Extinction

Animals become extinct because they don't behave in way that fit the place where they live. The dinosaurs were okay for millions and millions of years, then a comet put a lot of dust in the atmosphere, and the world couldn't grow enough food to support them. Evil scientists put deer on an island where there hadn't been any, and where there weren't any animals that eat deer. The deer had it pretty good until there were too many deer, and they had eaten all the food.

Environmentalists believe that humans are like the deer on the island, sometime before all the food was gone.

Occam's Razor

In understanding what we see, we invent explanations or hypotheses, and see if they always explain what happens.

The best ones account for everything that happens, and usually don't assume more than one new idea. Rube Goldberg's machines were just the opposite.

This is called Occam's Razor -- or the Law of Parsimony -- named after a Franciscan monk who wrote something like what I just did over five hundred years ago. The razor in the name "shaves" away extra assumptions. If the cookie jar is empty, our first thought is that somebody we know is in the house, and not Martians, took the cookies.

Greenhouse Effect Theory

Is it reasonable to believe carbon dioxide from human activity warms the Earth?

Ultraviolet radiation enters the atmosphere and warms soil, rock, and so on. The warmed matter radiates infrared radiation. The idea is that the infrared escapes into space more easily if there is less carbon dioxide in the air, and stays if there's more.

   * The physics is well understood, and can be demonstrated in a laboratory;

   *  The planet is warming;

   *  There has been a correlation between temperature (with a dip in the 1940s) and industrial production of carbon dioxide since about 1870, when consistent, global measurements began;

   * There has been a correlation between ancient temperatures and atmospheric carbon dioxide shown in ice cores and and mud cores taken from under the oceans;

* The atmosphere has warmed, as shown by a higher tropopause (the boundary between the lower atmosphere and the stratosphere; gases expand when they are warmed).

Why People Are Vegetarians

Some people stop eating meat. Why?

Certainly a lot of vegetarians are sympathetic with meat animals. Others have various health concerns about meat; some hold water; some don't.

The strongest argument, in my book, is that raising an animal for food requires several times more protein than that animal yields. Some people argue that we can feed the whole world on a vegetarian diet, but not a meat-based diet. People who act on this argument are called "trophic-pyramid vegetarians."

The argument against trophic-pyramid vegetarianism is that a world getting its protein from beans and grain would demand endless fields of nothing but grain and beans. I can't buy it, because we already have that to support the livestock.

I will say that, were the world to adopt an ecologically sensitive food system (call it "permaculture"), it would probably be irresponsible not to eat meat.

You Never Prove Anything

You can never prove anything.

2, 4, 6... 8, right? How about 10? (2+4=6, 4+6=10, or because I was pulling numbers out of a hat, and those were the ones that I happened to grab)

2, 4, 6, 10... 16, right? How about 12? (2, 4, 6, skip to ten any way you want, then start counting by twos again)

There's always the possibility, if not the likelihood that something unanticipated will explain your data in a way that invalidates your theory. (Everything is a theory.)

Still, there's a hierarchy of plausibility. Nobody is going to jump off any cliffs soon, expecting to fly.

We see something, think about what might make it happen, and get some ideas. Those ideas are hypotheses. We test a hypothesis by predicting things that would happen if it were true. "Objects will not float off the table." "Objects will fall if I drop them." "Planets will maintain certain orbits around the Sun." "Because Neptune's orbit isn't what we expect, we can expect another planet (Pluto) here."

When a hypothesis has a record as a reliable predictor, call it a theory.

The Gaia Hypothesis

The Gaia Hypothesis is an idea of James Lovelock's that says that life affects Earth's environment to maintain good conditions for itself.

In the 1960s, Lovelock was a scientist contracting with NASA to figure out how to find out if there is life on Mars. Lovelock said he would look for evidence that something was working against entropy. Entropy is the tendency for systems to become less organized. Life is the exception.

Lovelock began to look at our planet the same way. He noticed that the composition of the atmosphere stays within fairly tight limits. Oxygen, for instance, remains in the narrow range between being inadequate and enabling holocaust. In his book, The Gaia Hypothesis, Lovelock cites other planetary material cycles, particularly methane, as evidence.

Negative Feedback

In a system, something that limits an output is called "negative feedback."

An example is a house's thermostat. The family uses a furnace to heat their house. They decide what temperature to keep the house, and set the thermostat for that temperature. The thermostat is simply a temperature sensor that flips an on-off switch to maintain the assigned temperature.

The police have a function similar to a thermostat's. They arrest criminals, and introduce negative feedback to crime.

Regulatory agencies introduce negative feedback to pollution, and other costs which businesses might attempt to externalize, or pass on to parts of society which don't share in their profits.

Another example of negative feedback on pollution has been offshoring of American manufacturing. Move a factory to Hangzhou, and move its pollution.