Wednesday, December 18, 2013

island universe

exponentially accelerated cosmic expansion drives all objects away from us, and in the future we will think that there would just be the Virgo cluster as an island of galaxies in an otherwise empty Universe. when will that be? (it is funny to imagine that humans then would have historical information about the large-scale structure, but would they believe it?)

with that question we would like to wish our readers a merry Xmas and a happy New Year 2014 and we hope to see you again in January. if you want to contribute to CQW, please drop us a mail at cosmologyquestionoftheweek["AT"]gmail["DOT"]com.

Wednesday, December 11, 2013

life in the early universe

in his paper "the habitable epoch in the early universe" A. Loeb makes the observation that the CMB in the early universe would have kept everything at temperatures allowing water to be liquid, and that during that time the Universe was a giant habitable zone. can you estimate how long (in years) this period lasted?

Wednesday, December 4, 2013

quantum microwave background

CQW celebrates its second anniversary!

would a classical description of the microwave background today be applicable? please justify your answer using the thermal wavelength.

bonus question: motion extremises the action in classical Lagrangian mechanics. is that extremum a maximum or a minimum?