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Showing posts from 2012

### Galactic storm

My New Year's resolution #1: Take the boys to a dark site. We might not see something exactly like this, but I gotta give the boys a chance to see the night sky before its all lost to light pollution.

http://epod.usra.edu/blog/2012/02/galactic-storm.html "The photo above showing the Milky Way stretching across the desert sky and a distant monsoonthunderstorm on the horizon was captured just outside of Dead Horse Point State Park in Utah."

### On the number of guns and planets out there, Part 2

(Note: It might take a while for the math symbols to load.)

In my previous post I set up the problem of gun statistics and planet statistics (where I mean math-problem, rather than trouble-problem). There's a question of the number of guns per capita, versus the fraction of the population with a gun (fraction of citizenry that are gun-owners). Also in there is the number of guns per gun-owner.

Similarly, there's the question of the number of planets per star throughout the galaxy, the fraction of stars with a planetary system, and the number of planets per system.

To illustrate this mathematically (and this involves nothing but multiplication and division, so stay with me!), let's set up two scenarios. Both scenarios have five stars and five planets:

Now let's introduce some mathematical terms. The first is the total number of stars in our sample, $N_\star$. Next is the number of planets, $n_p$. In both of the cases in the figure above, $n_p = 5$ and $N_\star = 5$. The…

### In orbit around 1 Mjup at 1 AU

What if Jupiter were at 1 AU and we were its moon? This is what it'd look like:
The NASA Kepler mission might help us find a situation like this. David Kipping at the Harvard Center for Astrophysics is on the case.

### On the number of guns and planets out there, Part 1

Ta-Nehisi Coates recently asked his readership to "talk to him like he's stupid" about gun ownership rates in the US and in other countries. I really like it when he makes these requests. It's how I often feel about stories in the news, which make me feel like I'm walking in on the middle of a grown-up conversation. I need someone to talk to me like I'm stupid about Benghazi or the fiscal cliff. Fortunately, Slate and Salon are good sources for this sort of information, as is Andrew Sullivan.

Anyway, regarding gun ownership rates, the discussion that Ta-Nehisi sparked got a bit muddled over the question of guns per capita (number of guns per person) versus the number of guns per gun-owner. This is an important distinction. There are two ways to get 1 gun per person in a hypothetical town of 100 people. One way is to give a gun to every person in town. The other is to have one person in town with 100 guns.

Of course this whole discussion goes back to the most…

### Me and my sisters

Via Facebook, this picture from earlier this year of me, and my sisters (from left to right, youngest to most experienced) Erin, Rachel and Christina. I'm often amazed that I came from the same beautiful gene pool. Fun facts: They are all artists and singers. I'm a scientist who can't carry a tune. We also all live along the same 20-mile stretch of the 210 freeway north of LA. We all have two kids each: 6 boys and 2 girls, and all 8 kids were born within a 10-year interval. Finally, our kids have skin tones that span Kenya to Sweden. Fun with genetics!
Sisters: Sorry we missed each other at Thanksgiving while I was out of town. I'm looking forward to seeing all of you at our Christmas celebration!

### Montana has very few people

I'm hanging out with Prof. Nate McCrady right now in Prof. Jason Wright's kitchen. Given that I once sat in Frank Shu's stellar astrophysics class with both of them, it's a lot of fun to append "Prof" to each of their names!

Anyway, this post is about how Nate blew my mind. He's a professor at U. Montana and he just informed me of the following facts:

There is one area code in Montana. There are only 1,000,000 people in the whole state.The biggest city is Billings, pop. 105,000 (Pasadena has 138,000)There are only fourteen high schools with 1000+ students...in all of Montana

### Discrete events, continuous flow, and why I love basketball

In high school I played football and ran track. After high school, I've tried running, biking, ultimate frisbee and a few other sports. But if you read my blog often, you know that my passion these days is basketball.

I find it challenging and exciting in much the same way that I enjoy science. There's just so many combinations of events and so much improvisation. Plus, it's something I can play alone (shooting around), with one other person, 2-on-2 or full-court 5-on-5, giving me plenty of opportunities to practice and participate. This is in contrast to, say, football, which I'll likely never be able to play again with a full team. And as a sport to watch live or on TV, it's fun and fast-paced without all the head trauma of my old sport.

