Unrelated to my other comment: this is a decent sample of open problems related to the structure formation and element composition in the early universe. Cosmic inflation is an umbrella term for a number of models designed to solve the horizon and flatness problems by a rapid expansion many orders of magnitude shortly after the big bang. Several predictions of such models have been confirmed, while some others falsified, though with low confidence (e.g. the quadrupole moment in the CMB spectrum). Fine tuning of inflationary parameters is aesthetically the most unsatisfactory feature of inflation, but any known alternative is even worse. I am not qualified to judge the validity of the Steinhardt's claims, but other experts in the field don't seem as pessimistic.
The rapid expansion happens because some mysterious dark energy that is apparently far more abundant than the energy we observe all around us, for no other reason than maybe if anything can happen (multiverse), the entire cosmic web gets produced in the blink of an eye.
I am submitting this on behalf of MazeHatter, who originally posted it here in the most recent open tread. Go there to upvote if you like this submission.
Begin MazeHatter:
I grew up thinking that the Big Bang was the beginning of it all. In 2013 and 2014 a good number of observations have thrown some of our basic assumptions about the theory into question. There were anomalies observed in the CMB, previously ignored, now confirmed by Planck:
http://www.esa.int/Our_Activities/Space_Science/Planck/Planck_reveals_an_almost_perfect_Universe
We are also getting a better look at galaxies at greater distances, thinking they would all be young galaxies, and finding they are not:
http://carnegiescience.edu/news/some_galaxies_early_universe_grew_quickly
http://mq.edu.au/newsroom/2014/03/11/granny-galaxies-discovered-in-the-early-universe/
B. D. Simmons et al. Galaxy Zoo: CANDELS Barred Disks and Bar Fractions. Monthly Notices of the Royal Astronomical Society, 2014 DOI: 10.1093/mnras/stu1817
http://www.sciencedaily.com/releases/2014/10/141030101241.htm
http://www.nasa.gov/jpl/spitzer/splash-project-dives-deep-for-galaxies/#.VBxS4o938jg
Although it seems we don't have to look so far away to find evidence that galaxy formation is inconsistent with the Big Bang timeline.
http://www.natureworldnews.com/articles/7528/20140611/galaxy-formation-theories-undermined-dwarf-galaxies.htm
http://arxiv.org/abs/1406.1799
Another observation is that lithium abundances are way too low for the theory in other places, not just here:
http://news.nationalgeographic.com/news/2014/09/140910-space-lithium-m54-star-cluster-science/
It also seems there is larger scale structure continually being discovered larger than the Big Bang is thought to account for:
http://www.sciencedaily.com/releases/2014/11/141119084506.htm
D. Hutsemékers, L. Braibant, V. Pelgrims, D. Sluse. Alignment of quasar polarizations with large-scale structures. Astronomy & Astrophysics, 2014
http://www.sciencedaily.com/releases/2013/01/130111092539.htm
These observations have been made just recently. It seems that in the 1980's, when I was first introduced to the Big Bang as a child, the experts in the field knew then there were problems with it, and devised inflation as a solution. And today, the validity of that solution is being called into question by those same experts:
http://www.physics.princeton.edu/~steinh/0411036.pdf
What are the odds 2015 will be more like 2014 where we (again) found larger and older galaxies at greater distances, or will it be more like 1983?