Recent content by dum-dum

thanks for all your hard work marcus

marcus, i have another small question...if we are looking for the age of the universe at certain redshift...do we need the Einstein de Sitter model (a = time2/3? is the redshift and the current (assumed) age of universe enough??

http://www.astro.washington.edu/astro323/WebLectures/lec10_small.pdf try this guys if you are having trouble w/ scale factor and how to incorporate them.

umm, i don't think that's right mixx. we're trying to solve for "z"...

look at marcus's explanation...it's about as thorough as i can think of as well.

use the E=hv equation for energy density of photon (meaning radiation) h = Planck's constant v = frequency (you're giving wavelength, so freq = spd of light/wavelength)

we are to use the mass of a proton for 'm'... you don't plug 109 into anything, you need to multiple that to the energy density of a photon (representing the radiation) to make it on par w/ the energy density of a baryon (representing the matter)

well, the prof wanted us to solve the redshift using the photon-baryon ratio, hence the first assumption...and combined w/ your explanation marcus, I'm deducing that i can use E=mc2 to work out the energy density for matter & use E=hv to work out the energy density for radiation...which will...

Hi guys, I'm in a pickle here with an assignment. I'm required to find the redshift at which the energy density in radiation equals the energy density in matter. The following are the givens we were...well, given: 1) assume 1 baryon = 10^9 photon 2) assume all photons have energy to the...