Recent content by smallphi

My Acer Timeline laptop battery stopped being recognized after I pulled it out while on AC power. It may be that your battery or the measuring circuit of the battery needs some kind of a reset. I solved my problem by shutting down the laptop, then I pulled out the AC power cord AND the...

The mass of a planet or a star can be infered by observing a body orbiting around it - you have to measure the orbital period (time) and the dimensions of the orbit (radius for circles, semimajor axis for ellipse) and then use Newton's law for gravitation to calculate the gravitating mass. The...

Tried a few in the wallpaper section. All have multicolored pixel noise, especially the nebulaes. My monitor is 1680x1050 pixels and I can clearly see non-uniform colors and colored noise in the darker areas, it's either they didn't process the pics well or it's just limitation of the telescope...

I've never seen 'Mc/s' before but at the end of the original paper http://adsabs.harvard.edu/abs/1965ApJ...142..419P they mention it's a measure of frequency so probably means 'Mega cycles/ second' which is MHz nowadays. The CMB temperature characterizes the whole spectrum, it is the spectrum...

I bet string theory can derive its own existence LOL

Too bad they are not good for desktop wallpaper - tried a few, turned out grainy. Photoshop definitely needs to play on those.

I got it finally. The delta_rho/rho of dark matter for that scale is around 0.06 at last scattering. I was using wrong formula for it since I took for the wave vector k= Pi/60 when I should have taken k=1/60 Mpc which puts it in a different case formula.

I'm interested in void scales, d ~ 60Mpc. The only number that might be wrong is d_rho/rho ~ 10^-5 at last scattering but not very probable - I checked it already with semianalytical formulas. In linear regime, the growing perturbation mode in matter dominated universe is proportional to the...

CMB fluctuations and large scale fluctuations nowadays do not match ? The CMB dark matter density fluctuations for big scales is d_rho/rho~ 10^-5 and lower. The scale factor increased ~ 1000 times from last scattering to now. Linear perturbation theory predicts that the density fluctuations...

Thanks for the CosmoCoffee link. They have very interesting discussions of up to date articles in the astro-ph sections.

Very fun to play with, thanks !

Thanks for the articles. What I had in mind though was something like an update of the article I cited since its more than 10 years old. The first article you posted talks about N-body simmulations of dark matter - I need actual measurements not simmulations of something that hasn't been...

are there more advanced forums than this for astronomy/cosmology? I asked a few questions without reply on here so I guess I need higher level forum.

The residiuals for high redshift supernovas clearly indicate the best fit curve overshoots those.

What is the current measured density contrast inside the cosmological voids of radius about 30 Mpc? By measured I mean somebody constructed a density map based on peculiar velocities map or weak lensing. I've read a Paper by L. da Costa - Astrophysical Journal 468, L5, 1996 - that constructed...