A lot about why I love basketball is summarized in this outstanding sports article (h/t Bri) about the "Kobe Assist." The main point is that Basketball cannot be thought of and analyzed in the same way as baseball. Whil…

### The next level after grad school

Here's a great blog post about one postdoc's first-year experience:
As of October, I have now spent one year as an astronomy postdoctoral researcher straight out of graduate school. It has been a great year, though with plenty of ups and downs. I figure I should write down my thoughts about this experience. I have both good things and bad things to say, but I try to be honest, fair, and positive throughout. This may be of interest to curious grad students, or anyone really, especially if they have wondered about pursuing a postdoc or are just interested in astronomy in Chile. One thing to keep in mind is that this is an individual, personal experience and your own story or circumstances may be quite different. It's obviously difficult to approach this critically and unbiasedly, but here goes nothing...

### Correction: Those were real spectra!

In my last post I said that the spectra I was showing were not real, but instead models. However, it turns out those spectra I showed, the so-called Pickles library spectra, are actual stellar spectra! My bad. I was correct that there isn't a single instrument that provides that wide wavelength coverage. But that Pickles guy was pretty clever: "Each library spectrum was formed by combining data from several sources overlapping in wavelength coverage."

### Stars and the Exolab on PhD Comics!

Like most former and current grad students, I'm a huge fan of PhD comics. I'm also a fan of the artist behind PhD Comics, Jorge Cham, in particular his online shows on scientific topics such as dark matter, the Higgs boson and Open Access publishing. When I first watched Dark Matters, my immediate thought was "Wow, this is an amazing teaching tool. I wonder if Jorge would like to do one on exoplanets."

So, even though I had never met him, I nervously typed out an email, proof-read it, reread it, and finally hit send. Lo and behold, I managed to set up a lunch meeting with Jorge and we talked about academia, comics, teaching, and my research. He agreed that it would be fun to do a video on Exoplanets and we scheduled a date to record the audio last Summer. I also applied for and received funding from the Caltech Innovation in Education fund to contract Jorge's expertise for the whole endeavor.

Jorge and I decided to do things a bit differently than his past animat…

### Annika Peter: First, the Facts

To continue my exploration of gender parity in astronomy, I have called on my friend and fellow astronomer Annika Peter to guest blog for me.Annika and I have had several illuminating discussions over coffee about academia in general and women in science in particular. Here's the first in a series of posts from Annika.
My name is Annika Peter.  I am a dark-matter and gravitational-dynamics junkie, currently finishing up a postdoctoral position at UC Irvine, and moving to a faculty position in the Departments of Physics and Astronomy at The Ohio State University.  My husband is also an astrophysicist, currently a professor of astrophysics at Caltech.  He is taking a professorship at OSU, too, so we have successfully found an excellent solution to our two-body problem!  My two favorite aspects of my job are thinking deeply about and trying to solve some of the major mysteries of the universe, and working with undergraduate and graduate students.  I am also a practical problem solver…

### Turning a magical experience to a scene from a horror movie

Whale-flesh-eating sea gulls.
The attacks are causing the whales to change their natural behavior, making them increasingly hesitant to surface. They used to leap out of the water in dramatic displays; now, they simply skim the surface just quickly enough to catch a breath and retreat back to deeper waters. "It really worries us because the damage they're doing to the whales is multiplying, especially to infant whales that are born in these waters," says Marcelo Bertellotti of the National Patagonia Center, a government-sponsored conservation group. Experts also fear that the birds could affect the local tourism industry, changing whale-watching from "a magical experience to something from a horror movie," says Australia's Sky News.

### Career advice for new faculty members

Here's an amazingly comprehensive guide for new professors. It's geared toward bio types, but much of the advice is applicable to astro/physics:

Making the Right Moves: A Practical Guide to Scientifıc Management for Postdocs and New Faculty (pdf)

And here's the book that I recommend to every new prof:

Advice for New Faculty Members by Robert Boice
This book is based on a study of thousands of young (pre-tenure) faculty members. They identified the top 5% as the "fast starters" and found the common practices of these exemplars. The advice is very practical, but very difficult to implement because it requires you to change a lot of ingrained habits. But I've found a lot of success in implementing things like working in brief regular sessions (BRSs), being mindful of investing too much time into teaching, how to wait actively, and perhaps most importantly, how to build a group that I trust and delegate aggressively to them.

### How many people are in space right now?

This many (thanks Bri!)

