## Wednesday, July 30, 2014

### CQW holiday project: NFW-wave function

what's the wave-function of a quantum mechanical particle inside an NFW-potential?

with that question, we would like to wish all our readers a nice summer vacation and hope to see you again in October. if you'd like to contribute to CQW with a question, please contact us at cosmologyquestionoftheweek["AT"]gmail["DOT"]com.

## Wednesday, July 23, 2014

### Roche limit for a drop of water

can you compute the Roche limit, i.e. the closest distance at which an orbiting object can approach a central body without being disintegrated by tidal forces, for the case that the orbiting object is held together by surface tension instead of gravity?

## Wednesday, July 16, 2014

### periapsis recession

what would the shape of relativistic corrections to the gravitational potential need to be such that one would observe a periapsis recession instead of a periapsis advance in an orbiting object?

## Wednesday, July 9, 2014

### units of spectra

can you please show that the unit of the fluctuation spectrum $P_\phi$ of a field $\phi(\vec{x})$ is given by the unit of the variable $\vec{x}$ on which the field depends to the power of the dimension of the space on which the field is defined times the squared unit of the field amplitude?

## Wednesday, July 2, 2014

### a much smaller Planck-mass

could you define a set of Planck-units based on the speed of light $c$, the Planck-constant $\hbar$ and instead of the gravitational constant $G$ the cosmological constant $\Lambda$? what would the numerical values be?