On Mon, Jun 8, 2020 at 7:09 PM smitra <smi...@zonnet.nl> wrote: > On 07-06-2020 01:16, Bruce Kellett wrote: > > > Applying the idea of quantum fluctuations to the inflaton field is a > > mistake, since inflation is based on a classical field. And you do not > > quantize a classical field by adding "quantum fluctuations". > > It's an approximate way to do computations that can be justified > rigorously, see e.g. these lecture notes: > > https://www.nikhef.nl/~mpostma/inflation.pdf > > section 3 on page 15 and further. >
If that is your idea of a rigorous justification.............my mind boggles. It seems to rely on the old failed heuristic of "vacuum fluctuations" as particle-antiparicle pairs: "The quantum vacuum is never empty, particle and anti-particle pairs constantly pop out of the vacuum and annihilate again. During inflation, due to the enormous expansion, the particle and antiparticle are ripped apart, and they may get separated by a distance larger than the causal horizon H−1, and cannot find each other again to annihilate. They remain as perturbations on the background." This is nonsense, since there are no such particle-antiprticle pairs continuously formed in the vacuum state -- the vacuum does not fluctuate. > > >> It is this phenomena what Jason referred to. In the > >> scientific papers on inflation they may go about computing the > >> effects > >> of the fluctuations in a semi-classical way by putting in the > >> fluctuations by hand in classical equations of motion, but there is > >> a solid theoretical basis for such an approach. > > > > No, there is not. It is entirely ad hoc. The problem stems from the > > fact that the scalar inflaton field has the dimensions of energy, so, > > because energy is strictly conserved, the field value cannot > > fluctuate. > > > > It's not ad hoc, it's all explained here: > > https://www.nikhef.nl/~mpostma/inflation.pdf > That article is a reasonably comprehensive account of the standard notions of inflation -- but it still relies on failed heuristics and ad hoc notions. Nothing rigourous here. Closed virtual particle loops in the vacuum are a well-known phenomenon in perturbation approaches to QFT, but because of energy conservation, these loops are strictly of zero energy-momentum. Since they are not coupled to anything, so they do not affect any measurable physics. At most they add an overall undetectable phase to the wave function. Bruce -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/everything-list/CAFxXSLQKsPGKWY6wqRceQ43L3XLdCPPPwjRtchSnzx%2BfJS%3Dv1Q%40mail.gmail.com.
