You would think that is something the astronomers would have checked
for early on. Has anyone checked for gas pressure?

Meanwhile:

A New Probe of Dark Energy

What we know about dark energy can be pretty much summed up in these words: “We know that it dominates the universe. In fact, it comprises an estimated 73 percent of the universe, while so-called dark matter accounts for 23 percent, and matter of the familiar kind — the stars, galaxies, all known life — comprises only four percent.”

The speaker is David Lambert, a University of Texas at Austin astronomer and the director of UT’s McDonald Observatory. And it has always seemed to Centauri Dreams that these numbers — what we know and see of the universe is no more than four percent of the total — should inspire a certain humility. Yes, we know more than those before us, but just how far we are from comprehending the nature of ‘reality’ seems obvious. There are real reasons to wonder whether the human mind is capable of ever understanding ultimate reality.

...

But now we’re on the edges of string theory, so perhaps it’s time to focus on something less abstract. How about cold cash? Money talks in cosmology, or at least the study of it, and the news that businessman Harold C. Simmons has ponied up a $5 million challenge grant — he’ll match the next $5 million in private support received — to the University of Texas is heartening. Simmons is trying to support people like the aforementioned Dr. Lambert in their quest to run HETDEX — the Hobby-Eberly Telescope Dark Energy Experiment, at McDonald Observatory.

Full article and links here:

http://www.centauri-dreams.org/?p=641