### The Impostor Syndrome: Not Just in Academia

Here's a good read for those of you interested in the impostor syndrome. Apparently it's not just those in academia. The industry route is rife with the fear of being found out, or only being successful because of dumb luck rather than skill and practice:
In other ways, though, entrepreneurship is a perfect breeding ground for the syndrome. "People who have had bad experiences in organizations may see entrepreneurship as the only way out because it allows them to control their lives," says Manfred Kets de Vries, a psychoanalyst and professor of leadership development at Insead, in France. With no boss, company founders can avoid critical scrutiny. Buffered by their relative control of the environment, entrepreneurs may feel ill-equipped to survive in the outside world. "I've always felt if I stopped doing Cornucopia, who would hire me?" says Stockwell. "If I think about it rationally, I know there's good reason I'm successful. But it wouldn&…

### The snake portion of the thesis defense

From McSweeny's, via Heather:

FAQ:
THE “SNAKE FIGHT” PORTION OF YOUR THESIS DEFENSE. BY
- - - - Q: Do I have to kill the snake?
A: University guidelines state that you have to “defeat” the snake. There are many ways to accomplish this. Lots of students choose to wrestle the snake. Some construct decoys and elaborate traps to confuse and then ensnare the snake. One student brought a flute and played a song to lull the snake to sleep. Then he threw the snake out a window.

Q: Does everyone fight the same snake?
A: No. You will fight one of the many snakes that are kept on campus by the facilities department.

Q: Are the snakes big?
A: We have lots of different snakes. The quality of your work determines which snake you will fight. The better your thesis is, the smaller the snake will be.

Q: Does my thesis adviser pick the snake?
A: No. Your adviser just tells the guy who picks the snakes how good your thesis was.

Q: What does it mean if I get a small snake that is also very stron…

### Owen mod fractions = 0

Reading Is Fundamental paid a visit to Owen's school and the kids got to choose a free book. Owen chose Apple Fractions, which teaches fractions using slices of various fruit and other foods like pie and cake. When I learned that he had read the book, I tested him on fractions, math operations with fractions, and then percentages. He nailed all of my questions.

So I challenged him to figure out the modulo (mod) function. I gave him about ten examples---"3 mod 1 = 0, 3 mod 2 = 1, 3 mod 3 = 0, 4 mod 3 = 1, 5 mod 3 = 2..."---and he told me that he got it: "It's like divide then subtract!" He was ready for the test.

(for some reason the embedding code refers to the wrong video. Just click the link above)

### Surprise!

(By Erin)

About two months ago, John marked off last night for "special date night" and I was advised to ask no further questions. As I'm typically the activity/babysitter/household planner for our family... I had some serious questions! But I rolled with it - fought every urge to pry for hints, sleuth out possibilities and just enjoy not being in "charge". All I knew was that I should wear comfortable shoes and pack light.

With tremendous gratitude, we left the boys with Nana and made our way to the airport. I learned when we arrived that we were bound for OAK... Our old stomping grounds! But we hopped aboard BART and before I knew it we were in Union square in San Francisco. We'd fallen in love in this very place almost 13 years ago. Being in the Bay Area brings such strong and happy memories, it didn't matter to me what else John had planned for the night.

But there was more. I suspected we may be heading off to hear some live music, as was our p…

### Ohhhhh! That's what that's for

I was watching Apollo 13 with the boys the other day, when during the launch scene Owen asked, "Dad, what's that part that fell off the front?" He was referring to the tall mast on the front of the rocket that was jettisoned after the final burn stage, when they first arrive in Earth orbit. I've often wondered about that tower, but I always figured it was some sort of communications mast, and this is what I told Owen: "It's a radio antena."

Boy, was I wrong! That thing is actually the Launch Escape System (LES). Here's a picture from Wikipedia:

In case something goes wrong on the launch pad, or during ascent, the LES can be fired to redirect the Command Module (where the crew sits) away from the rest of the rocket or back down to Earth. Here's a photo of the LEM accidentally firing on a Mercury rocket (also from Wikipedia):

Who knew?!

### Random walking our way to radiative diffusion

I just figured out how to insert LaTeX commands directly into Blogger! Check out these instructions for how to use MathJax.

In what follows is a piece of supplemental info for my Ay20 class. Since LaTeX stopped working on my office computer after my recent move across the street, this is the easiest way to get this info to my students...

