Recent content by denism

sure, SR no way contradicts GR I disagree with you, the scale factor has first been naturally postulated because of the observation of Hubble. You describe one of the multiple a-posteriori attempts to calculate the expansion rate(s) from the universe constituents: (matter/energy and now...

I have a naive perception of topology: the number of dimensions of any shape is that of the minimal euclidean space capable of embedding it. Your torus is 4D to me, even for something confined in its surface the circle is a good example: unidimensional if envisioned from the interior, but in...

4D torus?

But how do you conceive a finite euclidean 3D space? with a peripheral boundary? looks strange

Many thanks for these informations does "infinite flat" means euclidean 3D?

Indeed I was not clear. I just wanted to say that authors talking about light connection rates in the expanding universe never make use of GR, but only derive their conclusions from the simple relationship cdt=a(t)*dl (note there is a typing error of sign in my previous equation). SR seems to...

Yes. But precisely, all what I read about universe expansion and horizons, begins with a redefinition of the line element of SR (ds2=(cdt)2+a(t)2dl2)

thank you very much for your kind answer George. In fact, I was not particularly afraid by recession velocities higher than c given that this limit does not apply to space expansion, but I just wondered (for other reasons) if Vrec > c were really observed because H has been proven to be lower...

I would be very pleased seeing any supporting data! I did not want to be contrarian. Considering my poor knowledge in this field, I am sure that data (more convincing than the theoretical extension of Vrec = HD) should exist. This was precisely the purpose of my question

thank you very much. It is stated in this site that "For distant galaxies, v (or D) cannot be calculated from z without specifying a detailed model" Of course, if postulating Vrec=HD and H constant, one easily obtains Vrec > c beyond a certain distance, but this appears purely theoretical to me...

I looked at: http://en.wikipedia.org/wiki/Redshifts it is stated that for a flat Minkowski space and for light motion in the transverse direction 1+z=1/sqrt(1-(v/c)^2) from which z is infinite when v=c

thanks how this fact has been determined?...or indirectly infered?

in my mind, the fact that universe size could be within c/H would not mean that we are at its centre if it is closed. If there is no reason to believe that it is true, conversely is there any support that there is plenty beyond. In fact, this belief is only based on the assumption that...

My question was about the total size, or more precisely: do we have (indirect) evidences that there is really something beyond the Hubble sphere (of radius c/H)

if you prefer: What are the tools used by reputable sources to estimate the minimum radius of universe?