According to NASA the ACS3 has an altitude roughly twice that of the ISS. But according to NASAs ACS3 tracker it is visible about every 1.5 hours, same as ISS. How can it have twice the altitude but the same orbital period? I don't have a background in physics but I believe orbital period is dire...

Consider a generic magnetic system of $N$ spin; let $M(\{s_i\})=\sum_i s_i$ be the magnetization of the system. Defining the spin-spin correlation function as $$ g_{ij}=\langle s_i s_j \rangle -\langle s_i\rangle \langle s_j\rangle \,, $$ is then $$ \sum_{ij}g_{ij}=\langle M^2 \rangle -\langle M\...

today I have a computational doubt and a theoric one. Starting with the theoric question, suppose I have a generic ideal gas in a cylinder and each particle is subject to a potential dependent on the distance from the center: $ H_i=\frac{p^2}{2m_i}-U(r) $. If I were to find the probability to fin...