eldavojohn writes "There exists a little-known problem of missing regular matter that has perhaps been overshadowed by the mysteries of dark matter and dark energy. Computer models show that there should be about 40% more regular matter than we see... so where is it? From the article: 'The study indicated a significant portion of the gas is in the filaments — which connect galaxy clusters — hidden from direct observation in enormous gas clouds in intergalactic space known as the Warm-Hot Intergalactic Medium, or WHIM, said CU-Boulder Professor Jack Burns... The team performed one of the largest cosmological supercomputer simulations ever, cramming 2.5 percent of the visible universe inside a computer to model a region more than 1.5 billion light-years across.' This hypothesis will be investigated and hopefully proved/disproved when telescopes are completed in Chile and the Antarctic. The paper will be up for review in this week's edition of the the Astrophysical Journal."