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3 votes

Dirac's quantisation condition and non-quantised charge

The identity $e g = 2\pi n$ (setting $\hbar=1$) has to hold for ALL electric and magnetic charges. Let $e_0$ be the smallest electric charge and let $g_0$ be the smallest magnetic charge (smallest in ...
Prahar's user avatar
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0 votes

How does blackbody radiation suggest the quantization of energy?

In Rayleigh's calculations, the average energy is calculated by integration (continuous): $$\langle E \rangle = \frac{\int^{\infty}_{0} E ~e^{-E/kT} \mathrm{d}E}{\int^{\infty}_{0} e^{-E/kT} \mathrm{d}...
manojg's user avatar
  • 1
0 votes

Is energy contained in/transferred by light really discrete or is it continuous?

I am by no means an expert in this, and what I say might be wrong, but I'm pretty sure the classical electromagnetic theory doesn't hold for such small time intervals. As you mention, the emission of ...
Lagrangiano's user avatar
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3 votes

Epidemic spreading model

Let me first note that SI model is a simplified version of a more general SIR model (in fact, there is a whole zoo of related models.) The number of persons that get infected at time step $t$ is ...
Roger V.'s user avatar
  • 59.4k
4 votes

Epidemic spreading model

You almost nailed it. Notice that $$I(t+1)-I(t) = \frac {dI}{dt}$$ Now, why they use $\beta \alpha I(t)$ instead of simply $\beta I$,- the reason is simple. Limiting reason is that infection each day ...
Agnius Vasiliauskas's user avatar
0 votes

Is there an error in Susskinds' derivation of Euler-Lagrange equations?

In order to add more context to anyone else that stumbles upon this, in the book directly above the screenshot posted, the author defines the action as follows: $$A = \sum_{n} L\left(\frac{{x_{n+1}} - ...
kenzzo13's user avatar

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