belated Earth Day

Here are a few interesting articles I found this past week:

• The Next Generation of Biofuels (Scientific American) and California Takes on King Corn (The Daily Climate) talk about alternatives to corn-based ethanol
• How to Fix a Climate Emergency (Newsweek) is a pretty interesting look at some radical ideas about slowing down global climate change (and it makes a good point about how this shouldn't be a replacement for cutting emissions)
• and Wil Wheaton found a cool video of Earth rising over the moon's horizon (must have been taken near new moon)
  

bad news for iron fertilization

I follow a few environmental blogs, and for a while I was occasionally seeing posts about the possibility of using iron fertilization for carbon sequestration. The idea (as I understand it) is that scientists would dissolve a bunch of iron near the ocean surface, phytoplankton would consume the iron (causing the phytoplankton to flourish), the phytoplankton would inhale a bunch of carbon dioxide, and the phytoplankton would sink to the bottom of the ocean, taking the CO2 with it, forever.

So they tried it.

They dumped a bunch of iron in the ocean, and the phytoplankton dutifully multiplied (and presumably inhaled a lot of CO2). But before the phytoplankton could sink, it ended up at the bottom of the food chain of a series of increasingly large sea creatures that live near the surface.

Nice try.

xephem in Ubuntu

I was out with friends last night (4th of July fireworks), and they asked me to identify a bright object in the sky (I used to be an astronomer). I'm really out of practice at that kind of thing, so I speculated that it was Sirius (there was some light cloud cover, and I couldn't see whether or not this object was southeast of Orion, but it was pretty bright). Turns out I was wrong.

There's a really cool desktop ephemeris program called Xephem from the Clear Sky Institute. So I installed that on my Ubuntu desktop this morning to find what that thing was last night. I had to fulfill a few dependencies to compile xephem. Here's what I had to install first (I just explicitly installed the ones in bold--apt-get installed the packages in parentheses as dependencies):

• libxt-dev (libsm-dev, libice-dev)
• x11proto-print-dev
• libxp-dev
• libxext-dev (x11proto-xext-dev)
• libxmu-headers (?)
• libxmu-dev
  

(I'm not sure I needed libxmu-headers.)

After that I mostly just followed the directions in the INSTALL file from the xephem download. I copied the data directories (auxil, catalogs, etc.) to /usr/share/xephem (a directory I created) and put the following in ~/.xephem/XEphem (xephem didn't seem to want to read /usr/X11R6/lib/X11/app-defaults/XEphem as the INSTALL file suggested):

XEphem.ShareDir: /usr/share/xephem

I also gziped the man page (xephem.1) before copying it to /usr/share/man/man1/xephem.1.gz. And I created /usr/share/doc/xephem-3.7.3/ and copied in the Copyright, INSTALL, and README files.

By the way, that object turned out to be Jupiter. shrug

relativistic economics

There was an interesting Slashdot article the other day about a satirical speculative analysis of the economics of interstellar trade. The idea is that if you're shipping something to another star system, you've made a significant financial investment in the goods you are shipping, and the duration of the voyage will be long enough that there should be an interest rate applied to your investment.

The interesting wrinkle appears when you consider that for interstellar trade to be worthwhile, the cargo vessels will need to travel at relativistic speeds. Special relativity describes the effect of time dilation, the phenomenon of a measurable discrepancy in the voyage duration as measured by the ship's crew versus that of a stationary observer (like the investor).

So whose measurement of time do you use to compute the interest?

To extend this nonsense to other predictions of special relativity, the ship's mass and length will also be affected, which might complicate matters for the interstellar equivalents of weigh stations.

Cosmologically illogical

I don't get into astronomy much any more, but I thought this Ars Technica article was pretty interesting. The article talks about a paper to be published in the journal General Relativity and Gravitation. The paper claims that in 100 billion years the universe's cosmological evidence will have disappeared. The cosmic microwave background will be buried in interstellar plasma, and light from other galaxies will have been redshifted (from Hubble expansion) too much to be detectable.

Reminds me of that Simpsons episode: "Let's burn down the observatory so that this can never happen again!" (If I only had a dime for every time I've thought those very words.)