Real vs. Virtual Photons: A Comparison

AI Thread Summary
Real photons are measurable entities that satisfy Einstein's energy relation, while virtual photons are theoretical constructs that do not exist in a measurable sense. Virtual photons serve as force carriers in electromagnetic interactions, facilitating the repulsion between electrons without energy exchange. The discussion emphasizes that virtual photons are part of the mathematical framework used in quantum field theory, particularly in Feynman diagrams, to describe interactions. Despite their mathematical utility, virtual photons do not have a physical presence like real photons. Understanding this distinction is crucial for grasping the underlying principles of quantum mechanics and electromagnetic forces.
Ezio3.1415
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What is the difference between real photons and virtual photons?
 
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Real photons satisfy Einstein's energy relation (or: they are on-shell). Virtual photons don't. As a consequence, the first can be directly measured, the second cannot.
 
Virtual photons are the force carriers of e.m. While real photons are little packets of energy... When two electrons repulse each other they do it because of the interaction of virtual photons... If they exchaned energy real photon would be emitted and absorbed... And in case of virtual photons no energy is exchanged... Did I get it?
 
you have to be careful about the two repelling each other argument...

how would a proton and electron attract each other with that logic?
 
Welcome to PF!

Hi Ezio3.1415! Welcome to PF! :smile:
Ezio3.1415 said:
What is the difference between real photons and virtual photons?

real photons are physics (they exist)

virtual photons are just maths (they don't)
Ezio3.1415 said:
When two electrons repulse each other they do it because of the interaction of virtual photons...

no, they do so because of the fields

the virtual photons in the maths help us to calculate the fields :wink:
 
As tiny-tim explains, virtual photons appear in between the actual interactions, for the mathematical approach to QFT first used by Feynman. Normal photons enter into interactions (vertices of Feynman diagrams), and they can also emerge. As indicated by the name, you won't see one.
 
Dipstick: I would say the same thing I guess... Interaction! :rolleyes:

Tim: Thank you... Hope to get a lot of help here... The forum's so active... :)

no, they do so because of the fields

the virtual photons in the maths help us to calculate the fields

But I thought standard model visualizes the field with the help of field particles,doesn't it? Or is it just the maths? But it makes total sense... It explains why the range of forces with virtual particles(the force carriers) so well...

Mark:
virtual photons appear in between the actual interactions, for the mathematical approach to QFT first used by Feynman. Normal photons enter into interactions (vertices of Feynman diagrams), and they can also emerge. As indicated by the name, you won't see one.
Can u explain that without Feynman diagram? :confused:
 

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