A countdown clock that continued to increase past 00:00; a security guard whose face turned ghostly-white in an instant; a lack of response from the Columbia crew to repeated calls from Capcom/Astronaut Charlie Hobaugh; and the words of "Get ready," uttered quietly from the lips of Steve Lindsey, told me that it was time - time to be strong in the face of true adversity.

It was the most difficult day of my life; even harder than when my father died, as that was what we were expecting. I do my best to describe the day's events in my book, but suffice it to say I felt a huge emptiness inside and it is a burden I still carry today. That day changed me inside; it made me much more emotional than I can ever remember being. It tested my faith and it still tests me.

But it never dulled my dream to fly in space. It only strengthened my resolve. We (NASA) would figure this out. We would make it safer than before. That's what we do. That's "how we roll."

Spaceflight is dangerous. Spaceflight is hard. We must keep that in mind as we move forward into the era of commercial spaceflight endeavors, lest we forget the lessons of our past.

Godspeed Challenger; Godspeed Columbia.

This from Clayton Anderson's answer to What was it like to watch either the Challenger or Columbia space shuttle disasters live? on Quora.

Today, of course, is the twelfth anniversary of the Columbia disaster, and earlier this week marked the twenty-ninth of Challenger.

Classes started yesterday (though my median class wasn't until 11:30 today), and, on a lark, I decided to take my notes, not on paper (as I have for the first five semesters of my college career), nor in \(\LaTeX\) (like a reasonable person), but here, on my blog site. This has the benefits of (1) being easier to share with other people and (2) lowering the activation energy for me looking them up come finals-time.

It has the problems of it being really annoying to write MathJax-compatible Markdown. (For other people facing this problem, Ore Babarinsa / Ben Kuhn suggest Madoko.) But I'm getting better at it, and I'm already at the rate where I can live-write these things, so it's not so bad.

Anyway, without further ado:

• CS 181 (Machine Learning)
• CS 223 (Randomized Algorithms)
• CS 225 (Pseudorandomness)

Maybe if I build up some momentum, I'll finally have enough motivation to stop skipping cl--OH WAIT MY MOM READS THIS BLOG NEVER MIND THAT.

Today, in Harvard Ballroom's Wintersession series, the advanced class was doing Waltz. The only thing you need to know about Waltz to read this post is that steps come in repeating sets of three:

1. drive (forward)
2. swing/rise/shape
3. float/lower/prepare

Our instructor had this to say about what to fix when things go wrong:

...And here's the thing: Everyone has strengths and weaknesses. Some people have strong drive, but problems with float. Others have problems with swing. But remember this: If a step feels bad, the problem is with the previous step.

If you have problems with float, it's probably because your swing left you off balance. If you can't drive, it's probably because you didn't lower out of your float in time...

And I think that there's a bit of this that makes good sense in general, in a pattern I'll dub the Law of the Culpable Prior: If you see a problem in a thing, look for the real problem in the thing that came before it:

• If there's a financial crisis...look at the economic policies that were instituted three-to-five years ago.

• If Millenials are whiny, fragile, entitled, and unmotivated...look at the Millenials-parents generation. (I'd link to an appropriate editorial, but, like everything else including the word "Millenial", you can pretty much extrapolate the entire text from the title and your imagination.)

• If a student -- or a discrete subset of students -- is doing poorly at grade level [N]...look at their educational

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The first was going to be about my favorite Operating Systems professor ending up in the Financial Times for her quotes at Davos on David Cameron's proposed policies banning strong encryption, but then it passed 450 words, and I spun it off into its own post.

Instead, (speaking of economics and expert opinions,) The Upshot asks how economists came to dominate the [public-policy] conversation, beating out historians, psychologists, sociologists, anthropologists, and demographers:

Two hundred years ago, the field of economics barely existed. Today, it is arguably the queen of the social sciences.

These are the conclusions I draw from a deep dive into The New York Times archives first suggested to me by a Twitter follower. While the idea of measuring influence through newspaper mentions will elicit howls of protest from tweed-clad boffins sprawled across faculty lounges around the country, the results are fascinating. And not only because they fit my preconceived biases.

Using the new Chronicle tool that catalogs the entire Times archive, I discovered that in recent years around one in 100 articles mention the term “economist,” and these typically occur in the context of introducing a proponent of the dark arts. Far fewer articles mention the terms historian or psychologist, while sociologists, anthropologists and demographers rarely rate a mention. (...)

