FEBRUARY 2003

http://antwrp.gsfc.nasa.gov/apod/astropix.html

Hal Womack's Taxi Ventures into the Lyman Alpha Forest

2003 January 26
The Lyman Alpha Forest
Credit & Copyright: J. Shalf, Y. Zhang (UIUC) et al., GCCC

Explanation: We live in a forest. Strewn throughout the universe are "trees" of hydrogen gas that absorb light from distant objects. These gas clouds leave numerous absorption lines in a distant quasar's spectra, together called the Lyman-alpha forest. Distant quasars appear to be absorbed by many more Lyman-alpha clouds than nearby quasars, indicating a Lyman-alpha thicket early in our universe. The above image depicts one possible computer realization of how Lyman-alpha clouds were distributed at a redshift of 3. Each side of the box measures 30 million light-years across. Much remains unknown about the Lyman-alpha forest, including the real geometry and extent of the clouds, and why there are so many fewer clouds today.

Hal Womak took a little holiday splashing in the sea.

"One is called to live nonviolently, even if
the change one works for seems impossible.
It may or may not be possible to turn the
US around through nonviolent revolution.
  But one thing favors such an attempt:
the total inability of violence to change
  anything for the better."
   -Daniel Berrigan