# The nature of dark energy

1. Sep 7, 2006

### Jan Janssens

The Higgs field, the inflaton field, the cosmological constant, quintessence,... are all mentioned as possible candidates in explaining dark energy (expansion of space).
My questions are:
1. In what exactly do these possibilities differ from each other?
2. Are there other candidates in explaining this dark energy?

Thanks to everybody responding to these questions!

2. Sep 7, 2006

### hellfire

I think the current acceleration of expansion is mainly explained by cosmological constant or quintessence. The first has a constant equation of state $p = \omega \rho$ with $\omega = -1$, and the second has a dynamic equation of state $p = \omega(t) \rho$ with $\omega < -1/3$. There is also the possibility for "phantom energy" with $\omega < -1$.

The Higgs and the inflaton field are postulated to be responsible for inflation, which is a phase of accelerated expansion at a very early stage of the universe. The Higgs is the same than in particle physics and AFAIK it difers from the inflation in that it's potential is not flat enough to provide a long enough inflationary phase that makes space flat enough. I am not aware of any theory that postulates a common mechanism for inflation and the current accelerated expansion.