The curious physics of domino chain reactions.
Category Archives: Mathematics
Starships And Wormholes
There’s an interesting new book
Book Bleg
Does anyone know what the plane change would have been between Columbia and the ISS (ballpark, I know it moved during the mission)? I could figure out the RAAN of Columbia from launch time, but I don’t know what it was for the ISS at the time.
[Sunday evening update]
Here’s what I added as a footnote to the chapter, as a result of discussion here:
The difference in orbital planes at the time was about ninety degrees. A sixty-degree plane change requires as much velocity as it takes to get into orbit (ignoring atmospheric drag and gravity losses), and ninety would take about forty percent more than that (or about as much as it would take to escape from earth’s orbit from the earth’s surface, again, ignoring those factors), so even if there had been a full external tank attached to the Columbia in orbit and the main engines could have been restarted, it still wouldn’t have had nearly enough propellant to get to the ISS.
FWIW.
Soulmates
Those who believe in them are much more likely to divorce. It makes sense that a marriage founded on an irrational myth is less likely to survive. There are billions of people in the world. If there’s only one right person for you, what are the odds of finding him?
Escher
Very cool.
Warp Drive
What if NASA could figure out the math?
Well, Alpha Centauri in two weeks is nothing to sneeze at. Of course, this could be a problem:
…other scientists have raised concerns that warp drive could be potentially very dangerous, potentially destroying the destination in its path.
Luddite whiners, standing in the way of progress.
Optical Illusions
Anamorphic ones.
Michael Barone
I take some pleasure in finding I have been wrong, because it’s an opportunity to learn more. As I prowl through the 2012 election statistics I will have an opportunity to learn much more about America and where we are today. A nation dissatisfied with the results of a Democratic president, Democratic Senate and Republican House has decided to return a Democratic president, Democratic Senate and Republican House. Lots to learn for all of us.
Indeed.
Imaginary Abaci
I wouldn’t be able to do this:
And the high point of the championship is the category called “Flash Anzan” – which does not require an abacus at all.
Or rather, it requires contestants to use the mental image of an abacus. Since when you get very good at the abacus it is possible to calculate simply by imagining one.
In Flash Anzan, 15 numbers are flashed consecutively on a giant screen. Each number is between 100 and 999. The challenge is to add them up.
Simple, right? Except the numbers are flashed so fast you can barely read them.
I just don’t have the capability to visualize things like that (or much of anything). It’s just not how my mind works. Some people think in pictures. I do it with words.
78.4%
Some thoughts on Nate Silver’s latest prediction:
…one can think that Silver is probably right about the Electoral College, and simultaneously think that the 78.4 percent number is basically meaningless. Or rather, that it is impossible to formulate the epistemological difference between “There is a 78.4 percent chance that Obama will win” and “There is a pretty good chance Obama will win.”
My problem with it is that I don’t believe that he knows all of his data inputs to three figures. Yes, I know that’s how the polls purport to measure them, but three figures of precision are meaningless unless you also believe that the number is accurate. As another plug for my (still to be published) space safety book, here’s a relevant excerpt:
One of the very first things that scientists and engineers are taught is that you can’t get an answer more precise than the precision of the least precise factor from which it is derived. For example, we know the gravitational constant to many places, but when you multiply it by a mass that you only know to two places, that is the maximum precision that can be reasonably used to express the local gravitational field for that body. A good professor will mark down an answer on a student’s test that, while accurate, is unjustifiably precise. When I see engineers doing the same thing, I tend to think that they’re trying to impress the innumerate who don’t understand the difference between precision and accuracy. And I think that the safety numbers for Ares I were precisely wrong.
As is Nate’s election prediction. To me, it would be more credible if he just said 80%, though I still don’t buy it.