Monthly Archives: November 2010

Wear Your Safety Goggles

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Because this story might cause something to get into your eyes

Vietnam War bracelets come full circle

Air Force Capt. James Hivner was 60 miles north of Hanoi on Oct. 5, 1965, when his F-4 fighter was hit. He dropped his bombs onto the ammunition dump he was targeting and ejected from the burning plane.

Hivner was quickly captured and endured nearly eight years of brutality. He was beaten and whipped, starved, and held in near-total isolation. In 1973, he was one of 590 American POWs in Vietnam released as part of the cease-fire agreement that ended the war.

“I was in the hospital recovering when I started getting these little packages,” Hivner said.

Inside each was a bracelet with his name etched on it and a note of thanks.

Through the years, the 79-year-old retired colonel has received scores of bracelets. The most recent came last Memorial Day. He keeps them in a shoebox.

Going Through a Phase

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A Phase Transition for Light

When a laser beam is intense enough, it can interact with the air around it in ways that lead to surprising effects. According to computer simulations to be published in the 12 November Physical Review Letters, the beam can act like a gas of quantum particles (fermions) or like a liquid droplet–and switch between the two as intensity is increased. Observing this transition in the lab would help researchers confirm that they understand the behavior of high intensity lasers in air, which they hope to use for improved transmission of signals across long distances.

It's Like Building a Bridge

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Uncertain Principles: Physics Is All About Analogies

I’ve got a little speech about this that I give when I talk about simple harmonic oscillators in the intro mechanics class, that I started giving because I got sick of the students giving me pitying looks when I went on about masses on springs. Because, really, who gives a damn about masses on springs?

Of course, any physicist knows that the reason we spend time talking about masses on springs is not because masses on springs are inherently fascinating, but because so many systems that are interesting can be made to look like masses on springs. That is, there is an analogy to be made between the behavior of a really simple system that we can solve exactly (the mass-on-a-spring problem) and much more complicated systems that we would really like to be able to solve exactly.

This goes along with Every Problem Looks Like a Nail, my link to brief comment on an xkcd cartoon: To first order, everything is an harmonic oscillator.

In science, we build models. Analogies are pre-fab models, based on an already-existing floor plan. Or, in the Feynman context of discussing magnets

I really can’t do a good job, any job, of explaining magnetic force in terms of something else that you’re more familiar with, because I don’t understand it in terms of anything else you’re more familiar with.

to put a concept in terms of concepts you do understand, and to use another analogy, it’s a bridge to a concept you understand.

Brother Maynard! Bring Up the Holy Hand Grenade!

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Radioactive rabbit trapped at Hanford

Workers first found contaminated rabbit droppings last week in the 300 Area, said Todd Nelson, spokesman for Washington Closure Hanford, the Department of Energy contractor cleaning up Hanford.

Several rabbits were trapped and the one was found to be highly contaminated with radioactive cesium.

I wonder what superpowers (of a non-breeding nature) you would get if bitten by a radioactive rabbit?

Rotten Burgers

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The Burger Lab: Revisiting the Myth of The 12-Year Old McDonald’s Burger That Just Won’t Rot (Testing Results!)

Dozens of other examples exist, and most of them come to the same conclusion: McDonald’s hamburgers don’t rot.

The problem with coming to that conclusion, of course, is that if you are a believer in science (and I certainly hope you are!), in order to make a conclusion, you must first start with a few observable premises as a starting point with which you form a theorem, followed by a reasonably rigorous experiment with controls built in place to verify the validity of that theorem.
Thus far, I haven’t located a single source that treats this McDonald’s hamburger phenomenon in this fashion. Instead, most rely on speculation, specious reasoning, and downright obtuseness to arrive at the conclusion that a McDonald’s burger “is a chemical food[, with] absolutely no nutrition.”

