To clarify Phoenix’s light travel time: the spacecraft did not cruise straight to Mars but took a longer path following an elliptical orbit around the sun, with Mars at the aphelion. Because the distance from Mars to Earth was about 250 million kilometers during the mission, the one-way light travel time was a little less than 15 minutes.
“Thought Experiments,” by Joshua Knobe, describes the question of free will versus determinism. I think it’s impossible to determine (pun intended) whether we live in a deterministic or free-will world.
I believe I have free will. But suppose I’m wrong. Then it’s determined that I will believe that I have free will. We can conduct the experiments that Knobe talks about, but doing so assumes free will. Otherwise, the outcomes are determined.
Berkeley Heights, N.J.
There is another way of thinking about morality than the one put forward by Knobe. Instead of it being essentially altruistic, noble and somehow emanating from inside us, we can think of it as focused largely on how we want others to behave toward us.
If others behave morally, they create an environment that is generally beneficial to us. Our own “moral” behavior, however, is dependent on whether there are effective social sanctions that make it advantageous to behave in a particular way. From this perspective, it is easy to understand the relatively constrained behavior of people who are part of a religious or other mainstream group and the more fluid “morality” of those who are “open to experience.”
West Vancouver, B.C.
In “A Formula for Economic Calamity,” by David H. Freedman, David Colander of Middlebury College asserts that climate models often have no terms to account for the effects of clouds. This is not true. In my class on climate change problem solving, I use a 2005 paper by M. H. Zhang et al. that compares modeled clouds with observed ones from 10 climate models. There are many earlier and later references that document over three decades of ever more sophisticated inclusion of clouds in weather and climate models.
The statement that clouds are not included is misinformation that has been propagated in political arguments used to discredit such models. There is an important difference between physical climate models and economic ones: namely, physics. The physics of climate change are simple classical physics in a stunningly complex, multiscale system, so it is possible to design experiments based on cause and effect. The uncertainty associated with future climate projections linked to economic possibilities of what people will do is far larger than the uncertainty associated with physical climate models.
Richard B. Rood
Department of Atmospheric, Oceanic and Space Sciences
University of Michigan
FREEDMAN REPLIES: Rood is right to point out that climate models are often designed to try to account for clouds. The statement in the article, which was attributed to an economist and not a climate scientist, was a vague oversimplification that suggested climate models frequently fail to account for clouds. In fact, the climate science literature is replete with papers that call out the challenges of accurately accounting for clouds in models. Surely if we have to err in gauging uncertainty in science, it’s better to err on the side of overestimating it. If only economists working in financial risk models had done just that.