe this. For I understand he grants that unobserved nature does behave this way—namely according to the wave equation. The aforesaid alternatives come into play only when we make an observation — which need, of course, not be a scientific observation. Still it would seem that, according to the quantum theorist, nature is prevented from rapid jellification only by our perceiving or observing it … it is a strange decision. Some cosmologists have espoused the Many Worlds Interpretation as the best way to explain the existence of the Universe itself.

Freeman Dyson and Me

Put quantum physics to work — make sense of Schrödinger's equation and handle particles bound in square wells and harmonic oscillators Put quantum physics to work -- make sense of Schr dinger's equation and handle particles bound in square wells and harmonic oscillators What makes a quantum computer qualitatively different from a conventional computer is that the “switches” inside it exist in a superposition of states. A conventional computer is built up from a collection of switches (units in electrical circuits) that can be either on or off, corresponding to the digits 1 or 0. This makes it possible to carry out calculations by manipulating strings of numbers in binary code. Each switch is known as a bit, and the more bits there are, the more powerful the computer is. Eight bits make a byte, and computer memory today is measured in terms of billions of bytes — gigabytes, or Gb. Strictly speaking, since we are dealing in binary, a gigabyte is 2 30 bytes, but that is usually taken as read. Each switch in a quantum computer, however, is an entity that can be in a superposition of states. These are usually atoms, but you can think of them as being electrons that are either spin up or spin down. The difference is that in the superposition, they are both spin up and spin down at the same time — 0 and 1. Each switch is called a qbit, pronounced “cubit.”