New posts in Faq

How are classical optics phenomena explained in QED (Snell's law)?

Why does holding something up cost energy while no work is being done?

Physical dimensions for the Coulomb force in SI and CGS

What really allows airplanes to fly?

Why does the sky change color? Why is the sky blue during the day, red during sunrise/set and black during the night?

What is the error in this fake proof which uses series to show that $1=0$?

How can a function with a hole (removable discontinuity) equal a function with no hole?

Does an increasing sequence of reals converge if the difference of consecutive terms approaches zero?

How to tell whether two graphs are isomorphic?

Proof of the Hockey-Stick Identity: $\sum\limits_{t=0}^n \binom tk = \binom{n+1}{k+1}$