- #1
NanakiXIII
- 392
- 0
I'm trying to understand how exchange of particles can constitute a force. I read a chapter on this in Zee's Quantum Field Theory in a Nutshell, which covers it very briefly, presumably only to make it plausible to the reader, but there is something I'm not content with.
To illustrate, he places two time-independent delta functions ([itex]J(x) = \delta(\vec{x} - \vec{x}_a) + \delta(\vec{x} - \vec{x}_b)[/itex]) on a scalar field to represent two massive particles that couple to the field. Then he claims that these particles generate disturbances in the field, propagating from one particle to the other to constitute a force. But how can a time-independent disturbance create a propagating (i.e. time-dependent) particle? In his jumping-on-a-mattress analogy, this doesn't make sense.
He illustrates that placement of two delta functions causes a decrease in energy and that the energy is lowered even further if you put them closer together, but that doesn't clarify to me how any exchanged particles are generated or involved in the mechanism.
Another thing I don't understand is why any disturbance caused by one massive particle would propagate only towards the other particle. Shouldn't it propagate in all directions?
To illustrate, he places two time-independent delta functions ([itex]J(x) = \delta(\vec{x} - \vec{x}_a) + \delta(\vec{x} - \vec{x}_b)[/itex]) on a scalar field to represent two massive particles that couple to the field. Then he claims that these particles generate disturbances in the field, propagating from one particle to the other to constitute a force. But how can a time-independent disturbance create a propagating (i.e. time-dependent) particle? In his jumping-on-a-mattress analogy, this doesn't make sense.
He illustrates that placement of two delta functions causes a decrease in energy and that the energy is lowered even further if you put them closer together, but that doesn't clarify to me how any exchanged particles are generated or involved in the mechanism.
Another thing I don't understand is why any disturbance caused by one massive particle would propagate only towards the other particle. Shouldn't it propagate in all directions?