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Trip2
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what does Feynman's diagram prove? i know it deals with something "going back in time"
muppet said:But the idea is that they are a representation of subatomic processes.
f95toli said:Actually, they are much more general than that. Diagrams are also used in e.g. many-body problems in solid state physics. They are basically a very general tool used in field theory that can be used to perform certain calculations (if I remember correctly each diagram represents a term in an expansion of the S-matrix), i.e. they are not only used to illustrate various processes; the extra "loops" etc seen in more complicated diagrams do actually have a specfic meaning.
f95toli said:Actually, they are much more general than that. Diagrams are also used in e.g. many-body problems in solid state physics. They are basically a very general tool used in field theory that can be used to perform certain calculations (if I remember correctly each diagram represents a term in an expansion of the S-matrix), i.e. they are not only used to illustrate various processes; the extra "loops" etc seen in more complicated diagrams do actually have a specfic meaning.
muppet said:As I understand it, the extra loops are allowing for possibilities such as events relating to virtual particles? I seem to remember reading that to accurately determine the probability of a particular process you'd have to draw infinitely many Feynman diagrams, but that the correction associated with each diagram grew smaller and smaller as the number of vertices increased ...
I think that most particle theorists would say that anti-particles actually go back in time- they do, after all, work on the assumption that their maths describes reality! Obviously, as we can't go back in time, you could never "see" an anti-particle going backwards in time; its creation and annhiliation would always be stored in our memories the same way every other kind of event we see is.
There's a separate thread for particle physics: perhaps if an admin moved this you might find people more knowledgeable about the subject there?
Feynman diagrams are graphical representations that are used in theoretical physics to visualize and calculate the interactions between subatomic particles. They were developed by physicist Richard Feynman in the 1940s and have become an important tool in understanding quantum field theory.
Feynman diagrams are composed of arrows representing the direction of time. In these diagrams, the direction of time can be reversed, meaning that the same physical process can occur in both forward and backward time. This demonstrates the concept of time reversibility in quantum mechanics.
Time reversibility is important in physics because it shows that the fundamental laws of physics are symmetric with respect to time. This means that the same physical processes can occur regardless of whether time is moving forward or backward.
Feynman diagrams show the interactions between particles as lines connecting the different particles. These lines represent the exchange of energy and momentum between the particles, and the total energy and momentum before and after the interaction must be equal, thus demonstrating the conservation of energy and momentum.
No, Feynman diagrams are primarily used to visualize and calculate the interactions between elementary particles, such as electrons and quarks. They are not suitable for visualizing more complex quantum processes, such as those involving many particles or gravitational interactions.