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Question: Starting with the assumption that a general wave function may be treated as an algebraic sum of sinusoidal functions of various wave numbers, explain concisely why there is an uncertainty principle.

Short Answer

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Answer:

The more sinusoidal wave functions are required to express a function, the less spreading it has in space, and vice versa. This follows immediately from the Fourier theorem and has a connection to the Heisenberg uncertainty principle.

Step by step solution

01

Uncertainty relation

Mathematically, the uncertainty relation can be stated as ΔxΔp⩾h2.

02

Explanation

Fourier established this theory, which connects the function spreading in spaceΔx to the range of wavenumberΔk , long before the Heisenberg uncertainty principle. The relation states that ΔxΔk⩾12.

In other words, if we require a function with a very small spatial bandwidth, we must cover a wide variety of wavelengths or wavenumbers; λ=2πkas a result, we must combine many sinusoidal functions.

If we only take note that the momentum is equal to , then this may be directly connected to the Heisenberg connection. Consequently, if we substitute that back in, we will reestablish our original relationship ΔxΔk⩾h2. So, the same conclusion is drawn: the more wavenumbers added together (greater uncertainty in momentum), the less uncertainty there is in location, and the opposite is also true.

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