Crowded skies

What are these Earthlings going? Millions of people move about planet Earth by airplane every day. Hundreds of thousands of airplane flights take place over the US every day. A dramatic graphical depiction of these flights was created by Aaron Koblin and is shown above. Clicking on the above image will bring up a movie in many web browsers, a movie that might better be visible here. The movie depicts flight patterns that occurred over a few days in 2005 March. The count on the lower left shows the number of USA-related flights at the time listed on the lower right. The trails shown are not contrails but rather generated artificially by a computer algorithm. Major cities in North America and the USA are discernable. Inspection of the movie shows that some times of the day are busier than others, indicating that flights leave some destinations at times that are convenient for travelers. In terms of distance, flying to a distant location is much safer than driving to that location. Flying in an airplane, however, remains slightly more dangerous than driving to a nearby airport.

To the Editor:

"Concern Over Airline Safety" (editorial, Nov. 16) perpetuates a myth that has surfaced periodically for years. That is that "flying is still safer than driving to the airport."

Not true. The only acceptable method to compare risk between air travel and automobile travel is based on the number of deaths per hour of exposure.

Data from a respected safety analyst, Trevor Kletz, show that air travel has a fatal-accident frequency rate four times higher than that for driving a car. For airplane travel there are approximately 2.4 deaths per million hours of exposure; for travel by car the figure is 0.6 deaths per million hours of exposure.

Simply put, for the same number of hours riding in a car or riding in an airplane, you are four times more likely to be killed in an airplane than in a car. JOHN M. HOFFMANN President Safety Engineering Labs Inc. Detroit, Nov. 22, 1994

How to destroy the Earth, part 5

5.You will need: some means of accelerating the Earth's rotation.

Accelerating the Earth's rotation is a rather different matter from moving it. External interactions with asteroids might move the Earth but won't have a significant effect on how fast it spins. And certainly it won't spin the Earth fast enough. You need to build rockets or railguns at the Equator, all facing West. Or perhaps something more exotic...

Method: The theory is, if you spin the Earth fast enough, it'll fly apart as the bits at the Equator start moving fast enough to overcome gravity. In theory, one revolution every 84 minutes should do it - even slower would be fine, in fact, as the Earth would become flatter and thus more prone to breaking apart as you spun it faster.

Feasibility rating: 4/10. This could be done - there is a definite upper limit on how fast something like the Earth can spin before it breaks apart. However, spinning a planet is even more difficult than moving it. It's not as simple as attaching rockets pointing in each direction to each side...

Source: This method suggested by Matthew Wakeling.