Computer games, cosmology, the universe, and the environment

This year after eating my Thanksgiving turkey but before we served apple pie, I had an interesting discussion with my brother, cousin, and father's friend's son. The conversation started with my brother, cousin, and father's friend's son (let's call him a friend) bonding over computer games. I asked my cousin (a senior in high school) what other interests he had (we only see one another once a year at Thanksgiving) and he mentioned being interested in space. The three boys being well studied in the marvels of Wikipedia, the Discovery Channel, and Ted—and myself and brother having taken an astronomy-related course in college—the dialogue ranged from the cosmological principle to finding water (or not) on Mars. We eventually reached the point of discussing the possibility of other sentient life being "out there" in our universe and had a neat discussion on how likely we were to be inimical to them or them to us ("if they're radioactive they're probably not going to come looking for a planet like ours, they'll first seek planets that have environments similar to their own home planet."—"Yeah, like how we're not digging at every planet within our reach."—"But if they're advanced enough to go beyond their own solar system they'll probably just "glance" at other planets and focus on finding ones they can terraform to suit their needs...")

At some point the discussion segued from "radioactive sentient life" to "nuclear energy" to "global warming" and we had a nice, long, somewhat fruitless discussion about just how much mankind is responsible for the current crisis. My brother and family friend took the view that humans couldn't be held as responsible for global warming as many environmental activists make us out to be. My cousin and I took the counterargument, and "debated" with them, trying to convince them that humans were more responsible than they were giving us credit for. I was very tempted to whip out some of the graphs/charts/figures we've looked at in class, but that would have (logistically speaking) been rather counterproductive, so I stuck to arguing with the facts and figures that I could dredge up at that moment. Thankfully, all of use were at least somewhat informed about the issue, so we all had some reasoning to back up our arguments. My brother and family friend were aware of the cyclical nature of climate change so they threw out the argument that every so often our planet undergoes a drastic change in temperature ("like the last Ice Age," commented my brother). His mention of ice reminded me of the ice cores drilled from Antarctica to measure carbon levels. I also brought up the history of the ozone regime.

Nevertheless, despite our differences, we all agreed that human-induced carbon emissions were a serious problem for the sustainability of our planet. Our only real disagreement was regarding the extent of human influence on the environment. We went on to discuss future capacity for alternative energy. The family friend was studying to be an electrician, and he was excited about the future prospects for photovoltaic technology, and the nitty gritty of making homes more electricity-efficient. My cousin was interested in the dynamics of carbon storage, and I talked a little bit about nuclear energy (bringing us back for a moment to the radioactive alien discussion).

Needless to say, it was a very interesting Thanksgiving night.