Wednesday, March 30, 2016

Zeno and cosmology

can you give an intuitive argument why in a FLRW-cosmology with only a cosmological constant $\Lambda$ distant objects appear at a constant angular size irrespective of their redshift?

Wednesday, March 23, 2016

equivalence

if gravity is equivalent to an inertial force, are then all inertial forces gravitational? if so, where does the bulging of the Earth come from, which is usual attributed to centrifugal acceleration due to its rotation?

Wednesday, March 16, 2016

$\pi$ in the sky

one needs the value of $\pi$ for quite a number of computations in FLRW-cosmologies: can you list them and say to what accuracy $\pi$ is actually needed?

bonus question: which of the approximations of $\pi$ would work for these particular purposes?

(this post in in celebration of 14.Mar.2016 just 2 days ago)

Wednesday, March 9, 2016

scale of homogeneity

can you estimate on what scale one would need to observe cosmological redshift such that peculiar motion is small enough compared to cosmological recession?

Wednesday, March 2, 2016

non-ideal fluids

FLRW-cosmologies assume aside homogeneity and isotropy of the metric ideal fluids - but how would non-ideal fluids change FLRW-solutions?