Friday, August 06, 2010
As the 20th century approached its end, the age-old speculation that
planets must orbit other suns was confirmed by wobble in the position of
Gamma Cephi. Whose pulse did not quicken at the discovery? Any doubts
about the interpretation were swept away in 1999 when HD 209458 d was
directly observed transiting the disc of its parent star. It was time for
the Discovery Program, Dan Goldin's vision of "faster, cheaper, better"
missions focused on specific goals. Kepler uses a photometer to
continuously monitor the brightness of over 145,000 main sequence stars in
a fixed field of view. The data is analyzed to detect periodic fluctuations
from planets transiting the disc of the star. So what have they found?
According to an essay by Dennis Overbye in the New York Times on Tuesday,
there was great excitement a couple of weeks ago when Dimitar Sasselov of
Harvard announced at a TED conference in Oxford, UK that 140 earthlike
planets have been found in one small patch of sky. In fact, many planets
have been found, but so far not one is earthlike. Of course, it was all
over the web. The Web puts all of the world's knowledge at our fingertips;
unfortunately it.s mixed with all of the world.s bullshit.
The question of whether we are alone gnaws at us. In 1950, in a discussion
of whether advanced civilizations might exist elsewhere in the Milky Way
galaxy, Enrico Fermi famously asked, "Where are they?" This has come to be
known as the Fermi paradox. If planets are a common feature of stars, the
naturalistic assumption would be that life exists throughout the Milky Way
galaxy. Sentient beings with the capacity to develop advanced technologies
would be expected to evolve. Implicit in Fermi.s question was an
assumption that advanced technologies would be capable of interstellar
travel. Where are they? At home, as we are. Interstellar distances are
too great. Travel time is not the principal obstacle. The barrier is the
energy it would take to accelerate a spacecraft to a reasonable fraction of
the speed of light. I hope that's the end of the Fermi paradox, and the
Dyson sphere, and all that science fiction crap.
Stable systems all rely on negative feedback to keep them that way. As the
Arctic Ocean warms, however, methane produced by organic decay bubbles up
from the seabed. Vast areas of permafrost will release large amounts of
methane as they thaw (WN 4 Sep 09). Methane is a powerful greenhouse gas,
25 times more powerful than CO2. This is positive feedback, like putting a
microphone in front of the speaker. It can be unpleasant.
No! Norman Borlaug was not some organic farmer. High-yield agriculture
demands more machinery, fossil fuel, fertilizer, and water, as well as
transportation from where food is produced to where it's needed.
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