Monthly Archives: January 2011

Context Matters

Posted on by

In physics, units matter (just ask the Mars Climate Crasher Orbiter). They put a context on the number. That isn’t always enough, because you don’t know if the number is big or small unless you compare it to a familiar quantity, which is why it’s a good exercise to be Putting a number in its context

[I]s the failure rate exceptional? A figure means nothing if it has no context: 600 pregnancies sounds like a big number, but there is no way to know what it means unless we know how many women had Implanon, and for how long.

By Gum it's Glass!

Posted on by

The hover tag on the recent xkcd cartoon Misconceptions mentions the common glass mistake, that it is a slow moving fluid (also seen: supercooled fluid). I remarked to a colleague that part of the foundation for that was not understanding that there is a glass transition, while the more common observation is a first-order phase transition from liquid to solid. He mentioned a good example of a glass transition:

Take a cold piece of chewing gum. Break it in half. That’s a material in the glassy state.

Put the gum in your mouth and wait a short time. Then bite. Elastic and rubbery, but still a solid. Somewhere in that temperature span is the glass transition,

Doctor Obvious Goes to College

Posted on by

College students lack scientific literacy, study finds

Students trying to explain weight loss, for example, could not trace matter once it leaves the body; instead they used informal reasoning based on their personal experiences (such as the fat “melted away” or was “burned off”). In reality, the atoms in fat molecules leave the body (mostly through breathing) and enter the atmosphere as carbon dioxide and water.

Rough calculation: Assume you breathe in around a liter each time at 20 breaths per second minute. To make the math a little easier, let’s make that 22.4 L of an ideal gas per minute, which is one mole. Increase the CO2 by 1.5% in each cycle, which takes a Carbon atom out of your body. That’s 0.015*12g*60*24 = 260 g. You lose more than half a pound just breathing each day.

Most students also incorrectly believe plants obtain their mass from the soil rather than primarily from carbon dioxide in the atmosphere. “When you see a tree growing,” Anderson said, “it’s a lot easier to believe that tree is somehow coming out of the soil rather than the scientific reality that it’s coming out of the air.”

Feynman told us this.

College upperclassmen still fail at scientific reasoning

Related to/based on the first article; it adds a few other points.

Overheard in the Lab of the Day

Posted on by

A colleague was whistling the marching tune one hears in The Bridge in on the River Kwai, and after I asked him if we were suddenly in the British Army, I wondered what the name of the song was. Luckily, there’s a way to find such things out, called the internet (which is apparently a series of tubes.) Turns out it’s called The Colonel Bogey March, and the Wikipedia entry implies it has some interesting (not G-rated) lyrics, which it does.

Drop the Chalupa!

Posted on by

Florida Professor Arrested for Having a “Suspicious” Bagel on a Plane

A Florida professor was arrested and removed from a plane Monday after his fellow passengers alerted crew members they thought he had a suspicious package in the overhead compartment.
That “suspicious package” turned out to be keys, a bagel with cream cheese and a hat.

…

Monday’s incident is another example of other passengers essentially becoming the authority on terrorist activity on planes.

Got this from Daring Fireball, not Schneier (I suspect it will be there soon*), and Gruber had a comment:

“Suspicious Bagels” would be a good name for a bagel store.

I think it would be a good name for a band.

* and he will point out that when you have amateurs doing your security, that what you get is amateur security.

Here, Fishy Fish!

Posted on by

Firs for the Fish (and the Fishermen)

Leftover Christmas trees used as fish habitats in lakes, somewhat like old ships being sunk and used as artificial reefs.

The trees are taken to a different lake each year, where volunteers bundle them and secure them to the lake bed. Within days, the newly denuded branches become covered with algae, which attract aquatic insects, fish and, ultimately, fishermen.

The incentive to get volunteers?

“If they help, we give them the GPS coordinates of the trees,” Mr. Mitchell said of the volunteers, many of whom are anglers. “You can go right to the spot, and it’ll be good fishing there.”

Lego Letterpress

Posted on by

Letterpress Made of Legos

[T]hese two graphic designers have put Lego to yet another wonderfully off-label use by constructing a working letterpress printer out of the bricks. By clicking smooth Lego tiles into place on plastic baseboards and inking the plates, they create handmade prints with an 8-bit aesthetic.