### Overheard in class this term

One of my students, Mike, took very detailed notes during this term's Ay117 Astrostats course. Here are the highlights from my and my TA's, lectures:

Aaron:

“I don’t have great things to say about Mathematica.”

“Who’s feeling lucky?”

“Are there any questions? Great! Actually, it’s better when there are questions. I should stop saying [great!] and say, ‘Are there any questions? No? Aw, that’s too bad.’”

“Oh god, I do NOT understand Mathematica.”

“Never anything positive out of Mathematica—EVER.”

“Let’s say you wanted to raise your hand at a colloquium. You wouldn’t say—unless you’re Dave Stevenson—‘THAT’S WRONG!’”

“Blackboard myopia—when you’re at the blackboard and it’s harder to do math.”

“Chris, why don’t you come up here? I just ran a random number generator to choose one of you guys randomly!”

“Hopefully everybody’s nodding or getting close to being able to nod.”

“This pen, of course, as always, sucks.”

“It’s both profound and profoundly dumb at the same time.”

“I don’t know what the real name for this is. I call it the ‘stair-step plot.’ I’m pretty sure I didn’t make that up.”

“Look, I want to hear a cacophony of, ‘EXPONENTIAL MINUS ONE HALF…’”

“So how did you guys do with the problem set? I see a lot of guilty smiles.”

“Six months ago, I stopped being able to use Caltech Registered. It’s like they really want me to get out of here.”

“The number of words you think should be on your slides, divide that by 2, 3, or maybe infinity, and that’s the number of words that should be on your slide.”

“I hate whiteboard pens.”

“You’ll never find errors if you can’t see them.”

“I hate texting. I’m so bad at it.”

“If you are worried about the difference between N and N–1 , then you are probably up to no good.”

“I don’t even believe in Mathematica.”

Prof. Johnson:

[Trying to show an online video] “Whoa—don’t look at my inbox.”

“I’ll slap your hand if you get those mixed up. No, I probably won’t. I’ll get sued if I do that.”

“As long as we believe in multiplying probability distributions, we’re all Bayesians!”

“Go ahead and talk about that, or just stare at each other confused.”

[On the approximately equal sign]
“Bacon equal!”

“Since Saturday, I’ve been sick, and I’m still sick, but I’m going to power through this!”

“There are many things that I’ll defer to the National Academy of Sciences guy on. I am a fourth-year professor. At the time, I was a first-year professor. But this is one of those times that I didn’t back down. He was wrong.

“This is why astronomers walk around murmuring under their breath, ‘Root N, root N, root N…’”

“The funny thing is, the more you go into astrophysics, especially if you’re an observer, the more your calculus atrophies. If I were a theorist, things would be different.”

“I didn’t know that. That’s hot.”

“We have a guest today, Renée Hložek, which sounds like ‘logic,’ but looks nothing like it.”

“I went so many years hearing people say, ‘I just did MCMC blah blah blah blah,’ and I thought, wow, those guys must be so smart because that thing has so many syllables and one of the words is the name of a Russian guy. It has to be good and it has to be hard.”

“There are more syllables in Markov Chain Monte Carlo than there are lines of code in the simplest MCMC code.”

“A Markov Chain is like when I have too much burbon. What I do now is dependent on where I was last, but I have no memory of how I got there.” [ed note: h/t to Bri on this one]

“Does anybody not understand how cool that is? Because I want to tell you how cool that is.”

“Every talk that I give, I never apologize for saying things that are supposed to be obvious.”

“Every science talk I do, I aim towards the first-year graduate students in the back row. And the professors love my talks because they get to sit there and sagely nod their heads while the graduate students are getting really excited about my field because they can actually understand what’s going on.”

“You don’t need to know this unless you’re fans of trivia.”

“How about that little happy cosmic coincidence?”

Student: “I’m troubled.”

[On making fun of other people]
“It’s not so much that I like putting people down as it is I’m trying to instill a fear in you of doing those things too.”

“It’s every astronomer’s—or every experimentalist’s—mantra: more data, more data, gotta get more data.”

“You see an outlier and you say, ‘Out, liar!’”

“I’m going to use a little pidgin math because I haven’t fully thought this through.”

“I’m notorious because I’m known to throw pop finals.”

“That was a previous measurement that was made of the universe in the Journal of Life, the Universe, and Everything.”

### On the Height of J.J. Barea

Dallas Mavericks point guard J.J. Barea standing between two very tall people (from: Picassa user photoasisphoto).

Congrats to the Dallas Mavericks, who beat the Miami Heat tonight in game six to win the NBA championship.

Okay, with that out of the way, just how tall is the busy-footed Maverick point guard J.J. Barea? He's listed as 6-foot on NBA.com, but no one, not even the sports casters, believes that he can possibly be that tall. He looks like a super-fast Hobbit out there. But could that just be relative scaling, with him standing next to a bunch of extremely tall people? People on Yahoo! Answers think so---I know because I've been Google searching "J.J. Barea Height" for the past 15 minutes.

So I decided to find a photo and settle the issue once and for all.

I then used the basketball as my metric. Wikipedia states that an NBA basketball is 29.5 inches in circumfe…

### The Force is strong with this one...

Last night we were reviewing multiplication tables with Owen. The family fired off doublets of numbers and Owen confidently multiplied away. In the middle of the review Owen stopped and said, "I noticed something. 2 times 2 is 4. If you subtract 1 it's 3. That's equal to taking 2 and adding 1, and then taking 2 and subtracting 1, and multiplying. So 1 times 3 is 2 times 2 minus 1."

I have to admit, that I didn't quite get it at first. I asked him to repeat with another number and he did with six: "6 times 6 is 36. 36 minus 1 is 35. That's the same as 6-1 times 6+1, which is 35."

Ummmmm....wait. Huh? Lemme see...oh. OH! WOW! Owen figured out

x^2 - 1 = (x - 1) (x +1)

So $6 \times 8 = 7 \times 7 - 1 = (7-1) (7+1) = 48$. That's actually pretty handy!

You can see it in the image above. Look at the elements perpendicular to the diagonal. There's 48 bracketing 49, 35 bracketing 36, etc... After a bit more thought we…

### The Long Con

Hiding in Plain Sight

ESPN has a series of sports documentaries called 30 For 30. One of my favorites is called Broke which is about how professional athletes often make tens of millions of dollars in their careers yet retire with nothing. One of the major "leaks" turns out to be con artists, who lure athletes into elaborate real estate schemes or business ventures. This naturally raises the question: In a tightly-knit social structure that is a sports team, how can con artists operate so effectively and extensively? The answer is quite simple: very few people taken in by con artists ever tell anyone what happened. Thus, con artists can operate out in the open with little fear of consequences because they are shielded by the collective silence of their victims.
I can empathize with this. I've lost money in two different con schemes. One was when I was in college, and I received a phone call that I had won an all-expenses-paid trip to the Bahamas. All I needed to do was p…