Timescale is Everything!

In my last post, I waxed about my field of rheology in an attempt to show that the boundary between solids and liquids is fuzzier than you might think.

One other thing that rheology teaches you to appreciate is the importance of timescales. To rheologists the "pitch-drop experiment" is exciting; the difference between something that flows and something that doesn't is patience.

In fact, there is widely used dimensionless number called the Deborah number named after the prophetess Deborah, who said "The mountains flowed before the Lord".

Presumably "the Lord" works on much longer timescales.

All this is a long prelude to some amazing videos by the Slow Mo Guys. They film things squishing, popping, dropping or exploding, with a high-speed camera, and set it to music. The result is beauty and a deep appreciation for everyday phenomena that we miss because we sense and process visual data at "faster" time scales.

Here are specific links to a few that I really enjoyed: bubble bursting, underwater bullets, exploding water-melons and rubber bands, droplet collisions, etc.

Heck! Check them all out.

Hard Work versus Intelligence

I am currently reading Jonah Lehrer's fascinating book "How We Decide". If the rest of the book lives up to the three chapters I have read so far, I will recommend it enthusiastically.

In chapter 2, there is an intriguing discussion of the role of mistakes in the learning process, that are potentially relevant in an academic setting (apparently, Neils Bohr once remarked that an expert was a person who had committed all the mistakes possible in a narrow field).

The whole idea is that mistakes aren't things to be discouraged, but rather they should be "cultivated, and carefully investigated". Lehrer talks about a series of experiments performed by Stanford psychologist Carol Dweck on the correlation between future performance and quality of praise.

A bunch of fifth-graders  students were given a relatively easy test. Half the kids were praised for their intelligence ("you must be smart at this"). The other half were praised for their effort ("you must have worked really hard").

These kids were allowed to choose the level of difficulty of their next exam. The first choice was described as hard, but educational, while the other was described as being similar to the one they had just taken.  

90% of the kids praised for effort chose the harder test, while a majority of the kids praised for intelligence picked the easy test. They shunned the risk of making mistakes. This aversion can seriously inhibit learning.

Dweck then gave all the kids yet another test. This one was really really hard. In fact, it was written for eighth-graders. Dweck wanted to see how kids respond to the challenge. The "effort" kids got very involved, and tried to tease the test apart, while the "intelligent" group got easily discouraged.

After the test she asked the two groups of students to make a further choice. They could look at the exams of kids who did better than them, or worse than them. The "intelligence" kids almost always chose to bolster their self-esteem by comparing themselves with someone who had done worse. The other cohort were more interested in the higher-scoring exams - "trying to understand their mistakes, to learn from their errors , to figure out how to do better."

She was not done yet.

She gave one final "exit" exam, which was supposed to be similar to the initial test. The "intelligent" group saw their scores drop by 20% on average, while the other group improved by 30%.

As a teacher and parent, this is really important practical stuff. In fact here (pdf) is a relatively recent article on how to raise smart kids by Dweck.

Lecture on Bottled v/s Tap Water

In this nearly hour long video lecture, delivered at the California Academy of Sciences, the speaker talks about how bottled water is really not as safe as we think it is.

Consumption of bottled water in the US has grown nearly exponentially since the 1970s. Interestingly consumption over the last couple of years seems to have abruptly declined (not merely a decrease in the rate of growth).

Check it out, although you may not learn anything that you didn't already know or suspect.

Handwriting

I came across this not-very-surprising summary of a research report on how legible handwriting earns better grades, in the Editor's choice portion of a recent Science magazine (the original citation Soc. Psychol. Pers. Sci. 1, 230 (2010) is not available at my University).

Essentially, better handwriting earned an approximately 8% premium, for otherwise identical essays.

When evaluators are made aware of this bias, the premium disappears.

It served as a painful reminder of how shoddy my own handwriting has become.