Monday, December 12, 2011

Toward less boredom aboard the aircraft

kw: book reviews, nonfiction, flying, science

Brian Clegg is trying to interest more people in everyday science. His latest effort, pitched at a very general audience, is Inflight Science: A Guide to the World From Your Airplane Window. Need I say it is an easy read? I actually Fogged six paragraphs, a total of 640 words, to find that the reading level is 10.4, suitable for anyone who managed a couple years of high school at least, and is accessible to a bright middle-schooler.

The book is in seven sections, from your wait in the airport lounge, to various aspects of the flight, to landing and deplaning. Have you been worried about the new backscatter x-ray machines you're asked to stand inside? (Unless you want a very thorough body search…) They are not at all airports yet, but give it time. They work on a different principle than the dental and medical x-ray machines, which take a picture right through your body. The airport machines use "soft" x-rays, that mostly bounce off your skin, but do pass through your clothing. They bounce particularly well off things harder than skin, such as weapons, whether metal or ceramic or even hard plastic. While there is some x-ray exposure, you'll experience ten times the radiation during the flight itself if you're going to be "up there" more than a couple of hours.

As you'll learn later in the book, being at an altitude of 35,000 to 45,000 feet (11-12 km) places you above 70% of the protective atmosphere, so you experience an increased dose of cosmic rays. However, six hours aboard an airplane is about like six months in Denver—compared to San Diego—so far as radiation exposure goes. These low levels are well within the range our bodies can tolerate. It is only a concern if you fly across the U.S. or across an ocean every week for year after year. As it happens, a schoolmate of mine is an international businessman, based in both Hong Kong and Los Angeles. He does fly that much. I ran into him (in an airport, natch!) last year, and he is healthy. I fly about yearly, but I am the one who had cancer! Go figure.

There is a lot more than radiation going on, though. There is the Einstein effect. My friend flies enough that, by now, he is 1/1000th of a second younger than if he'd stayed on the ground. Maybe 2/1000ths. Not a huge effect, of course, but consider satellites such as the GPS system that we all use now to find our way. They have to correct for time dilation, as it is called, or their errors would add up to 38 microseconds daily. Light goes 300 meters per microsecond, and 38x300 = 11.4 km. If we didn't know about relativity, errors would accumulate at the rate of 11.4 km per day, or about 8 meters every minute.

The author has a great way of putting things into perspective. He also discusses the implications of e = mc², the equivalence of energy and matter. The Sun converts four million tons of matter into energy, by producing helium from hydrogen, every second. That rate of energy production equals having 3/4 million million million large power stations running flat out. The portion that is intercepted by Earth is 1/7 billionth of this, or 108 million power stations. That is about 5,000 times as many stations as we actually have running.

I'd like to compare that another way. The Earth's sunny side intercepts 5,000 times as much energy as we are currently using. While modern, cutting-edge solar cells have efficiencies in the 30-40% range, affordable ones are about 15% efficient … while the Sun is shining. Averaged over a day, and assuming they are somewhat steerable, such solar cells can be 6% efficient. Grind out the numbers, and it would take 1/1,200th of Earth's total surface, spread around the tropical and subtropical latitudes, to capture enough energy to power all of modern civilization. That is a small matter of 160,000 square kilometers. Hmm. That is a rather big project, but not as big as doubling the number of coal-fired power plants, which is what we can expect if China and India expect to use even 20% of the energy levels the West enjoys.

OK, back to what the author wrote. While at altitude, if there is not too much cloud cover, the landforms come in for review. There is nothing quite like seeing a mountain range from above to appreciate their sheer scale. I haven't crossed the Himalayas, but I have crossed the Rockies several times. Even through the little window at my seat, they are impressive. Then I realize that they are in view for an hour or more, and I'm zipping along at 600 mph (950 kph), more or less.

Before or after the main part of the flight, during the climb to altitude or during the descent, you can see the ground from above a little more intimately. These portions of the flight are likely to be in or near cities, unless your airport is Denver Stapleton, which is way the heck and gone out on the prairie. So the author has interesting tips for estimating the population of a given area by counting street lights or city blocks in a smaller area and estimating how many of these smaller areas the town covers. He has tips for seeing archaeological features such as buried walls or building foundations, particularly if the light is low, such as late in the afternoon or in early morning (I tend to fly at dawn, which is perfect).

I have to take issue with one blunder. Discussing volcanoes, he mentions the 1883 eruption of Krakatoa, that it emitted 20 cubic kilometers of ash. That is true. Then he writes, "…the equivalent of a cube 20 kilometers on a side." Very not true. Such a cube would contain 8,000 cubic km. Twenty cubic km is a cube with a side that is the cube root of 20, or 2.7 km on a side. That is still a lot of ash. The much smaller eruption in Iceland last year shut down much of European air space for weeks. If a Krakatoa-size eruption happens again, nobody is likely to take to the air for about a year! We would all get very, very good at telecommuting. Skype's servers would likely be swamped! Citrix and other "go to my PC" services would boom. Not a bad idea, actually. I video Skype with my Dad a few times a week. It sure helps I don't have to fly six hours every time we want to chat face to face.

It has been said that the most dangerous part of a flight is the landing. Actually, it is the approach. By the time the wheels are locked down, the plane is close enough to the runway to glide in if needed. Modern autopilot systems can take off and land without human help. As long as nothing goes wrong, the pilot and copilot are actually the backup system, particularly during many landings. Could we replace them? Not likely. Little things can still go wrong, and frequently do, so even during automated landings, the pilot is not just present, but is holding the controls, ready to take over immediately. Most airlines actually require a certain number of "hand" landings to keep the skills of the pilots up to date.

With this book in hand, there ought to be plenty to do during the whole flight experience, from being dropped off at the airport to gathering your luggage. No matter how much fun the book is, however, I am always glad to get off the plane and experience the relative freedom of being able to walk more than a few dozen feet. At least, knowing a few things the author has passed along, the flight itself can be more interesting than before.

No comments: