Recent content by Javier Chornet

Sorry again, But then, if I measure the redshift, I'm measuring the speed that the galaxy had when she emmited the light. So for knowing the speed at the proper distance for know the value of Hubble's constant, you must calculate it theoretically based on the data collected from when the ligth...

In the epoch of the atomic formation (that finished when the CMB light was emmited) all the energetic photons was absorved by the electrons of the atoms (basically hydrogen), and the only photons that was not absorved was these whose energy at these moment was lower than the first energy of...

We should know where the Ω function comes. \Omega_i=\frac{\rho_i}{\rho_c} where ρc is the critical density (those who gives a flat universe) and ρi is the density of what we're considering (matter, dark energy...). If the universe is flat, the critical density and the density is the same, so...

I was thinking about a gendanken experiment that I don't know how to solve: Imagine we tie one extrem of a rope in the Earth and the other one in the Sun, with some tension, and connected to a dynamometer (obviously in ideal conditions: no heat, no rotation etc.). My question is: when will the...

So the used disance is the real distance of the galaxy at the moment of the observation (further than the distance we observe because the finite spee light). Thank you! Your answer was so iluminating, and the paper you've referred is great! Thanks again!

Hello, I was thinking about the Hubble's law and I know that it's determined as H(t)=\frac{1}{a(t)}\frac{da(t)}{dt} and then, thinking in the derivate of the scale factor as the speed, we've de usual formula v(t)=H(t)D But my question is: the distance is the distance we observe the object (so...