Cosmology

Assume there are one billion neutrinos for every proton. Using the limits on baryon density given by big bang nucleosynthesis, and assuming a Hubble constant of 70 km s−1 Mpc−1, how massive would... more

What I need is an accurate description of the methods used to determine the distance to Andromeda. The Parallax method is for nearby objects as I presume. The red shift method applies, but how do... more

Doppler redshift of distant galaxies gave first hint that the universe is expanding. I am curious to know how this redshift is actually measured and interpreted from observation. Suppose I observe... more

Consider an object travelling near the speed of light relative to us (let it be a spaceship or a star), which is emitting light (consider it monochromatic resulting from a two level electronic... more

As far as I know, astronomy is generally an observational science. We see something and then try to explain why it is happening. The one exception that I know of is black holes: first it was... more

There are two extremes known as **creationism** vs **evolutionism**. Let's consider creationism for a moment, and imagine that God exists, and he/she has created us. The question that obsesses my... more

I often think about problems that require an understanding of the very essence of computation and its inherent limitations. So, my questions are as followed: - Is the universe isomorphic to a... more

The most oft-cited [triumphs](http://en.wikipedia.org/wiki/Tests_of_general_relativity) of GR are things such as the shifting perihelion of Mercury, gravitational redshift experiments, and... more

Just what the question asks. Assuming the Friedmann-Rovertson-Walker (FRW) metric, what measurements can be performed to determine the spatial curvature of the universe.

The synthesis of heavier elements started with the formation of deuterium (n+p -> D+γ). Deuterium has a binding energy BD = 2.22MeV, so we might expect that deuterium forms when kT ~ BD, since a... more