I'm reading a paper by Art Hobson called "There are no particles, there are only fields" and had a question about something in there. (http://arxiv.org/abs/1204.4616) (Page 20-21) He basically says that since the vacuum in QFT has energy and non-vanishing expectation values, it is ultimately inconsistent with a particle view. If particles are fundamental, than what is it that has energy in a state that has no particles? Fields! That's all fine, but then he mentions three things that can be measured, which has the vacuum as their source: Lamb Shift, Casimir Effect and the electron's magnetic anomalous moment. However, he also mentions the vacuum as the source for Dark Energy (despite our current 120 order magnitude problem between theory and observation) Since, apparently these 4 phenomenon are ALL related to the vacuum in QFT, I am trying to figure out how they are all related to each other. Is Dark Energy essentially the same thing as the Casimir effect, except on a global scale? Does the fact that the three above phenomenon can be experimentally/empirically verified lend support to Dark Energy? Dark Energy can be represented by a term of constant energy density under GR. Are these other effects the result of (local) energy density from the vacuum? Thanks!