CASIMIR EFFECT |
To understand this phenomenon (so contrasting with common sense) the uncertainty principle should be invoked (a principle due to Heisenberg, as well known, at least in its original form) . This law of nature puts a constraint on the values that can take on particular pairs of physical quantities, so called conjugatequantities; one of these couples is represented by ENERGY and TIME. For it, the Uncertainty Principle basically states that in the simultaneous measurement of these variables in any phenomenon, we must have: |
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| Creating "ex nihilo" a pair of particles, one the antiparticle of the other, does not violate the majority of conservation laws (since they have, for example, equal and opposite electric charge, and so on for other variables such as spin) ... except the energy conservation. The same applies to the creation of photons. But ... and here comes the Heisenberg principle, Nature allows you to borrow energy from nothing, as long as it come back soon! How soon? The sooner, the greater the amount of energy from nothing! This means that it is possible that a particle-antiparticle pair be created from vacuum, provided that its time of existence is sufficiently small (according to the inverse proportionality relationship to the energy given above). Thus, in particular, photons can be created, called “virtual photons”, which immediately disappear in the "nothing". |