Is the Uncertainty Principle just a cop-out??

Question

Seems to have the same smell as the Cosmological Constant.

Answer 1

No, the Uncertainty Principle (U.P. from now on) reflects the fundamental nature of quantum theory. It would be basically impossible to keep anything of quantum mechanics but throw out the U.P. And quantum mechanics, however you feel about it, is well supported by experiment and observation.

The U.P. is a reflection of the wave-particle duality of nature. That is, it's a consequence of particles acting both as waves and as point objects. In particular, it comes from the wave nature of particles. Basically, you can either construct a wave by specifying the value or "height" of the wave at every point in space, or give the set of wavelengths which compose the wave (three sets of wavelengths would be needed, one for the x-direction, one for the y-direction, and one for the z-direction). There is a precisely defined mathematical relationship between these two ways of describing a wave. This mathematical relationship is called the Fourier transform.

Now, it's an early result (even a pre-quantum mechanics result) that the momentum of a wave is directly determined by the wavelength of the wave, so every time I said wavelength I could have said momentum (where momentum is mass times speed in classical mechanics, though that's a simplification). So the position of a wave and its momentum are related by a Fourier transformation.

However, if you described a particle as existing at exactly one position (so the wave was piled up all at one point), this would (by the math behind the Fourier transformation) mean that the wave would be composed of infinitely many wavelengths, and thus infinitely many momentums, ranging from zero momentum to infinite momentum in any given direction. Thus, if you know exactly where a particle was, you could say absolutely nothing about how fast it was moving (because momentum is related to speed).

The converse holds true too. If you knew the momentum exactly, mathematically you could not know where the particle is. And, as is usually true, if you knew either the momentum or position to some precision, the precision with which you could know the other value is determined by that.

Thus, the U.P. depends upon two assumptions. First, that the momentum of a wave is directly determined by the wavelength of that wave. This comes into play in some ways in many areas of physics, including thermodynamics and relativity, and is thus likely to be correct. Second, that particles have a wave nature to them, which every experiment seems to indicate that they do. With these two assumptions, and mathematics, the Uncertainty Principle follows naturally.

As to the Cosmological Constant, what's wrong with that? It's an allowed term in Einstein's theory of gravity (General Relativity). It can also be represented by a weird mass or energy which uniformly fills the universe (the two ways of including it are mathematically equivalent). And it is conceivably the answer to one of astronomy's most perplexing questions: why is the expansion of the universe accelerating (speeding up)? We can not say that the Cosmological Constant *is* the answer, but it is one of several possibilities.

In science, and perhaps modern physics above all else, it is important to keep an open mind. Established theories which seem weird may indeed be good descriptions of the universe. But it is always possible, if perhaps highly unlikely, that they will be disproven in the future.

Answer 2

In a sense it is. Science has observed the phenomena and has contrived ways of making predictions and calculations which have been completely accurate. Like Newton's law of universal gravitation, it has excellent predictive value, and no counterexamples have been found. But also like Newton's law, it doesn't say why these things happen. Some day we might understand why both are true. Meanwhile, we use the laws within their domain of applicability with confidence that they are effective.