In chapter 11, Lancaster takes us through the 5 steps for canonical quantization of fields, and in example 11.3 he derives a mode expansion of the Hamiltonian which ends in this:(adsbygoogle = window.adsbygoogle || []).push({});

$$E=\int d^3 p E_p (a _p^{\dagger} a_p + \frac{1}{2} \delta^{(3)}(0)) $$

Which I have no problem with, but then he says the integral of the latter term, the Dirac delta, will "give us an infinite contribution to energy." I must be missing something because I thought the integral of the $$\delta$$ was 1, not infinity. Apologies in advance if I am overlooking something basic and thanks for looking.

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# I QFT for the Gifted Amateur Question (2)

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