the solar system is encapsulated in Oorts cloud, a vast cloud of small rocks beyond the orbit of Pluto. can you set up a model for the obscuration of the Sun from this cloud? by how much would the optical magnitude of the Sun decrease?
with that, we wish all our readers a nice summer vacation and hope to see you again in october. if you happen to have an interesting question, please contact us under cosmologyquestionoftheweek"[AT]"gmail"[DOT]"com.
Wednesday, July 27, 2016
Wednesday, July 20, 2016
in classical mechanics and electrodynamics one obtains a second-order equation of motion from squares of the first derivatives, either of the position with time or of the derivatives of the potentials. gravity seems to be different: the Ricci-scalar in the Einstein-Hilbert action contains already second derivatives: can you explain this difference?
Eingestellt von spirou um 7/20/2016 12:00:00 AM
Wednesday, July 13, 2016
Wednesday, July 6, 2016
Wednesday, June 29, 2016
Wednesday, June 22, 2016
following up on last week's question: imagine a FLRW-model with only one fluid characterised by a density parameter $\Omega$. could you find in a second model with a different $\Omega$ a time with the same expansion rate and acceleration as the first model?
Eingestellt von spirou um 6/22/2016 12:00:00 AM
Wednesday, June 15, 2016
can you construct a similarity transform that relates the Schwarzschild-metrics of black holes with different mass to each other? what would be a sensible parameter? would it be possible to formulate an addition theorem for masses and gravitational fields using that relation, which could replace linear superposition for a nonlinear field theory?
Eingestellt von spirou um 6/15/2016 12:00:00 AM