There’s a 99% chance that whoever filed this brief is not licensed to practice law.
Heh.
Category Archives: Mathematics
Randall Munroe
[Via Sarah Hoyt]
Math
As usual, the Democrats were apparently told there would be none.
Just add the stadium fiasco (from the very beginning — Bank of America Stadium? Really?) to the list of this week’s convention disasters.
One Soul Mate
While it’s a nice romantic notion, the idea that there is just one person for you always struck me as nonsense, because the chances of finding them would be infinitesimal. But the indispensable XKCD actually runs the numbers.
Prisoner’s Dilemma
A new twist on game and evolutionary theory.
Ryan’s Plan
…against the team with no plan. I recall when Turbotax Timmy Geithner said, “…we don’t have a plan, but we know we don’t like yours.”
We’ll see how trying to beat something with nuthin’ works out for them this fall.
Burn The Math Witch!
The Freepers have some fun with Iowahawk’s new hashtag game.
Barack Obama: “I was told there would be no math.”
[Update a few minutes later]
One of my favorite comments over there: “Math is racist.”
Mars Spreadsheet Update
For anyone interested, I’ve got a new, improved version up. It’s basically more organized, with the constants grouped together, and with no references to rows below the formula.
My Mars Spreadsheet
As a response to popular request (actually, no one asked except Jon Goff), I’ve cleaned up and uploaded my spreadsheet.
Other than the astonishing results themselves, the only thing that makes me suspicious is that the total delta V required for the mission with the stop for gas is less than that required for the direct trip (about seven km/s for the latter and about six for the former). But I’ve looked at it multiple times, and don’t see anything wrong with what I did. I’m guessing that, if this is right, it has something to do with the oddities of patched conics. But it would be nice to get some more eyes looking at the problem.
[Update a few minutes later]
Don’t waste too much time looking at that. I just noticed some problems. I’ll update when I’ve fixed.
[Update a few minutes later]
OK, I’ve uploaded a new version. The good news is that I found the problem, and the total delta V is now more for the trip with the gas stop than without (which it seemed it should have been). It’s now about four and a half kilometers per second for the direct case, and about six for the gas stop. The bad news is that the advantage has dropped significantly. The propellant ratio, rather than ten and more than twenty for the EML1 and LEO cases without refueling, is now more like three and five. Still, it’s a significant improvement.
I should note that this is an excellent example of a need to have a feel for the numbers, and not just trust what comes out of a computer (as I fear too many young people do these days). If you don’t know intuitively proper orders of magnitude, or recognize suspicious results, you’re likely to make a lot of errors when doing complex calculations, particularly if you are operating in an environment of confirmation bias (I really, really liked the first, incorrect results). I’m looking at you, climate modelers…
[Update a few minutes later]
One more update to the spreadsheet. I noticed that in fixing the calculations, my delta Vs had become unbalanced, so I adjusted the gas station orbit slightly to rebalance them. The new orbit is 1.256 AU.
ObamaCare Costs
This is an illustration of a pet peeve, though. I hate misleading scaling of graphs and bar charts. Because they chose to use $900 as a baseline, it makes it appear that the estimates have increased by more than an order of magnitude over two years, when in fact they have only doubled. It seems to me that doubling is bad enough without playing games with graphics.