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According to the rules of qft there are virtual photons in the vacuĆ¼m. No, according to QFT the vacuum is static, in the sense that $P^\mu|\Omega\rangle=0$. Or put it another way, The vacuum at a time $t$ is exactly the same vacuum at a time $t+\Delta t$ for any $\Delta t$. This means that the picture of particles constantly appearing and disappearing ...


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In quantum mechanical domain these type of question does not have meaning. Every single photon is associated with a wave and vice versa. But to talk whether an electromagnetic wave contains a single photon or not is an ambiguous statement. When people say an electromagnetic wave necessarily contains many photons it only means that a incident beam of ...


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But I don't understand the mechanism of the force creation But the concept of electric charge and electric field is, by definition, the mechanism of the force creation - that humans have invented to model that which has been observed. Never forget that the observed is the metaphysically given. It is up to us, as beings possessing a rational faculty, ...


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The Lagrangian for Dirac's equation is $$ \mathcal L=-mc^2\psi^2+\cdots \tag{1} $$ As we know that $H\sim\mathrm d^3\boldsymbol x\ \mathcal L$ has units of energy, we conclude that $$ \psi^2\sim x^{-3}\tag{2} $$ and therefore $\psi$ has units of $[\mathrm{length}]^{-3/2}$. If you use a different convention for $\mathcal L$ instead of $(1)$ you'll get a ...


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What are photons? Photons get emitted every time when a body has a temperature higher 0 Kelvin (the absolute zero temperature). All bodies, surrounding us (except black holes) at any time radiate. They emit radiation into the surrounding as well as the receive radiation from the surrounding. Max Planck was the physicist who found out that this radiation has ...


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It comes about by assuming that the wavelength ($\sim k^{-1}$) is much larger than the typical atomic length scales ($r$).



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