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Name: Liu J.
Status: student
Age: 15
Location: N/A
Country: N/A
Date: 3/22/2004


Question:
recently in space.com, it mentioned in the Hubble ultra deep field a topic about quantum fluctuations spawning 'our' universe and other universes. My question is what are quantum fluctuations?


Replies:
In the strange strange non-intuitive world of quantum mechanics some very peculiar things are allowed. Within the limits of the Heisenberg uncertainty principle, changes in mass, energy, position, momentum and time are allowed that otherwise are impossible. Although the uncertainty principle is simply stated its consequences are complex and profound. Heisenberg showed that the product of momentum and position as well as the product of energy and time cannot be known in the usual sense to a precision less than of the order of magnitude of Planck's constant which is a very small number (about 10^-34 joule sec) but not zero. Below that limit the variables above are no longer conserved. What this "means" is energy can spontaneously appear from no where so long as it does not last too long. Particles can "pop up" out of a vacuum so long as they do not have too large a mass or do not last too long. One might be inclined to dismiss all this as the wild imagination of physicists, but some things have been observed that require that interpretation. One example is black holes from which nothing, not even light, is able to escape -- well not quite. Black holes are not quite black -- they leak -- due to quantum fluctuations. So called "virtual particles" appear out of a vacuum only to disappear very quickly -- in times less than the limits set by the uncertainty principle. Richard Feynman once said that anyone who claims to understand quantum mechanics does not understand the problem!!! So on the very small scale our intuition fails us completely. The Big Bang theory of the Universe is generally accepted as the best explanation of the evolution of the Universe, but even that theory does not begin at time = 0 (exactly) but only after a infinitesimally short time later. Such is the world of quantum fluctuations.

Vince Calder



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