Wednesday, May 28, 2014

temperature in a FLRW-universe

what temperature would you associate with gravity in a FLRW-universe and how would that temperature compare to the actual temperature or the Planck-temperature?

Wednesday, May 21, 2014

Sunyaev-Zel'dovich effects with neutrinos

would there be analogies of the Sunyaev-Zel'dovich effects due to electron-scattering with the cosmic neutrino background? can you point out similarities and differences and estimate the magnitude of the effects?

Wednesday, May 14, 2014

cluster cooling by immersion into the CMB

on what time scale would the intra-cluster medium of a cluster cool down by Compton-scattering of the cold cosmic microwave background (ignoring thermal replenishment by the negative specific heat)?

Wednesday, May 7, 2014

boundary to quantum cosmology

can you estimate the distance between two points in a FLRW-universe at which the quantum mechanical uncertainty in the velocity measurement is as large as the redshifting effect?

(this fun question is discussed in detail in the paper "the quantum indeterminancy of cosmic systems" by C.J. Hogan)