Probing the equation of state of the early universe with a space laser interferometer

We propose a method to probe the equation of state of the early universe and its evolution, using the stochastic gravitational wave background from inflation. A small deviation from purely radiation dominated universe ($w= 1/3$)wouldbeclearlyimprintedonthegravitationalwavespectrum$\Omega_{GW}(f)$ due to the nearly scale invariant nature of inflationary generated waves.