Tuesday, December 22, 2009

What one really means with virtual particle?

Massive particles are the basic problem of the twistor program. The twistorialization of massive particles does not seem to be a problem in TGD framework thanks to the possibility to interpret them as massless particles in 8-D sense but the situation has been unsatisfactory for virtual particles (see this).

The ideas possibly allowing to circumvent this problem emerged from a totally unexpected direction (the finding of Martin Grusenick described in previous posting). The TGD inspired explanation of the results together with quantum classical correspondence (see this) led to the proposal that Einstein tensor in space-time regions where the energy density vanishes describes the presence of virtual particles assignable to the exchange of momentum between massive objects. This identification is consistent with Einstein's equations in zero energy ontology and leads to a proposal for a concrete geometric identification of virtual particles in TGD framework.

The basic idea is following. In TGD gauge bosons are identified as wormhole contacts with positive energy fermion and negative energy antifermion at the opposite light-like throats of the contact. The observation is that even if the fermions are on mass shell particles, the sum of their momenta has a continuum of values so that interpretation as a virtual boson makes sense. Free fermions do not correspond to single light-like throat but if the interaction region involves a pair of parallel space-time sheets with distance of order CP2 length of order 104 Planck lengths, the CP2 extremal describing fermion has a high probably to touch the second space-time sheet so that topological sum giving rise to second light-like throat is formed. This throat has spherical topology and carries purely bosonic quantum numbers. If on mass shell state with opposite energy is in question, the situation reduces to that for bosons. One can also formulate conditions guaranteing that no new momentum degrees of freedom appear in loops integrals. Since only on mass shell throats are involved one can apply TGD based twistorial description also to virtual particles without any further assumptions.

The detailed explanation of the idea is given by this short article. The reader interested in background can study the chapter Twistors, N=4 Super-Conformal Symmetry, and Quantum TGD of "Towards M-Matrix".


Anonymous said...

If we assume that all our reality are different patterns of phase existence, how can then virtual particles be described in a phase diagram?

I read sometimes that for a very low magnetic field the particles are smearing out. Also the Faraday cage doesn't function for very low electromagnetism.

Matti Pitkänen said...

In order to answer I should have precise meaning for what phase existence and phase diagram means in this context. In any case, phase diagram in the sense of condensed matter does not apply to virtual particles.

Virtual particles have a precise meaning as fictitious mathematical objects in quantum field theory. The proposal of the posting was that in TGD framework they are real physical objects.

Anonymous said...

That was true. If I ask in this way: massless particles are interpreted in 8-D framework. Can massless particles be described in a phase diagram? I thought of that dark matter, of course.
Higgs boson, like also other bosons are 'virtual' too until they are found.

Can real physical objects be impossible to measure?

Matti Pitkänen said...

Yes. I propose that dark matter corresponds to phases of matter with different values of Planck constant and these phases are are analogous to phases in condensed matter physics.

Virtual means many things. In particle physics "virtual" means that particle is not on mass shell. For instance virtual photon would be massive state or even tachyonic state. The question is whether these virtual states are more than mathematical fictions and my proposal is that they are.

Quarks are not directly detectable but their explanatory power of the notion is so high that very few particle physicists question their existence.

Zephir said...

In water surface analogy virtual particles are density fluctuations of Brownian noise, which are spreading through underwater. They affect surface waves by dispersion.