dark energy

Could it be that dark energy/matter is just heat that hasn't condensed into stars, planets, and galaxies? 

LAST 'MISSING' NORMAL MATTER FOUND---The things in the universe that we can easily see--stars, nebulae--amount to less than 1% of all the matter and energy out there.  We know that dark matter and dark energy account for 95.4% of everything, judging by many lines of evidence (June issue, page 14), but that still leaves 4.6% as "ordinary" matter: everything made of protons, neutrons, and electrons.  Until recent years, astronomers could only tally up about half as much normal matter as cosmologists said there ought to be.   
     Now the mystery seems solved.  Astronomers already had signs that the missing half indeed exists, as a thin, elusive gas between galaxies known as the warm-hot intergalactic medium" or WHIM.  The evidence for WHIM just became firmer.  It's spectral signature showed up in x-rays from a distant source; absorption lines were imprinted on the x-rays where they passed through the 'Fornax Wall', an enormous structure of thousands of galaxies in the vast web of galaxy strings, sheets, and clusters pervading the cosmos.  The spectral signature matches the predicted amount and temperature (about 1 million K) of the elusive WHIM. ---from Sky and Telescope 8/2010.