There's a lot of background mess in our mental pictures of the world. We try and be accurate on important issues, but a whole lot of the less important stuff we pick up from the media, the movies, and random impressions. And once these impressions are in our mental pictures, they just don't go away - until we find a fact that causes us to say "huh", and reassess.
Here are three facts that have caused that "huh" in me, recently, and completely rearranged minor parts of my mental map. I'm sharing them here, because that experience is a valuable one.
Think terrorist attack on Israel - did the phrase "suicide bombing" spring to mind? If so, you're so out of fashion: the last suicide bombing in Israel was in 2008 - a year where dedicated suicide bombers managed the feat of killing a grand total of 1 victim. Suicide bombings haven't happened in Israel for over half a decade.
Large scale plane crashes seem to happen all the time, all over the world. They must happen at least a few times a year, in every major country, right? Well, if I'm reading this page right, the last time there was an airline crash in the USA that killed more that 50 people was... in 2001 (2 months after 9/11). Nothing on that scale since then. And though there has been crashes on route to/from Spain and France since then, it seems that major air crashes in western countries is something that essentially never happens.
The major cost of a rocket isn't the fuel, as I'd always thought. It seems that the Falcon 9 rocket costs $54 million per launch, of which fuel is only $0.2 million (or, as I prefer to think of it - I could sell my house to get enough fuel to fly to space). In the difference between those two prices, lies the potential for private spaceflight to low-Earth orbit.
Anna and I actually did a Fermi estimate of the fuel for the Apollo 11 mission over dinner last week, and we were off by a factor of two. Some of the available inputs:
A crude estimate of the potential energy of mass lifted from Earth's surface to a distance of many times its radius
The heights reached by jet aircraft using fuel amounting to only a very small portion of their mass
A crude estimate of the energy content of gasoline (one approximation is to energy content of food, and/or the energy output of humans), with adjustment for the need to carry oxygen into space
Images of rockets launching, which show that the fuel tanks are much bigger than payload, but not thousands or millions of times bigger
Knowledge of the price of consumer gasoline, or the price of oil
The existence of science fiction writers with physics backgrounds, SpaceX, the L-5 societies, and other groups seriously pushing for advancements to slash cost-to-orbit
Rough knowledge of NASA's budget, either directly or by bounding it relative to known US budget items
Knowledge of the enormous cost of producing military aircraft and naval vessels, which can be in the hundreds of millions to billions of dollars
The existence of an ecology of NASA contractors condemned for their enormous costs (these would be trivial if fuel was the major cost)
There's a lot of background mess in our mental pictures of the world. We try and be accurate on important issues, but a whole lot of the less important stuff we pick up from the media, the movies, and random impressions. And once these impressions are in our mental pictures, they just don't go away - until we find a fact that causes us to say "huh", and reassess.
Here are three facts that have caused that "huh" in me, recently, and completely rearranged minor parts of my mental map. I'm sharing them here, because that experience is a valuable one.