Wednesday, May 30, 2012

black body in 4 dimensions

what would be a black body's flux-frequency relation in 4 spatial dimensions? in $n$ spatial dimensions? what would be equivalent relations for the Wien displacement law and the Stefan-Boltzmann law?

bonus question: what's $\mathrm{d}/\mathrm{d}x\: \mathrm{arcosh}(x)$?

Wednesday, May 23, 2012

selection bias - cosmo CSI

during the 1960's, criminal investigators were puzzled by an observation that in many countries with a seaside a considerable number of dismembered feet in sports sneakers were washed ashore. a logical explanation seemed to be a serial killer murdering joggers, but the truth is different and involves statistics, and the biasedness of observations: what would be your guess?

Wednesday, May 16, 2012

time-variation of the CMB

does the pattern of hot and cold patches of the CMB change in time? if yes, on what time scale?

bonus question: which parts of the CMB spectrum will gain in amplitude and which effects will loose in their importance?

Thursday, May 10, 2012

CDM particle properties

what statements about the properties of the dark matter particles can we make by observing cosmic structures?

Thursday, May 3, 2012

negative redshifts

would negative cosmological redshifts (aka blueshifts  ;) ) be useful to describe events in the future evolution of the Universe? if yes, what'd be the largest (most negative) redshift which can be defined in a sensible way?