Photon is a point like particle?
QED (Quantum ElectroDynamic) predicts that a photon can decay into a virtual electron-antielectron pair and then combine back into a photon.
This is known as vacuum polarisation.
Now, the best way to describe a photon in this case is not as a point like particle but as a quantum cloud of radius equal to that of the Compton wavelength of an electron.
That means a photon has an effective radius of ~ 2.4 x 10 -12 m.
La scala di Planck dei tempi è 5.4 x 10-44 s e delle lunghezze,
1.6 x 10-35 m.