skade88 writes "From the article 'Is the nature of a vacuum really fixed? Not so, according to two forthcoming papers. Researchers have identified a quantum level mechanism for interpreting a vacuum as being filled with pairs of virtual particles with fluctuating energy values. They've also discovered that physical constraints, such as the speed of light and the so-called impedance of free space, are indications of the total number of elementary particles in nature.'"
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