The Wilkinson Microwave Anisotropy Probe WMAP [4] and PLANCK [29] led to cosmological parameters that are becoming generally accepted. There are two components of expansion. The second component develops later and is related to Einstein’s constant lambda, associated with dark energy. The concept of critical density (H= (8/3 pi G rhoC)^.5) is related to the accepted Hubble constant 2.26e-18/sec. Critical density (omega total=1) according to year 9 WMAP parameters [26] is composed of density fractions: omega dark=0.719, omega mass=0.235 and omega baryons mass=0.046. The low value for baryons (protons) leads to a problem known as missing mass. This paper reviews the equations used to estimate expansion. The concept of critical density is examined by converting the basic equations to the kinetic energy and potential energy associated with expansion. It is shown that the concept is being misused. The equation (H= (8/3 pi G rhoC)^.5) is useful but rhoC is simply the density at the present time. We will review historical limitations on baryon content. A reliable expansion history and temperature history are constructed. With this we can re-analyze the baryon/photon ratio important to understanding residual deuterium. Also, He4 calculations are examined considering dark matter. The other historical limitation on baryon content is interpretation of WMAP temperature anisotropy data. The period from equality to decoupling was re-analyzed with omega baryons=0.5 of final density. It is proposed that dark energy is photon energy release from stars, not lambda. The author believes that the correct cosmological parameters are 0.5 normal and 0.5 dark matter fraction of final density. Key words: dark energy, missing mass, expansion kinetic energy, cosmological parameters, nucleosynthesis, expansion models.