If you haven't clicked through yet, ask yourself as a quiz: what major world event let economists pass historians? It's pretty obvious when you think.

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Elsewhere in "economists", George Mason professor of Economics Tyler Cowen (of Marginal Revolution) is one half of MRUniversity, a site full of free open courseware covering topics in economics. Specifically, in the form of three-minute bites like this:

This semester, I'm a Teaching Fellow for CS 161, Operating Systems, taught by the legendary Margo Seltzer, former president of USENIX, advisor to Harvard WiCS, and mother of two.

She's quoted in an article by the Financial Times^[1] alongside two other Harvard professors speaking at Davos^[?], criticizing David Cameron's post-Charlie proposals to criminalize strong encryption:

If bad guys who are breaking laws cannot use encryption, they will find another way. It is an arms race and if governments say you cannot do this, that means the good guys can't and the bad guys can. End to end encryption is the way to go. (...)

Jonathan Zittrain weighs in:

This is not just about hardware but software. You would have to find a way for a phone not to be able to download any app that could defeat [the breaking of] encryption... That would be a referendum on our entire ecosystem. (...)

Making Zittrain's comment a little more concrete, messaging app WhatsApp would run afoul of Cameron's proposed securities policies, as will Snapchat and recent versions of the iPhone.

Cameron's comments:

Speaking on Monday, the Prime Minister asked whether "we want to allow a means of communication between two people which, even in extemis with a signed warrant from the Home Secretary personally, that we cannot read?

"My answer to that question is no, we must not. The first duty of any government is to keep our country and our people safe." (...)

Let's be very clear here -- we're talking about programs so basic, I've been asked to code them as a homework exercise twice, once in an undergraduate math course for sophomores (and the other time, in

I was having an interesting discussion over dinner the other day with my aunt and cousins, which began as a relatively minor complaint about the propensity of Agents of SHIELD screenwriters (yes, I only just discovered this show) to use real science words in absurd ways, rather than making things up. At some point, the conversation had morphed into something about the general habit of filmmakers to publish misleading science as if it were plausible. (I found myself attempting -- but failing -- to communicate a point better made by Eliezer Yudkowsky in his post Science as Attire.) Some of us were of the opinion that this was a pretty bad thing that should probably stop; others didn't see much harm in it, so long as it was in works that were clearly fiction (false-science documentaries another matter entirely.)

My aunt, in the latter group,

"It's fiction, and it's art. If you're watching it as an audience and as a scientist, then it means one thing to you, but if you're just watching it as an audience, the science doesn't really matter, unless it's somehow important to the plot. Besides, anyone who's getting their science education from movies should really educate themselves better."

My one cousin and I had spent some time pushing against this head-on, without much success, when my other cousin tried a different tactic:

"You two, you're framing the stakes wrong. Mom, what would you say about a movie, clearly fiction, which had some offhand scenes involving domestic violence in a light that made it seem acceptable, or even normal? I mean, it's clearly fiction, and the screenwriter isn't an expert or adviser on

1

The Harvard Political Review reports that a Chicago nonprofit is scraping Twitter to pass on complaints about food poisoning in restaurants to the Chicago Department of Public Health:

Foodborne Chicago depends on human judgment in addition to computerized predictions. First, the algorithm "surfaces tweets that are related to foodborne illnesses." Next, "a human classifier goes through those complaints that the machine classifies, [...determining] what is really about food poisoning and what may be other noise." The Foodborne team then tweets back at the likely cases, providing a link for users to file an official complaint. In short, computers deal with the massive quantity of Twitter data, and humans ensure the quality of the result. According to its website, between its launch on March 23, 2013 and November 10, 2014, the Foodborne algorithm flagged 3,594 tweets as potential food poisoning cases. Of these tweets, human coders have identified 419, roughly 12 percent, as likely cases meriting a reply on Twitter.

But does it actually work?

In its first nine months of operation, Foodborne initiated 133 health inspections. Approximately 40 percent of these investigations uncovered critical or severe violations of the health code -- the kinds of violations that force restaurants to shut down or to remain open only under strict conditions. As Richardson noted, "that percentage is equivalent to the ... percentage of violations we find based on reports we get from 311" -- the phone number citizens can call to report food poisoning to their city’s municipal services. (...)

Apparently, yes.

Elsewhere in the brave new