Let the Warm Fuzzies Begin

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In case your week wasn’t bad enough:

Money for Scientific Research May Be Scarce With a Republican-Led House

In the Republican platform, Pledge to America, the party vows to cut discretionary nonmilitary spending to 2008 levels. Under that plan, research and development at nonmilitary agencies — including those that sponsor science and health research — would fall 12.3 percent, to $57.8 billion, from the Mr. Obama’s request of $65.9 billion for fiscal year 2011.

’cause what has science ever done for us? (You know, if you squint, the elephant looks like an insane clown posse mask)

This, on top of the continuing resolution that is cramping my style at work. There are only a few things that congress has to do each year, and one of them is pass the budget. Don’t let ’em leave Washington until it gets done. Wanna go on vacation? No. Wanna campaign? No. Do your effing job first.

(at the request of J)

edit to add, since it’s sort of related: Where Drugs Come From: The Numbers

You cut government research dollars and you reduce university research, which is an important source of new drug treatments, especially novel ones.

Clang!

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Imagine, as I sometime ask, that you are doing an experiment which is very sensitive to external magnetic fields. (Like, oh, I don’t know, an atomic clock). And you find evidence of some stray field gremlin that has taken up residence. Since every previous time this has happened it has been the result of a thermoelectric current, you might be lulled into thinking that it’s the same thing, and fixing it will be a piece of cake. A colleague might even announce something to that effect: “It’s a current. It’s always a current. If there’s one thing you can depend on, it’s that stray fields are always currents.”

Welcome to the phenomenon of the sportscaster’s curse.

The sportscaster’s curse, in case you’re not familiar with it, is a phenomenon seen during sportscasts, in which the announcer will basically guarantee an outcome, which then dooms the effort to failure. The athlete is tagged as “Mister Automatic” in some way, with a mention of how he hasn’t missed a free throw/short putt/chip-shot field goal in X attempts, at which point the attempt clangs off the upright or rim, or lips out of the cup. (I’m sure a fair bit of confirmation bias is present here, since the curse doesn’t strike every time, but I cringe nonetheless if it’s a player on my team being lauded for his reliability)

So this is what happened. After we convinced ourselves that it was a simple problem and a quick fix, as happened earlier, we took all the steps to fix it. These steps include taking off the nested layers of magnetic shielding which make the fountain look like a Russian-doll hot-water heater. (or really just a water heater, because you don’t need to heat the water if it’s already hot)

(Such a device might look something like this)
rubidiumfountain

Nada. No obvious connections. We let it cool down to room temperature to minimize gradients and reassembled, but there was no change in the signal. OK, disassemble again and start checking for some magnetic component. But we’re looking for a milligauss-ish field, which isn’t going to be seen amidst the half a gauss of the earth’s field, so the only real way to do this systematically is to change one thing and reassemble it so we can look at the signal in a shielded environment.

 

We did that a lot over the past few days.

 

We finally decided that looking with a magnet might be a good idea — a strong one might stick to the offending component. There shouldn’t be any downside — the nonmagnetic materials aren’t going to become magnetized, and if there is a magnetic part, it will only change the scale of the already-existing problem. The latter is exactly what happened. The magnet didn’t stick to anything, but all of the sudden (after yet another reassembling and degaussing of the shields) the problem was much bigger — we had induced more magnetization, and that made it easier to find the offending component. Kinda like finding a needle in a haystack by being able to make the needle a lot bigger.

It was the salmon mousse a washer on a bolt in the vacuum system. Somehow a shiny stainless steel washer had successfully been hiding among the copper ones, and nobody noticed; it either had acquired a similar-looking tarnish, or because of the shininess it looked coppery when it was in the bin. In any event, transplant surgery was indicated and carried out successfully without a vacuum breach (which is good because losing vacuum would have sucked in all the wrong ways)

Uncommon Sense

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Pseudoscience, common sense, and the problem of scale

Fundamentally, this is a problem of scale. What is common sense? It is a body of knowledge derived from common experience. Even toddlers know that objects always fall down not up and objects that are out of sight still exist. These rudimentary scientific observations form the bedrock of common sense. But for something to be common sense, it must take place on a level we can appreciate with our senses. Simply put, common sense can only tell us about events that are common to human experience.