Silly me, making the mistake of reading TFA on
You want to know how we 'know' all of those things with such great precision? It's all about the scale of temperature fluctuations in the cosmic microwave background. The CMB is a snapshot of the universe some 30k years after the big bang, during the time of first neutralization, when the pathlength of photons quickly (on cosmic scales) went form very short in the hot plasma (think neon light tube) to mostly neutral hydrogen. The spectrum of density fluctuations there tells an incredible amount about how the small perturbations left over from inflation evolved during that early time, and is the main stick by which all of our cosmological models are tested. The incredible agreement with the standard cosmological model and the CMB using only 7 free parameters is probably the most successful accomplishment in scientific history.
Nowhere on the article's page of drivel is the CMB mentioned, nor the WMAP or Planck satellites which were responsible for bringing us that data. I didn't read much of the article, but there is simply no way to speak intelligently about early universe models without the CMB. If you actually want to learn about this stuff, take a look at some of the public stuff NASA has put together for WMAP at http://map.gsfc.nasa.gov/missi... ; some of the animations are really quite revealing, and I use them in seminars on the subject all the time. Then if you're still hungry for more and can handle the math, take a look at Dodelson's Modern Cosmology.
Bah, still too angry about this kind of crap. Not a good way to start the week.