quick question on field quanta...

I2004

what does it mean when someone says field quanta are not spatially localized?

does it mean they are in superpostion or they are just moving very fast?

sorry if I sound daft

I2004

and are field quanta virtual particles that pop in and out of existence?

I read "field quanta are not spatially localized since they are not excition states at a certain point of the field but have to be assigned to the field system as whole"

can someone explain why they have to be assigned to the system as a whole?


please help...

Bill_K

When describing a complex system we try to use the excitations which are simplest, namely the normal modes. For a free field the normal modes are the plane waves. A disturbance that was initially localized would not stay that way, it would spread to neighboring points and be rather difficult to deal with!

I2004

what I dont get is when it says you must take into account the whole field.

like these field quanta spread accross the whole universe, because the field is everywhere...

I2004

I just dont get it when he says they are not exition states at a point in the field.

what are they then? a single quantum is spread everywhere?

please help...