Accelerating Universe

It is just a decade from revolutionary foundings of two SuperNova Suravy teams:

1)Supernova Cosmology Project , at the Lawrence Berkeley National Laboratory and the 2)High-z Supernova Search Team

/Riess(1998) and Perlmutter (1999)/ .They cliam that the SNIa ,which asserted to be standard candels are dimmer than that they seem to be in Standard CDM -model.

So...

What does it mean?

It means that if SNIa are really standard candels, we must wait to something revolutionary in cosmology.

This is because that in the context (becareful about the term used here,it means that we accept the GR and big-bang model ) of general relativity(GR)and Big-Bang model and cosmological principle(Homogenious,Isotropic universe) , we confront with two choises in order to describe the supernova observation:

1)The universe is open- K>0 /k is curvature/

or

2)Universe expansion is accelerating - q<0>

Now day with precise measurement in cosmology like WMAP-5 years result

,we know that curvature of our universe is nearly flat and from Large scale structure measurement the 30% of our known universe is Dark-ordinary Matter.

So ...

Universe is in phase of accelerated expansion and an unknown component of universe which contain 70% of it that may cause this(if we accept GR and cosmological principle) is Dark Energy.

"What is this unknown Dark Energy ,what causes of this acceleration?"

this is one of the greatest questions of physics for new millennium.