Quantum vacuum

For the physicist the Vide was always a concept extremely difficult to define. The quantum Mechanical , in particular, comes to complicate the definition of the vacuum. It is easy (at least on paper) to consider that a system in the vacuum is isolated (i.e. nondisturbed by an external force). Nevertheless quantum mechanics envisages many effects appearing in the vacuum.

Inequality of Heisenberg

The inequalities of Heisenberg (more known under the unsuitable term of Principle of uncertainty) are a direct consequence of the Dualité wave-corpuscle. One of it makes it possible to write: \ Delta E \ Delta T \ geq \ hbar where \ hbar is the standardized Constante of Planck. This equation means that the product of uncertainty on energy by uncertainty over time is obligatorily higher than a nonnull value. What wants to say that it is possible to borrow energy from the vacuum during a very short time. It is this mechanism which is at the origin of the fluctuations of the vacuum.

Fluctuation of the vacuum and creation of pairs of particles

The most famous equation of physics E=mc^2 translates equivalence between mass and energy. Thus by borrowing energy from the vacuum it is possible to create massive particles. This mechanism is at the origin of the appearance of pairs of virtual particles. Thus in quantum mechanics the vacuum is filled of virtual particles appearing during a very short time before disappearing. These virtual particles appear in Quantum theory of the fields: their effects imply corrections on calculations, in the theories known as renormalisables. These relatively complicated calculations are built on rules: rules of the diagrams of Feynman. Those have just been included/understood by work of Pierre Cartier and Alain Connes.

Fluctuation of the vacuum and force of Casimir

The experimental demonstration most obvious of the fluctuations of the vacuum is the force of Casimir. Between two perfect plane mirrors is exerted a gravitational attraction which originates in the fluctuations of the vacuum. It is today a perfectly checked experimental fact.

Fluctuation of the vacuum and Shift of Lamb

The first effect observed of the fluctuations of the vacuum is the unfolding of the emission lines in the atomic spectra.

Fluctuation of the vacuum and radiation

Stephen Hawking also explains the evaporation of the black holes using the fluctuations of the vacuum. Under the effect of intense the gravitational Champ of these stars, the quantum vacuum is affected, which involves the appearance of a Rayonnement of black Corps.

The Effet Unruh also rests on an interpretation of the fluctuations of the vacuum. The shift towards the red of the virtual photons, due to a uniform Accélération involves the appearance of a Rayonnement of black Corps.

See too

External bond

  • Energy of the vacuum
  • Force of Casimir (Univ. Pierre and Marie Curie)
  • File of astronomy (10 pages) --> 7°: “Mechanical quantum and fluctuations of the vacuum”.

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