# Is the acceleration of the expansion of the universe a direct observation or an interpretation?

Is the acceleration of expansion we observe with supernovae direct or is this an interpretation according $$\Lambda$$CDM model ?

I mean what we observe is luminosity distance versus redshift, so to see acceleration we should have scale factor vs time, which need a model, right (assuming Friendmann-Lemaître equations in which we need to consider homogenous universe for example) ?

Is it possible to say "our universe is in accelerated expansion" without any interpretation with a model ?

• Supernova brightness vs redshift. – Wayfaring Stranger Sep 26 '18 at 14:44
• Redshift of line emission – Kornpob Bhirombhakdi Sep 28 '18 at 13:44