- #1
Husserliana97
- 34
- 5
Hi !
In a Feynman diagram, can we consider that the propagator specifying the transition amplitude of a particle (let's say, of a "real" electron, or of a "virtual" photon) between two points or two vertices, is in fact itself the sum of a multiplicity of probability amplitudes, each one corresponding to the contribution, in this sum, of a certain trajectory or world line?
Without going so far as to say that the electron effectively follows "all the world lines at once" -- a phrase which would be at best an interpretation, at worst a gross error of understanding -- it seems to me legitimate to assert that the particle does not follow a well-determined trajectory ; and that, as such, the symbol of a very straight and rigid line for fermions in diagrams could well mislead the beginner in quantum physics (which I am, by the way).
In this respect, the idea of a sum over all paths seems to me to be quite respectful of Heisenberg's principle ("no definite trajectory", which can also be translated as: let us consider all possible trajectories in the initial and final conditions, without privileging any of them); and to draw a well-determined line is not more than a convenience of representation.
But on balance, it would perhaps be better to think about each of these straight lines as one of the "space-time tubes", by means of which we represent the integral of the paths...
What do you think ? Thanks in advance !
In a Feynman diagram, can we consider that the propagator specifying the transition amplitude of a particle (let's say, of a "real" electron, or of a "virtual" photon) between two points or two vertices, is in fact itself the sum of a multiplicity of probability amplitudes, each one corresponding to the contribution, in this sum, of a certain trajectory or world line?
Without going so far as to say that the electron effectively follows "all the world lines at once" -- a phrase which would be at best an interpretation, at worst a gross error of understanding -- it seems to me legitimate to assert that the particle does not follow a well-determined trajectory ; and that, as such, the symbol of a very straight and rigid line for fermions in diagrams could well mislead the beginner in quantum physics (which I am, by the way).
In this respect, the idea of a sum over all paths seems to me to be quite respectful of Heisenberg's principle ("no definite trajectory", which can also be translated as: let us consider all possible trajectories in the initial and final conditions, without privileging any of them); and to draw a well-determined line is not more than a convenience of representation.
But on balance, it would perhaps be better to think about each of these straight lines as one of the "space-time tubes", by means of which we represent the integral of the paths...
What do you think ? Thanks in advance !