Random Walks

A photon undergoing a random walk will travel a distance $l$ before suffering a "collision," which sends it off in a random direction. It seems counter intuitive, but this random walk process results in a net displacement. Read Astrophysics in a Nutshell, Chapter 3 pages 38-39 (starting with Thus, photons...'' and ending with equation 3.45. What you'll see is the expectation value for the mean displacement $\left<D\right>$ is

\left<D\right> = N^{\frac{1}{2}}l

If we think of the distance $\Delta r$ as the net distance traveled, $\Delta r = \left<D\right>$, then each s…

### The conservative candidate won

I was actually gearing up to write an open letter to downcast conservatives. But then William Saletan went out and did a much better job than I could have done (at Slate.com). He argues that conservatives---not modern-day Republicans, but true conservatives--should take heart: Obama is the best moderate conservative candidate we've had in decades.
Obama’s no right-winger. You might have serious issues with his Supreme Court justices or his moves on immigration or the Bush tax cuts. But you probably would have had similar issues with Dwight Eisenhower, Richard Nixon, or Gerald Ford. Obama’s in the same mold as those guys. So don’t despair. Your country didn’t vote for a socialist tonight. It voted for the candidate of traditional Republican moderation. What should gall you, haunt you, and goad you to think about the future of your party is that that candidate wasn’t yours. This is the thing that had me scratching my head for so long. Obama is pretty damn far from a liberal or progre…

### Obama Wins

Erin and I switched from NBC to Fox News at 8pm. The pundits and newscasters were in the middle of a discussion about what would happen when Obama becomes president. The conversation was so dour, so sad, so muted. Then 18 minutes later, they called it for Obama.

What ever happened to the "squeaker?" What ever happened to neck-and-neck?

### Report from the voting lines

This morning after meeting with some of my students, I grabbed my voter guide and headed down to my local voting place, the Marlinda Convalescent home. In the era of Obamacare, you can imagine how crowded that place was, what with all the death panelists hovering around. After wading my way through the mobs of black and brown people committing in-person voter fraud (CA has no voter ID initiative! You can imagine the chaos.), I grabbed a stack of ballots and went to my booth.

First up: CA has two propositions for funding state public education. Being a conservative, and a fairly well paid one at that, this was an easy call. No more welfare-addicted, single moms mooching on my tax dollars. NO and NO.

Next: Repeal of the state death penalty. Um, no thanks. My policy is to execute 'em all and let Peter sort  'em out at the pearly gates.

I didn't really understand the other ones. Nothing about gun rights, abortion or stopping teh gays, so I didn't have any horses left in t…

### A Guide to Introverts

Good advising means adapting your style to different advisees. I realize that I just wrote that that as if I'm an expert. But I'm learning about this all the time, especially since I'm a junior prof with a huge group. Fortunately, with the communication I encourage within my group, I get lots of advise from my advisees. Here's a beautiful illustrated guide to introverts (click to enlarge):

### Gender Parity: Ask a Scientist...

...but know that your answer will depend on the gender of said scientist:

Women are underrepresented in science in general, but the gender gap is bigger in some fields than others: physics, for instance, has a much lower percentage of women than biology. Researchers decided to ask scientists themselves why they thought this was — and male and female scientists turned out to have pretty different ideas.

### The Boys Prep for Halloween

Marcus is wearing his favorite shirt, featuring the Mars Science Laboratory. It's a size small, but we had to cut about a foot off the bottom. Also, he insists on wearing it backwards so he can see the cool rover.  This is now day 4 wearing the shirt. Fortunately, I got two, so he's now wearing the backup shirt while we wash the primary.

### Ouch

Football head injuries are receiving a lot of attention lately. So are Headbrick injuries. The criticism stings since I enjoy watching football so much. It's quite a moral quandr---whoa, did you see that one-handed catch by Jason Witten?!

### Marcus the Deer Hunter

We went on a Saturday afternoon family adventure up to Palomar Observatory yesterday. On our way up, we passed a couple of pickup trucks with several hunters in camouflage and guns milling about on the side of the road. Marcus and Owen had a lot of questions about the hunters and hunting. Erin was able to fill them in on the details since her father (Papi, as Owen and Marcus know him) and uncles are avid deer hunters. This morning, Marcus very authoritatively told me what he knows about deer hunting: