We bought some art for the grad student lounge

The noble panda is the unofficial mascot of the Hopkins Department of Physics and Astronomy (P and A - panda); so when we saw panda-themed art on display in a local hangout we just had to put in an offer to buy it. Congrats, PandAs, we are now fancy art collectors! Here we are discussing the painting it in my office. On Friday we're going to unveil it at happy hour and hang it in the grad student lounge.

Well done, everyone!

WSJ editorial on "the culture of privilege"

A relative of mine posted a WSJ article on my Facebook wall recently which sort of ticked me off. Since it's relatively rare that I manage to write out anything that isn't technical, I've put the article and my response below. The bulk of this post is going to be just the Facebook response, but I've added a little context on how it touches me personally:

The fields of physics and astronomy have a huge demographics problem, in that they are dominated by white men and have very few women and minorities, way out of proportion to the population of the US. For what it's worth, for these purposes I count myself as one of the white dudes -- growing up Cuban in Miami, especially as the son of two doctors, doesn't exactly put you at a disadvantage. Anyway, historically, a lot of this demographic bias was the result of conscious exclusion of everybody who wasn't white and male. Nowadays, while intentional exclusion is not nearly as bad (and fortunately illegal), its remnants hang around in the form of things like unconscious bias and the lack of women and minorities coming through the pipeline to enter the sciences. It's still easier for white guys to get to -- and through -- graduate school than for everyone else. This is our privilege, and we should be aware of it.

The article is here, and here's my response:

Harsh words:
>Perhaps, then, the ideology of "privilege" amounts to a pretense of egalitarianism, analogous to an ostentatious display of charity whose real motive is the philanthropist's self-aggrandizement. Elite universities are marketing themselves--to prospective students and to the broader society--as bastions of power and privilege. Humility can be a form of vanity, self-abnegation a means of status-seeking.

But even worse, we are asked this rhetorical question:
>If it's not about making individuals feel guilty, what is it about?

(To be 100% clear, the unspoken answer is that of course the ideology of privilege is only about making individual's feel guilty.)

It's a fair accusation, I guess, but it really misses the point of the conversation on "privilege". I like Alexandra Petri's amazing response to that incredibly obtuse editorial in Time Magazine that made the rounds recently:

>It seems that Tal may have mistaken the origin of this phrase, as though being told to Check Your Privilege meant “apologize for or explain away the advantages you’ve had” rather than “consider the perspective from which you come before you enter a conversation.”
(from )

What this writer – James Taranto – is missing is that Harvard is responding to the wishes of its students, as any good university should. It is emphatically NOT hypocritcal of Harvard to support its students in pursuing their interests, when it has admitted these students precisely because it believes their interests, and the perspectives from which they approach those interests, are valuable.

The central character of this article is Ms. Reetu Mody, the student who pushed for the class on privilege and structures of power. It is unclear to me if Mr. Taranto believes that the false humility belongs only to Harvard or extends to her as well. Why? Because he apparently couldn't be bothered to interview her for an article about something she did! We have no idea what her story is, and have no basis on which to judge her actions! Going by the article, it is clear that Mr. Taranto has simply assumed – without knowing anything about her – that her opinions should be tossed out by default.

What should Harvard do? Should Harvard simply dictate to its students what issues should matter, what issues are important enough for them to concern themselves with, and condescendingly tell them what issues are not? Fortunately, Harvard values the ideas and perspectives of its students more than Mr. Taranto does.

The effects of drafting!

Here's a very cool video on how much benefit you get from drafting in cycling:


This really helps explain why riders on a break try so hard to get others to come with them. The most interesting part of the video, though, is how the rider still benefits even when someone is drafting off him. The drafting rider smooths the airflow, creating less turbulence and therefore less drag on the lead rider!

CERN switches to Comic Sans

In the midst of all the press about how much money can be saved by changing fonts (see e.g. http://www.cnn.com/2014/03/27/living/student-money-saving-typeface-garamond-schools/), it's nice to see CERN getting on board by switching over to Comic Sans, effective today, April 1: http://home.web.cern.ch/about/updates/2014/04/cern-switch-comic-sans

Updates, and I'm an astronomer now?

It's been a while since my last post, and a lot has changed!

First, I'm married! To the wonderful Katie Felkins, who is featured in some of the earliest posts here. We had a great time celebrating with our friends and family at the Maryland Zoo. It's hard to believe that was 8 months ago.

Second, I left high energy physics and joined the quest for Earth-like planets around other stars! For me, this is the most exciting field of science right now (and it's the fastest growing field of astronomy, so I'm not alone in thinking this). Recent advances in technology have finally made this possible on a large scale (see e.g. http://www.jpl.nasa.gov/news/news.php?release=2014-062). My data comes from Project 1640, whose goal is to blot out as much of the light from the host star as possible so that we can see the faint planets nearby. Aaaand I now have a research website! www.pha.jhu.edu/~jaguilar

Last, I am going to try focusing on shorter, less content-heavy posts to try to lower the activation barrier for writing here. We'll see how that goes.

Neutrino flavor oscillations

One of my classes this semester covers topics in experimental particle physics, and tomorrow I have to give a quick presentation about the first time neutrino flavor oscillations were experimentally confirmed. If you didn't know, one of the great physics problems of the last few decades was why, for 30 years, people measured 1/3 fewer neutrinos coming out of the Sun than they expected to see. 30 years! The problem became so infamous that it ended up being called the Solar Neutrino Problem - capital letters and a "the" in front. From 1967, when the first experiment saw this deficit, until 2001, this remained unsolved.

Basically, what was happening was that most of the experiments were sensitive only (or mostly) to one of the three types of neutrinos. It took until 2001 to collect enough heavy water to do the first observation that measured *all* types of neutrinos equally, at Sudbury Neutrino Observatory in Ontario.

But this post is not about that measurement. This post is about what you do if you have to find another way.

In June of 2001, just before SNO published its results in August, another one of these one-neutrino-only experiments (Super-Kamiokande, in Japan) released the results from its observations. While previous experiments had only confirmed the measurement of the neutrino deficit, Super-Kamiokande managed to provide evidence (albeit indirect) of the oscillations themselves by having the temerity to treat the entire Earth as nothing more than a part of its experimental apparatus (other experiments, like DAMA, do this now as part of the search for dark matter).

Why did this work? The reason electron, muon, and tau neutrinos oscillate between each other is that they are flavor eigenstates, not mass eigenstates. The flavor eigenstates are in fact built out of a superposition of mass eigenstates (the values of the matrix elements relating them is an active topic of research), and as they evolve in time each mass eigenstate picks up a time-dependent phase factor proportional to its energy. The upshot is that as the particle propagates along, the probability of it being in any particular flavor eigenstate changes. If you have a detector that can only see electron neutrinos, but two thirds of the electron neutrinos have evolved into the muon or tau neutrino state, you'll get only one-third of the neutrinos you expect!*

So what do you do if you can only measure electron neutrinos? Since the probability of a neutrino being in the electron neutrino state depends on its distance to the Sun, you just wait for the Earth to move closer or further away. You'd expect the flux of electron neutrinos to go up and down with the seasons.

And that's exactly what you get:

arxiv link, PRL link

There's something really special about this kind of magnificent simplicity.



*With some complications, but this is the simplified version.

Balloon-borne camera, part 9: Finally, success (and a final post)

I'm happy to report that after a lot of unhelpful weather got in the way, we finally have successful video! Before we get to that, I have a few more details to fill you in on. The first is that, emboldened by the success of our tiny $4 kite, we invested in what can only be described as Kite Kong, Lord of the Kites, with a whopping 9 square feet of surface area. We also bought 500 feet of 150-lb rated kite line. We went with a delta-shaped kite because they have a reputation as being easy to fly and very stable, although this parafoil kite was also an option due to a similar reputation for stability and good performance in low wind conditions. In the end, the real difference maker was that giant kites look way more awesome, so if a big parafoil kite had been available, we may have gone with that.

Anyway, with the help of one of the camp counselors, on Monday we had our first successful video-capturing flight! Here's a short excerpt from the video - as you can tell from the audio, we were having a little trouble getting altitude and needed a little help from the campers :)

Edit: Nix that for now, I'm having trouble

getting an excerpt from the video.

Will add it later.